__BUILTIN_RETURN_ADDRESS(3)

✨ __BUILTIN_RETURN_ADDRESS(3) ✨

okay bestie, so this one's a page from the Library Functions Manual and it's all about two little GNU compiler built-ins that let you peek at the call stack 🫶. Buckle up, it's giving "intro to stack frames but make it cute" 💅

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🌸 NAME 🌸

__builtin_return_address — literally just: the return address of a function 💖

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🎀 SYNOPSIS 🎀

void *
__builtin_return_address(unsigned int level);

void *
__builtin_frame_address(unsigned int level);

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🦋 DESCRIPTION 🦋

So __builtin_return_address() is a GNU extension — aka not standard C, it's a GCC thing — and what it does is hand you the return address of the current function, or of one of the callers up the chain. Iconic, honestly 🌈

The parameter level is the vibe check for how many frames you wanna scan up the call stack:

• 0 → you get the address of the current function
• 1 → you get the address of the caller of the current function
• 2 → you get the address of the caller's caller
• and so on, forever, until you run out of stack 🌸

If you've hit the top of the call stack, the function returns 0. Also important, bestie: on some architectures it's only possible to determine the address of the current function. In those cases it also returns 0. So like, it's usually safe to only use the value 0 for level — no cap, that's the move 🙈

Then there's __builtin_frame_address(), which behaves similarly but returns the address of the function frame instead of the function's return address. Same energy, different address 💫

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⭐ SEE ALSO ⭐

• gcc(1)
• __builtin_object_size(3)

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💀 CAVEATS 💀

These are non-standard, compiler-specific extensions. Periodt. Don't expect your other compilers to know what you're talking about 😭

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fr fr read the caveats again before you ship anything with these in it 👑

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and that's the whole page, bestie!! written by the Debian girlies, dated December 19, 2010 — oldie but a goodie, and this manual page is forever __BUILTIN_RETURN_ADDRESS(3) coded 💜🎀✨