Re: [patch] Linux MAY_FOLLOW_EXEC #2

[Jan Kratochvil <jan.kratochvil@redhat.com>]

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Hi Mark,

On Mon, 31 Jul 2006 22:38:43 +0200, Mark Kettenis wrote:
...
> That WNOHANG is wrong;

In fact yes, the patch is more correct without that WNOHANG hack there.


2006-07-29  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* inf-ptrace.c (inf_ptrace_mourn_inferior): waitpid(2) only if there
	is valid inferior_ptid to wait for.
	* linux-fork.c (linux_fork_mourn_inferior): Ditto.
	* infrun.c (follow_exec): Unconditionally enabled by MAY_FOLLOW_EXEC.
	Provide restoration of exec_bfd and symfile_objfile for any new "run".
	* linux-thread-db.c (thread_db_wait): Handle TARGET_WAITKIND_EXECD.
	* linux-thread-db.c (thread_db_mourn_inferior): Turn off threading.
	* foll-exec.exp: Uncoditionally enabled for all platforms.
	Relaxed regex to apply besides HP-UX also for GNU/Linux backtrace.


Thanks,
Jan

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Index: inf-ptrace.c
===================================================================
RCS file: /cvs/src/src/gdb/inf-ptrace.c,v
retrieving revision 1.32
diff -u -p -r1.32 inf-ptrace.c
--- inf-ptrace.c	24 Jan 2006 22:34:34 -0000	1.32
+++ inf-ptrace.c	5 Aug 2006 15:49:22 -0000
@@ -167,7 +167,8 @@ inf_ptrace_mourn_inferior (void)
      Do not check whether this succeeds though, since we may be
      dealing with a process that we attached to.  Such a process will
      only report its exit status to its original parent.  */
-  waitpid (ptid_get_pid (inferior_ptid), &status, 0);
+  if (! ptid_equal (inferior_ptid, null_ptid) && target_has_execution)
+    waitpid (ptid_get_pid (inferior_ptid), &status, 0);
 
   unpush_target (ptrace_ops_hack);
   generic_mourn_inferior ();
Index: infrun.c
===================================================================
RCS file: /cvs/src/src/gdb/infrun.c,v
retrieving revision 1.213
diff -u -p -r1.213 infrun.c
--- infrun.c	22 Jul 2006 14:48:03 -0000	1.213
+++ infrun.c	5 Aug 2006 15:49:28 -0000
@@ -47,6 +47,7 @@
 #include "language.h"
 #include "solib.h"
 #include "main.h"
+#include "objfiles.h"
 
 #include "gdb_assert.h"
 #include "mi/mi-common.h"
@@ -109,10 +110,10 @@ int sync_execution = 0;
 static ptid_t previous_inferior_ptid;
 
 /* This is true for configurations that may follow through execl() and
-   similar functions.  At present this is only true for HP-UX native.  */
+   similar functions.  */
 
 #ifndef MAY_FOLLOW_EXEC
-#define MAY_FOLLOW_EXEC (0)
+#define MAY_FOLLOW_EXEC (1)
 #endif
 
 static int may_follow_exec = MAY_FOLLOW_EXEC;
@@ -375,6 +376,37 @@ follow_inferior_reset_breakpoints (void)
   insert_breakpoints ();
 }
 
+static void
+follow_exec_restore_execfile (void *filename_new_untyped)
+{
+  char *filename_new = filename_new_untyped;
+
+  /* filename_new == NULL is not expected.  */
+  if (filename_new == NULL && exec_bfd != NULL)
+    exec_file_clear (0);
+  /* exec_bfd == NULL is not expected.  */
+  if (filename_new != NULL && 
+      (exec_bfd == NULL || strcmp (get_exec_file (0), filename_new)))
+    exec_file_attach (filename_new, 0);
+
+  free (filename_new);
+}
+
+static void
+follow_exec_restore_symfile (void *filename_new_untyped)
+{
+  char *filename_new = filename_new_untyped;
+
+  /* symfile_objfile == NULL is not expected.  */
+  if (filename_new == NULL && symfile_objfile != NULL)
+    symbol_file_clear (0);
+  if (filename_new != NULL && (symfile_objfile == NULL
+      || strcmp (symfile_objfile->name, filename_new)))
+    symbol_file_add_main (filename_new, 0);
+
+  free (filename_new);
+}
+
 /* EXECD_PATHNAME is assumed to be non-NULL. */
 
 static void
@@ -382,6 +414,7 @@ follow_exec (int pid, char *execd_pathna
 {
   int saved_pid = pid;
   struct target_ops *tgt;
+  struct objfile *objfile, *objfile_temp;
 
   if (!may_follow_exec)
     return;
@@ -427,6 +460,32 @@ follow_exec (int pid, char *execd_pathna
     error (_("Could find run target to save before following exec"));
 
   gdb_flush (gdb_stdout);
+
+  /* During the common "run" bare command we should run again the original
+   * program spawning us.  Stacking ordering is correct this way.  */
+  make_run_cleanup (follow_exec_restore_execfile,
+                    (!exec_bfd ? NULL : xstrdup (exec_bfd->filename)));
+  make_run_cleanup (follow_exec_restore_symfile, (!symfile_objfile ? NULL :
+                    xstrdup (symfile_objfile->name)));
+
+  /* As symbol_file_add_main()->thread_db_new_objfile()->check_for_thread_db()
+   * would fine already loaded libpthread.so while the threading structures
+   * would not be yet initialized for this early inferior.
+   * Call before target_mourn_inferior() as it will breakpoint_re_set().  */
+#ifdef CLEAR_SOLIB
+  CLEAR_SOLIB ();
+#else
+  clear_solib ();
+#endif
+  /* Do not: symbol_file_clear()->clear_symtab_users()->breakpoint_re_set().  */
+  ALL_OBJFILES_SAFE (objfile, objfile_temp)
+  {
+    free_objfile (objfile);
+  }
+  symfile_objfile = NULL;
+
+  /* Avoid stucked waitpid(2) as PID inferior_ptid is still running.  */
+  inferior_ptid = null_ptid;
   target_mourn_inferior ();
   inferior_ptid = pid_to_ptid (saved_pid);
   /* Because mourn_inferior resets inferior_ptid. */
Index: linux-fork.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-fork.c,v
retrieving revision 1.7
diff -u -p -r1.7 linux-fork.c
--- linux-fork.c	27 Apr 2006 23:03:41 -0000	1.7
+++ linux-fork.c	5 Aug 2006 15:49:45 -0000
@@ -366,7 +366,8 @@ linux_fork_mourn_inferior (void)
      only report its exit status to its original parent.  */
   int status;
 
-  waitpid (ptid_get_pid (inferior_ptid), &status, 0);
+  if (! ptid_equal (inferior_ptid, null_ptid) && target_has_execution)
+    waitpid (ptid_get_pid (inferior_ptid), &status, 0);
 
   /* OK, presumably inferior_ptid is the one who has exited.
      We need to delete that one from the fork_list, and switch
Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-thread-db.c,v
retrieving revision 1.19
diff -u -p -r1.19 linux-thread-db.c
--- linux-thread-db.c	2 Aug 2006 10:24:00 -0000	1.19
+++ linux-thread-db.c	5 Aug 2006 15:50:49 -0000
@@ -884,6 +884,10 @@ thread_db_wait (ptid_t ptid, struct targ
       return pid_to_ptid (GET_PID (ptid));
     }
 
+  /* Threading structures got reset.  Return as nonthreaded.  */
+  if (ourstatus->kind == TARGET_WAITKIND_EXECD)
+    return pid_to_ptid (GET_PID (ptid));
+
   if (ourstatus->kind == TARGET_WAITKIND_STOPPED
       && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
     /* Check for a thread event.  */
@@ -975,6 +979,9 @@ thread_db_mourn_inferior (void)
      the inferior, so that we don't try to uninsert them.  */
   remove_thread_event_breakpoints ();
 
+  /* Destroy thread info; it's no longer valid.  */
+  init_thread_list ();
+
   /* Detach thread_db target ops.  */
   unpush_target (&thread_db_ops);
   using_thread_db = 0;
Index: testsuite/gdb.base/foll-exec.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/foll-exec.exp,v
retrieving revision 1.2
diff -u -p -r1.2 foll-exec.exp
--- testsuite/gdb.base/foll-exec.exp	6 Mar 2001 08:21:50 -0000	1.2
+++ testsuite/gdb.base/foll-exec.exp	5 Aug 2006 15:50:50 -0000
@@ -45,12 +45,6 @@ if  { [gdb_compile "${srcdir}/${subdir}/
 }
 
 
-# Until "catch exec" is implemented on other targets...
-#
-if ![istarget "hppa*-hp-hpux*"] then {
-    continue
-}
-
 proc zap_session {} {
    global gdb_prompt
    global binfile
@@ -212,7 +206,9 @@ proc do_exec_tests {} {
    setup_xfail hppa2.0w-hp-hpux* CLLbs16760
    send_gdb "continue\n"
    gdb_expect {
-     -re ".*Executing new program:.*${testfile2}.*Catchpoint .*(exec\'d .*${testfile2}).*in .START..*$gdb_prompt $"\
+     # It is OS dependent and no symbols may be found, GNU/Linux has "_start"
+     # while HP-UX has " in .START..*$gdb_prompt" etc.
+     -re ".*Executing new program:.*${testfile2}.*Catchpoint .*(exec\'d .*${testfile2}).*in .*$gdb_prompt $"\
                      {pass "hit catch exec"}
      -re "$gdb_prompt $" {fail "hit catch exec"}
      timeout         {fail "(timeout) hit catch exec"}