UNW_IS...L_FRAME(3libunwind)

✨ UNW_IS_SIGNAL_FRAME — a libunwind moment ✨

okay bestie, welcome to the 3libunwind girlies 💖 this is unw_is_signal_frame, and she is exactly what she sounds like: the check that tells you whether the frame you're staring at is a signal frame or not. no cap.

---

🎀 SYNOPSIS 🎀

#include <libunwind.h>

int unw_is_signal_frame(unw_cursor_t *cp);

like. that's it. one function. one cursor. one vibe check. 💅

---

🌸 DESCRIPTION 🌸

so here's the tea ☕ — unw_is_signal_frame() hands back a positive value if the current frame identified by cp is a signal frame (aka a signal trampoline, iykyk), and a value of 0 if it isn't. that's the whole gig.

now, for the purposes of this discussion, a signal frame is a frame that got created in response to a potentially asynchronous interruption. on UNIX and UNIX-like platforms, those frames are normally made by the kernel when it delivers a signal. and in a kernel environment? a signal frame might, for example, correspond to a frame created in response to a device interrupt. so she's versatile, okay. main character energy across environments 🔥

signal frames are kinda unusual though, and here's why: the events that create them are asynchronous, and that async-ness means the contents of registers that are normally treated as scratch (the ``caller-saved'' ones) have to actually be stored. yeah. the "don't worry about it" registers have to be worried about. it's giving chaos but make it documented 🫶

---

💜 RETURN VALUE 💜

• on successful completion, unw_is_signal_frame() returns a positive value if the current frame is a signal frame, or 0 if it is not.
• otherwise, it returns a negative value of one of the error codes below 😭

---

🦋 THREAD AND SIGNAL SAFETY 🦋

unw_is_signal_frame() is thread safe as well as safe to use from a signal handler.

literally the whole package. she can do both. periodt 👑

---

⭐ ERRORS ⭐

• UNW_ENOINFO — libunwind is unable to determine whether or not the current frame is a signal frame. like she tried, bestie, she just doesn't know 😭

---

🌈 SEE ALSO 🌈

• libunwind(3libunwind)
• unw_get_reg(3libunwind)
• unw_set_reg(3libunwind)
• unw_get_fpreg(3libunwind)
• unw_set_fpreg(3libunwind)

go read the whole squad, fr fr 📚✨

---

👑 AUTHOR 👑

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

---

this whole page is part of the Programming Library, and this particular revision is dated 29 August 2023 — so yeah, she's got a timestamp, she's got a home in 3libunwind, and she's iconic. that's the sign-off, bestie, go unwind some frames 💖🎀🦋🌸💅