github.com/afumu/libc@v0.0.6/musl/src/thread/__timedwait.c (about)

     1  #include <pthread.h>
     2  #include <time.h>
     3  #include <errno.h>
     4  #include "futex.h"
     5  #include "syscall.h"
     6  #include "pthread_impl.h"
     7  
     8  #define IS32BIT(x) !((x)+0x80000000ULL>>32)
     9  #define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
    10  
    11  static int __futex4_cp(volatile void *addr, int op, int val, const struct timespec *to)
    12  {
    13  	int r;
    14  #ifdef SYS_futex_time64
    15  	time_t s = to ? to->tv_sec : 0;
    16  	long ns = to ? to->tv_nsec : 0;
    17  	r = -ENOSYS;
    18  	if (SYS_futex == SYS_futex_time64 || !IS32BIT(s))
    19  		r = __syscall_cp(SYS_futex_time64, addr, op, val,
    20  			to ? ((long long[]){s, ns}) : 0);
    21  	if (SYS_futex == SYS_futex_time64 || r!=-ENOSYS) return r;
    22  	to = to ? (void *)(long[]){CLAMP(s), ns} : 0;
    23  #endif
    24  	r = __syscall_cp(SYS_futex, addr, op, val, to);
    25  	if (r != -ENOSYS) return r;
    26  	return __syscall_cp(SYS_futex, addr, op & ~FUTEX_PRIVATE, val, to);
    27  }
    28  
    29  static volatile int dummy = 0;
    30  weak_alias(dummy, __eintr_valid_flag);
    31  
    32  int __timedwait_cp(volatile int *addr, int val,
    33  	clockid_t clk, const struct timespec *at, int priv)
    34  {
    35  	int r;
    36  	struct timespec to, *top=0;
    37  
    38  	if (priv) priv = FUTEX_PRIVATE;
    39  
    40  	if (at) {
    41  		if (at->tv_nsec >= 1000000000UL) return EINVAL;
    42  		if (__clock_gettime(clk, &to)) return EINVAL;
    43  		to.tv_sec = at->tv_sec - to.tv_sec;
    44  		if ((to.tv_nsec = at->tv_nsec - to.tv_nsec) < 0) {
    45  			to.tv_sec--;
    46  			to.tv_nsec += 1000000000;
    47  		}
    48  		if (to.tv_sec < 0) return ETIMEDOUT;
    49  		top = &to;
    50  	}
    51  
    52  	r = -__futex4_cp(addr, FUTEX_WAIT|priv, val, top);
    53  	if (r != EINTR && r != ETIMEDOUT && r != ECANCELED) r = 0;
    54  	/* Mitigate bug in old kernels wrongly reporting EINTR for non-
    55  	 * interrupting (SA_RESTART) signal handlers. This is only practical
    56  	 * when NO interrupting signal handlers have been installed, and
    57  	 * works by sigaction tracking whether that's the case. */
    58  	if (r == EINTR && !__eintr_valid_flag) r = 0;
    59  
    60  	return r;
    61  }
    62  
    63  int __timedwait(volatile int *addr, int val,
    64  	clockid_t clk, const struct timespec *at, int priv)
    65  {
    66  	int cs, r;
    67  	__pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
    68  	r = __timedwait_cp(addr, val, clk, at, priv);
    69  	__pthread_setcancelstate(cs, 0);
    70  	return r;
    71  }