OT: Crazy C Problem

From: Jeffrey Sharp <jss_at_subatomix.com>
Date: Sun Jan 19 03:02:00 2003

BTW, the code in question can be seen at:


On Sunday, January 19, 2003, Jeffrey Sharp wrote:
> I'm testing the code I've written to spamproof the ClassicCmp web site and
> archives. I call the system SpamCamo. The file filter works great and
> produces links as it should. The CGI program is not behaving and is giving
> me some *very* wierd behavior. I'm stumped.
> First, if I compile with this:
> $ cc -o spamcamo.cgi cgi.c spamcamo.cgi.c -lcipher
> I get a "Bus error (core dumped)" exception from the first statement in my
> program, which is printf("DEBUG: 0\n"). I have used gdb to verify this,
> and it tells me that SIGBUS is occuring inside isatty() in libc.
> Now, if I compile like this, switching the order of the source files but
> making NO changes to the source files themselves:
> $ cc -o spamcamo.cgi spamcamo.cgi.c cgi.c -lcipher
> The program proceeds to the first call of strdup(), which returns NULL and
> sets errno to EINVAL. strdup() is definitely receiving a valid string.
> Furthermore, malloc(1) (as in "allocate one byte") in the same place also
> fails with EINVAL. The machine is not low on memory. Even furthermore, the
> code that is failing in this case (in cgi.c) works correctly when compiled
> against a test program (proof: http://www.subatomix.com/test_cgi.cgi?a=b)
> instead of spamcamo.cgi.c. This is what the program does (i.e. not much)
> before calling strdup():
> printf()
> function call
> function call
> getenv()
> return
> strcmp()
> funcion call
> getenv()
> return
> strdup() <--- SIGBUS occurs here
> I get the same results on two FreeBSD boxen. One is running 4.5-RELEASE and
> the other is running 4.6-STABLE. I'd like to think this is something I've
> done wrong and not a bug in libc. Any ideas?

Jeffrey Sharp
Received on Sun Jan 19 2003 - 03:02:00 GMT

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