raiseSIGTRAP

raiseSIGTRAP is a term used to describe triggering a trap signal in a running process by raising the SIGTRAP signal. In POSIX-compliant systems, SIGTRAP is defined in signal.h and is commonly used by debuggers to interrupt a program’s execution, acting as a software breakpoint or trap.

In C or C++, the usual way to raise the trap is to call raise(SIGTRAP) or to send the signal to the current process with kill(getpid(), SIGTRAP). This signals to a debugger or the operating system that a trap condition has occurred and may be handled as a breakpoint during debugging or instrumentation. The exact effect can depend on the environment and whether a debugger is attached.

The behavior of raising SIGTRAP depends on the process’s signal disposition and the presence of a debugger. The default action for SIGTRAP is typically termination of the process with potential core dump, but debuggers commonly intercept the signal to pause execution. A program may also install a custom signal handler for SIGTRAP to implement specific behavior when the trap occurs.

Alternatives and related techniques include compiler built-ins such as __builtin_trap() (available in GCC and Clang), which generates a trap instruction without sending a signal, and platform-specific breakpoints such as __debugbreak() or DebugBreak on Windows. These methods provide breakpoint-like functionality in environments where POSIX signals are not available or desired.

Portability considerations: raise(SIGTRAP) is rooted in POSIX behavior and may not be portable to non-POSIX environments. For cross-platform debugging instrumentation, developers often prefer architecture-specific or compiler-supported mechanisms in addition to or instead of signals.