The unw_get_proc_name() routine returns the name of the procedure that created the stack frame identified by argument cp. The bufp argument is a pointer to a character buffer that is at least len bytes long. This buffer is used to return the name of the procedure. The offp argument is a pointer to a word that is used to return the byte-offset of the instruction-pointer saved in the stack frame identified by cp, relative to the start of the procedure. For example, if procedure foo() starts at address 0x40003000, then invoking unw_get_proc_name() on a stack frame with an instruction-pointer value of 0x40003080 would return a value of 0x80 in the word pointed to by offp (assuming the procedure is at least 0x80 bytes long).
Note that on some platforms there is no reliable way to distinguish between procedure names and ordinary labels. Furthermore, if symbol information has been stripped from a program, procedure names may be completely unavailable or may be limited to those exported via a dynamic symbol table. In such cases, unw_get_proc_name() may return the name of a label or a preceeding (nearby) procedure. However, the offset returned through offp is always relative to the returned name, which ensures that the value (address) of the returned name plus the returned offset will always be equal to the instruction-pointer of the stack frame identified by cp.
On successful completion, unw_get_proc_name() returns 0. Otherwise the negative value of one of the error-codes below is returned.
unw_get_proc_name() is thread-safe. If cursor cp is in the local address-space, this routine is also safe to use from a signal handler.