From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fernando Nasser To: Matt Schalit Cc: gdb@sourceware.cygnus.com Subject: Re: Need help with a backtrace Date: Thu, 15 Feb 2001 12:56:00 -0000 Message-id: <3A8C4285.674CE905@cygnus.com> References: <3A883607.BF2396E4@pacbell.net> <3A883F3C.6DB5C98D@cygnus.com> <3A888BCA.84305AE1@pacbell.net> <3A8BE44D.799A6BF4@redhat.com> <3A8C27A6.73CA238D@pacbell.net> X-SW-Source: 2001-02/msg00185.html Matt Schalit wrote: > > In general, when a backtrace gives a really meager output > like the following: > > > > (gdb) file /usr/local/cgi-bin/convert > > > (gdb) run > > > Program received signal SIGSEGV, Segmentation fault. > > > 0x80016d76 in ?? () from /usr/lib/libc.so.1 > > > (gdb) bt > > > #0 0x80016d76 in ?? () from /usr/lib/libc.so.1 > > > #1 0x80016c5c in ?? () from /usr/lib/libc.so.1 > > > #2 0x8001826d in ?? () from /usr/lib/libc.so.1 > > > #3 0x8001932d in ?? () from /usr/lib/libc.so.1 > > > #4 0x80014b20 in ?? () from /usr/lib/libc.so.1 > > and that's all the lines it output, am I supposed to > put breakpoints into my convert program to see when > it makes a call to a libc function? I can't understand > why there's so little info nor why it left out the function > values. > These addresses are inside the libc.so that was probably compiled without debugging symbols. That is why the debugger cannot give you more information. Unless you are dealing with a bug in libc (very unlikely), just forget about these lines and check how your program called the library function. Probably it called it with a bad argument and causes the crash. -- Fernando Nasser Red Hat - Toronto E-Mail: fnasser@redhat.com 2323 Yonge Street, Suite #300 Toronto, Ontario M4P 2C9