[PATCH 0/1] Fix internal warning when "gdb -p xxx"

[Hui Zhu <hui_zhu@mentor.com>]

ps -e | grep a.out
28886 pts/12   00:00:00 a.out
gdb -p 28886
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x0000003b0ccbc970 in __nanosleep_nocancel () from /lib64/libc.so.6
../../binutils-gdb/gdb/cleanups.c:265: internal-warning: restore_my_cleanups has found a stale cleanup
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)

The backtrace of this issue:
(gdb) bt
#0  0x0000003b0cc35c39 in raise () from /lib64/libc.so.6
#1  0x0000003b0cc37348 in abort () from /lib64/libc.so.6
#2  0x00000000006fdd38 in dump_core () at ../../binutils-gdb/gdb/utils.c:589
#3  0x00000000006fe039 in internal_vproblem (problem=0xcbdc90 <internal_warning_problem>,
     file=0x8b0c10 "s' failed.", line=265, fmt=0x8b0c38 "nutils-gdb/gdb/cleanups.c",
     ap=0x7fff803e3ed8) at ../../binutils-gdb/gdb/utils.c:748
#4  0x00000000006fe19c in internal_vwarning (file=0x8b0c10 "s' failed.", line=265,
     fmt=0x8b0c38 "nutils-gdb/gdb/cleanups.c", ap=0x7fff803e3ed8)
     at ../../binutils-gdb/gdb/utils.c:799
#5  0x00000000006fe246 in internal_warning (file=0x8b0c10 "s' failed.", line=265,
     string=0x8b0c38 "nutils-gdb/gdb/cleanups.c") at ../../binutils-gdb/gdb/utils.c:809
#6  0x000000000057da3d in restore_my_cleanups (pmy_chain=0xcba518 <cleanup_chain>, chain=0x14ec030)
     at ../../binutils-gdb/gdb/cleanups.c:265
#7  0x000000000057da67 in restore_cleanups (chain=0x14ec030)
     at ../../binutils-gdb/gdb/cleanups.c:276
#8  0x00000000005f0dc7 in catcher_pop () at ../../binutils-gdb/gdb/exceptions.c:116
#9  0x00000000005f0e62 in exceptions_state_mc (action=CATCH_ITER)
     at ../../binutils-gdb/gdb/exceptions.c:142
#10 0x00000000005f0fe6 in exceptions_state_mc (action=CATCH_ITER)
     at ../../binutils-gdb/gdb/exceptions.c:203
#11 0x00000000005f18ed in catch_command_errors (
     command=0x5d5fb8 <attach_command_continuation_free_args+18>, arg=0x7fff803e525b "2914",
     from_tty=1, mask=RETURN_MASK_ALL) at ../../binutils-gdb/gdb/exceptions.c:549
---Type <return> to continue, or q <return> to quit---
#12 0x00000000005f5ed7 in captured_main (data=0x7fff803e4280) at ../../binutils-gdb/gdb/main.c:968
#13 0x00000000005f180b in catch_errors (func=0x5f501c <VEC_cmdarg_s_safe_push+43>,
     func_args=0x7fff803e4280, errstring=0x8cf2e4 "/local/bin", mask=RETURN_MASK_ALL)
     at ../../binutils-gdb/gdb/exceptions.c:522
#14 0x00000000005f6180 in gdb_main (args=0x7fff803e4280) at ../../binutils-gdb/gdb/main.c:1061
#15 0x000000000045d087 in main (argc=3, argv=0x7fff803e4388) at ../../binutils-gdb/gdb/gdb.c:33

This is a new issue.  It is introduced by commit https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=8bc2fe488957946d2cdccda3ce8d4f39e4003ea0
It removed the discard_cleanups (back_to) inside attach_command.
Then restore_my_cleanups will throw a internal_warning.

The most of the pid_to_exec_file target_ops method for some platforms will
allocate memory for exec_file and add them to cleanup.
So I add a null cleanup to attach_command_post_wait to fix this issue.

It is tested and and passed regression test in x86_64-linux.

Thanks,
Hui

2014-03-17  Hui Zhu  <hui@codesourcery.com>

	* infcmd.c (attach_command_post_wait): Add null_cleanup.

--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -2337,6 +2337,7 @@ attach_command_post_wait (char *args, in
    char *exec_file;
    char *full_exec_path = NULL;
    struct inferior *inferior;
+  struct cleanup *back_to = make_cleanup (null_cleanup, NULL);
  
    inferior = current_inferior ();
    inferior->control.stop_soon = NO_STOP_QUIETLY;
@@ -2421,6 +2422,12 @@ attach_command_post_wait (char *args, in
        if (deprecated_attach_hook)
  	deprecated_attach_hook ();
      }
+
+  /* The pid_to_exec_file target_ops method for some platforms will
+     allocate memory for exec_file and add them to cleanup.
+     Release them in here because function attach_command will be call
+     by function captured_main too.  */
+  do_cleanups (back_to);
  }
  
  struct attach_command_continuation_args