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[binutils-gdb] Simplify child_terminal_inferior


https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=556e5da51349d00307bc05b7a6a813f71ac58664

commit 556e5da51349d00307bc05b7a6a813f71ac58664
Author: Pedro Alves <palves@redhat.com>
Date:   Mon Nov 6 15:36:47 2017 +0000

    Simplify child_terminal_inferior
    
    The comment about Lynx in child_terminal_init reads a bit odd, since
    it's not exactly clear what "This" in "This is for Lynx" is referring
    to.  Looking back in history makes it clearer.  When the comment was
    originally added, in commit 91ecc8efa9b9, back in 1994, the code
    looked like this:
    
    ~~~
    #ifdef PROCESS_GROUP_TYPE
    #ifdef PIDGET
          /* This is for Lynx, and should be cleaned up by having Lynx be
             a separate debugging target with a version of
             target_terminal_init_inferior which passes in the process
             group to a generic routine which does all the work (and the
             non-threaded child_terminal_init_inferior can just pass in
             inferior_pid to the same routine).  */
          inferior_process_group = PIDGET (inferior_pid);
    #else
          inferior_process_group = inferior_pid;
    #endif
    #endif
    ~~~
    
    So this looked like it was about when GDB was growing support for
    multi-threading, and inferior_pid was still a single int for most
    ports.
    
    Eventually we got ptid_t, so the comment isn't really useful today.
    Particularly more so since we no longer support Lynx as a GDB host.
    
    The only caller left of child_terminal_init_with_pgrp is gnu-nat.c
    (the Hurd), and that target uses fork-child, so when we reach
    gnu_terminal_init after spawning a new child, the current inferior
    must already have the PID set, and the child must be a process group
    leader.
    
    We can't add a 'getpgid(inf->pid) == inf->pid' assertion to
    child_terminal_init though (like a previous version of this patch was
    doing [1]), because child_terminal_init is also reached after
    attaching to a process.  If we did, the new
    gdb.base/attach-non-pgrp-leader.exp test would fail, with:
    
      (gdb) attach 12415
      Attaching to program: build/gdb/testsuite/outputs/gdb.base/attach-non-pgrp-leader/attach-non-pgrp-leader, process 12415
      src/gdb/inflow.c:180: internal-error: void child_terminal_init(target_ops*): Assertion `getpgid (inf->pid) == inf->pid' failed.
      A problem internal to GDB has been detected,
      further debugging may prove unreliable.
      Quit this debugging session? (y or n) FAIL: gdb.base/attach-non-pgrp-leader.exp: child: attach to child (GDB internal error)
    
    I'm not making GDB save the pgid for attached processes with getpgid
    for now, because the saved process group affects other things which
    I'm leaving for following patches, like e.g., the "interrupt" command.
    
    [1] - https://sourceware.org/ml/gdb-patches/2017-11/msg00039.html
    
    gdb/ChangeLog:
    2017-11-06  Pedro Alves  <palves@redhat.com>
    
    	* gnu-nat.c (gnu_terminal_init): Delete.
    	(gnu_target): Don't install gnu_terminal_init.
    	* inflow.c (child_terminal_init_with_pgrp): Delete, merged with ...
    	(child_terminal_init): ... this function.

Diff:
---
 gdb/ChangeLog |  7 +++++++
 gdb/gnu-nat.c |  7 -------
 gdb/inflow.c  | 22 +++++-----------------
 3 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7a90ea5..ac5b318 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2017-11-06  Pedro Alves  <palves@redhat.com>
 
+	* gnu-nat.c (gnu_terminal_init): Delete.
+	(gnu_target): Don't install gnu_terminal_init.
+	* inflow.c (child_terminal_init_with_pgrp): Delete, merged with ...
+	(child_terminal_init): ... this function.
+
+2017-11-06  Pedro Alves  <palves@redhat.com>
+
 	* common/common.m4 (GDB_AC_COMMON): No longer check termio.h nor
 	sgtty.h.
 	* config.in, configure: Regenerate.
diff --git a/gdb/gnu-nat.c b/gdb/gnu-nat.c
index 7cb6e4a..2ae2031 100644
--- a/gdb/gnu-nat.c
+++ b/gdb/gnu-nat.c
@@ -2279,12 +2279,6 @@ gnu_detach (struct target_ops *ops, const char *args, int from_tty)
   inf_child_maybe_unpush_target (ops);
 }
 
-static void
-gnu_terminal_init (struct target_ops *self)
-{
-  gdb_assert (gnu_current_inf);
-  child_terminal_init_with_pgrp (gnu_current_inf->pid);
-}
 
 static void
 gnu_stop (struct target_ops *self, ptid_t ptid)
@@ -2693,7 +2687,6 @@ gnu_target (void)
   t->to_wait = gnu_wait;
   t->to_xfer_partial = gnu_xfer_partial;
   t->to_find_memory_regions = gnu_find_memory_regions;
-  t->to_terminal_init = gnu_terminal_init;
   t->to_kill = gnu_kill_inferior;
   t->to_create_inferior = gnu_create_inferior;
   t->to_mourn_inferior = gnu_mourn_inferior;
diff --git a/gdb/inflow.c b/gdb/inflow.c
index d46d693..2fba0fa 100644
--- a/gdb/inflow.c
+++ b/gdb/inflow.c
@@ -165,7 +165,7 @@ gdb_has_a_terminal (void)
    before we actually run the inferior.  */
 
 void
-child_terminal_init_with_pgrp (int pgrp)
+child_terminal_init (struct target_ops *self)
 {
   struct inferior *inf = current_inferior ();
   struct terminal_info *tinfo = get_inflow_inferior_data (inf);
@@ -173,8 +173,10 @@ child_terminal_init_with_pgrp (int pgrp)
 #ifdef HAVE_TERMIOS_H
   /* Store the process group even without a terminal as it is used not
      only to reset the tty foreground process group, but also to
-     interrupt the inferior.  */
-  tinfo->process_group = pgrp;
+     interrupt the inferior.  A child we spawn should be a process
+     group leader (PGID==PID) at this point, though that may not be
+     true if we're attaching to an existing process.  */
+  tinfo->process_group = inf->pid;
 #endif
 
   if (gdb_has_a_terminal ())
@@ -204,20 +206,6 @@ gdb_save_tty_state (void)
     }
 }
 
-void
-child_terminal_init (struct target_ops *self)
-{
-#ifdef HAVE_TERMIOS_H
-  /* This is for Lynx, and should be cleaned up by having Lynx be a
-     separate debugging target with a version of target_terminal::init
-     which passes in the process group to a generic routine which does
-     all the work (and the non-threaded child_terminal_init can just
-     pass in inferior_ptid to the same routine).  */
-  /* We assume INFERIOR_PID is also the child's process group.  */
-  child_terminal_init_with_pgrp (ptid_get_pid (inferior_ptid));
-#endif /* HAVE_TERMIOS_H */
-}
-
 /* Put the inferior's terminal settings into effect.
    This is preparation for starting or resuming the inferior.


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