% gdb /Developer/Tools/otest 2008-10-31 19:29:50.834 otest[711:813] Error loading /blah/blah/blah/build/Debug/Tests.octest/Contents/MacOS/Tests: dlopen(/blah/blah/blah/build/Debug/Tests.octest/Contents/MacOS/Tests, 265): no suitable image found. Did find: /blah/blah/blah/build/Debug/Tests.octest/Contents/MacOS/Tests: mach-o, but wrong architecture 2008-10-31 19:29:50.887 otest[711:813] The test bundle at build/Debug/Tests.octest could not be loaded because it is built for a different architecture than the currently-running test rig (which is running as unknown). 2008-10-31 19:29:50.904 otest[714:203] *** NSTask: Task create for path '/blah/blah/blah/build/Debug/Tests.octest/Contents/MacOS/Tests' failed: 8, "Exec format error". Terminating temporary process.You can supply a -arch flag to pick what you want:
% gdb -arch i386 /Developer/Tools/otestAnd then debug your 32-bit unit test.
Borkdoku(11062,0xcec0600) malloc: *** error for object 0xd109010: incorrect checksum for freed object - object was probably modified after being freed, break at szone_error to debugWhich is fine and dandy, but it lies. I've never gotten
szone_errorto actually do anything. Try breaking on
2007-05-05 17:18:00.702 QueenStitcher[2804:117] *** Assertion failure in -[NSColorWell setColor:], NSColorWell.m:497, u suk l0s3r, and then the runloop happily runs again, giving you no clue where the problem is. I tell
gdbto always break on Cocoa exceptions:
fb -[NSException raise] fb objc_exception_throw()For maximal enjoyment, add these two lines to your
~/.gdbinitfile, so they'll get set no matter how you invoke
gdb(no need to add these to every single project, for instance).
I've been told VoiceOver uses exceptions heavily, so if you're doing VoiceOver development, these breaks may cause you pain.
'bork'. You can have gdb print them out if you need to look at one or two of them:
(gdb) print/T 1936746868 $4 = 'spit'(thanks to Daniel Jalkut for the print/T trick)
(gdb) po *(int*)($ebp+8)
(gdb) x /80xb attrBufferwill give you something like
0x7fff5fbfeeb0: 0x14 0x00 0x00 0x00 0xdb 0x0b 0x19 0x4c 0x7fff5fbfeeb8: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x7fff5fbfeec0: 0x00 0x00 0x00 0x00 0xec 0xc8 0x62 0xe5 0x7fff5fbfeec8: 0xc7 0x48 0x18 0xd2 0xe7 0x9e 0x88 0xd8 0x7fff5fbfeed0: 0xd9 0x60 0x9f 0x61 0xea 0x37 0x3b 0x0c 0x7fff5fbfeed8: 0x87 0x1b 0x4e 0x7e 0x6a 0x26 0x98 0x62 0x7fff5fbfeee0: 0x6d 0x01 0xed 0xed 0x17 0x6d 0xae 0x05 0x7fff5fbfeee8: 0xe7 0x22 0xd0 0x96 0x33 0x34 0x16 0x1a 0x7fff5fbfeef0: 0x17 0xa7 0x87 0xb2 0x76 0x7b 0x29 0x0b 0x7fff5fbfeef8: 0xea 0x51 0x4c 0x45 0x4f 0x45 0x65 0x88
(gdb) handle SIGTRAP nostop
The signal still goes to your program. Another handy option is 'ignore' to prevent it coming to the program. Also there is 'print' to print a message go on.
-waitfor option to make gdb lie in wait for a launching process:
% gdb /some/app/blah (gdb) attach -waitfor blahNow when a
blahprocess launches, gdb will stop it and attach to it.
$r3and go up from there. For Objective-C method sends,
$r3has 'self', and
$r4has the name of the method. Subsequent arguments are in
$5and so on.
(gdb) print (char*) $r4 $5 = 0x90874160 "drawRect:" (gdb) po $r5 <BWStitchView: 0x1a6670>
(gdb) print (int)[theObject retainCount]
If you're expecting to have an excessively high number of retains, you can use
(unsigned int) in the cast. I find
(int) a skootch faster to type.
.gdbinitand then you can use
define wchar_print echo " set $i = 0 while (1 == 1) set $c = (char)(($arg0)[$i++]) if ($c == '\0') loop_break end printf "%c", $c end echo " end document wchar_print wchar_print <wstr> Print ASCII part of <wstr>, which is a wide character string of type wchar_t*. end
info selectorswill show you all of the selectors in the application's symbol table.
info functionswill show you all of the functions. You can supply regular expressions to limit the output.
libgmallocputs guard pages at the end of malloc'd blocks of memory, letting you catch buffer overruns. (This will hugely inflate your program's working set, and may lead to swapping) To turn on
libgmallocin gdb, do this:
(gdb) set env DYLD_INSERT_LIBRARIES /usr/lib/libgmalloc.dylib
(gdb) call (void)[textField setStringValue: @"Bork"]
(gdb) call (id) objc_getClass("NSBundle") $1 = (struct objc_object *) 0xa0a051d8 gdb) call (id)[$1 bundleWithPath:@"/blah/blah/PoseAsClassBundle.bundle"] $2 = (struct objc_object *) 0x51467e0 (gdb) call (BOOL)[$2 load] Reading symbols for shared libraries . done