Date: Fri, 4 Jan 2002 03:52:23 -0600 (CST) From: Sean Kelly <smkelly@zombie.org> To: FreeBSD-gnats-submit@freebsd.org Subject: bin/33584: 'gcc -ggdb' doesn't work with GDB Message-ID: <20020104095223.E972566B04@edgemaster.zombie.org>
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>Number: 33584
>Category: bin
>Synopsis: 'gcc -ggdb' doesn't work with GDB
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Jan 05 14:10:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: Sean Kelly
>Release: FreeBSD 4.5-PRERELEASE i386
>Organization:
>Environment:
System: FreeBSD edgemaster.zombie.org 4.5-PRERELEASE FreeBSD 4.5-PRERELEASE #0: Tue Dec 25 03:26:19 CST 2001 root@edgemaster.zombie.org:/usr/obj/usr/src/sys/EDGEMASTER i386
gcc 2.95.3
gdb 4.18
>Description:
According to the 'gcc' manpage, there is a '-ggdb' flag which adds
more debugging information to the compiled binary. However, when
one attempts to use 'gdb' on a binary compiled with -ggdb, oddities
occur when dealing with pointers.
>How-To-Repeat:
Compile this code with '-ggdb':
#include <stdio.h>
int pointtest(char *arg)
{
printf("pointtest(\"%s\")\n", arg);
return 1;
}
int main(int argc, char *argv[])
{
char *x = (char *)malloc(512);
printf("argc=%d, argv=%X\n", argc, argv);
strcpy(x, "Got Milk?");
pointtest(x);
return 0;
}
Then 'gdb' it:
$ gcc -ggdb -o gdbtest gdbtest.c
$ gdb gdbtest
(gdb) break main
Breakpoint 1 at 0x804855e
(gdb) run
*keep 'step'ping through*
13 strcpy(x, "Got Milk?");
(gdb) step
14 pointtest(x);
* BAD BEHAVIOR FOLLOWS *
(gdb) print x
$1 = 0xbfbffbac "\210ü¿¿"
(gdb) print *x
$2 = -120 '\210'
(gdb) step
pointtest (arg=0xbfbffb58 "¤û¿¿¡\204\004\b\001") at gdbtest.c:5
5 printf("pointtest(\"%s\")\n", arg);
(gdb) step
pointtest("Got Milk?")
So it is clear that the program is working right, but gdb is totally broken
when dealing with the pointers in the program.
>Fix:
Wish I knew.
>Release-Note:
>Audit-Trail:
>Unformatted:
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