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.Dd February 15, 2007 .Dt backtrace 3 .Os "Mac OS X" .Sh NAME .Nm backtrace , .Nm backtrace_symbols , .Nm backtrace_symbols_fd .Nd call stack backtrace and display functions .Sh SYNOPSIS n execinfo.h .Ft int .Fo backtrace .Fa "void** array" .Fa "int size" .Fc .Ft char** .Fo backtrace_symbols .Fa "void* const* array" .Fa "int size" .Fc .Ft void .Fo backtrace_symbols_fd .Fa "void* const* array" .Fa "int size" .Fa "int fd" .Fc .Sh DESCRIPTION These routines provide a mechanism to examine the current thread's call stack.
p .Fn backtrace writes the function return addresses of the current call stack to the array of pointers referenced by .Fa array . At most, .Fa size pointers are written. The number of pointers actually written to .Fa array is returned.
p .Fn backtrace_symbols attempts to transform a call stack obtained by .Fn backtrace into an array of human-readable strings using .Fn dladdr . The array of strings returned has .Fa size elements. It is allocated using .Fn malloc and should be released using .Fn free . There is no need to free the individual strings in the array.
p .Fn backtrace_symbols_fd performs the same operation as .Fn backtrace_symbols , but the resulting strings are immediately written to the file descriptor .Fa fd , and are not returned. .Sh EXAMPLE
p #include <execinfo.h> #include <stdio.h> ... void* callstack[128]; int i, frames = backtrace(callstack, 128); char** strs = backtrace_symbols(callstack, frames); for (i = 0; i < frames; ++i) { printf("%s\\n", strs[i]); } free(strs); ...
p .Sh HISTORY These functions first appeared in Mac OS X 10.5. .Sh SEE ALSO .Xr dladdr 3 , .Xr malloc 3