pending/969: [RFA] Copy the command lines and value when copying a bpstat.

[Klee Dienes <klee at apple dot com>]

>Number:         969
>Category:       pending
>Synopsis:       [RFA] Copy the command lines and value when copying a bpstat.
>Confidential:   yes
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   unknown
>Arrival-Date:   Thu Jan 30 03:28:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     
>Release:        
>Organization:
>Environment:
>Description:
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 If you try to call a function in the inferior from user-defined 
 breakpoint commands, GDB crashes:
 
 $ ./gdb -nx -q ./gdb
 (gdb) break main
 Breakpoint 1 at 0x8074686: file 
 ./../../source/cygnus.cygnus/gdb/gdb.c, line 29.
 (gdb) commands
 Type commands for when breakpoint 1 is hit, one per line.
 End with a line saying just "end".
  >print (int) printf ("bobo\n")
  >end
 (gdb) run
 Starting program: /home/klee/build/cygnus.cygnus/gdb/gdb
 
 Breakpoint 1, main (argc=1, argv=0xbfffea34) at 
 ./../../source/cygnus.cygnus/gdb/gdb.c:29
 29        memset (&args, 0, sizeof args);
 
 Program received signal SIGSEGV, Segmentation fault.
 0x0807a246 in free_command_lines (lptr=0x18) at 
 ./../../source/cygnus.cygnus/gdb/cli/cli-script.c:983
 
 I believe this problem was introduced in the changes to breakpoint.c on 
 2002-08-26 --- the problem is that stop_bpstat gets cleared as part of 
 the cleanup after hand_function_call, which now includes removing the 
 commands data.  But unfortunately, it's restored by 
 restore_inferior_status, including a pointer to now-obsolete commands, 
 which eventually causes the crash in free_command_lines.
 save_inferior_status tries to "do the right thing," by making a copy of 
 stop_bpstat, but unfortunately, stop_bpstat only does a shallow copy, 
 not a deep one.
 
 The following patch updates stop_bpstat to do a deep copy of the 
 commands and the old watchpoint value.  It doesn't copy the breakpoint, 
 since I suspect this is supposed to just be a reference, and it's not 
 freed in clear_bpstat.
 
 2002-10-29  Klee Dienes  <kdienes@apple.com>
 
          * breakpoint.c (bpstat_copy): Copy the command lines as well
           as the old value, to match what is freed in bpstat_clear.
 
 
          * Makefile.in: Rename INTL_DEPS to INTL_DEP, to match other 
 variable names.
 Index: breakpoint.c
 ===================================================================
 RCS file: /cvs/Darwin/src/live/cygnus/src/gdb/breakpoint.c,v
 retrieving revision 1.48
 diff -u -r1.48 breakpoint.c
 --- breakpoint.c        2002/10/26 09:20:12     1.48
 +++ breakpoint.c        2002/10/30 09:01:01
 @@ -1844,6 +1844,10 @@
       {
         tmp = (bpstat) xmalloc (sizeof (*tmp));
         memcpy (tmp, bs, sizeof (*tmp));
 +      if (bs->commands != NULL)
 +       tmp->commands = copy_command_lines (bs->commands);
 +      if (bs->old_val != NULL)
 +       tmp->old_val = value_copy (bs->old_val);
         if (p == NULL)
          /* This is the first thing in the chain.  */
          retval = tmp;
 
 This patch adds a check for calls to the inferior to the testsuite.  
 The first part is straightforward --- it adds a call to the inferior to 
 the initial "silent" breakpoint check, and checks for the correct 
 output from it.  The second part, I'm less sure about:  it makes a 
 second call to marker2(), after setting breakpoint commands on it to 
 call the inferior as well.  Currently, these commands aren't hit (and 
 the test fails).  I'm appending the test-suite part of the patch as an 
 attachment, because, as you all know, my mailer is officially weird.
 
 2002-10-29  Klee Dienes  <kdienes@apple.com>
 
         * gdb.base/break.exp: Add multiple calls to the inferior in
          the user-commands for 'break 79'.  Add a check for the calls
          to the inferior in the check for the result.  Add new test, to
          check that user-defined breakpoint commands are called for 
 functions
         called by the user (currently fails).
 
 
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 Index: testsuite/gdb.base/break.exp
 ===================================================================
 RCS file: /cvs/Darwin/src/live/cygnus/src/gdb/testsuite/gdb.base/break.exp,v
 retrieving revision 1.3
 diff -u -r1.3 break.exp
 --- break.exp	2002/08/13 20:06:14	1.3
 +++ break.exp	2002/10/30 09:01:25
 @@ -440,7 +440,9 @@
  }
  
  # Verify that a "silent" breakpoint can be set, and that GDB is indeed
 -# "silent" about its triggering.
 +# "silent" about its triggering.  Include multiple nested calls to the
 +# inferior in the user-commands for the breakpoint, to verify that the
 +# cleanup code isn't trashing stop_bpstat.
  #
  if ![runto_main] then { fail "break tests suppressed" }
  
 @@ -455,6 +457,7 @@
  
  send_gdb "commands $expect_out(1,string)\n"
  send_gdb "silent\n"
 +send_gdb "call (int) printf (\"PREFIXbobo\\n\" + (int) strlen (\"PREFIXbobo\\n\") - 5)\n"
  send_gdb "end\n"
  gdb_expect {
    -re ".*$gdb_prompt $"\
 @@ -472,7 +475,7 @@
  }
  send_gdb "continue\n"
  gdb_expect {
 -  -re "Continuing.\r\n$gdb_prompt $"\
 +  -re "Continuing.\r\nbobo\r\n\\\$\[0-9\]* = 5\r\n$gdb_prompt $"\
            {pass "hit silent break 79"}
    -re "$gdb_prompt $"\
            {fail "hit silent break 79"}
 @@ -602,6 +605,13 @@
            {fail "set breakpoint on to-be-called function"}
    timeout {fail "(timeout) set breakpoint on to-be-called function"}
  }
 +
 +# save the breakpoint identifier for future use
 +#
 +set marker2_bpnum $expect_out(1,string)
 +
 +# Call the function.
 +#
  send_gdb "print marker2(99)\n"
  gdb_expect {
    -re "The program being debugged stopped while in a function called from GDB.\r\nWhen the function .marker2$proto. is done executing, GDB will silently\r\nstop .instead of continuing to evaluate the expression containing\r\nthe function call...*$gdb_pr ompt $"\
 @@ -626,6 +636,46 @@
      -re "$gdb_prompt $"\
              {fail "backtrace while in called function"}
      timeout {fail "(timeout) backtrace while in called function"}
 +}
 +
 +# Return from the called function.  For remote targets, it's important to do
 +# this before runto_main, which otherwise may silently stop on the dummy
 +# breakpoint inserted by GDB at the program's entry point.
 +#
 +send_gdb "finish\n"
 +gdb_expect {
 +    -re "Run till exit from .*marker2.* at .*4\[49\]\r\n.* in _sr4export.*$gdb_prompt $"\
 +            {pass "finish from called function"}
 +    -re "Run till exit from .*marker2.* at .*4\[49\]\r\n.*function called from gdb.*$gdb_prompt $"\
 +            {pass "finish from called function"}
 +    -re "Run till exit from .*marker2.* at .*4\[49\]\r\n.*Value returned.*$gdb_prompt $"\
 +            {pass "finish from called function"}
 +    -re "$gdb_prompt $"\
 +            {fail "finish from called function"}
 +    timeout {fail "(timeout) finish from called function"}
 +}
 +
 +# Add a user-command that calls the inferior to the breakpoint for marker2.
 +#
 +send_gdb "commands $marker2_bpnum\n"
 +send_gdb "silent\n"
 +send_gdb "call (int) printf (\"PREFIXbobo\\n\" + (int) strlen (\"PREFIXbobo\\n\") - 5)\n"
 +send_gdb "end\n"
 +gdb_expect {
 +  -re ".*$gdb_prompt $"\
 +          {pass "set printf break marker2"}
 +  timeout {fail "(timeout) set printf break marker2"}
 +}
 +
 +# Call the function again.
 +#
 +send_gdb "print marker2(99)\n"
 +gdb_expect {
 +    -re "The program being debugged stopped while in a function called from GDB.\r\nWhen the function .marker2$proto. is done executing, GDB will silently\r\nstop .instead of continuing to evaluate the expression containing\r\nthe function call...*bobo. *$gdb_prompt $"\
 +	{pass "called user-defined function on breakpoint in called function"}
 +    -re "$gdb_prompt $"\
 +	{fail "called user-defined function on breakpoint in called function"}
 +    timeout {fail "called user-defined function on breakpoint in called function"}
  }
  
  # Return from the called function.  For remote targets, it's important to do
 
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