site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com On Jan 31, 2008, at 7:42 PM, Anton Rang wrote: - Kevin _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... On Jan 31, 2008, at 6:52 PM, Edd Dawson wrote: int main(void) { ucontext_t ctx; getcontext(&ctx); return 0; } edd:guff developer$ gcc getcontext.c -o getcontext -W -Wall -ansi - pedantic edd:guff developer$ ./getcontext Bus error edd:guff developer$ Why the bus error? What am I doing wrong? This is a known issue where getcontext(3) is writing past the end of the ucontext_t struct when _XOPEN_SOURCE is not defined (rdar://problem/5578699 ). As a workaround, define _XOPEN_SOURCE before including ucontext.h. While I don't understand why you're getting a bus error (haven't looked at the library source), the problem appears to go away if you declare ctx as a global instead of on the stack. Perhaps getcontext() just won't let you save context onto the stack.... The buffer overflow that wipes out the return address, causing the bus error. By using a global, the memory corruption still occurs, but doesn't manifest itself as a bus error with main() returning so quickly. This email sent to site_archiver@lists.apple.com