UNW_GET...E_BY_IP(3libunwind)

✨ unw_get_elf_filename_by_ip — bestie edition ✨

okay so you wanna know which elf file some instruction pointer came from? say less. this is from libunwind, manual section 3libunwind, and it's giving detective energy but for addresses. 🕵️♀️💖

🌸 NAME 🌸

unw_get_elf_filename_by_ip — get the backing elf filename by instruction pointer. literally that's the whole job. no cap.

🎀 SYNOPSIS 🎀

#include <libunwind.h>

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

🦋 DESCRIPTION 🦋

so unw_get_elf_filename_by_ip() hands you the backing elf filename for an instruction pointer — exactly like unw_get_elf_filename() does, bestie, with one glow-up: the name gets looked up by instruction pointer (IP) instead of by a cursor. same vibe, different lookup key. 💅

here's what you gotta feed it, argument by argument:

• as — the address-space where the instruction pointer should be looked up. if you're looking things up in the local address-space, you can just pass unw_local_addr_space here and call it a day.
• ip — the instruction-pointer you want the elf filename for. the main character of this whole operation, honestly. ✨
• bufp — a pointer to a character buffer that's at least len bytes long. this is where the elf filename gets returned. make sure it's big enough or things get spicy (see UNW_ENOMEM below 👀).
• len — how long that buffer is, in bytes.
• offp — a pointer to a word used to return the byte offset of the instruction-pointer relative to the start of the elf filename. cute little positional receipt. 🧾
• arg — the address space argument used when accessing the address space. it has the same purpose as the argument of the same name for unw_init_remote().

⚠️ important bestie moment: when you're accessing the local address space (i.e. the first argument is unw_local_addr_space), you must pass NULL for arg. not optional. NULL. periodt.

💖 RETURN VALUE 💖

on successful completion, unw_get_elf_filename_by_ip() returns 0. slay. 🎉

otherwise, it returns the negative value of one of the error codes listed below. so like, negative. remember that.

🔥 THREAD AND SIGNAL SAFETY 🔥

unw_get_elf_filename_by_ip() is thread safe. 👑

and if the local address-space is passed in argument as, this routine is also safe to use from a signal handler. iconic behaviour, truly.

💀 ERRORS 💀

• UNW_EUNSPEC — an unspecified error occurred. mystery error, no further info, we move. 🙈
• UNW_ENOINFO — libunwind was unable to determine the elf filename of the instruction pointer. it tried, bestie. it just doesn't know. 😭
• UNW_ENOMEM — the elf filename is too long to fit in the buffer you provided. heads up: a truncated version of the name has been returned. so you got something, just not all of it. 🍓

🌈 SEE ALSO 🌈

• libunwind(3libunwind)
• unw_get_elf_filename(3libunwind)
• unw_create_addr_space(3libunwind)
• unw_init_remote(3libunwind)

👑 AUTHOR 👑

Xiang Lin Email: myd.xia@gmail.com

Programming Library · 15 September 2023 · UNW_GET...E_BY_IP(3libunwind)

and that's the whole page, bestie — go look up some elf filenames, you've got this 💅🫶✨