The unw_get_proc_info_by_ip() routine returns the same kind of auxiliary information about a procedure as unw_get_proc_info(), except that the info is looked up by instruction-pointer (IP) instead of a cursor. This is more flexible because it is possible to look up the info for an arbitrary procedure, even if it is not part of the current call-chain. However, since it is more flexible, it also tends to run slower (and often much slower) than unw_get_proc_info().
The routine expects the followins arguments: as is the address-space in which the instruction-pointer should be looked up. For a look-up in the local address-space, unw_local_addr_space can be passed for this argument. Argument ip is the instruction-pointer for which the procedure info should be looked up and pip is a pointer to a structure of type unw_proc_info_t which is used to return the info. Lastly, arg is the address-space argument that should be used when accessing the address-space. It has the same purpose as the argument of the same name for unw_init_remote(). When accessing the local address-space (first argument is unw_local_addr_space), NULL must be passed for this argument.
Note that for the purposes of libunwind, the code of a procedure is assumed to occupy a single, contiguous range of addresses. For this reason, it is alwas possible to describe the extent of a procedure with the start_ip and end_ip members. If a single function/routine is split into multiple, discontiguous pieces, libunwind will treat each piece as a separate procedure.
On successful completion, unw_get_proc_info_by_ip() returns 0. Otherwise the negative value of one of the error-codes below is returned.
unw_get_proc_info() is thread-safe. If the local address-space is passed in argument as, this routine is also safe to use from a signal handler.