diff options
Diffstat (limited to 'stdlib/random.c')
| -rw-r--r-- | stdlib/random.c | 30 |
1 files changed, 27 insertions, 3 deletions
diff --git a/stdlib/random.c b/stdlib/random.c index e2b191b..461b76f 100644 --- a/stdlib/random.c +++ b/stdlib/random.c @@ -22,6 +22,7 @@ * Rewritten to use reentrant functions by Ulrich Drepper, 1995. */ +#include <libc-lock.h> #include <limits.h> #include <stddef.h> #include <stdlib.h> @@ -162,6 +163,11 @@ static struct random_data unsafe_state = end_ptr : &randtbl[sizeof (randtbl) / sizeof (randtbl[0])] }; +/* POSIX.1c requires that there is mutual exclusion for the `rand' and + `srand' functions to prevent concurrent calls from modifying common + data. */ +__libc_lock_define_initialized (static, lock) + /* Initialize the random number generator based on the given seed. If the type is the trivial no-state-information type, just remember the seed. Otherwise, initializes state[] based on the given "seed" via a linear @@ -174,7 +180,9 @@ void __srandom (x) unsigned int x; { + __libc_lock_lock (lock) (void) __srandom_r (x, &unsafe_state); + __libc_lock_unlock (lock) } weak_alias (__srandom, srandom) @@ -197,10 +205,16 @@ __initstate (seed, arg_state, n) void *arg_state; size_t n; { - void *ostate = (void *) &unsafe_state.state[-1]; + void *ostate; + + __libc_lock_lock (lock) + + ostate = (void *) &unsafe_state.state[-1]; __initstate_r (seed, arg_state, n, &unsafe_state); + __libc_lock_unlock (lock) + return ostate; } @@ -218,10 +232,16 @@ void * __setstate (arg_state) void *arg_state; { - void *ostate = (void *) &unsafe_state.state[-1]; + void *ostate; + + __libc_lock_lock (lock) + + ostate = (void *) &unsafe_state.state[-1]; if (__setstate_r (arg_state, &unsafe_state) < 0) - return NULL; + ostate = NULL; + + __libc_lock_unlock (lock) return ostate; } @@ -244,8 +264,12 @@ __random () { int32_t retval; + __libc_lock_lock (lock) + (void) __random_r (&unsafe_state, &retval); + __libc_lock_unlock (lock) + return retval; } |