UNW_AP...G_STATE(3libunwind)

💖 unw_apply_reg_state — bestie, let's update that cursor 💖

okay so real talk, this is page UNW_AP...G_STATE(3libunwind) from the libunwind manual (section 3, programming library energy ✨). It's the one that takes a register state you already scooped up and applies it. Let's go 🫶

✨ NAME ✨

unw_apply_reg_state — apply a register state update to a cursor

Like, you've got a cursor, you've got some register state data, and this function is the matchmaker. 💅

🌸 SYNOPSIS 🌸

#include <libunwind.h>

int unw_apply_reg_state(unw_cursor_t *cp, void *reg_states_data);

🦋 DESCRIPTION 🦋

The unw_apply_reg_state() routine updates the register values of a cursor according to the instructions in reg_states_data, which have been obtained by calling unw_reg_states_iterate.

That's it. That's the whole vibe. You got the data from unw_reg_states_iterate, and now you're feeding it back in to actually move the cursor's registers where they need to go. Cursor gets a glow-up. 🌈

👑 RETURN VALUE 👑

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

So like, zero is the slay outcome. Anything negative? Not slay. Check the list. 😭

🔥 THREAD AND SIGNAL SAFETY 🔥

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

Translation bestie: threads? fine. Signal handler? only if cp is living in the local address space. Periodt. 💀

💜 ERRORS 💜

• UNW_EUNSPEC — An unspecified error occurred. (Mystery error. No further info. It's giving cryptic. 🙈)
• 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_apply_reg_state() may return any error returned by the access_mem() call-back (see unw_create_addr_space(3libunwind)).

ngl that last one is the sneaky one — the callback can hand you back its own errors and this function will just pass them along. iykyk.

🎀 SEE ALSO 🎀

• libunwind(3libunwind)
• unw_reg_states_iterate(3libunwind)

⭐ AUTHOR ⭐

David Mosberger-Tang

Email: dmosberger@gmail.com

WWW: http://www.nongnu.org/libunwind/

and that's the whole page, bestie 💖 it's from the Programming Library, dated 29 August 2023, filed under UNW_AP...G_STATE(3libunwind) — go forth and apply those register states, you absolute icon 👑✨