signal 0 command

["Seong-Kook Shin" <cinsky at gmail dot com>]

Hi.

While reading the gdb info manual, I found the  paragraph saying:

     Alternatively, if SIGNAL is zero, continue execution without
     giving a signal.  This is useful when your program stopped on
     account of a signal and would ordinary see the signal when resumed
     with the `continue' command; `signal 0' causes it to resume
     without a signal.

If I understand correctly, I can issue "signal 0" to ignore the current
signal GDB caught, right?  So I made a simple program to raise SIGSEGV:

void
foo(const char *str)
{
  char *p = 0;     /* This should be "char *p = str" */

  while (*p != '\0') {
    /* do something */
    p++;
  }
}

After reading the manual, I thought that it is possible to
undo the generation of SIGSEGV after modifying the value `p'.
But when I set the value of `p' corrently, and execute "signal 0",
I can still see the SIGSEGV is generated.

$ gdb -q a.out
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) r
Starting program: /home/cinsk/pesticide/a.out

Program received signal SIGSEGV, Segmentation fault.
0x08048399 in foo (str=0x80484b8 "hello, world") at segv.c:8
8	  while (*p != '\0') {
(gdb) p p
$1 = 0x0
(gdb) p p = str
$2 = 0x80484b8 "hello, world"
(gdb) signal 0
Continuing with no signal.

Program received signal SIGSEGV, Segmentation fault.
0x08048399 in foo (str=0x80484b8 "hello, world") at segv.c:8
8	  while (*p != '\0') {
(gdb) _

Am I missing something?  If I misunderstand the meaning of "signal 0" command,
please let me know.  (A short example session would be great!!)

Thanks in advance.

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