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https://github.com/fluencelabs/musl
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99b8a25e94
the new approach relies on the fact that the only ways to create sigset_t objects without invoking UB are to use the sig*set() functions, or from the masks returned by sigprocmask, sigaction, etc. or in the ucontext_t argument to a signal handler. thus, as long as sigfillset and sigaddset avoid adding the "protected" signals, there is no way the application will ever obtain a sigset_t including these bits, and thus no need to add the overhead of checking/clearing them when sigprocmask or sigaction is called. note that the old code actually *failed* to remove the bits from sa_mask when sigaction was called. the new implementations are also significantly smaller, simpler, and faster due to ignoring the useless "GNU HURD signals" 65-1024, which are not used and, if there's any sanity in the world, never will be used.
13 lines
273 B
C
13 lines
273 B
C
#include <signal.h>
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#include <errno.h>
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int sigismember(const sigset_t *set, int sig)
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{
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unsigned s = sig-1;
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if (s >= 8*sizeof(sigset_t) || s-32U<3) {
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errno = EINVAL;
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return -1;
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}
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return !!(set->__bits[s/8/sizeof *set->__bits] & 1UL<<(s&8*sizeof *set->__bits-1));
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}
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