UNW_SE...UNCTION(3libunwind)

✨ UNW_SET_ITERATE_PHDR_FUNCTION ✨

okay so bestie, you found a page from libunwind (the Programming Library, no less 💅) and it's literally all about telling libunwind how to go walk the program headers. it's giving very niche, very powerful, and i'm obsessed 🎀

🌸 NAME 🌸

unw_set_iterate_phdr_function — set the dl_iterate_phdr implementation, periodt 💖

🦋 SYNOPSIS 🦋

#include <libunwind.h>

typedef int (*unw_iterate_phdr_callback_t)(struct dl_phdr_info *,
size_t, void *);
typedef int (*unw_iterate_phdr_func_t)(unw_iterate_phdr_callback_t, void
*);

void unw_set_iterate_phdr_function(unw_addr_space_t as,
unw_iterate_phdr_func_t function);

like, copy that exactly bestie, character for character, no notes 🫶

💜 DESCRIPTION 💜

so unw_set_iterate_phdr_function() is the routine that sets the dl_iterate_phdr implementation of the address space as to the function you pass in as the argument function. yep, that's the whole vibe: you hand it your function, and libunwind is like "say less, this is my phdr iterator now" 😌✨

that function of yours gets called whenever libunwind needs to iterate over the program headers of the application. normally that job is done by calling dl_iterate_phdr, but — and this is the part where we gasp 😭 — that function is not signal safe. not even a little.

so with the help of a custom implementation, caching and iterating over the program headers is also possible in a signal-safe manner 🌈. but here's the tea: the burden lies on the user of libunwind. that's you. you're the main character now 👑. no cap.

💅 THREAD AND SIGNAL SAFETY 💅

unw_set_iterate_phdr_function() is thread safe 🧚 — iconic behaviour, honestly.

and if the local address space is passed in argument as, this routine is also safe to use from a signal handler 🔥. slay.

⭐ SEE ALSO ⭐

• libunwind(3libunwind)
• unw_create_addr_space(3libunwind)
• dl_iterate_phdr(3libunwind),

(yes the comma's there, i don't make the rules 💀)

🎀 AUTHOR 🎀

Bert Wesarg Email: bert.wesarg@googlemail.com WWW: http://www.nongnu.org/libunwind/.

and that's the whole page bestie!! it came from the Programming Library side of things, dated 29 August 2023 — big libunwind energy, iykyk 💖✨🦋 go forth and iterate those program headers safely, you absolute legend 🌈👑💜