Comments on: Apple’s GDB Bug ?

By: Singh

Singh — Sun, 13 Jun 2010 08:24:05 +0000

This is quite annoying. Here is an expect script to allow you to type “gdb file” and allow global variables to work:

$ cat gdbx
#!/usr/bin/expect
spawn gdb
expect “(gdb) ”
send “exec-file [lindex $argv 0]\n”
interact

$ ./gdbx /bin/ls
spawn gdb
GNU gdb 6.3.50-20050815 (Apple version gdb-962) (Sat Jul 26 08:14:40 UTC 2008)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type “show copying” to see the conditions.
There is absolutely no warranty for GDB. Type “show warranty” for details.
This GDB was configured as “i386-apple-darwin”.
(gdb) exec-file /bin/ls
Reading symbols for shared libraries …. done
(gdb) b *0x000023f0
Breakpoint 1 at 0x23f0
(gdb) r
Starting program: /bin/ls
Reading symbols for shared libraries ….. done

Breakpoint 1, 0x000023f0 in ?? ()
$1 = “test”
$2 = 10
$3 = 20
(gdb)

By: fG!

fG! — Fri, 10 Apr 2009 00:06:10 +0000

Sorry for my delay… Problem must be with gdb.
Check the following:

$ gdb /bin/ls
GNU gdb 6.3.50-20050815 (Apple version gdb-768) (Sun Mar 22 01:47:54 UTC 2009)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type “show copying” to see the conditions.
There is absolutely no warranty for GDB. Type “show warranty” for details.
This GDB was configured as “i386-apple-darwin”…Reading symbols for shared libraries …. done

(gdb) b *0x000023f0
Breakpoint 1 at 0x23f0
(gdb) r
Starting program: /bin/ls
Reading symbols for shared libraries +++. done

Breakpoint 1, 0x000023f0 in ?? ()
$1 = “test”
$2 = 10
$3 = void
(gdb) q
The program is running. Exit anyway? (y or n) y

$ gdb
GNU gdb 6.3.50-20050815 (Apple version gdb-768) (Sun Mar 22 01:47:54 UTC 2009)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type “show copying” to see the conditions.
There is absolutely no warranty for GDB. Type “show warranty” for details.
This GDB was configured as “i386-apple-darwin”.
(gdb) exec-file /bin/ls
Reading symbols for shared libraries …. done
(gdb) b *0x000023f0
Breakpoint 1 at 0x23f0
(gdb) r
Starting program: /bin/ls
Reading symbols for shared libraries .+++. done

Breakpoint 1, 0x000023f0 in ?? ()
$1 = “test”
$2 = 10
$3 = 20
(gdb)

This is the .gdbinit I used to test:
$ cat .gdbinit
set $globalvariable = 20
define bugtest
set $bugtest = 10
print $bugtest
end

define hook-stop
print “test”
bugtest
print $globalvariable
end

As you can see it doesn’t support global variables if you use a gdb /bin/ls from the command line, only if you load gdb without parameters and then point to the target using exec-file.

By: john doe

john doe — Wed, 08 Apr 2009 20:28:39 +0000

I have mammon’s gdbinit 6.1 working fine here
(10.5.6 intel, gdb 6.3.50-20050815 ) so i think
the problem lies somewhere else.

FYI the following works fine:

define bugtest
set $bugtest = 10
output $bugtest
end

no matter if i run gdb without args etc

By: Mike Myers

Mike Myers — Thu, 19 Mar 2009 20:16:35 +0000

I wish I had a list of ways in which the GDB on OS X doesn’t do what GDB on other platforms does. So far I have run into two ways (it won’t “find” things across a process’s memory, and it won’t “catch” the loading/unloading of libraries). And I’ve only been using it for a few weeks so who knows how many other ways it is broken.

By: firstsingle

firstsingle — Mon, 02 Mar 2009 22:05:11 +0000

Thanks!
At least I have some clue why I’m getting this error message.