---
name: "unw_is_signal_frame"
section: "3"
platform: "linux"
package: "libunwind"
version: "1.8.3-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/unw_is_signal_frame"
---

# unw\_is\_signal\_frame(3)

## NAME

unw\_is\_signal\_frame -- check if current frame is a signal frame

## SYNOPSIS

\#include \<libunwind.h\>\

int unw\_is\_signal\_frame(unw\_cursor\_t \*cp);\

## DESCRIPTION

The unw\_is\_signal\_frame() routine returns a positive value  if the current frame identified by cp is a signal frame,  also known as a signal trampoline,  and a value of 0 otherwise.  For the purpose of this discussion,  a signal frame is a frame that was created in response to a potentially  asynchronous interruption.  For UNIX and UNIX-like platforms,  such frames are normally created by the kernel when delivering a signal.  In a kernel environment, a signal frame might, for example, correspond  to a frame created in response to a device interrupt.

Signal frames are somewhat unusual because the asynchronous nature of  the events that create them require storing the contents of registers  that are normally treated as scratch (\`\`caller-saved'') registers.

## 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, a negative value of one of the error codes below is  returned.

## THREAD AND SIGNAL SAFETY

unw\_is\_signal\_frame() is thread safe as well as safe to use  from a signal handler.

## ERRORS

- UNW\_ENOINFO

   Libunwind is unable to determine  whether or not the current frame is a signal frame.

## SEE ALSO

libunwind(3libunwind), unw\_get\_reg(3libunwind), unw\_set\_reg(3libunwind), unw\_get\_fpreg(3libunwind), unw\_set\_fpreg(3libunwind)

## AUTHOR

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