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overhaul implementation-internal signal protections

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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.
This commit is contained in:
Rich Felker
2011-05-07 23:23:58 -04:00
parent 77f15d108e
commit 99b8a25e94
13 changed files with 32 additions and 50 deletions
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20
src/signal/sigprocmask.c
View File

@ -4,27 +4,11 @@
#include "libc.h"
#include "pthread_impl.h"
int __libc_sigprocmask(int how, const sigset_t *set, sigset_t *old)
int sigprocmask(int how, const sigset_t *set, sigset_t *old)
{
return syscall(SYS_rt_sigprocmask, how, set, old, 8);
}
int __sigprocmask(int how, const sigset_t *set, sigset_t *old)
{
sigset_t tmp;
if (how > 2U) {
errno = EINVAL;
return -1;
}
/* Disallow blocking thread control signals */
if (set && how != SIG_UNBLOCK) {
tmp = *set;
set = &tmp;
sigdelset(&tmp, SIGCANCEL);
sigdelset(&tmp, SIGSYSCALL);
sigdelset(&tmp, SIGTIMER);
}
return __libc_sigprocmask(how, set, old);
return syscall(SYS_rt_sigprocmask, how, set, old, 8);
}
weak_alias(__sigprocmask, sigprocmask);