unw_init_remote man page
unw_init_remote -- initialize cursor for remote unwinding
int unw_init_remote(unw_cursor_t *c, unw_addr_space_t as, void *arg);
The unw_init_remote() routine initializes the unwind cursor pointed to by c for unwinding in the address space identified by as. The as argument can either be set to unw_local_addr_space (local address space) or to an arbitrary address space created with unw_create_addr_space().
The arg void-pointer tells the address space exactly what entity should be unwound. For example, if unw_local_addr_space is passed in as, then arg needs to be a pointer to a context structure containing the machine-state of the initial stack frame. However, other address-spaces may instead expect a process-id, a thread-id, or a pointer to an arbitrary structure which identifies the stack-frame chain to be unwound. In other words, the interpretation of arg is entirely dependent on the address-space in use; libunwind never interprets the argument in any way on its own.
Note that unw_init_remote() can be used to initiate unwinding in any process, including the local process in which the unwinder itself is running. However, for local unwinding, it is generally preferable to use unw_init_local() instead, because it is easier to use and because it may perform better.
On successful completion, unw_init_remote() returns 0. Otherwise the negative value of one of the error-codes below is returned.
Thread and Signal Safety
unw_init_remote() is thread-safe. If the local address-space is passed in argument as, this routine is also safe to use from a signal handler.
unw_init_remote() was called in a version of libunwind which supports local unwinding only (this normally happens when defining UNW_LOCAL_ONLY before including <libunwind.h> and then calling unw_init_remote()).
An unspecified error occurred.
A register needed by unw_init_remote() wasn't accessible.
libunwind(3), unw_create_addr_space(3), unw_init_local(3)
libunwind(3), unw_create_addr_space(3), unw_get_proc_info_by_ip(3), unw_init_local(3).