@@ -470,7 +470,7 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
470470 /* Defer to CryptGenRandom on Windows */
471471 if (php_win32_get_random_bytes (bytes , size ) == FAILURE ) {
472472 if (should_throw ) {
473- zend_throw_exception (zend_ce_exception , "Could not gather sufficient random data " , 0 );
473+ zend_throw_exception (zend_ce_exception , "Failed to retrieve randomness from the operating system (BCryptGenRandom) " , 0 );
474474 }
475475 return FAILURE ;
476476 }
@@ -483,7 +483,7 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
483483 */
484484 if (CCRandomGenerateBytes (bytes , size ) != kCCSuccess ) {
485485 if (should_throw ) {
486- zend_throw_exception (zend_ce_exception , "Error generating bytes " , 0 );
486+ zend_throw_exception (zend_ce_exception , "Failed to retrieve randomness from the operating system (CCRandomGenerateBytes) " , 0 );
487487 }
488488 return FAILURE ;
489489 }
@@ -496,6 +496,8 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
496496 /* Linux getrandom(2) syscall or FreeBSD/DragonFlyBSD getrandom(2) function*/
497497 /* Keep reading until we get enough entropy */
498498 while (read_bytes < size ) {
499+ errno = 0 ;
500+ 499501 /* Below, (bytes + read_bytes) is pointer arithmetic.
500502
501503 bytes read_bytes size
@@ -522,7 +524,7 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
522524 /* Try again */
523525 continue ;
524526 } else {
525- /* If the syscall fails, fall back to reading from /dev/urandom */
527+ /* If the syscall fails, fall back to reading from /dev/urandom */
526528 break ;
527529 }
528530 }
@@ -539,15 +541,22 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
539541 struct stat st ;
540542
541543 if (fd < 0 ) {
544+ errno = 0 ;
542545# if HAVE_DEV_URANDOM
543546 fd = open ("/dev/urandom" , O_RDONLY );
544547# endif
545548 if (fd < 0 ) {
546549 if (should_throw ) {
547- zend_throw_exception (zend_ce_exception , "Cannot open source device" , 0 );
550+ if (errno != 0 ) {
551+ zend_throw_exception_ex (zend_ce_exception , 0 , "Cannot open /dev/urandom: %s" , strerror (errno ));
552+ } else {
553+ zend_throw_exception_ex (zend_ce_exception , 0 , "Cannot open /dev/urandom" );
554+ }
548555 }
549556 return FAILURE ;
550557 }
558+ 559+ errno = 0 ;
551560 /* Does the file exist and is it a character device? */
552561 if (fstat (fd , & st ) != 0 ||
553562# ifdef S_ISNAM
@@ -558,14 +567,19 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
558567 ) {
559568 close (fd );
560569 if (should_throw ) {
561- zend_throw_exception (zend_ce_exception , "Error reading from source device" , 0 );
570+ if (errno != 0 ) {
571+ zend_throw_exception_ex (zend_ce_exception , 0 , "Error reading from /dev/urandom: %s" , strerror (errno ));
572+ } else {
573+ zend_throw_exception_ex (zend_ce_exception , 0 , "Error reading from /dev/urandom" );
574+ }
562575 }
563576 return FAILURE ;
564577 }
565578 RANDOM_G (random_fd ) = fd ;
566579 }
567580
568581 for (read_bytes = 0 ; read_bytes < size ; read_bytes += (size_t ) n ) {
582+ errno = 0 ;
569583 n = read (fd , bytes + read_bytes , size - read_bytes );
570584 if (n <= 0 ) {
571585 break ;
@@ -574,7 +588,11 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
574588
575589 if (read_bytes < size ) {
576590 if (should_throw ) {
577- zend_throw_exception (zend_ce_exception , "Could not gather sufficient random data" , 0 );
591+ if (errno != 0 ) {
592+ zend_throw_exception_ex (zend_ce_exception , 0 , "Could not gather sufficient random data: %s" , strerror (errno ));
593+ } else {
594+ zend_throw_exception_ex (zend_ce_exception , 0 , "Could not gather sufficient random data" );
595+ }
578596 }
579597 return FAILURE ;
580598 }
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