unw_get_proc_name_by_ip - Man Page

get procedure name


#include <libunwind.h>

int unw_get_proc_name_by_ip(unw_addr_space_t as, unw_word_t ip, char *bufp, size_t len, unw_word_t *offp, void *arg);


The unw_get_proc_name_by_ip() routine returns the name of a procedure just like unw_get_proc_name(), except that the name is looked up by instruction-pointer (IP) instead of a cursor.

The routine expects the following 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 name should be looked up. 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 relative to the start of the procedure. 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 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_by_ip() may return the name of a label or a preceding (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 ip.

Return Value

On successful completion, unw_get_proc_name_by_ip() returns 0. Otherwise the negative value of one of the error-codes below is returned.

Thread and Signal Safety

unw_get_proc_name_by_ip() is thread-safe. If the local address-space is passed in argument as, this routine is also safe to use from a signal handler.



An unspecified error occurred.


Libunwind was unable to determine the name of the procedure.


The procedure name is too long to fit in the buffer provided. A truncated version of the name has been returned.

In addition, unw_get_proc_name_by_ip() may return any error returned by the access_mem() call-back (see unw_create_addr_space(3)).

See Also

libunwind(3), unw_create_addr_space(3), unw_get_proc_name(3), unw_init_remote(3)


David Mosberger-Tang
Email: dmosberger@gmail.com
WWW: http://www.nongnu.org/libunwind/.


30 August 2021 Programming Library