bsd_signal - signal handling with BSD semantics
typedef void (*sighandler_t)(int);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.26: _XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L)
Glibc 2.25 and earlier: _XOPEN_SOURCE
The difference between the two is that bsd_signal() is guaranteed to provide reliable signal semantics, that is: a) the disposition of the signal is not reset to the default when the handler is invoked; b) delivery of further instances of the signal is blocked while the signal handler is executing; and c) if the handler interrupts a blocking system call, then the system call is automatically restarted. A portable application cannot rely on signal(2) to provide these guarantees.
The bsd_signal() function returns the previous value of the signal handler, or SIG_ERR on error.
The use of
sighandler_t is a GNU extension; this type is
defined only if the _GNU_SOURCE feature test macro is
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