Problems debugging forked processes

[Frank Schaefer]

Hi there,

I've written a network daemon and client. The daemon forks to serve a
client request.
Everything runs fine outside of the debugger, but I want to trace the
code at least once, before I release it.

Here goes my problem:
# gdb daemon
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This GDB was configured as "i686-pc-linux-gnu"...
(gdb) b 13
Breakpoint 1 at 0x8048899: file daemon.c, line 13.
(gdb) show follow-fork-mode
Debugger response to a program call of fork or vfork is "parent".
(gdb) set follow-fork-mode child
(gdb) show follow-fork-mode
Debugger response to a program call of fork or vfork is "child".
(gdb) run
Starting program: /v_dsk/home/p10209/Tests/daemon 

Breakpoint 1, main () at syncboot.c:15
15      int                On = 1;
(gdb) n
...
(gdb) n
67   ChildPid = fork();
(gdb) n
69      sleep( 10 );
(gdb) print ChildPid
$1 = 3700

So it seems, I'm tracing the parent process - don't it? The same
happens, If I do:
	(gdb) set follow-fork-mode ask
instead of child. I'm not asked anything and remain debugging the
parent.

If I use the attach method from a second instance of gdb ( there's the
sleep() above for ), the child process exits on exceptions ( mostly
segmentation fault and sometimes invalid operation ) on different
(random???) lines in the code. This happens everytime in the fixup()
from ld.linux.so.

I'm using gdb 5.0, my compiler is gcc 2.95.3 on a glibc-2.2.4
linux-2.4.16 system. I have Binutils 2.11 installed.

Furtheron I've attached reduced versions of the code, for which the
fault still occurs.

Any suggestions?

Regards
Frank
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