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What make the directive run twice?
- From: Jason Luo <jasonl at turbolinux dot com dot cn>
- To: gdb at sources dot redhat dot com
- Date: Thu, 03 Jun 2004 15:07:59 +0800
- Subject: What make the directive run twice?
Hi all,
I use gdb 6.1 to debug Grub 0.94.When I debug the function check_device
in lib/device.c,I found that the fopen directive was run twice.
[root@jason build]# gdb grub/grub
.........
(gdb) b device.c:617
Breakpoint 1 at 0x805dc29: file ../../lib/device.c, line 617.
(gdb) r
Starting program: /home/jason/sources/grub-0.94/build/grub/grub
Probing devices to guess BIOS drives. This may take a long time.
Breakpoint 1, init_device_map (map=0x806609c, map_file=0xbfffd350 "",
floppy_disks=1)
at ../../lib/device.c:617
617 get_ide_disk_name (name, i);
(gdb) n
618 if (check_device (name))
(gdb) s //here,I step in check_device
check_device (device=0xbfffd350 "/dev/hda") at ../../lib/device.c:321
321 if (*device == 0)
(gdb) p device
$1 = 0xbfffd350 "/dev/hda"
(gdb) n
324 fp = fopen (device, "r");
(gdb)
325 if (! fp)
(gdb)
346 return 0; //return from here,but...
(gdb)
324 fp = fopen (device, "r"); //come to here!!!
(gdb) p device
$2 = 0x8073860 "\210$?" //the parameter device was changed!!!!
(gdb) n
346 return 0; //return from here,but
(gdb)
353 if (ioctl (fileno (fp), CDROM_GET_CAPABILITY, 0) >= 0)
(gdb)
When this section in gdb,the process is not correct and the device
parameter of check_device function was changed.
what cause it?How can I do it?
My env is gcc 3.3.1,glibc 2.3.2,Intel(R) Pentium(R) 4 CPU 2.60GHz with HT.
Jason