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[PATCH v2 3/5] Introduce gdb_chdir


In order to be able to change the inferior's directory before its
execution, it is necessary to perform a tilde expansion of the
directory provided by the user and then chdir into the resulting dir.
This is what gdb_chdir does.

Unfortunately it is not possible to use "tilde_expand" from readline
because this is common code and gdbserver doesn't use readline.  For
that reason I decided to go with "glob" and its GNU extension,
GLOB_TILDE.  With the import of the "glob" module from gnulib, this is
a no-brainer.

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

	* Makefile.in (SFILES): Add gdb_chdir.c.
	(HFILES_NO_SRCDIR): Add gdb_chdir.h.
	(COMMON_OBS): Add gdb_chdir.o.
	* cli/cli-cmds.c: Include "gdb_chdir.h".
	(cd_command): Use "gdb_chdir" instead of "tilde_expand
	plus chdir".
	* common/gdb_chdir.c: New file.
	* common/gdb_chdir.h: Likewise.

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

	* Makefile.in (SFILES): Add $(srcdir)/common/gdb_chdir.c.
	(OBS): Add gdb_chdir.o.
---
 gdb/Makefile.in           |  3 ++
 gdb/cli/cli-cmds.c        | 20 +++++-----
 gdb/common/gdb_chdir.c    | 96 +++++++++++++++++++++++++++++++++++++++++++++++
 gdb/common/gdb_chdir.h    | 26 +++++++++++++
 gdb/gdbserver/Makefile.in |  2 +
 5 files changed, 136 insertions(+), 11 deletions(-)
 create mode 100644 gdb/common/gdb_chdir.c
 create mode 100644 gdb/common/gdb_chdir.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 9dfc117b2f..1f093e6c0f 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1245,6 +1245,7 @@ SFILES = \
 	common/filestuff.c \
 	common/format.c \
 	common/job-control.c \
+	common/gdb_chdir.c \
 	common/gdb_vecs.c \
 	common/new-op.c \
 	common/print-utils.c \
@@ -1529,6 +1530,7 @@ HFILES_NO_SRCDIR = \
 	common/fileio.h \
 	common/format.h \
 	common/gdb_assert.h \
+	common/gdb_chdir.h \
 	common/gdb_locale.h \
 	common/gdb_setjmp.h \
 	common/gdb_signals.h \
@@ -1734,6 +1736,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
 	frame-unwind.o \
 	gcore.o \
 	gdb_bfd.o \
+	gdb_chdir.o \
 	gdb-dlfcn.o \
 	gdb_obstack.o \
 	gdb_regex.o \
diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 85d6d21113..653dd56a64 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -54,6 +54,8 @@
 #include "tui/tui.h"	/* For tui_active et.al.  */
 #endif
 
+#include "gdb_chdir.h"
+
 #include <fcntl.h>
 #include <algorithm>
 #include <string>
@@ -408,12 +410,7 @@ cd_command (char *dir, int from_tty)
      repeat might be useful but is more likely to be a mistake.  */
   dont_repeat ();
 
-  gdb::unique_xmalloc_ptr<char> dir_holder
-    (tilde_expand (dir != NULL ? dir : "~"));
-  dir = dir_holder.get ();
-
-  if (chdir (dir) < 0)
-    perror_with_name (dir);
+  gdb_chdir (dir != NULL ? dir : "~");
 
 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
   /* There's too much mess with DOSish names like "d:", "d:.",
@@ -436,20 +433,21 @@ cd_command (char *dir, int from_tty)
 	len--;
     }
 
-  dir_holder.reset (savestring (dir, len));
-  if (IS_ABSOLUTE_PATH (dir_holder.get ()))
+  std::string newdir = std::string (dir, len);
+  const char *newdir_str = newdir.c_str ();
+  if (IS_ABSOLUTE_PATH (newdir_str))
     {
       xfree (current_directory);
-      current_directory = dir_holder.release ();
+      current_directory = xstrdup (newdir_str);
     }
   else
     {
       if (IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1]))
-	current_directory = concat (current_directory, dir_holder.get (),
+	current_directory = concat (current_directory, newdir_str,
 				    (char *) NULL);
       else
 	current_directory = concat (current_directory, SLASH_STRING,
-				    dir_holder.get (), (char *) NULL);
+				    newdir_str, (char *) NULL);
     }
 
   /* Now simplify any occurrences of `.' and `..' in the pathname.  */
diff --git a/gdb/common/gdb_chdir.c b/gdb/common/gdb_chdir.c
new file mode 100644
index 0000000000..6eebeb2d02
--- /dev/null
+++ b/gdb/common/gdb_chdir.c
@@ -0,0 +1,96 @@
+/* chdir(2) wrapper for GDB and gdbserver.
+
+   Copyright (C) 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 "gdb_chdir.h"
+#include <glob.h>
+
+/* RAII-style class wrapping "glob".  */
+
+class gdb_glob
+{
+public:
+  /* Construct a "gdb_glob" object by calling "glob" with the provided
+     parameters.  This function can throw if "glob" fails.  */
+  gdb_glob (const char *pattern, int flags,
+	    int (*errfunc) (const char *epath, int eerrno))
+  {
+    int ret = glob (pattern, flags, errfunc, &m_glob);
+
+    if (ret != 0)
+      {
+	if (ret == GLOB_NOMATCH)
+	  error (_("Could not find a match for '%s'."), pattern);
+	else
+	  error (_("glob could not process pattern '%s'."),
+		 pattern);
+      }
+  }
+
+  /* Destroy the object and free M_GLOB.  */
+  ~gdb_glob ()
+  {
+    globfree (&m_glob);
+  }
+
+  /* Return the GL_PATHC component of M_GLOB.  */
+  int
+  pathc () const
+  {
+    return m_glob.gl_pathc;
+  }
+
+  /* Return the GL_PATHV component of M_GLOB.  */
+  char **
+  pathv () const
+  {
+    return m_glob.gl_pathv;
+  }
+
+private:
+  /* The actual glob object we're dealing with.  */
+  glob_t m_glob;
+};
+
+/* Perform path expansion (i.e., tilde expansion) on DIR, and return
+   the full path.  */
+
+static std::string
+gdb_tilde_expand (const char *dir)
+{
+  gdb_glob glob (dir, GLOB_TILDE | GLOB_TILDE_CHECK | GLOB_ONLYDIR, NULL);
+
+  gdb_assert (glob.pathc () > 0);
+  /* "glob" may return more than one match to the path provided by the
+     user, but we are only interested in the first match.  */
+  std::string expanded_dir = glob.pathv ()[0];
+
+  return expanded_dir;
+}
+
+/* See gdb_chdir.h.  */
+
+void
+gdb_chdir (const char *dir)
+{
+  std::string expanded_dir = gdb_tilde_expand (dir);
+
+  if (chdir (expanded_dir.c_str ()) < 0)
+    perror_with_name (expanded_dir.c_str ());
+}
diff --git a/gdb/common/gdb_chdir.h b/gdb/common/gdb_chdir.h
new file mode 100644
index 0000000000..5e6253e3b5
--- /dev/null
+++ b/gdb/common/gdb_chdir.h
@@ -0,0 +1,26 @@
+/* chdir(2) wrapper for GDB and gdbserver.
+
+   Copyright (C) 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 HAVE_GDB_CHDIR_H
+#define HAVE_GDB_CHDIR_H
+
+/* Perform a "chdir" to DIR, doing the proper tilde expansion before.  */
+extern void gdb_chdir (const char *dir);
+
+#endif /* ! HAVE_GDB_CHDIR_H */
diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
index 1bbe515629..ecd12a7dcc 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/gdb_chdir.c \
 	$(srcdir)/common/gdb_vecs.c \
 	$(srcdir)/common/new-op.c \
 	$(srcdir)/common/print-utils.c \
@@ -247,6 +248,7 @@ OBS = \
 	fileio.o \
 	filestuff.o \
 	format.o \
+	gdb_chdir.o \
 	gdb_vecs.o \
 	hostio.o \
 	inferiors.o \
-- 
2.13.3


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