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https://github.com/fluencelabs/musl
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ebf82447be
the goal is to be able to use pthread_setcancelstate internally in the implementation, whenever a function might want to use functions which are cancellation points but avoid becoming a cancellation point itself. i could have just used a separate internal function for temporarily inhibiting cancellation, but the solution in this commit is better because (1) it's one less implementation-specific detail in functions that need to use it, and (2) application code can also get the same benefit. previously, pthread_setcancelstate dependend on pthread_self, which would pull in unwanted thread setup overhead for non-threaded programs. now, it temporarily stores the state in the global libc struct if threads have not been initialized, and later moves it if needed. this way we can instead use __pthread_self, which has no dependencies and assumes that the thread register is already valid.
40 lines
870 B
C
40 lines
870 B
C
#include "pthread_impl.h"
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static struct pthread main_thread;
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/* pthread_key_create.c overrides this */
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static const void *dummy[1] = { 0 };
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weak_alias(dummy, __pthread_tsd_main);
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#undef errno
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static int *errno_location()
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{
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return __pthread_self()->errno_ptr;
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}
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static int init_main_thread()
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{
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main_thread.canceldisable = libc.canceldisable;
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main_thread.tsd = (void **)__pthread_tsd_main;
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main_thread.self = &main_thread;
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if (__set_thread_area(&main_thread) < 0)
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return -1;
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main_thread.errno_ptr = __errno_location();
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libc.errno_location = errno_location;
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main_thread.tid = main_thread.pid =
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syscall(SYS_set_tid_address, &main_thread.tid);
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return 0;
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}
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pthread_t pthread_self()
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{
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static int init, failed;
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if (!init) {
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if (failed) return 0;
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if (init_main_thread() < 0) failed = 1;
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if (failed) return 0;
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init = 1;
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}
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return __pthread_self();
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}
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