UNW\\_GET\\_PROC\\_INFO

Section: Programming Library (3)
Updated: 16 August 2007
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NAME

unw_get_proc_info -- get info on current procedure

SYNOPSIS

int unw_get_proc_info(unw_cursor_t *cp, unw_proc_info_t *pip);

DESCRIPTION

The unw_get_proc_info() routine returns auxiliary information about the procedure that created the stack frame identified by argument cp. The pip argument is a pointer to a structure of type unw_proc_info_t which is used to return the information. The unw_proc_info_t has the following members:

unw_word_t start_ip: The address of the first instruction of the procedure. If this address cannot be determined (e.g., due to lack of unwind information), the start_ip member is cleared to 0.
unw_word_t end_ip: The address of the first instruction beyond the end of the procedure. If this address cannot be determined (e.g., due to lack of unwind information), the end_ip member is cleared to 0.
unw_word_t lsda: The address of the language-specific data-area (LSDA). This area normally contains language-specific information needed during exception handling. If the procedure has no such area, this member is cleared to 0.
unw_word_t handler: The address of the exception handler routine. This is sometimes called the personality routine. If the procedure does not define a personality routine, the handler member is cleared to 0.
unw_word_t gp: The global-pointer of the procedure. On platforms that do not use a global pointer, this member may contain an undefined value. On all other platforms, it must be set either to the correct global-pointer value of the procedure or to 0 if the proper global-pointer cannot be obtained for some reason.
unw_word_t flags: A set of flags. There are currently no target-independent flags. For the IA-64 target, the flag UNW_PI_FLAG_IA64_RBS_SWITCH is set if the procedure may switch the register-backing store.
int format: The format of the unwind-info for this procedure. If the unwind-info consists of dynamic procedure info, format is equal to UNW_INFO_FORMAT_DYNAMIC. If the unwind-info consists of a (target-specific) unwind table, it is equal to to UNW_INFO_FORMAT_TABLE. All other values are reserved for future use by libunwind. This member exists for use by the find_proc_info() call-back (see unw_create_addr_space(3)). The unw_get_proc_info() routine may return an undefined value in this member.
int unwind_info_size: The size of the unwind-info in bytes. This member exists for use by the find_proc_info() call-back (see unw_create_addr_space(3)). The unw_get_proc_info() routine may return an undefined value in this member.
void *unwind_info: The pointer to the unwind-info. If no unwind info is available, this member must be set to NULL. This member exists for use by the find_proc_info() call-back (see unw_create_addr_space(3)). The unw_get_proc_info() routine may return an undefined value in this member.

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.

RETURN VALUE

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

THREAD AND SIGNAL SAFETY

unw_get_proc_info() is thread-safe. If cursor cp is in the local address-space, this routine is also safe to use from a signal handler.

ERRORS

UNW_EUNSPEC: An unspecified error occurred.
UNW_ENOINFO: Libunwind was unable to locate unwind-info for the procedure.
UNW_EBADVERSION: The unwind-info for the procedure has version or format that is not understood by libunwind.

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

AUTHOR

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