3737#include <sys/sem.h>
3838#endif
3939
40+ #ifdef __GLIBC__
41+ #include <gnu/libc-version.h> /* gnu_get_libc_version() */
42+ #endif
43+
4044#undef NANOSEC
4145#define NANOSEC ((uint64_t) 1e9)
4246
@@ -419,109 +423,145 @@ int uv_sem_trywait(uv_sem_t* sem) {
419423 return UV_EINVAL ; /* Satisfy the compiler. */
420424}
421425
426+ #else /* !(defined(__APPLE__) && defined(__MACH__)) */
427+
428+ #ifdef __GLIBC__
429+
430+ /* Hack around https://sourceware.org/bugzilla/show_bug.cgi?id=12674
431+ * by providing a custom implementation for glibc < 2.21 in terms of other
432+ * concurrency primitives.
433+ * Refs: https://github.com/nodejs/node/issues/19903 */
434+
435+ /* To preserve ABI compatibility, we treat the uv_sem_t as storage for
436+ * a pointer to the actual struct we're using underneath. */
437+
438+ static uv_once_t glibc_version_check_once = UV_ONCE_INIT ;
439+ static int platform_needs_custom_semaphore = 0 ;
440+
441+ static void glibc_version_check (void ) {
442+ const char * version = gnu_get_libc_version ();
443+ platform_needs_custom_semaphore =
444+ version [0 ] == '2' && version [1 ] == '.' &&
445+ atoi (version + 2 ) < 21 ;
446+ }
447+
422448#elif defined(__MVS__ )
423449
424- int uv_sem_init (uv_sem_t * sem , unsigned int value ) {
425- uv_sem_t semid ;
450+ #define platform_needs_custom_semaphore 1
451+
452+ #else /* !defined(__GLIBC__) && !defined(__MVS__) */
453+
454+ #define platform_needs_custom_semaphore 0
455+
456+ #endif
457+
458+ typedef struct uv_semaphore_s {
459+ uv_mutex_t mutex ;
460+ uv_cond_t cond ;
461+ unsigned int value ;
462+ } uv_semaphore_t ;
463+
464+ #if defined(__GLIBC__ ) || platform_needs_custom_semaphore
465+ STATIC_ASSERT (sizeof (uv_sem_t ) >= sizeof (uv_semaphore_t * ));
466+ #endif
467+
468+ static int uv__custom_sem_init (uv_sem_t * sem_ , unsigned int value ) {
426469 int err ;
427- union {
428- int val ;
429- struct semid_ds * buf ;
430- unsigned short * array ;
431- } arg ;
470+ uv_semaphore_t * sem ;
432471
472+ sem = uv__malloc (sizeof (* sem ));
473+ if (sem == NULL )
474+ return UV_ENOMEM ;
433475
434- semid = semget (IPC_PRIVATE , 1 , S_IRUSR | S_IWUSR );
435- if (semid == -1 )
436- return UV__ERR (errno );
476+ if ((err = uv_mutex_init (& sem -> mutex )) != 0 ) {
477+ uv__free (sem );
478+ return err ;
479+ }
437480
438- arg .val = value ;
439- if (-1 == semctl (semid , 0 , SETVAL , arg )) {
440- err = errno ;
441- if (-1 == semctl (* sem , 0 , IPC_RMID ))
442- abort ();
443- return UV__ERR (err );
481+ if ((err = uv_cond_init (& sem -> cond )) != 0 ) {
482+ uv_mutex_destroy (& sem -> mutex );
483+ uv__free (sem );
484+ return err ;
444485 }
445486
446- * sem = semid ;
487+ sem -> value = value ;
488+ * (uv_semaphore_t * * )sem_ = sem ;
447489 return 0 ;
448490}
449491
450- void uv_sem_destroy (uv_sem_t * sem ) {
451- if (-1 == semctl (* sem , 0 , IPC_RMID ))
452- abort ();
492+
493+ static void uv__custom_sem_destroy (uv_sem_t * sem_ ) {
494+ uv_semaphore_t * sem ;
495+
496+ sem = * (uv_semaphore_t * * )sem_ ;
497+ uv_cond_destroy (& sem -> cond );
498+ uv_mutex_destroy (& sem -> mutex );
499+ uv__free (sem );
453500}
454501
455- void uv_sem_post (uv_sem_t * sem ) {
456- struct sembuf buf ;
457502
458- buf .sem_num = 0 ;
459- buf .sem_op = 1 ;
460- buf .sem_flg = 0 ;
503+ static void uv__custom_sem_post (uv_sem_t * sem_ ) {
504+ uv_semaphore_t * sem ;
461505
462- if (-1 == semop (* sem , & buf , 1 ))
463- abort ();
506+ sem = * (uv_semaphore_t * * )sem_ ;
507+ uv_mutex_lock (& sem -> mutex );
508+ sem -> value ++ ;
509+ if (sem -> value == 1 )
510+ uv_cond_signal (& sem -> cond );
511+ uv_mutex_unlock (& sem -> mutex );
464512}
465513
466- void uv_sem_wait (uv_sem_t * sem ) {
467- struct sembuf buf ;
468- int op_status ;
469-
470- buf .sem_num = 0 ;
471- buf .sem_op = -1 ;
472- buf .sem_flg = 0 ;
473514
474- do
475- op_status = semop (* sem , & buf , 1 );
476- while (op_status == -1 && errno == EINTR );
515+ static void uv__custom_sem_wait (uv_sem_t * sem_ ) {
516+ uv_semaphore_t * sem ;
477517
478- if (op_status )
479- abort ();
518+ sem = * (uv_semaphore_t * * )sem_ ;
519+ uv_mutex_lock (& sem -> mutex );
520+ while (sem -> value == 0 )
521+ uv_cond_wait (& sem -> cond , & sem -> mutex );
522+ sem -> value -- ;
523+ uv_mutex_unlock (& sem -> mutex );
480524}
481525
482- int uv_sem_trywait (uv_sem_t * sem ) {
483- struct sembuf buf ;
484- int op_status ;
485526
486- buf .sem_num = 0 ;
487- buf .sem_op = -1 ;
488- buf .sem_flg = IPC_NOWAIT ;
527+ static int uv__custom_sem_trywait (uv_sem_t * sem_ ) {
528+ uv_semaphore_t * sem ;
489529
490- do
491- op_status = semop ( * sem , & buf , 1 );
492- while ( op_status == -1 && errno == EINTR ) ;
530+ sem = * ( uv_semaphore_t * * ) sem_ ;
531+ if ( uv_mutex_trylock ( & sem -> mutex ) != 0 )
532+ return UV_EAGAIN ;
493533
494- if (op_status ) {
495- if (errno == EAGAIN )
496- return UV_EAGAIN ;
497- abort ();
534+ if (sem -> value == 0 ) {
535+ uv_mutex_unlock (& sem -> mutex );
536+ return UV_EAGAIN ;
498537 }
499538
539+ sem -> value -- ;
540+ uv_mutex_unlock (& sem -> mutex );
541+
500542 return 0 ;
501543}
502544
503- #else /* !(defined(__APPLE__) && defined(__MACH__)) */
504-
505- int uv_sem_init (uv_sem_t * sem , unsigned int value ) {
545+ static int uv__sem_init (uv_sem_t * sem , unsigned int value ) {
506546 if (sem_init (sem , 0 , value ))
507547 return UV__ERR (errno );
508548 return 0 ;
509549}
510550
511551
512- void uv_sem_destroy (uv_sem_t * sem ) {
552+ static void uv__sem_destroy (uv_sem_t * sem ) {
513553 if (sem_destroy (sem ))
514554 abort ();
515555}
516556
517557
518- void uv_sem_post (uv_sem_t * sem ) {
558+ static void uv__sem_post (uv_sem_t * sem ) {
519559 if (sem_post (sem ))
520560 abort ();
521561}
522562
523563
524- void uv_sem_wait (uv_sem_t * sem ) {
564+ static void uv__sem_wait (uv_sem_t * sem ) {
525565 int r ;
526566
527567 do
@@ -533,7 +573,7 @@ void uv_sem_wait(uv_sem_t* sem) {
533573}
534574
535575
536- int uv_sem_trywait (uv_sem_t * sem ) {
576+ static int uv__sem_trywait (uv_sem_t * sem ) {
537577 int r ;
538578
539579 do
@@ -549,6 +589,49 @@ int uv_sem_trywait(uv_sem_t* sem) {
549589 return 0 ;
550590}
551591
592+ int uv_sem_init (uv_sem_t * sem , unsigned int value ) {
593+ #ifdef __GLIBC__
594+ uv_once (& glibc_version_check_once , glibc_version_check );
595+ #endif
596+
597+ if (platform_needs_custom_semaphore )
598+ return uv__custom_sem_init (sem , value );
599+ else
600+ return uv__sem_init (sem , value );
601+ }
602+
603+
604+ void uv_sem_destroy (uv_sem_t * sem ) {
605+ if (platform_needs_custom_semaphore )
606+ uv__custom_sem_destroy (sem );
607+ else
608+ uv__sem_destroy (sem );
609+ }
610+
611+
612+ void uv_sem_post (uv_sem_t * sem ) {
613+ if (platform_needs_custom_semaphore )
614+ uv__custom_sem_post (sem );
615+ else
616+ uv__sem_post (sem );
617+ }
618+
619+
620+ void uv_sem_wait (uv_sem_t * sem ) {
621+ if (platform_needs_custom_semaphore )
622+ uv__custom_sem_wait (sem );
623+ else
624+ uv__sem_wait (sem );
625+ }
626+
627+
628+ int uv_sem_trywait (uv_sem_t * sem ) {
629+ if (platform_needs_custom_semaphore )
630+ return uv__custom_sem_trywait (sem );
631+ else
632+ return uv__sem_trywait (sem );
633+ }
634+
552635#endif /* defined(__APPLE__) && defined(__MACH__) */
553636
554637
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