From edabe3d8b479e47a1bb3ed495f2a1d94b0ecbb2d Mon Sep 17 00:00:00 2001 From: Alexander Monakov Date: Thu, 21 Sep 2017 15:58:14 +0300 Subject: [PATCH] toplev: read from /dev/urandom only when needed * toplev.h (set_random_seed): Adjust return type. * toplev.c (init_local_tick): Move eager initialization of random_seed to get_random_seed. Adjust comment. (init_random_seed): Inline to get_random_seed, delete. (get_random_seed): Initialize random_seed lazily. (set_random_seed): Do not return previous value. (print_switch_value): Do not call get_random_seed. From-SVN: r253069 --- gcc/ChangeLog | 12 +++++++++++- gcc/toplev.c | 52 ++++++++++++++++----------------------------------- gcc/toplev.h | 2 +- 3 files changed, 28 insertions(+), 38 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 90dc208d572..7c0674d5ad7 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,4 +1,14 @@ -2017-09-21 Evgeny Kudryashov +2017-09-21 Alexander Monakov + + * toplev.h (set_random_seed): Adjust return type. + * toplev.c (init_local_tick): Move eager initialization of random_seed + to get_random_seed. Adjust comment. + (init_random_seed): Inline to get_random_seed, delete. + (get_random_seed): Initialize random_seed lazily. + (set_random_seed): Do not return previous value. + (print_switch_value): Do not call get_random_seed. + +2017-09-21 Evgeny Kudryashov * cgraph.c (delete_function_version): New, broken out from... (cgraph_node::delete_function_version): ...here. Rename to diff --git a/gcc/toplev.c b/gcc/toplev.c index 6f48e10850d..bee79d313b2 100644 --- a/gcc/toplev.c +++ b/gcc/toplev.c @@ -239,7 +239,7 @@ announce_function (tree decl) } } -/* Initialize local_tick with a random number or -1 if +/* Initialize local_tick with the time of day, or -1 if flag_random_seed is set. */ static void @@ -247,19 +247,6 @@ init_local_tick (void) { if (!flag_random_seed) { - /* Try urandom first. Time of day is too likely to collide. - In case of any error we just use the local tick. */ - - int fd = open ("/dev/urandom", O_RDONLY); - if (fd >= 0) - { - if (read (fd, &random_seed, sizeof (random_seed)) - != sizeof (random_seed)) - random_seed = 0; - close (fd); - } - - /* Now get the tick anyways */ #ifdef HAVE_GETTIMEOFDAY { struct timeval tv; @@ -280,34 +267,33 @@ init_local_tick (void) local_tick = -1; } -/* Set up a default flag_random_seed and local_tick, unless the user - already specified one. Must be called after init_local_tick. */ - -static void -init_random_seed (void) -{ - if (!random_seed) - random_seed = local_tick ^ getpid (); /* Old racey fallback method */ -} - /* Obtain the random_seed. Unless NOINIT, initialize it if it's not provided in the command line. */ HOST_WIDE_INT get_random_seed (bool noinit) { - if (!flag_random_seed && !noinit) - init_random_seed (); + if (!random_seed && !noinit) + { + int fd = open ("/dev/urandom", O_RDONLY); + if (fd >= 0) + { + if (read (fd, &random_seed, sizeof (random_seed)) + != sizeof (random_seed)) + random_seed = 0; + close (fd); + } + if (!random_seed) + random_seed = local_tick ^ getpid (); + } return random_seed; } -/* Modify the random_seed string to VAL. Return its previous - value. */ +/* Set flag_random_seed to VAL, and if non-null, reinitialize random_seed. */ -const char * +void set_random_seed (const char *val) { - const char *old = flag_random_seed; flag_random_seed = val; if (flag_random_seed) { @@ -318,7 +304,6 @@ set_random_seed (const char *val) if (!(endp > flag_random_seed && *endp == 0)) random_seed = crc32_string (0, flag_random_seed); } - return old; } /* Handler for fatal signals, such as SIGSEGV. These are transformed @@ -818,11 +803,6 @@ print_switch_values (print_switch_fn_type print_fn) int pos = 0; size_t j; - /* Fill in the -frandom-seed option, if the user didn't pass it, so - that it can be printed below. This helps reproducibility. */ - if (!flag_random_seed) - init_random_seed (); - /* Print the options as passed. */ pos = print_single_switch (print_fn, pos, SWITCH_TYPE_DESCRIPTIVE, _("options passed: ")); diff --git a/gcc/toplev.h b/gcc/toplev.h index 2f6b587d233..aed806eb28f 100644 --- a/gcc/toplev.h +++ b/gcc/toplev.h @@ -91,7 +91,7 @@ extern bool set_src_pwd (const char *); /* Functions used to manipulate the random seed. */ extern HOST_WIDE_INT get_random_seed (bool); -extern const char *set_random_seed (const char *); +extern void set_random_seed (const char *); extern void initialize_rtl (void); -- 2.30.2