FreeBSD manual

download PDF document: unw_backtrace.3.pdf

UNW_BACKTRACE(3libunwind) Programming Library UNW_BACKTRACE(3libunwind) NAME unw_backtrace -- return backtrace for the calling program SYNOPSIS #include <libunwind.h> int unw_backtrace(void **buffer, int size); int unw_backtrace2(void **buffer, int size, unw_context_t *ctxt, int flag); #include <execinfo.h> int backtrace(void **buffer, int size); DESCRIPTION unw_backtrace() is a convenient routine for obtaining the backtrace for the calling program. The routine fills up to size addresses in the array pointed by buffer. The routine is only available for local unwinding. Note that many (but not all) systems provide a practically identical function called backtrace(). The prototype for this function is usually obtained by including the <execinfo.h> header file -- a prototype for backtrace() is not provided by libunwind. libunwind weakly aliases backtrace() to unw_backtrace(), so when a program calling backtrace() is linked against libunwind, it may end up calling unw_backtrace(). In case you want to obtain the backtrace from a specific unw_context_t, you can call unw_backtrace2 with that context passing 0 for flag. If the unw_context_t is known to be a signal frame (i.e., from the third argument in a sigaction handler on linux), unw_backtrace2 can be used to collect only the frames before the signal frame passing the UNW_INIT_SIGNAL_FRAME flag. RETURN VALUE The routine returns the number of addresses stored in the array pointed by buffer. The return value may be zero to indicate that no addresses were stored. SEE ALSO libunwind(3libunwind), unw_step(3libunwind) AUTHOR David Mosberger-Tang Email: dmosberger@gmail.com WWW: http://www.nongnu.org/libunwind/. Programming Library 29 August 2023 UNW_BACKTRACE(3libunwind)