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[PATCH v5 4/5] Share fork_inferior et al with gdbserver


This is the most important (and the biggest, sorry) patch of the
series.  It moves fork_inferior from gdb/fork-child.c to
common/common-fork-child.c and makes all the necessary adjustments to
both GDB and gdbserver to make sure everything works OK.

There is no "most important change" with this patch; all changes are
made in a progressive way, making sure that gdbserver had the
necessary features while not breaking GDB at the same time.

I decided to go ahead and implement a partial support for starting the
inferior with a shell on gdbserver, although the full feature comes in
the next patch.  The user won't have the option to disable the
startup-with-shell, and also won't be able to change which shell
gdbserver will use (other than setting the $SHELL environment
variable, that is).

Everything is working as expected, and no regressions were present
during the tests.

gdb/ChangeLog:
yyyy-mm-dd  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add "common/common-fork-child.c".
	(HFILES_NO_SRCDIR): Add "common/common-inferior.h".
	(COMMON_OBS): Add "common-fork-child.o".
	* common-fork-child.c: New file, with the majority of
	"gdb/fork-child.c".
	* common/common-inferior.h: New file, with contents from
	"gdb/inferior.h".
	* commom/common-utils.c (stringify_argv): New function.
	* common/common-utils.h (gdb_flush_out_err): New prototype.
	(stringify_argv): Likewise.
	* corefile.c (get_exec_file): Update comment.
	* darwin-nat.c (darwin_ptrace_him): Call "gdb_startup_inferior"
	instead of "startup_inferior".
	* fork-child.c: Cleanup unnecessary includes.
	(SHELL_FILE): Move to "common/common-fork-child.c".
	(environ): Likewise.
	(exec_wrapper): Initialize.
	(get_exec_wrapper): New function.
	(breakup_args): Move to "common/common-fork-child.c"; rename to
	"breakup_args_for_exec".
	(escape_bang_in_quoted_argument): Move to
	"common/common-fork-child.c".
	(saved_ui): New variable.
	(prefork_hook): New function.
	(postfork_hook): Likewise.
	(postfork_child_hook): Likewise.
	(gdb_startup_inferior): Likewise.
	(fork_inferior): Move to "common/common-fork-child.c".  Update
	function to support gdbserver.
	(startup_inferior): Likewise.
	* gnu-nat.c (gnu_create_inferior): Call "gdb_startup_inferior"
	instead of "startup_inferior".
	* inf-ptrace.c (inf_ptrace_create_inferior): Likewise.
	* inferior.h: Include "common-inferior.h".
	(fork_inferior): Move prototype to "common-inferior.h".
	(startup_inferior): Likewise.
	(gdb_startup_inferior): New prototype.
	* procfs.c (procfs_init_inferior): Call "gdb_startup_inferior"
	instead of "startup_inferior".
	* target.h (target_terminal_init): Move prototype to
	"target/target.h".
	(target_terminal_inferior): Likewise.
	(target_terminal_ours): Likewise.
	* target/target.h (target_terminal_init): New prototype, moved
	from "target.h".
	(target_terminal_inferior): Likewise.
	(target_terminal_ours): Likewise.
	* utils.c (gdb_flush_out_err): New function.

gdb/gdbserver/ChangeLog:
yyyy-mm-dd  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add "common/common-fork-child.c".
	(OBS): Add common-fork-child.o.
	* linux-low.c: Include "common-inferior.h" and "environ.h".
	(linux_update_process): New function.
	(linux_add_process): Update comment.  Adjust function to call
	"linux_update_process".
	(update_thread_lwp): New function.
	(linux_ptrace_fun): Likewise.
	(linux_create_inferior): Adjust function prototype to reflect
	change on "target.h".  Adjust function code to use
	"fork_inferior".
	* lynx-low.c: Include "common-inferior.h".
	(lynx_update_process): New function.
	(lynx_add_process): Update comment.  Adjust function to call
	"lynx_update_process".
	(lynx_ptrace_fun): New function.
	(lynx_create_inferior): Adjust function prototype to reflect
	change on "target.h".  Adjust function code to use
	"fork_inferior".
	* nto-low.c (nto_create_inferior): Adjust function prototype and
	code to reflect change on "target.h".  Update comments.
	* server.c: Include "common-inferior.h", "common-terminal.h",
	"environ.h".
	(our_environ): New variable.
	(startup_with_shell): Likewise.
	(program_name): Likewise.
	(program_argv): Rename to...
	(program_args): ...this.
	(start_inferior): Delete function.
	(get_exec_wrapper): New function.
	(get_exec_file): Likewise.
	(get_environ): Likewise.
	(prefork_hook): Likewise.
	(post_fork_inferior): Likewise.
	(postfork_hook): Likewise.
	(postfork_child_hook): Likewise.
	(handle_v_run): Update code to deal with arguments coming from the
	remote host.  Update calls from "start_inferior" to
	"create_inferior".
	(captured_main): Likewise.  Initialize environment variable.  Call
	"have_job_control".
	* server.h: Include <vector>.
	(post_fork_inferior): New prototype.
	(get_environ): Likewise.
	* spu-low.c: Include "common-inferior.h".
	(spu_ptrace_fun): New function.
	(spu_create_inferior): Adjust function prototype to reflect change
	on "target.h".  Adjust function code to use "fork_inferior".
	* target.c (target_terminal_init): New function.
	(target_terminal_inferior): Likewise.
	(target_terminal_ours): Likewise.
	* target.h: Include <vector>.
	(struct target_ops) <create_inferior>: Update prototype.
	(create_inferior): Update macro.
	* utils.c (gdb_flush_out_err): New function.
	* utils.h: Include <vector>.
	(free_vector_argv): New prototype.
	* win32-low.c (win32_create_inferior): Adjust function prototype
	and code to reflect change on "target.h".

gdb/testsuite/ChangeLog:
2017-01-17  Sergio Durigan Junior  <sergiodj@redhat.com>

	* gdb.server/non-existing-program.exp: Update regex in order to
	reflect the fact that gdbserver is now using fork_inferior (with a
	shell) to startup the inferior.
---
 gdb/Makefile.in                                   |   3 +
 gdb/common/common-fork-child.c                    | 547 +++++++++++++++++++++
 gdb/common/common-inferior.h                      | 123 +++++
 gdb/common/common-utils.c                         |  20 +
 gdb/common/common-utils.h                         |   8 +
 gdb/corefile.c                                    |   4 +-
 gdb/darwin-nat.c                                  |   2 +-
 gdb/fork-child.c                                  | 550 +++-------------------
 gdb/gdbserver/Makefile.in                         |   2 +
 gdb/gdbserver/linux-low.c                         | 144 ++++--
 gdb/gdbserver/lynx-low.c                          |  80 ++--
 gdb/gdbserver/nto-low.c                           |  10 +-
 gdb/gdbserver/server.c                            | 257 +++++++---
 gdb/gdbserver/server.h                            |  10 +
 gdb/gdbserver/spu-low.c                           |  49 +-
 gdb/gdbserver/target.c                            |  24 +
 gdb/gdbserver/target.h                            |  13 +-
 gdb/gdbserver/utils.c                             |   9 +
 gdb/gdbserver/utils.h                             |   2 +
 gdb/gdbserver/win32-low.c                         |  22 +-
 gdb/gnu-nat.c                                     |   3 +-
 gdb/inf-ptrace.c                                  |   2 +-
 gdb/inferior.h                                    |  27 +-
 gdb/procfs.c                                      |   2 +-
 gdb/target.h                                      |  17 -
 gdb/target/target.h                               |  14 +
 gdb/testsuite/gdb.server/non-existing-program.exp |  12 +-
 gdb/utils.c                                       |   9 +
 28 files changed, 1233 insertions(+), 732 deletions(-)
 create mode 100644 gdb/common/common-fork-child.c
 create mode 100644 gdb/common/common-inferior.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index e5b0363..e24c66c 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1211,6 +1211,7 @@ SFILES = \
 	common/filestuff.c \
 	common/format.c \
 	common/job-control.c \
+	common/common-fork-child.c \
 	common/gdb_vecs.c \
 	common/new-op.c \
 	common/print-utils.c \
@@ -1498,6 +1499,7 @@ HFILES_NO_SRCDIR = \
 	common/gdb_sys_time.h \
 	common/gdb_vecs.h \
 	common/gdb_wait.h \
+	common/common-inferior.h \
 	common/host-defs.h \
 	common/print-utils.h \
 	common/ptid.h \
@@ -1641,6 +1643,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
 	common-debug.o \
 	common-exceptions.o \
 	job-control.o \
+	common-fork-child.o \
 	common-regcache.o \
 	common-utils.o \
 	complaints.o \
diff --git a/gdb/common/common-fork-child.c b/gdb/common/common-fork-child.c
new file mode 100644
index 0000000..64dbd0c
--- /dev/null
+++ b/gdb/common/common-fork-child.c
@@ -0,0 +1,547 @@
+/* Fork a Unix child process, and set up to debug it, for GDB and GDBserver.
+
+   Copyright (C) 1990-2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "common-defs.h"
+#include "target/waitstatus.h"
+#include "common-terminal.h"
+#include "filestuff.h"
+#include "target/target.h"
+#include "common-inferior.h"
+#include "common-gdbthread.h"
+#include "signals-state-save-restore.h"
+#include <vector>
+
+extern char **environ;
+
+/* Default shell file to be used if 'startup-with-shell' is set but
+   $SHELL is not.  */
+#define SHELL_FILE "/bin/sh"
+
+/* Break up SCRATCH into an argument vector suitable for passing to
+   execvp and store it in ARGV.  E.g., on "run a b c d" this routine
+   would get as input the string "a b c d", and as output it would
+   fill in ARGV with the four arguments "a", "b", "c", "d".  */
+
+static void
+breakup_args_for_exec (const std::string &scratch, std::vector<char *> &argv)
+{
+  for (size_t cur_pos = 0; cur_pos < scratch.size ();)
+    {
+      /* Skip whitespace-like chars.  */
+      std::size_t pos = scratch.find_first_not_of (" \t\n", cur_pos);
+
+      if (pos != std::string::npos)
+	cur_pos = pos;
+
+      /* Find the position of the next separator.  */
+      std::size_t next_sep = scratch.find_first_of (" \t\n", cur_pos);
+
+      /* No separator found, which means this is the last
+	 argument.  */
+      if (next_sep == std::string::npos)
+	next_sep = scratch.size ();
+
+      std::string arg = scratch.substr (cur_pos, next_sep - cur_pos);
+
+      argv.push_back (xstrdup (arg.c_str ()));
+
+      cur_pos = next_sep;
+    }
+
+  /* NULL-terminating the vector.  */
+  argv.push_back (NULL);
+}
+
+/* When executing a command under the given shell, return non-zero if
+   the '!' character should be escaped when embedded in a quoted
+   command-line argument.  */
+
+static int
+escape_bang_in_quoted_argument (const char *shell_file)
+{
+  const int shell_file_len = strlen (shell_file);
+
+  /* Bang should be escaped only in C Shells.  For now, simply check
+     that the shell name ends with 'csh', which covers at least csh
+     and tcsh.  This should be good enough for now.  */
+
+  if (shell_file_len < 3)
+    return 0;
+
+  if (shell_file[shell_file_len - 3] == 'c'
+      && shell_file[shell_file_len - 2] == 's'
+      && shell_file[shell_file_len - 1] == 'h')
+    return 1;
+
+  return 0;
+}
+
+/* See common/common-inferior.h.  */
+
+char *
+get_startup_shell (void)
+{
+  static char *ret;
+
+  ret = getenv ("SHELL");
+  if (ret == NULL)
+    ret = SHELL_FILE;
+
+  return ret;
+}
+
+/* Quote the shell command that will be executed.  This function is
+   called when the inferior is going to be executed under a shell
+   (i.e., when 'startup-with-shell' is set).
+
+   SHELL_FILE is the shell which will be used to execute the inferior
+   (e.g., /bin/sh).
+
+   EXEC_FILE is the inferior executable itself.
+
+   ALLARGS contains all the arguments that will be passed to the
+   inferior.
+
+   EXEC_WRAPPER, if set, is the wrapper that will be used to execute
+   the inferior.
+
+   SHELL_CMD is a pointer to the resulting shell command that will be
+   executed.  The resulting shell command will be returned in it.  It
+   must be pre-allocated and have a reasonable size.  For an example
+   on how to determine its size, see 'fork_inferior' on
+   fork-child.c.  */
+
+static std::string
+quote_shell_command (const char *shell_file, const char *exec_file,
+		     const std::string &allargs, const char *exec_wrapper)
+{
+  std::string shell_command;
+  const char *p;
+  int need_to_quote;
+  const int escape_bang = escape_bang_in_quoted_argument (shell_file);
+
+  shell_command = std::string ("exec ");
+
+  /* Add any exec wrapper.  That may be a program name with arguments, so
+     the user must handle quoting.  */
+  if (exec_wrapper)
+    {
+      shell_command += exec_wrapper;
+      shell_command += " ";
+    }
+
+  /* Now add exec_file, quoting as necessary.  */
+
+  fprintf (stderr, "exec_file = %s\n", exec_file);
+  /* Quoting in this style is said to work with all shells.  But
+     csh on IRIX 4.0.1 can't deal with it.  So we only quote it if
+     we need to.  */
+  p = exec_file;
+  while (1)
+    {
+      switch (*p)
+	{
+	case '\'':
+	case '!':
+	case '"':
+	case '(':
+	case ')':
+	case '$':
+	case '&':
+	case ';':
+	case '<':
+	case '>':
+	case ' ':
+	case '\n':
+	case '\t':
+	  need_to_quote = 1;
+	  goto end_scan;
+
+	case '\0':
+	  need_to_quote = 0;
+	  goto end_scan;
+
+	default:
+	  break;
+	}
+      ++p;
+    }
+ end_scan:
+  if (need_to_quote)
+    {
+      shell_command += "'";
+      for (p = exec_file; *p != '\0'; ++p)
+	{
+	  if (*p == '\'')
+	    shell_command += "'\\''";
+	  else if (*p == '!' && escape_bang)
+	    shell_command += "\\!";
+	  else
+	    shell_command += *p;
+	}
+      shell_command += "'";
+    }
+  else
+    shell_command += exec_file;
+
+  shell_command += " " + allargs;
+
+  return shell_command;
+}
+
+/* See common/common-inferior.h.  */
+
+void
+trace_start_error (const char *fmt, ...)
+{
+  va_list ap;
+
+  va_start (ap, fmt);
+  warning ("Could not trace the inferior process.\nError: ");
+  vwarning (fmt, ap);
+  va_end (ap);
+
+  gdb_flush_out_err ();
+  _exit (0177);
+}
+
+/* See common/common-inferior.h.  */
+
+void
+trace_start_error_with_name (const char *string)
+{
+  trace_start_error ("%s: %s", string, safe_strerror (errno));
+}
+
+/* See common/common-inferior.h.  */
+
+int
+fork_inferior (const char *exec_file_arg, const std::string &allargs,
+	       char **env, void (*traceme_fun) (void),
+	       void (*init_trace_fun) (int), void (*pre_trace_fun) (void),
+	       char *shell_file_arg,
+               void (*exec_fun)(const char *file, char * const *argv,
+                                char * const *env))
+{
+  int pid;
+  /* Set debug_fork then attach to the child while it sleeps, to debug.  */
+  static int debug_fork = 0;
+  static char *shell_file;
+  static const char *exec_file;
+  char **save_our_env;
+  int shell = 0;
+  std::vector<char *> argv;
+  int i;
+  int save_errno;
+
+  /* If no exec file handed to us, get it from the exec-file command
+     -- with a good, common error message if none is specified.  */
+  if (exec_file_arg == NULL)
+    exec_file = get_exec_file (1);
+  else
+    exec_file = exec_file_arg;
+
+  /* 'startup_with_shell' is declared in inferior.h and bound to the
+     "set startup-with-shell" option.  If 0, we'll just do a
+     fork/exec, no shell, so don't bother figuring out what shell.  */
+  shell_file = shell_file_arg;
+  if (startup_with_shell)
+    {
+      /* Figure out what shell to start up the user program under.  */
+      if (shell_file == NULL)
+	shell_file = get_startup_shell ();
+
+      gdb_assert (shell_file != NULL);
+      shell = 1;
+    }
+
+  if (!shell)
+    {
+      /* We're going to call execvp.  Create argument vector.  */
+      argv.push_back (xstrdup (exec_file));
+      breakup_args_for_exec (allargs, argv);
+    }
+  else
+    {
+      /* We're going to call a shell.  */
+      std::string shell_command;
+      const char *exec_wrapper = get_exec_wrapper ();
+      size_t len;
+
+      shell_command = quote_shell_command (shell_file, exec_file,
+					   allargs, exec_wrapper);
+
+      /* If we decided above to start up with a shell, we exec the
+	 shell, "-c" says to interpret the next arg as a shell command
+	 to execute, and this command is "exec <target-program>
+	 <args>".  We xstrdup all the strings here because they will
+	 be free'd later in the code.  */
+      argv.push_back (xstrdup (shell_file));
+      argv.push_back (xstrdup ("-c"));
+      argv.push_back (xstrdup (shell_command.c_str ()));
+      argv.push_back (NULL);
+    }
+
+  /* Retain a copy of our environment variables, since the child will
+     replace the value of environ and if we're vforked, we have to
+     restore it.  */
+  save_our_env = environ;
+
+  /* Perform any necessary actions regarding to TTY before the
+     fork/vfork call.  */
+  prefork_hook (allargs.c_str ());
+
+  /* It is generally good practice to flush any possible pending stdio
+     output prior to doing a fork, to avoid the possibility of both
+     the parent and child flushing the same data after the fork.  */
+  gdb_flush_out_err ();
+
+  /* If there's any initialization of the target layers that must
+     happen to prepare to handle the child we're about fork, do it
+     now...  */
+  if (pre_trace_fun != NULL)
+    (*pre_trace_fun) ();
+
+  /* Create the child process.  Since the child process is going to
+     exec(3) shortly afterwards, try to reduce the overhead by
+     calling vfork(2).  However, if PRE_TRACE_FUN is non-null, it's
+     likely that this optimization won't work since there's too much
+     work to do between the vfork(2) and the exec(3).  This is known
+     to be the case on ttrace(2)-based HP-UX, where some handshaking
+     between parent and child needs to happen between fork(2) and
+     exec(2).  However, since the parent is suspended in the vforked
+     state, this doesn't work.  Also note that the vfork(2) call might
+     actually be a call to fork(2) due to the fact that autoconf will
+     ``#define vfork fork'' on certain platforms.  */
+  if (pre_trace_fun || debug_fork)
+    pid = fork ();
+  else
+    pid = vfork ();
+
+  if (pid < 0)
+    perror_with_name (("vfork"));
+
+  if (pid == 0)
+    {
+      /* Execute any necessary post-fork actions before we exec.  */
+      postfork_child_hook (debug_fork);
+
+      /* Changing the signal handlers for the inferior after
+         a vfork can also change them for the superior, so we don't mess
+         with signals here.  See comments in
+         initialize_signals for how we get the right signal handlers
+         for the inferior.  */
+
+      /* "Trace me, Dr. Memory!"  */
+      (*traceme_fun) ();
+
+      /* The call above set this process (the "child") as debuggable
+        by the original gdb process (the "parent").  Since processes
+        (unlike people) can have only one parent, if you are debugging
+        gdb itself (and your debugger is thus _already_ the
+        controller/parent for this child), code from here on out is
+        undebuggable.  Indeed, you probably got an error message
+        saying "not parent".  Sorry; you'll have to use print
+        statements!  */
+
+      restore_original_signals_state ();
+
+      /* There is no execlpe call, so we have to set the environment
+         for our child in the global variable.  If we've vforked, this
+         clobbers the parent, but environ is restored a few lines down
+         in the parent.  By the way, yes we do need to look down the
+         path to find $SHELL.  Rich Pixley says so, and I agree.  */
+      environ = env;
+
+      if (exec_fun != NULL)
+        (*exec_fun) (argv[0], &argv[0], env);
+      else
+        execvp (argv[0], &argv[0]);
+
+      /* If we get here, it's an error.  */
+      save_errno = errno;
+      warning ("Cannot exec %s", argv[0]);
+
+      for (i = 1; argv[i] != NULL; i++)
+	warning (" %s", argv[i]);
+
+      warning ("Error: %s\n", safe_strerror (save_errno));
+
+      _exit (0177);
+    }
+
+  for (char *el : argv)
+    {
+      /* Free the strings allocated on ARGV.  */
+      xfree (el);
+    }
+
+  /* Restore our environment in case a vforked child clob'd it.  */
+  environ = save_our_env;
+
+  postfork_hook (pid);
+
+  /* We have something that executes now.  We'll be running through
+     the shell at this point, but the pid shouldn't change.  Targets
+     supporting MT should fill this task's ptid with more data as soon
+     as they can.  */
+  add_thread_silent (pid_to_ptid (pid));
+
+  /* Now that we have a child process, make it our target, and
+     initialize anything target-vector-specific that needs
+     initializing.  */
+  if (init_trace_fun)
+    (*init_trace_fun) (pid);
+
+  /* We are now in the child process of interest, having exec'd the
+     correct program, and are poised at the first instruction of the
+     new program.  */
+  return pid;
+}
+
+/* See common/common-inferior.h.  */
+
+ptid_t
+startup_inferior (pid_t pid, int ntraps,
+		  struct target_waitstatus *last_waitstatus,
+		  ptid_t *last_ptid)
+{
+  int pending_execs = ntraps;
+  int terminal_initted = 0;
+  ptid_t resume_ptid;
+
+  if (startup_with_shell)
+    {
+      /* One trap extra for exec'ing the shell.  */
+      pending_execs++;
+    }
+
+  if (target_supports_multi_process ())
+    resume_ptid = pid_to_ptid (pid);
+  else
+    resume_ptid = minus_one_ptid;
+
+  /* The process was started by the fork that created it, but it will
+     have stopped one instruction after execing the shell.  Here we
+     must get it up to actual execution of the real program.  */
+  if (get_exec_wrapper () != NULL)
+    pending_execs++;
+
+  while (1)
+    {
+      enum gdb_signal resume_signal = GDB_SIGNAL_0;
+      ptid_t event_ptid;
+
+      struct target_waitstatus ws;
+      memset (&ws, 0, sizeof (ws));
+      event_ptid = target_wait (resume_ptid, &ws, 0);
+
+      if (last_waitstatus != NULL)
+	*last_waitstatus = ws;
+      if (last_ptid != NULL)
+	*last_ptid = event_ptid;
+
+      if (ws.kind == TARGET_WAITKIND_IGNORE)
+	/* The inferior didn't really stop, keep waiting.  */
+	continue;
+
+      switch (ws.kind)
+	{
+	  case TARGET_WAITKIND_SPURIOUS:
+	  case TARGET_WAITKIND_LOADED:
+	  case TARGET_WAITKIND_FORKED:
+	  case TARGET_WAITKIND_VFORKED:
+	  case TARGET_WAITKIND_SYSCALL_ENTRY:
+	  case TARGET_WAITKIND_SYSCALL_RETURN:
+	  case TARGET_WAITKIND_VFORK_DONE:
+	  case TARGET_WAITKIND_IGNORE:
+	  case TARGET_WAITKIND_NO_HISTORY:
+	  case TARGET_WAITKIND_NO_RESUMED:
+	  case TARGET_WAITKIND_THREAD_CREATED:
+	  case TARGET_WAITKIND_THREAD_EXITED:
+	    /* Ignore gracefully during startup of the inferior.  */
+	    switch_to_thread (event_ptid);
+	    break;
+
+	  case TARGET_WAITKIND_SIGNALLED:
+	    target_terminal_ours ();
+	    target_mourn_inferior (event_ptid);
+	    error (_("During startup program terminated with signal %s, %s."),
+		   gdb_signal_to_name (ws.value.sig),
+		   gdb_signal_to_string (ws.value.sig));
+	    return resume_ptid;
+
+	  case TARGET_WAITKIND_EXITED:
+	    target_terminal_ours ();
+	    target_mourn_inferior (event_ptid);
+	    if (ws.value.integer)
+	      error (_("During startup program exited with code %d."),
+		     ws.value.integer);
+	    else
+	      error (_("During startup program exited normally."));
+	    return resume_ptid;
+
+	  case TARGET_WAITKIND_EXECD:
+	    /* Handle EXEC signals as if they were SIGTRAP signals.  */
+	    xfree (ws.value.execd_pathname);
+	    resume_signal = GDB_SIGNAL_TRAP;
+	    switch_to_thread (event_ptid);
+	    break;
+
+	  case TARGET_WAITKIND_STOPPED:
+	    resume_signal = ws.value.sig;
+	    switch_to_thread (event_ptid);
+	    break;
+	}
+
+      if (resume_signal != GDB_SIGNAL_TRAP)
+	{
+	  /* Let shell child handle its own signals in its own way.  */
+	  target_continue (resume_ptid, resume_signal);
+	}
+      else
+	{
+	  /* We handle SIGTRAP, however; it means child did an exec.  */
+	  if (!terminal_initted)
+	    {
+	      /* Now that the child has exec'd we know it has already
+	         set its process group.  On POSIX systems, tcsetpgrp
+	         will fail with EPERM if we try it before the child's
+	         setpgid.  */
+
+	      /* Set up the "saved terminal modes" of the inferior
+	         based on what modes we are starting it with.  */
+	      target_terminal_init ();
+
+	      /* Install inferior's terminal modes.  */
+	      target_terminal_inferior ();
+
+	      terminal_initted = 1;
+	    }
+
+	  if (--pending_execs == 0)
+	    break;
+
+	  /* Just make it go on.  */
+	  target_continue_no_signal (resume_ptid);
+	}
+    }
+
+  return resume_ptid;
+}
diff --git a/gdb/common/common-inferior.h b/gdb/common/common-inferior.h
new file mode 100644
index 0000000..239cab4
--- /dev/null
+++ b/gdb/common/common-inferior.h
@@ -0,0 +1,123 @@
+/* Variables that describe the inferior process running under GDB and
+   GDBserver: Where it is, why it stopped, and how to step it.
+
+   Copyright (C) 1986-2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef COMMON_INFERIOR_H
+#define COMMON_INFERIOR_H
+
+#include <vector>
+
+/* Number of traps that happen between exec'ing the shell to run an
+   inferior and when we finally get to the inferior code, not counting
+   the exec for the shell.  This is 1 on all supported
+   implementations.  */
+#define START_INFERIOR_TRAPS_EXPECTED 1
+
+struct inferior;
+
+/* Whether to start up the debuggee under a shell.
+
+   If startup-with-shell is set, GDB's "run" will attempt to start up
+   the debuggee under a shell.  This also happens when using GDBserver
+   under extended remote mode.
+
+   This is in order for argument-expansion to occur.  E.g.,
+
+   (gdb) run *
+
+   The "*" gets expanded by the shell into a list of files.
+
+   While this is a nice feature, it may be handy to bypass the shell
+   in some cases.  To disable this feature, do "set startup-with-shell
+   false".
+
+   The catch-exec traps expected during start-up will be one more if
+   the target is started up with a shell.  */
+extern int startup_with_shell;
+
+/* Report an error that happened when starting to trace the inferior
+   (i.e., when the "traceme_fun" callback is called on fork_inferior)
+   and bail out.  This function does not return.  */
+
+extern void trace_start_error (const char *fmt, ...)
+  ATTRIBUTE_NORETURN;
+
+/* Like "trace_start_error", but the error message is constructed by
+   combining STRING with the system error message for errno.  This
+   function does not return.  */
+
+extern void trace_start_error_with_name (const char *string)
+  ATTRIBUTE_NORETURN;
+
+/* Accept NTRAPS traps from the inferior.
+
+   Return the ptid of the inferior being started.  */
+extern ptid_t startup_inferior (pid_t pid, int ntraps,
+				struct target_waitstatus *mystatus,
+				ptid_t *myptid);
+
+/* Start an inferior Unix child process and sets inferior_ptid to its
+   pid.  EXEC_FILE is the file to run.  ALLARGS is a string containing
+   the arguments to the program.  ENV is the environment vector to
+   pass.  SHELL_FILE is the shell file, or NULL if we should pick
+   one.  EXEC_FUN is the exec(2) function to use, or NULL for the default
+   one.  */
+
+/* This function is NOT reentrant.  Some of the variables have been
+   made static to ensure that they survive the vfork call.  */
+extern int fork_inferior (const char *exec_file_arg,
+			  const std::string &allargs,
+			  char **env, void (*traceme_fun) (void),
+			  void (*init_trace_fun) (int),
+			  void (*pre_trace_fun) (void), char *shell_file_arg,
+			  void (*exec_fun) (const char *file,
+					    char * const *argv,
+					    char * const *env));
+
+/* Perform any necessary tasks before a fork/vfork takes place.  ARGS
+   is a string containing all the arguments received by the inferior.
+   This function is mainly used by fork_inferior.  */
+extern void prefork_hook (const char *args);
+
+/* Perform any necessary tasks after a fork/vfork takes place.  This
+   function is mainly used by fork_inferior.  */
+extern void postfork_hook (pid_t pid);
+
+/* Perform any necessary tasks *on the child* after a fork/vfork takes
+   place.  DEBUG_FORK is the number of seconds that we should sleep
+   before exec'ing (see fork_inferior).
+
+   This function is mainly used by fork_inferior.  */
+extern void postfork_child_hook (int debug_fork);
+
+/* Return the shell that must be used to startup the inferior.  The
+   first attempt is the environment variable SHELL; if it is not set,
+   then we default to SHELL_FILE.  */
+extern char *get_startup_shell (void);
+
+/* Return the exec wrapper to be used when starting the inferior, or NULL
+   otherwise.  */
+extern const char *get_exec_wrapper (void);
+
+/* Return the name of the executable file as a string.
+   ERR nonzero means get error if there is none specified;
+   otherwise return 0 in that case.  */
+extern char *get_exec_file (int err);
+
+#endif /* ! COMMON_INFERIOR_H */
diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c
index e94fdc4..6682c51 100644
--- a/gdb/common/common-utils.c
+++ b/gdb/common/common-utils.c
@@ -328,3 +328,23 @@ free_vector_argv (std::vector<char *> &v)
 
   v.clear ();
 }
+
+/* See common/common-utils.h.  */
+
+std::string
+stringify_argv (const std::vector<char *> &args)
+{
+  std::string ret ("");
+
+  if (!args.empty ())
+    {
+      for (auto s : args)
+	if (s != NULL)
+	  ret += s + std::string (" ");
+
+      /* Erase the last whitespace.  */
+      ret.erase (ret.end () - 1);
+    }
+
+  return ret;
+}
diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h
index c331f0d..934d207 100644
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@@ -108,4 +108,12 @@ extern const char *skip_to_space_const (const char *inp);
    freeing all the elements.  */
 extern void free_vector_argv (std::vector<char *> &v);
 
+/* Given a vector of arguments ARGV, return a string equivalent to
+   joining all the arguments with a whitespace separating them.  */
+extern std::string stringify_argv (const std::vector<char *> &argv);
+
+/* Flush both stdout and stderr.  This function needs to be
+   implemented differently on GDB and GDBserver.  */
+extern void gdb_flush_out_err (void);
+
 #endif
diff --git a/gdb/corefile.c b/gdb/corefile.c
index 54cb789..d76fa1a 100644
--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -170,9 +170,7 @@ validate_files (void)
     }
 }
 
-/* Return the name of the executable file as a string.
-   ERR nonzero means get error if there is none specified;
-   otherwise return 0 in that case.  */
+/* See common/common-inferior.h.  */
 
 char *
 get_exec_file (int err)
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index 47ec922..2d80ad5 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -1790,7 +1790,7 @@ darwin_ptrace_him (int pid)
 
   darwin_init_thread_list (inf);
 
-  startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
+  gdb_startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED);
 }
 
 static void
diff --git a/gdb/fork-child.c b/gdb/fork-child.c
index e586c3e..e111fad 100644
--- a/gdb/fork-child.c
+++ b/gdb/fork-child.c
@@ -21,386 +21,52 @@
 
 #include "defs.h"
 #include "inferior.h"
+#include "gdbcmd.h"
 #include "terminal.h"
-#include "target.h"
-#include "gdb_wait.h"
-#include "gdb_vfork.h"
-#include "gdbcore.h"
 #include "gdbthread.h"
-#include "command.h" /* for dont_repeat () */
-#include "gdbcmd.h"
-#include "solib.h"
-#include "filestuff.h"
 #include "top.h"
-#include "signals-state-save-restore.h"
-#include <signal.h>
-#include <vector>
-
-/* This just gets used as a default if we can't find SHELL.  */
-#define SHELL_FILE "/bin/sh"
+#include "filestuff.h"
 
-extern char **environ;
+/* The exec-wrapper, if any, that will be used when starting the
+   inferior.  */
 
-static char *exec_wrapper;
+static char *exec_wrapper = NULL;
 
-/* Break up SCRATCH into an argument vector suitable for passing to
-   execvp and store it in ARGV.  E.g., on "run a b c d" this routine
-   would get as input the string "a b c d", and as output it would
-   fill in ARGV with the four arguments "a", "b", "c", "d".  */
+/* See common/common-inferior.h.  */
 
-static void
-breakup_args (const std::string &scratch, std::vector<char *> &argv)
+const char *
+get_exec_wrapper (void)
 {
-  for (size_t cur_pos = 0; cur_pos < scratch.size ();)
-    {
-      /* Skip whitespace-like chars.  */
-      std::size_t pos = scratch.find_first_not_of (" \t\n", cur_pos);
-
-      if (pos != std::string::npos)
-	cur_pos = pos;
-
-      /* Find the position of the next separator.  */
-      std::size_t next_sep = scratch.find_first_of (" \t\n", cur_pos);
-
-      /* No separator found, which means this is the last
-	 argument.  */
-      if (next_sep == std::string::npos)
-	next_sep = scratch.size ();
-
-      std::string arg = scratch.substr (cur_pos, next_sep - cur_pos);
-
-      argv.push_back (xstrdup (arg.c_str ()));
-
-      cur_pos = next_sep;
-    }
-
-  /* NULL-terminating the vector.  */
-  argv.push_back (NULL);
+  return exec_wrapper;
 }
 
-/* When executing a command under the given shell, return non-zero if
-   the '!' character should be escaped when embedded in a quoted
-   command-line argument.  */
-
-static int
-escape_bang_in_quoted_argument (const char *shell_file)
-{
-  const int shell_file_len = strlen (shell_file);
+/* The ui structure that will be saved on 'prefork_hook' and
+   restored on 'postfork_hook'.  */
+static struct ui *saved_ui = NULL;
 
-  /* Bang should be escaped only in C Shells.  For now, simply check
-     that the shell name ends with 'csh', which covers at least csh
-     and tcsh.  This should be good enough for now.  */
-
-  if (shell_file_len < 3)
-    return 0;
-
-  if (shell_file[shell_file_len - 3] == 'c'
-      && shell_file[shell_file_len - 2] == 's'
-      && shell_file[shell_file_len - 1] == 'h')
-    return 1;
-
-  return 0;
-}
-
-/* See inferior.h.  */
-
-void
-trace_start_error (const char *fmt, ...)
-{
-  va_list ap;
-
-  va_start (ap, fmt);
-  fprintf_unfiltered (gdb_stderr, "Could not trace the inferior "
-		                  "process.\nError: ");
-  vfprintf_unfiltered (gdb_stderr, fmt, ap);
-  va_end (ap);
-
-  gdb_flush (gdb_stderr);
-  _exit (0177);
-}
-
-/* See inferior.h.  */
+/* See common/common-inferior.h.  */
 
 void
-trace_start_error_with_name (const char *string)
+prefork_hook (const char *args)
 {
-  trace_start_error ("%s: %s", string, safe_strerror (errno));
-}
-
-/* Start an inferior Unix child process and sets inferior_ptid to its
-   pid.  EXEC_FILE is the file to run.  ALLARGS is a string containing
-   the arguments to the program.  ENV is the environment vector to
-   pass.  SHELL_FILE is the shell file, or NULL if we should pick
-   one.  EXEC_FUN is the exec(2) function to use, or NULL for the default
-   one.  */
-
-/* This function is NOT reentrant.  Some of the variables have been
-   made static to ensure that they survive the vfork call.  */
-
-int
-fork_inferior (const char *exec_file_arg, const std::string &allargs,
-	       char **env, void (*traceme_fun) (void),
-	       void (*init_trace_fun) (int), void (*pre_trace_fun) (void),
-	       char *shell_file_arg,
-               void (*exec_fun)(const char *file, char * const *argv,
-                                char * const *env))
-{
-  int pid;
-  static char default_shell_file[] = SHELL_FILE;
-  /* Set debug_fork then attach to the child while it sleeps, to debug.  */
-  static int debug_fork = 0;
-  /* This is set to the result of setpgrp, which if vforked, will be visible
-     to you in the parent process.  It's only used by humans for debugging.  */
-  static int debug_setpgrp = 657473;
-  static char *shell_file;
-  static const char *exec_file;
-  char **save_our_env;
-  int shell = 0;
-  std::vector<char *> argv;
   const char *inferior_io_terminal = get_inferior_io_terminal ();
-  struct inferior *inf;
-  int i;
-  int save_errno;
-  struct ui *save_ui;
-
-  /* If no exec file handed to us, get it from the exec-file command
-     -- with a good, common error message if none is specified.  */
-  if (exec_file_arg == NULL)
-    exec_file = get_exec_file (1);
-  else
-    exec_file = exec_file_arg;
-
-  /* 'startup_with_shell' is declared in inferior.h and bound to the
-     "set startup-with-shell" option.  If 0, we'll just do a
-     fork/exec, no shell, so don't bother figuring out what shell.  */
-  shell_file = shell_file_arg;
-  if (startup_with_shell)
-    {
-      /* Figure out what shell to start up the user program under.  */
-      if (shell_file == NULL)
-	shell_file = getenv ("SHELL");
-      if (shell_file == NULL)
-	shell_file = default_shell_file;
-      shell = 1;
-    }
-
-  if (!shell)
-    {
-      /* We're going to call execvp.  Create argument vector.  */
-      argv.push_back (xstrdup (exec_file));
-      breakup_args (allargs, argv);
-    }
-  else
-    {
-      /* We're going to call a shell.  */
-      std::string shell_command;
-      const char *p;
-      int need_to_quote;
-      const int escape_bang = escape_bang_in_quoted_argument (shell_file);
-
-      shell_command = std::string ("exec ");
-
-      /* Add any exec wrapper.  That may be a program name with arguments, so
-	 the user must handle quoting.  */
-      if (exec_wrapper)
-	{
-	  shell_command += exec_wrapper;
-	  shell_command += " ";
-	}
-
-      /* Now add exec_file, quoting as necessary.  */
-
-      /* Quoting in this style is said to work with all shells.  But
-         csh on IRIX 4.0.1 can't deal with it.  So we only quote it if
-         we need to.  */
-      p = exec_file;
-      while (1)
-	{
-	  switch (*p)
-	    {
-	    case '\'':
-	    case '!':
-	    case '"':
-	    case '(':
-	    case ')':
-	    case '$':
-	    case '&':
-	    case ';':
-	    case '<':
-	    case '>':
-	    case ' ':
-	    case '\n':
-	    case '\t':
-	      need_to_quote = 1;
-	      goto end_scan;
-
-	    case '\0':
-	      need_to_quote = 0;
-	      goto end_scan;
-
-	    default:
-	      break;
-	    }
-	  ++p;
-	}
-    end_scan:
-      if (need_to_quote)
-	{
-	  shell_command += "'";
-	  for (p = exec_file; *p != '\0'; ++p)
-	    {
-	      if (*p == '\'')
-		shell_command += "'\\''";
-	      else if (*p == '!' && escape_bang)
-		shell_command += "\\!";
-	      else
-		shell_command += *p;
-	    }
-	  shell_command += "'";
-	}
-      else
-	shell_command += exec_file;
-
-      shell_command += " " + allargs;
-
-      /* If we decided above to start up with a shell, we exec the
-	 shell, "-c" says to interpret the next arg as a shell command
-	 to execute, and this command is "exec <target-program>
-	 <args>".  We xstrdup all the strings here because they will
-	 be free'd later in the code.  */
-      argv.push_back (xstrdup (shell_file));
-      argv.push_back (xstrdup ("-c"));
-      argv.push_back (xstrdup (shell_command.c_str ()));
-      argv.push_back (NULL);
-    }
 
-  /* Retain a copy of our environment variables, since the child will
-     replace the value of environ and if we're vforked, we have to
-     restore it.  */
-  save_our_env = environ;
-
-  /* Likewise the current UI.  */
-  save_ui = current_ui;
+  gdb_assert (saved_ui == NULL);
+  /* Retain a copy of our UI, since the child will replace this value
+     and if we're vforked, we have to restore it.  */
+  saved_ui = current_ui;
 
   /* Tell the terminal handling subsystem what tty we plan to run on;
      it will just record the information for later.  */
   new_tty_prefork (inferior_io_terminal);
+}
 
-  /* It is generally good practice to flush any possible pending stdio
-     output prior to doing a fork, to avoid the possibility of both
-     the parent and child flushing the same data after the fork.  */
-  gdb_flush (main_ui->m_gdb_stdout);
-  gdb_flush (main_ui->m_gdb_stderr);
-
-  /* If there's any initialization of the target layers that must
-     happen to prepare to handle the child we're about fork, do it
-     now...  */
-  if (pre_trace_fun != NULL)
-    (*pre_trace_fun) ();
-
-  /* Create the child process.  Since the child process is going to
-     exec(3) shortly afterwards, try to reduce the overhead by
-     calling vfork(2).  However, if PRE_TRACE_FUN is non-null, it's
-     likely that this optimization won't work since there's too much
-     work to do between the vfork(2) and the exec(3).  This is known
-     to be the case on ttrace(2)-based HP-UX, where some handshaking
-     between parent and child needs to happen between fork(2) and
-     exec(2).  However, since the parent is suspended in the vforked
-     state, this doesn't work.  Also note that the vfork(2) call might
-     actually be a call to fork(2) due to the fact that autoconf will
-     ``#define vfork fork'' on certain platforms.  */
-  if (pre_trace_fun || debug_fork)
-    pid = fork ();
-  else
-    pid = vfork ();
-
-  if (pid < 0)
-    perror_with_name (("vfork"));
-
-  if (pid == 0)
-    {
-      /* Switch to the main UI, so that gdb_std{in/out/err} in the
-	 child are mapped to std{in/out/err}.  This makes it possible
-	 to use fprintf_unfiltered/warning/error/etc. in the child
-	 from here on.  */
-      current_ui = main_ui;
-
-      /* Close all file descriptors except those that gdb inherited
-	 (usually 0/1/2), so they don't leak to the inferior.  Note
-	 that this closes the file descriptors of all secondary
-	 UIs.  */
-      close_most_fds ();
-
-      if (debug_fork)
-	sleep (debug_fork);
-
-      /* Create a new session for the inferior process, if necessary.
-         It will also place the inferior in a separate process group.  */
-      if (create_tty_session () <= 0)
-	{
-	  /* No session was created, but we still want to run the inferior
-	     in a separate process group.  */
-	  debug_setpgrp = gdb_setpgid ();
-	  if (debug_setpgrp == -1)
-	    perror (_("setpgrp failed in child"));
-	}
-
-      /* Ask the tty subsystem to switch to the one we specified
-         earlier (or to share the current terminal, if none was
-         specified).  */
-      new_tty ();
-
-      /* Changing the signal handlers for the inferior after
-         a vfork can also change them for the superior, so we don't mess
-         with signals here.  See comments in
-         initialize_signals for how we get the right signal handlers
-         for the inferior.  */
-
-      /* "Trace me, Dr. Memory!"  */
-      (*traceme_fun) ();
-
-      /* The call above set this process (the "child") as debuggable
-        by the original gdb process (the "parent").  Since processes
-        (unlike people) can have only one parent, if you are debugging
-        gdb itself (and your debugger is thus _already_ the
-        controller/parent for this child), code from here on out is
-        undebuggable.  Indeed, you probably got an error message
-        saying "not parent".  Sorry; you'll have to use print
-        statements!  */
-
-      restore_original_signals_state ();
-
-      /* There is no execlpe call, so we have to set the environment
-         for our child in the global variable.  If we've vforked, this
-         clobbers the parent, but environ is restored a few lines down
-         in the parent.  By the way, yes we do need to look down the
-         path to find $SHELL.  Rich Pixley says so, and I agree.  */
-      environ = env;
-
-      if (exec_fun != NULL)
-        (*exec_fun) (argv[0], &argv[0], env);
-      else
-        execvp (argv[0], &argv[0]);
-
-      /* If we get here, it's an error.  */
-      save_errno = errno;
-      fprintf_unfiltered (gdb_stderr, "Cannot exec %s", argv[0]);
-      for (i = 1; argv[i] != NULL; i++)
-	fprintf_unfiltered (gdb_stderr, " %s", argv[i]);
-      fprintf_unfiltered (gdb_stderr, ".\n");
-      fprintf_unfiltered (gdb_stderr, "Error: %s\n",
-			  safe_strerror (save_errno));
-      gdb_flush (gdb_stderr);
-      _exit (0177);
-    }
-
-  free_vector_argv (argv);
-
-  /* Restore our environment in case a vforked child clob'd it.  */
-  environ = save_our_env;
+/* See common/common-inferior.h.  */
 
-  /* Likewise the current UI.  */
-  current_ui = save_ui;
+void
+postfork_hook (pid_t pid)
+{
+  struct inferior *inf;
 
   if (!have_inferiors ())
     init_thread_list ();
@@ -412,144 +78,64 @@ fork_inferior (const char *exec_file_arg, const std::string &allargs,
   /* Needed for wait_for_inferior stuff below.  */
   inferior_ptid = pid_to_ptid (pid);
 
-  new_tty_postfork ();
+  gdb_assert (saved_ui != NULL);
+  current_ui = saved_ui;
+  saved_ui = NULL;
 
-  /* We have something that executes now.  We'll be running through
-     the shell at this point, but the pid shouldn't change.  Targets
-     supporting MT should fill this task's ptid with more data as soon
-     as they can.  */
-  add_thread_silent (inferior_ptid);
-
-  /* Now that we have a child process, make it our target, and
-     initialize anything target-vector-specific that needs
-     initializing.  */
-  if (init_trace_fun)
-    (*init_trace_fun) (pid);
-
-  /* We are now in the child process of interest, having exec'd the
-     correct program, and are poised at the first instruction of the
-     new program.  */
-  return pid;
+  new_tty_postfork ();
 }
 
-/* Accept NTRAPS traps from the inferior.  */
+/* See common/common-inferior.h.  */
 
 void
-startup_inferior (int ntraps)
+postfork_child_hook (int debug_fork)
 {
-  int pending_execs = ntraps;
-  int terminal_initted = 0;
-  ptid_t resume_ptid;
-
-  if (startup_with_shell)
-    {
-      /* One trap extra for exec'ing the shell.  */
-      pending_execs++;
-    }
+  /* This is set to the result of setpgrp, which if vforked, will be
+     visible to you in the parent process.  It's only used by humans
+     for debugging.  */
+  static int debug_setpgrp = 657473;
 
-  if (target_supports_multi_process ())
-    resume_ptid = pid_to_ptid (ptid_get_pid (inferior_ptid));
-  else
-    resume_ptid = minus_one_ptid;
+  /* Make sure we switch to main_ui here in order to be able to
+     use the fprintf_unfiltered/warning/error functions.  */
+  current_ui = main_ui;
 
-  /* The process was started by the fork that created it, but it will
-     have stopped one instruction after execing the shell.  Here we
-     must get it up to actual execution of the real program.  */
+  /* Close all file descriptors except those that gdb inherited
+     (usually 0/1/2), so they don't leak to the inferior.  Note
+     that this closes the file descriptors of all secondary
+     UIs.  */
+  close_most_fds ();
 
-  if (exec_wrapper)
-    pending_execs++;
+  if (debug_fork)
+    sleep (debug_fork);
 
-  while (1)
+  /* Create a new session for the inferior process, if necessary.
+     It will also place the inferior in a separate process group.  */
+  if (create_tty_session () <= 0)
     {
-      enum gdb_signal resume_signal = GDB_SIGNAL_0;
-      ptid_t event_ptid;
-
-      struct target_waitstatus ws;
-      memset (&ws, 0, sizeof (ws));
-      event_ptid = target_wait (resume_ptid, &ws, 0);
-
-      if (ws.kind == TARGET_WAITKIND_IGNORE)
-	/* The inferior didn't really stop, keep waiting.  */
-	continue;
-
-      switch (ws.kind)
-	{
-	  case TARGET_WAITKIND_SPURIOUS:
-	  case TARGET_WAITKIND_LOADED:
-	  case TARGET_WAITKIND_FORKED:
-	  case TARGET_WAITKIND_VFORKED:
-	  case TARGET_WAITKIND_SYSCALL_ENTRY:
-	  case TARGET_WAITKIND_SYSCALL_RETURN:
-	    /* Ignore gracefully during startup of the inferior.  */
-	    switch_to_thread (event_ptid);
-	    break;
-
-	  case TARGET_WAITKIND_SIGNALLED:
-	    target_terminal_ours ();
-	    target_mourn_inferior (event_ptid);
-	    error (_("During startup program terminated with signal %s, %s."),
-		   gdb_signal_to_name (ws.value.sig),
-		   gdb_signal_to_string (ws.value.sig));
-	    return;
-
-	  case TARGET_WAITKIND_EXITED:
-	    target_terminal_ours ();
-	    target_mourn_inferior (event_ptid);
-	    if (ws.value.integer)
-	      error (_("During startup program exited with code %d."),
-		     ws.value.integer);
-	    else
-	      error (_("During startup program exited normally."));
-	    return;
-
-	  case TARGET_WAITKIND_EXECD:
-	    /* Handle EXEC signals as if they were SIGTRAP signals.  */
-	    xfree (ws.value.execd_pathname);
-	    resume_signal = GDB_SIGNAL_TRAP;
-	    switch_to_thread (event_ptid);
-	    break;
-
-	  case TARGET_WAITKIND_STOPPED:
-	    resume_signal = ws.value.sig;
-	    switch_to_thread (event_ptid);
-	    break;
-	}
-
-      if (resume_signal != GDB_SIGNAL_TRAP)
-	{
-	  /* Let shell child handle its own signals in its own way.  */
-	  target_continue (resume_ptid, resume_signal);
-	}
-      else
-	{
-	  /* We handle SIGTRAP, however; it means child did an exec.  */
-	  if (!terminal_initted)
-	    {
-	      /* Now that the child has exec'd we know it has already
-	         set its process group.  On POSIX systems, tcsetpgrp
-	         will fail with EPERM if we try it before the child's
-	         setpgid.  */
-
-	      /* Set up the "saved terminal modes" of the inferior
-	         based on what modes we are starting it with.  */
-	      target_terminal_init ();
-
-	      /* Install inferior's terminal modes.  */
-	      target_terminal_inferior ();
-
-	      terminal_initted = 1;
-	    }
-
-	  if (--pending_execs == 0)
-	    break;
-
-	  /* Just make it go on.  */
-	  target_continue_no_signal (resume_ptid);
-	}
+      /* No session was created, but we still want to run the inferior
+	 in a separate process group.  */
+      debug_setpgrp = gdb_setpgid ();
+      if (debug_setpgrp == -1)
+	perror (_("setpgrp failed in child"));
     }
 
+  /* Ask the tty subsystem to switch to the one we specified
+     earlier (or to share the current terminal, if none was
+     specified).  */
+  new_tty ();
+}
+
+/* See inferior.h.  */
+
+ptid_t
+gdb_startup_inferior (pid_t pid, int num_traps)
+{
+  ptid_t ptid = startup_inferior (pid, num_traps, NULL, NULL);
+
   /* Mark all threads non-executing.  */
-  set_executing (resume_ptid, 0);
+  set_executing (ptid, 0);
+
+  return ptid;
 }
 
 /* Implement the "unset exec-wrapper" command.  */
diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
index 340c9c0..d8d6ff6 100644
--- a/gdb/gdbserver/Makefile.in
+++ b/gdb/gdbserver/Makefile.in
@@ -205,6 +205,7 @@ SFILES = \
 	$(srcdir)/common/fileio.c \
 	$(srcdir)/common/filestuff.c \
 	$(srcdir)/common/job-control.c \
+	$(srcdir)/common/common-fork-child.c \
 	$(srcdir)/common/gdb_vecs.c \
 	$(srcdir)/common/new-op.c \
 	$(srcdir)/common/print-utils.c \
@@ -236,6 +237,7 @@ OBS = \
 	common-debug.o \
 	common-exceptions.o \
 	job-control.o \
+	common-fork-child.o \
 	common-regcache.o \
 	common-utils.o \
 	debug.o \
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index e27cbf8..2e5d4f7 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -47,6 +47,8 @@
 #include "tracepoint.h"
 #include "hostio.h"
 #include <inttypes.h>
+#include "common-inferior.h"
+#include "environ.h"
 #ifndef ELFMAG0
 /* Don't include <linux/elf.h> here.  If it got included by gdb_proc_service.h
    then ELFMAG0 will have been defined.  If it didn't get included by
@@ -415,15 +417,20 @@ delete_lwp (struct lwp_info *lwp)
   free (lwp);
 }
 
-/* Add a process to the common process list, and set its private
-   data.  */
+/* Update an existing process represented by PID with the necessary
+   info.  Make sure that the private data structure is allocated, as
+   well as fill the ->arch_private structure if needed.
+
+   This function exists because fork_inferior already creates a
+   process when called, but it is up to us to complete the
+   process_info structure with extra information.  */
 
 static struct process_info *
-linux_add_process (int pid, int attached)
+linux_update_process (int pid)
 {
-  struct process_info *proc;
+  struct process_info *proc = find_process_pid (pid);
 
-  proc = add_process (pid, attached);
+  gdb_assert (proc != NULL);
   proc->priv = XCNEW (struct process_info_private);
 
   if (the_low_target.new_process != NULL)
@@ -432,6 +439,16 @@ linux_add_process (int pid, int attached)
   return proc;
 }
 
+/* Add a process to the common process list, and set its private
+   data.  */
+
+static struct process_info *
+linux_add_process (int pid, int attached)
+{
+  add_process (pid, attached);
+  return linux_update_process (pid);
+}
+
 static CORE_ADDR get_pc (struct lwp_info *lwp);
 
 /* Call the target arch_setup function on the current thread.  */
@@ -929,6 +946,33 @@ save_stop_reason (struct lwp_info *lwp)
   return 1;
 }
 
+/* Update the lwp associated to thread represented by PTID.
+
+   This function exists because fork_inferior already calls
+   'add_thread_silent', which creates the 'struct thread_info'.
+   However, we still need to set a few more things on the struct.  */
+
+static struct lwp_info *
+update_thread_lwp (ptid_t ptid)
+{
+  struct lwp_info *lwp;
+  struct thread_info *thread;
+
+  lwp = XCNEW (struct lwp_info);
+
+  lwp->waitstatus.kind = TARGET_WAITKIND_IGNORE;
+
+  if (the_low_target.new_thread != NULL)
+    the_low_target.new_thread (lwp);
+
+  thread = find_thread_ptid (ptid);
+  gdb_assert (thread != NULL);
+  thread->target_data = lwp;
+  lwp->thread = thread;
+
+  return lwp;
+}
+
 static struct lwp_info *
 add_lwp (ptid_t ptid)
 {
@@ -946,68 +990,68 @@ add_lwp (ptid_t ptid)
   return lwp;
 }
 
+/* Callback to be used when calling fork_inferior, responsible for
+   actually initiating the tracing of the inferior.  */
+
+static void
+linux_ptrace_fun (void)
+{
+  if (ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0,
+	      (PTRACE_TYPE_ARG4) 0) < 0)
+    trace_start_error_with_name ("ptrace");
+
+  if (setpgid (0, 0) < 0)
+    trace_start_error_with_name ("setpgid");
+
+  /* If GDBserver is connected to gdb via stdio, redirect the inferior's
+     stdout to stderr so that inferior i/o doesn't corrupt the connection.
+     Also, redirect stdin to /dev/null.  */
+  if (remote_connection_is_stdio ())
+    {
+      if (close (0) < 0)
+	trace_start_error_with_name ("close");
+      if (open ("/dev/null", O_RDONLY) < 0)
+	trace_start_error_with_name ("open");
+      if (dup2 (2, 1) < 0)
+	trace_start_error_with_name ("dup2");
+      if (write (2, "stdin/stdout redirected\n",
+		 sizeof ("stdin/stdout redirected\n") - 1) < 0)
+	{
+	  /* Errors ignored.  */;
+	}
+    }
+}
+
 /* Start an inferior process and returns its pid.
-   ALLARGS is a vector of program-name and args. */
+   PROGRAM is the name of the program to be started, and PROGRAM_ARGS
+   are its arguments.  */
 
 static int
-linux_create_inferior (char *program, char **allargs)
+linux_create_inferior (const char *program,
+		       const std::vector<char *> &program_args)
 {
   struct lwp_info *new_lwp;
   int pid;
   ptid_t ptid;
   struct cleanup *restore_personality
     = maybe_disable_address_space_randomization (disable_randomization);
+  std::string str_program_args = stringify_argv (program_args);
 
-#if defined(__UCLIBC__) && defined(HAS_NOMMU)
-  pid = vfork ();
-#else
-  pid = fork ();
-#endif
-  if (pid < 0)
-    perror_with_name ("fork");
-
-  if (pid == 0)
-    {
-      close_most_fds ();
-      ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0);
-
-      setpgid (0, 0);
-
-      /* If gdbserver is connected to gdb via stdio, redirect the inferior's
-	 stdout to stderr so that inferior i/o doesn't corrupt the connection.
-	 Also, redirect stdin to /dev/null.  */
-      if (remote_connection_is_stdio ())
-	{
-	  close (0);
-	  open ("/dev/null", O_RDONLY);
-	  dup2 (2, 1);
-	  if (write (2, "stdin/stdout redirected\n",
-		     sizeof ("stdin/stdout redirected\n") - 1) < 0)
-	    {
-	      /* Errors ignored.  */;
-	    }
-	}
-
-      restore_original_signals_state ();
-
-      execv (program, allargs);
-      if (errno == ENOENT)
-	execvp (program, allargs);
-
-      fprintf (stderr, "Cannot exec %s: %s.\n", program,
-	       strerror (errno));
-      fflush (stderr);
-      _exit (0177);
-    }
+  pid = fork_inferior (program,
+		       str_program_args.c_str (),
+		       environ_vector (get_environ ()), linux_ptrace_fun,
+		       NULL, NULL, NULL, NULL);
 
   do_cleanups (restore_personality);
 
-  linux_add_process (pid, 0);
+  linux_update_process (pid);
 
   ptid = ptid_build (pid, pid, 0);
-  new_lwp = add_lwp (ptid);
+  new_lwp = update_thread_lwp (ptid);
   new_lwp->must_set_ptrace_flags = 1;
 
+  post_fork_inferior (pid, program);
+
   return pid;
 }
 
diff --git a/gdb/gdbserver/lynx-low.c b/gdb/gdbserver/lynx-low.c
index d300aae..6040599 100644
--- a/gdb/gdbserver/lynx-low.c
+++ b/gdb/gdbserver/lynx-low.c
@@ -28,6 +28,7 @@
 #include "gdb_wait.h"
 #include <signal.h>
 #include "filestuff.h"
+#include "common-inferior.h"
 
 int using_threads = 1;
 
@@ -208,15 +209,21 @@ lynx_ptrace (int request, ptid_t ptid, int addr, int data, int addr2)
   return result;
 }
 
-/* Call add_process with the given parameters, and initializes
-   the process' private data.  */
+/* Update an existing process represented by PID with the necessary
+   info.  Make sure that the private data structure is allocated, as
+   well as fill the ->arch_private structure if needed.
+
+   This function exists because fork_inferior already creates a
+   process when called, but it is up to us to complete the
+   process_info structure with extra information.  */
 
 static struct process_info *
-lynx_add_process (int pid, int attached)
+lynx_update_process (int pid)
 {
-  struct process_info *proc;
+  struct process_info *proc = find_process_pid (pid);
+
+  gdb_assert (proc != NULL);
 
-  proc = add_process (pid, attached);
   proc->tdesc = lynx_tdesc;
   proc->priv = XCNEW (struct process_info_private);
   proc->priv->last_wait_event_ptid = null_ptid;
@@ -224,41 +231,60 @@ lynx_add_process (int pid, int attached)
   return proc;
 }
 
+/* Call add_process with the given parameters, and initializes
+   the process' private data.  */
+
+static struct process_info *
+lynx_add_process (int pid, int attached)
+{
+  add_process (pid, attached);
+  return lynx_update_process (pid);
+}
+
+/* Callback used by fork_inferior to start tracing the inferior.  */
+
+static void
+lynx_ptrace_fun (void)
+{
+  int pgrp;
+
+  /* Switch child to its own process group so that signals won't
+     directly affect GDBserver. */
+  pgrp = getpid();
+  if (pgrp < 0)
+    trace_start_error_with_name ("pgrp");
+  if (setpgid (0, pgrp) < 0)
+    trace_start_error_with_name ("setpgid");
+  if (ioctl (0, TIOCSPGRP, &pgrp) < 0)
+    trace_start_error_with_name ("ioctl");
+  if (lynx_ptrace (PTRACE_TRACEME, null_ptid, 0, 0, 0) < 0)
+    trace_start_error_with_name ("lynx_ptrace");
+}
+
 /* Implement the create_inferior method of the target_ops vector.  */
 
 static int
-lynx_create_inferior (char *program, char **allargs)
+lynx_create_inferior (const char *program,
+		      const std::vector<char *> &program_args)
 {
   int pid;
+  std::string str_program_args = stringify_argv (program_args);
 
   lynx_debug ("lynx_create_inferior ()");
 
-  pid = fork ();
-  if (pid < 0)
-    perror_with_name ("fork");
+  pid = fork_inferior (program,
+		       str_program_args.c_str (),
+		       environ_vector (get_environ ()), lynx_ptrace_fun,
+		       NULL, NULL, NULL, NULL);
 
-  if (pid == 0)
-    {
-      int pgrp;
-
-      close_most_fds ();
-
-      /* Switch child to its own process group so that signals won't
-         directly affect gdbserver. */
-      pgrp = getpid();
-      setpgid (0, pgrp);
-      ioctl (0, TIOCSPGRP, &pgrp);
-      lynx_ptrace (PTRACE_TRACEME, null_ptid, 0, 0, 0);
-      execv (program, allargs);
-      fprintf (stderr, "Cannot exec %s: %s.\n", program, strerror (errno));
-      fflush (stderr);
-      _exit (0177);
-    }
+  post_fork_inferior (pid, program);
 
-  lynx_add_process (pid, 0);
+  lynx_update_process (pid, 0);
   /* Do not add the process thread just yet, as we do not know its tid.
      We will add it later, during the wait for the STOP event corresponding
      to the lynx_ptrace (PTRACE_TRACEME) call above.  */
+  remove_thread (find_thread_ptid (ptid_build (pid, pid, 0)));
+
   return pid;
 }
 
diff --git a/gdb/gdbserver/nto-low.c b/gdb/gdbserver/nto-low.c
index 6229b4c..a5f1543 100644
--- a/gdb/gdbserver/nto-low.c
+++ b/gdb/gdbserver/nto-low.c
@@ -347,14 +347,17 @@ nto_read_auxv_from_initial_stack (CORE_ADDR initial_stack,
   return len_read;
 }
 
-/* Start inferior specified by PROGRAM passing arguments ALLARGS.  */
+/* Start inferior specified by PROGRAM, using PROGRAM_ARGS as its
+   arguments.  */
 
 static int
-nto_create_inferior (char *program, char **allargs)
+nto_create_inferior (const char *program,
+		     const std::vector<char *> &program_args)
 {
   struct inheritance inherit;
   pid_t pid;
   sigset_t set;
+  std::string str_program_args = stringify_argv (program_args);
 
   TRACE ("%s %s\n", __func__, program);
   /* Clear any pending SIGUSR1's but keep the behavior the same.  */
@@ -367,7 +370,8 @@ nto_create_inferior (char *program, char **allargs)
   memset (&inherit, 0, sizeof (inherit));
   inherit.flags |= SPAWN_SETGROUP | SPAWN_HOLD;
   inherit.pgroup = SPAWN_NEWPGROUP;
-  pid = spawnp (program, 0, NULL, &inherit, allargs, 0);
+  pid = spawnp (program, 0, NULL, &inherit,
+		(char *) str_program_args.c_str (), 0);
   sigprocmask (SIG_BLOCK, &set, NULL);
 
   if (pid == -1)
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index b22dfab..31c6a6e 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -36,6 +36,19 @@
 #include "dll.h"
 #include "hostio.h"
 #include <vector>
+#include "common-inferior.h"
+#include "common-terminal.h"
+#include "environ.h"
+
+/* The environment to pass to the inferior when creating it.  */
+
+struct gdb_environ *our_environ = NULL;
+
+/* Start the inferior using a shell.  */
+
+/* We always try to start the inferior using a shell.  */
+
+int startup_with_shell = 1;
 
 /* The thread set with an `Hc' packet.  `Hc' is deprecated in favor of
    `vCont'.  Note the multi-process extensions made `vCont' a
@@ -79,7 +92,8 @@ static int vCont_supported;
    space randomization feature before starting an inferior.  */
 int disable_randomization = 1;
 
-static std::vector<char *> program_argv;
+static char *program_name = NULL;
+static std::vector<char *> program_args;
 static std::vector<char *> wrapper_argv;
 
 int pass_signals[GDB_SIGNAL_LAST];
@@ -238,25 +252,58 @@ target_running (void)
   return get_first_thread () != NULL;
 }
 
-static int
-start_inferior (char **argv)
+/* See common/common-inferior.h.  */
+
+const char *
+get_exec_wrapper (void)
 {
-  std::vector<char *> new_argv;
+  static std::string ret;
+  static bool initialized_p = false;
 
-  if (!wrapper_argv.empty ())
-    new_argv.insert (new_argv.begin (),
-		     wrapper_argv.begin (),
-		     wrapper_argv.end ());
+  if (wrapper_argv.empty ())
+    return NULL;
 
-  for (int i = 0; argv[i] != NULL; ++i)
-    new_argv.push_back (argv[i]);
+  if (!initialized_p)
+    {
+      for (auto s : wrapper_argv)
+	ret += s + std::string (" ");
 
-  new_argv.push_back (NULL);
+      /* Erase the last whitespace.  */
+      ret.erase (ret.end () - 1);
+
+      initialized_p = true;
+    }
+
+  return ret.c_str ();
+}
+
+/* See common/common-inferior.h.  */
+
+char *
+get_exec_file (int err)
+{
+  if (err && program_name == NULL)
+    error (_("No executable file specified."));
+
+  return program_name;
+}
+
+/* See server.h.  */
+
+struct gdb_environ *
+get_environ (void)
+{
+  return our_environ;
+}
+
+/* See common-inferior.h.  */
 
+void
+prefork_hook (const char *args)
+{
   if (debug_threads)
     {
-      for (int i = 0; i < new_argv.size (); ++i)
-	debug_printf ("new_argv[%d] = \"%s\"\n", i, new_argv[i]);
+      debug_printf ("args: %s\n", args);
       debug_flush ();
     }
 
@@ -265,67 +312,64 @@ start_inferior (char **argv)
   signal (SIGTTIN, SIG_DFL);
 #endif
 
-  signal_pid = create_inferior (new_argv[0], &new_argv[0]);
+  /* Clear this so the backend doesn't get confused, thinking
+     CONT_THREAD died, and it needs to resume all threads.  */
+  cont_thread = null_ptid;
+}
 
-  /* FIXME: we don't actually know at this point that the create
-     actually succeeded.  We won't know that until we wait.  */
-  fprintf (stderr, "Process %s created; pid = %ld\n", argv[0],
-	   signal_pid);
-  fflush (stderr);
+/* See server.h.  */
+
+void
+post_fork_inferior (int pid, const char *program)
+{
+  /* Number of traps to be expected by startup_inferior.  We always
+     expect at least one trap for the main executable.  */
+  int num_traps = START_INFERIOR_TRAPS_EXPECTED;
 
 #ifdef SIGTTOU
   signal (SIGTTOU, SIG_IGN);
   signal (SIGTTIN, SIG_IGN);
   terminal_fd = fileno (stderr);
   old_foreground_pgrp = tcgetpgrp (terminal_fd);
-  tcsetpgrp (terminal_fd, signal_pid);
+  tcsetpgrp (terminal_fd, pid);
   atexit (restore_old_foreground_pgrp);
 #endif
 
-  if (!wrapper_argv.empty ())
-    {
-      ptid_t ptid = pid_to_ptid (signal_pid);
-
-      last_ptid = mywait (pid_to_ptid (signal_pid), &last_status, 0, 0);
-
-      if (last_status.kind == TARGET_WAITKIND_STOPPED)
-	{
-	  do
-	    {
-	      target_continue_no_signal (ptid);
-
-	      last_ptid = mywait (pid_to_ptid (signal_pid), &last_status, 0, 0);
-	      if (last_status.kind != TARGET_WAITKIND_STOPPED)
-		break;
+  startup_inferior (pid, num_traps, &last_status, &last_ptid);
+  current_thread->last_resume_kind = resume_stop;
+  current_thread->last_status = last_status;
+  signal_pid = pid;
+  target_post_create_inferior ();
+  fprintf (stderr, "Process %s created; pid = %d\n", program, pid);
+  fflush (stderr);
+}
 
-	      current_thread->last_resume_kind = resume_stop;
-	      current_thread->last_status = last_status;
-	    }
-	  while (last_status.value.sig != GDB_SIGNAL_TRAP);
-	}
-      target_post_create_inferior ();
-      return signal_pid;
-    }
+/* See common/common-inferior.h.  */
 
-  /* Wait till we are at 1st instruction in program, return new pid
-     (assuming success).  */
-  last_ptid = mywait (pid_to_ptid (signal_pid), &last_status, 0, 0);
+void
+postfork_hook (pid_t pid)
+{
+}
 
-  /* At this point, the target process, if it exits, is stopped.  Do not call
-     the function target_post_create_inferior if the process has already
-     exited, as the target implementation of the routine may rely on the
-     process being live. */
-  if (last_status.kind != TARGET_WAITKIND_EXITED
-      && last_status.kind != TARGET_WAITKIND_SIGNALLED)
-    {
-      target_post_create_inferior ();
-      current_thread->last_resume_kind = resume_stop;
-      current_thread->last_status = last_status;
-    }
-  else
-    target_mourn_inferior (last_ptid);
+/* See common/common-inferior.h.  */
 
-  return signal_pid;
+void
+postfork_child_hook (int debug_fork)
+{
+  /* This is set to the result of setpgrp, which if vforked, will be
+     visible to you in the parent process.  It's only used by humans
+     for debugging.  */
+  static int debug_setpgrp = 657473;
+
+  /* Close all file descriptors except those that gdb inherited
+     (usually 0/1/2), so they don't leak to the inferior.  Note
+     that this closes the file descriptors of all secondary
+     UIs.  */
+  close_most_fds ();
+
+  debug_setpgrp = gdb_setpgid ();
+  if (debug_setpgrp == -1)
+    perror (_("setpgrp failed in child"));
 }
 
 static int
@@ -2848,6 +2892,7 @@ handle_v_run (char *own_buf)
 {
   char *p, *next_p;
   std::vector<char *> new_argv;
+  char *new_program_name = NULL;
   int i, new_argc;
 
   new_argc = 0;
@@ -2866,42 +2911,95 @@ handle_v_run (char *own_buf)
       if (i == 0 && p == next_p)
 	{
 	  /* No program specified.  */
-	  new_argv.push_back (NULL);
+	  new_program_name = NULL;
+	}
+      else if (p == next_p)
+	{
+	  /* Empty argument.  */
+	  new_argv.push_back ("''");
 	}
       else
 	{
+	  /* FIXME: Fail request if out of memory instead of dying.  */
 	  size_t len = (next_p - p) / 2;
+	  /* ARG is the unquoted argument received via the RSP.  */
 	  char *arg = (char *) xmalloc (len + 1);
+	  /* FULL_ARGS will contain the quoted version of ARG.  */
+	  char *full_arg = (char *) xmalloc ((len + 1) * 2);
+	  /* These are pointers used to navigate the strings above.  */
+	  char *tmp_arg = arg;
+	  char *tmp_full_arg = full_arg;
+	  int need_quote = 0;
 
 	  hex2bin (p, (gdb_byte *) arg, len);
 	  arg[len] = '\0';
-	  new_argv.push_back (arg);
-	}
 
+	  while (*tmp_arg != '\0')
+	    {
+	      switch (*tmp_arg)
+		{
+		case '\n':
+		  /* Quote \n.  */
+		  *tmp_full_arg = '\'';
+		  ++tmp_full_arg;
+		  need_quote = 1;
+		  break;
+
+		case '\'':
+		  /* Quote single quote.  */
+		  *tmp_full_arg = '\\';
+		  ++tmp_full_arg;
+		  break;
+
+		default:
+		  break;
+		}
+
+	      *tmp_full_arg = *tmp_arg;
+	      ++tmp_full_arg;
+	      ++tmp_arg;
+	    }
+
+	  if (need_quote)
+	    *tmp_full_arg++ = '\'';
+
+	  /* Finish FULL_ARG and push it into the vector containing
+	     the argv.  */
+	  *tmp_full_arg = '\0';
+	  if (i == 0)
+	    new_program_name = full_arg;
+	  else
+	    new_argv.push_back (full_arg);
+	  xfree (arg);
+	}
       if (*next_p)
 	next_p++;
     }
   new_argv.push_back (NULL);
 
-  if (new_argv[0] == NULL)
+  if (new_program_name == NULL)
     {
       /* GDB didn't specify a program to run.  Use the program from the
 	 last run with the new argument list.  */
-      if (program_argv.empty ())
+      if (program_name == NULL)
 	{
 	  write_enn (own_buf);
 	  free_vector_argv (new_argv);
 	  return 0;
 	}
-
-      new_argv.push_back (xstrdup (program_argv[0]));
+    }
+  else
+    {
+      xfree (program_name);
+      program_name = new_program_name;
     }
 
   /* Free the old argv and install the new one.  */
-  free_vector_argv (program_argv);
-  program_argv = new_argv;
+  free_vector_argv (program_args);
+  program_args = new_argv;
+
+  create_inferior (program_name, program_args);
 
-  start_inferior (&program_argv[0]);
   if (last_status.kind == TARGET_WAITKIND_STOPPED)
     {
       prepare_resume_reply (own_buf, last_ptid, &last_status);
@@ -3661,8 +3759,13 @@ captured_main (int argc, char *argv[])
       exit (1);
     }
 
+  /* Gather information about the environment.  */
+  our_environ = make_environ ();
+  init_environ (our_environ);
+
   initialize_async_io ();
   initialize_low ();
+  have_job_control ();
   initialize_event_loop ();
   if (target_supports_tracepoints ())
     initialize_tracepoint ();
@@ -3676,12 +3779,13 @@ captured_main (int argc, char *argv[])
       int i, n;
 
       n = argc - (next_arg - argv);
-      for (i = 0; i < n; i++)
-	program_argv.push_back (xstrdup (next_arg[i]));
-      program_argv.push_back (NULL);
+      program_name = xstrdup (next_arg[0]);
+      for (i = 1; i < n; i++)
+	program_args.push_back (xstrdup (next_arg[i]));
+      program_args.push_back (NULL);
 
       /* Wait till we are at first instruction in program.  */
-      start_inferior (&program_argv[0]);
+      create_inferior (program_name, program_args);
 
       /* We are now (hopefully) stopped at the first instruction of
 	 the target process.  This assumes that the target process was
@@ -4296,9 +4400,10 @@ process_serial_event (void)
 	  fprintf (stderr, "GDBserver restarting\n");
 
 	  /* Wait till we are at 1st instruction in prog.  */
-	  if (!program_argv.empty ())
+	  if (program_name != NULL)
 	    {
-	      start_inferior (&program_argv[0]);
+	      create_inferior (program_name, program_args);
+
 	      if (last_status.kind == TARGET_WAITKIND_STOPPED)
 		{
 		  /* Stopped at the first instruction of the target
diff --git a/gdb/gdbserver/server.h b/gdb/gdbserver/server.h
index d5fee38..5087614 100644
--- a/gdb/gdbserver/server.h
+++ b/gdb/gdbserver/server.h
@@ -132,6 +132,7 @@ extern int in_queued_stop_replies (ptid_t ptid);
 #include "utils.h"
 #include "debug.h"
 #include "gdb_vecs.h"
+#include <vector>
 
 /* Maximum number of bytes to read/write at once.  The value here
    is chosen to fill up a packet (the headers account for the 32).  */
@@ -148,4 +149,13 @@ extern int in_queued_stop_replies (ptid_t ptid);
 /* Definition for any syscall, used for unfiltered syscall reporting.  */
 #define ANY_SYSCALL (-2)
 
+/* After fork_inferior has been called, we need to adjust a few
+   signals and call startup_inferior.  This is done here.  PID is the
+   pid of the new inferior, and PROGRAM is its name.  */
+extern void post_fork_inferior (int pid, const char *program);
+
+/* Get the 'struct gdb_environ *' being used in the current
+   session.  */
+extern struct gdb_environ *get_environ (void);
+
 #endif /* SERVER_H */
diff --git a/gdb/gdbserver/spu-low.c b/gdb/gdbserver/spu-low.c
index 117b871..8ab3c1c 100644
--- a/gdb/gdbserver/spu-low.c
+++ b/gdb/gdbserver/spu-low.c
@@ -27,6 +27,7 @@
 #include <sys/syscall.h>
 #include "filestuff.h"
 #include "hostio.h"
+#include "common-inferior.h"
 
 /* Some older glibc versions do not define this.  */
 #ifndef __WNOTHREAD
@@ -261,42 +262,42 @@ spu_proc_xfer_spu (const char *annex, unsigned char *readbuf,
   return ret;
 }
 
+/* Callback to be used when calling fork_inferior, responsible for
+   actually initiating the tracing of the inferior.  */
+
+static void
+spu_ptrace_fun (void)
+{
+  if (ptrace (PTRACE_TRACEME, 0, 0, 0) < 0)
+    trace_start_error_with_name ("ptrace");
+  if (setpgid (0, 0) < 0)
+    trace_start_error_with_name ("setpgid");
+}
 
 /* Start an inferior process and returns its pid.
-   ALLARGS is a vector of program-name and args. */
+   PROGRAM is the name of the program to be started, and PROGRAM_ARGS
+   are its arguments.  */
+
 static int
-spu_create_inferior (char *program, char **allargs)
+spu_create_inferior (const char *program,
+		     const std::vector<char *> &program_argv)
 {
   int pid;
   ptid_t ptid;
   struct process_info *proc;
+  std::string str_program_args = stringify_argv (program_args);
 
-  pid = fork ();
-  if (pid < 0)
-    perror_with_name ("fork");
-
-  if (pid == 0)
-    {
-      close_most_fds ();
-      ptrace (PTRACE_TRACEME, 0, 0, 0);
-
-      setpgid (0, 0);
+  pid = fork_inferior (program,
+		       str_program_args.c_str (),
+		       environ_vector (get_environ ()), spu_ptrace_fun,
+		       NULL, NULL, NULL, NULL);
 
-      execv (program, allargs);
-      if (errno == ENOENT)
-	execvp (program, allargs);
+  post_fork_inferior (pid, program);
 
-      fprintf (stderr, "Cannot exec %s: %s.\n", program,
-	       strerror (errno));
-      fflush (stderr);
-      _exit (0177);
-    }
-
-  proc = add_process (pid, 0);
+  proc = find_process_pid (pid);
+  gdb_assert (proc != NULL);
   proc->tdesc = tdesc_spu;
 
-  ptid = ptid_build (pid, pid, 0);
-  add_thread (ptid, NULL);
   return pid;
 }
 
diff --git a/gdb/gdbserver/target.c b/gdb/gdbserver/target.c
index fda72e8..1e1d193 100644
--- a/gdb/gdbserver/target.c
+++ b/gdb/gdbserver/target.c
@@ -387,3 +387,27 @@ default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
   (*the_target->sw_breakpoint_from_kind) (0, &size);
   return size;
 }
+
+/* See target/target.h.  */
+
+void
+target_terminal_init (void)
+{
+  /* To be implemented.  */
+}
+
+/* See target/target.h.  */
+
+void
+target_terminal_inferior (void)
+{
+  /* To be implemented.  */
+}
+
+/* See target/target.h.  */
+
+void
+target_terminal_ours (void)
+{
+  /* To be implemented.  */
+}
diff --git a/gdb/gdbserver/target.h b/gdb/gdbserver/target.h
index 3cc2bc4..be89258 100644
--- a/gdb/gdbserver/target.h
+++ b/gdb/gdbserver/target.h
@@ -28,6 +28,7 @@
 #include "target/waitstatus.h"
 #include "mem-break.h"
 #include "btrace-common.h"
+#include <vector>
 
 struct emit_ops;
 struct buffer;
@@ -67,13 +68,13 @@ struct target_ops
   /* Start a new process.
 
      PROGRAM is a path to the program to execute.
-     ARGS is a standard NULL-terminated array of arguments,
-     to be passed to the inferior as ``argv''.
+     PROGRAM_ARGS is a standard NULL-terminated array of arguments,
+     to be passed to the inferior as ``argv'' (along with PROGRAM).
 
      Returns the new PID on success, -1 on failure.  Registers the new
      process with the process list.  */
-
-  int (*create_inferior) (char *program, char **args);
+  int (*create_inferior) (const char *program,
+			  const std::vector<char *> &program_args);
 
   /* Do additional setup after a new process is created, including
      exec-wrapper completion.  */
@@ -480,8 +481,8 @@ extern struct target_ops *the_target;
 
 void set_target_ops (struct target_ops *);
 
-#define create_inferior(program, args) \
-  (*the_target->create_inferior) (program, args)
+#define create_inferior(program, program_args)	\
+  (*the_target->create_inferior) (program, program_args)
 
 #define target_post_create_inferior()			 \
   do							 \
diff --git a/gdb/gdbserver/utils.c b/gdb/gdbserver/utils.c
index 307d15a..a7a5f81 100644
--- a/gdb/gdbserver/utils.c
+++ b/gdb/gdbserver/utils.c
@@ -137,3 +137,12 @@ pfildes (gdb_fildes_t fd)
   return plongest (fd);
 #endif
 }
+
+/* See common/common-utils.h.  */
+
+void
+gdb_flush_out_err (void)
+{
+  fflush (stdout);
+  fflush (stderr);
+}
diff --git a/gdb/gdbserver/utils.h b/gdb/gdbserver/utils.h
index b4ded31..48804c5 100644
--- a/gdb/gdbserver/utils.h
+++ b/gdb/gdbserver/utils.h
@@ -19,6 +19,8 @@
 #ifndef UTILS_H
 #define UTILS_H
 
+#include <vector>
+
 char *paddress (CORE_ADDR addr);
 char *pfildes (gdb_fildes_t fd);
 
diff --git a/gdb/gdbserver/win32-low.c b/gdb/gdbserver/win32-low.c
index d3ddbf5..e4c6fc7 100644
--- a/gdb/gdbserver/win32-low.c
+++ b/gdb/gdbserver/win32-low.c
@@ -608,13 +608,13 @@ create_process (const char *program, char *args,
 }
 
 /* Start a new process.
-   PROGRAM is a path to the program to execute.
-   ARGS is a standard NULL-terminated array of arguments,
-   to be passed to the inferior as ``argv''.
+   PROGRAM is the program name.
+   PROGRAM_ARGS is the vector containing the inferior's args.
    Returns the new PID on success, -1 on failure.  Registers the new
    process with the process list.  */
 static int
-win32_create_inferior (char *program, char **program_args)
+win32_create_inferior (const char *program,
+		       const std::vector<char *> &program_args)
 {
 #ifndef USE_WIN32API
   char real_path[PATH_MAX];
@@ -627,6 +627,8 @@ win32_create_inferior (char *program, char **program_args)
   int argc;
   PROCESS_INFORMATION pi;
   DWORD err;
+  std::string str_program_args = stringify_argv (program_argv);
+  char *args = (char *) str_program_args.c_str ();
 
   /* win32_wait needs to know we're not attaching.  */
   attaching = 0;
@@ -652,18 +654,6 @@ win32_create_inferior (char *program, char **program_args)
   program = real_path;
 #endif
 
-  argslen = 1;
-  for (argc = 1; program_args[argc]; argc++)
-    argslen += strlen (program_args[argc]) + 1;
-  args = (char *) alloca (argslen);
-  args[0] = '\0';
-  for (argc = 1; program_args[argc]; argc++)
-    {
-      /* FIXME: Can we do better about quoting?  How does Cygwin
-	 handle this?  */
-      strcat (args, " ");
-      strcat (args, program_args[argc]);
-    }
   OUTMSG2 (("Command line is \"%s\"\n", args));
 
 #ifdef CREATE_NEW_PROCESS_GROUP
diff --git a/gdb/gnu-nat.c b/gdb/gnu-nat.c
index 818be15..25336df 100644
--- a/gdb/gnu-nat.c
+++ b/gdb/gnu-nat.c
@@ -2162,7 +2162,8 @@ gnu_create_inferior (struct target_ops *ops,
   thread_change_ptid (inferior_ptid,
 		      ptid_build (inf->pid, inf_pick_first_thread (), 0));
 
-  startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
+  gdb_startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED);
+
   inf->pending_execs = 0;
   /* Get rid of the old shell threads.  */
   prune_threads ();
diff --git a/gdb/inf-ptrace.c b/gdb/inf-ptrace.c
index 787310d..b754b74 100644
--- a/gdb/inf-ptrace.c
+++ b/gdb/inf-ptrace.c
@@ -112,7 +112,7 @@ inf_ptrace_create_inferior (struct target_ops *ops,
 
   discard_cleanups (back_to);
 
-  startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
+  gdb_startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED);
 
   /* On some targets, there must be some explicit actions taken after
      the inferior has been started up.  */
diff --git a/gdb/inferior.h b/gdb/inferior.h
index bf06ac1..2fa6ae9 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -42,6 +42,7 @@ struct target_desc_info;
 
 #include "progspace.h"
 #include "registry.h"
+#include "common-inferior.h"
 
 #include "symfile-add-flags.h"
 
@@ -132,28 +133,10 @@ extern void child_terminal_init_with_pgrp (int pgrp);
 
 /* From fork-child.c */
 
-/* Report an error that happened when starting to trace the inferior
-   (i.e., when the "traceme_fun" callback is called on fork_inferior)
-   and bail out.  This function does not return.  */
-
-extern void trace_start_error (const char *fmt, ...)
-  ATTRIBUTE_NORETURN;
-
-/* Like "trace_start_error", but the error message is constructed by
-   combining STRING with the system error message for errno.  This
-   function does not return.  */
-
-extern void trace_start_error_with_name (const char *string)
-  ATTRIBUTE_NORETURN;
-
-extern int fork_inferior (const char *, const std::string &, char **,
-			  void (*)(void),
-			  void (*)(int), void (*)(void), char *,
-                          void (*)(const char *,
-                                   char * const *, char * const *));
-
-
-extern void startup_inferior (int);
+/* Helper function to call STARTUP_INFERIOR with PID and NUM_TRAPS.
+   This function already calls set_executing.  Return the ptid_t from
+   STARTUP_INFERIOR.  */
+extern ptid_t gdb_startup_inferior (pid_t pid, int num_traps);
 
 extern char *construct_inferior_arguments (int, char **);
 
diff --git a/gdb/procfs.c b/gdb/procfs.c
index e8f26be..ca7882b 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -4377,7 +4377,7 @@ procfs_init_inferior (struct target_ops *ops, int pid)
   thread_change_ptid (pid_to_ptid (pid),
 		      ptid_build (pid, lwpid, 0));
 
-  startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
+  gdb_startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED);
 
 #ifdef SYS_syssgi
   /* On mips-irix, we need to stop the inferior early enough during
diff --git a/gdb/target.h b/gdb/target.h
index bc935ef..78b9728 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1538,17 +1538,6 @@ extern int target_terminal_is_inferior (void);
 
 extern int target_terminal_is_ours (void);
 
-/* Initialize the terminal settings we record for the inferior,
-   before we actually run the inferior.  */
-
-extern void target_terminal_init (void);
-
-/* Put the inferior's terminal settings into effect.  This is
-   preparation for starting or resuming the inferior.  This is a no-op
-   unless called with the main UI as current UI.  */
-
-extern void target_terminal_inferior (void);
-
 /* Put some of our terminal settings into effect, enough to get proper
    results from our output, but do not change into or out of RAW mode
    so that no input is discarded.  This is a no-op if terminal_ours
@@ -1557,12 +1546,6 @@ extern void target_terminal_inferior (void);
 
 extern void target_terminal_ours_for_output (void);
 
-/* Put our terminal settings into effect.  First record the inferior's
-   terminal settings so they can be restored properly later.  This is
-   a no-op unless called with the main UI as current UI.  */
-
-extern void target_terminal_ours (void);
-
 /* Return true if the target stack has a non-default
   "to_terminal_ours" method.  */
 
diff --git a/gdb/target/target.h b/gdb/target/target.h
index 582852c..f12262e 100644
--- a/gdb/target/target.h
+++ b/gdb/target/target.h
@@ -95,4 +95,18 @@ extern void target_mourn_inferior (ptid_t ptid);
 
 extern int target_supports_multi_process (void);
 
+/* Initialize the terminal settings we record for the inferior,
+   before we actually run the inferior.  */
+extern void target_terminal_init (void);
+
+/* Put the inferior's terminal settings into effect.  This is
+   preparation for starting or resuming the inferior.  This is a no-op
+   unless called with the main UI as current UI.  */
+extern void target_terminal_inferior (void);
+
+/* Put our terminal settings into effect.  First record the inferior's
+   terminal settings so they can be restored properly later.  This is
+   a no-op unless called with the main UI as current UI.  */
+extern void target_terminal_ours (void);
+
 #endif /* TARGET_COMMON_H */
diff --git a/gdb/testsuite/gdb.server/non-existing-program.exp b/gdb/testsuite/gdb.server/non-existing-program.exp
index d404564..68d4d53 100644
--- a/gdb/testsuite/gdb.server/non-existing-program.exp
+++ b/gdb/testsuite/gdb.server/non-existing-program.exp
@@ -39,8 +39,16 @@ set spawn_id [remote_spawn target "$gdbserver stdio non-existing-program"]
 set msg "gdbserver exits cleanly"
 set saw_exiting 0
 expect {
-    # This is what we get on ptrace-based targets.
-    -re "stdin/stdout redirected.*No program to debug\r\nExiting\r\n$" {
+    # This is what we get on ptrace-based targets with
+    # startup-with-shell disabled (e.g., when the SHELL variable is
+    # unset).
+    -re "stdin/stdout redirected.*gdbserver: Cannot exec non-existing-program\r\ngdbserver: Error: No such file or directory\r\n\r\nDuring startup program exited with code 127\.\r\nExiting\r\n$" {
+	set saw_exiting 1
+	exp_continue
+    }
+    # Likewise, but with startup-with-shell enabled, which is the
+    # default behaviour.
+    -re "stdin/stdout redirected.*exec: non-existing-program: not found\r\nDuring startup program exited with code 127\.\r\nExiting\r\n$" {
 	set saw_exiting 1
 	exp_continue
     }
diff --git a/gdb/utils.c b/gdb/utils.c
index d7a1993..888445e 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -3389,6 +3389,15 @@ strip_leading_path_elements (const char *path, int n)
   return p;
 }
 
+/* See common/common-utils.h.  */
+
+void
+gdb_flush_out_err (void)
+{
+  gdb_flush (main_ui->m_gdb_stdout);
+  gdb_flush (main_ui->m_gdb_stderr);
+}
+
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 extern initialize_file_ftype _initialize_utils;
 
-- 
2.9.3


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