From 76ace254e171ee9ca7a13f36335ccad9cc6ae6e1 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Mon, 12 Oct 2009 15:25:01 +0200 Subject: [PATCH] ash,hush: fix $RANDOM in children being repeated function old new delta next_random 46 68 +22 forkshell 248 263 +15 expand_vars_to_list 2118 2131 +13 run_pipe 1775 1782 +7 popstring 134 140 +6 builtin_umask 123 121 -2 ash_main 1356 1336 -20 get_local_var_value 125 104 -21 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 5/3 up/down: 63/-43) Total: 20 bytes Signed-off-by: Denys Vlasenko --- shell/ash.c | 17 ++++------------- shell/hush.c | 6 ++++-- shell/math.c | 2 +- shell/random.c | 7 +++++++ shell/random.h | 6 ++++++ 5 files changed, 22 insertions(+), 16 deletions(-) diff --git a/shell/ash.c b/shell/ash.c index cc2677126..d81dbd3f5 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -4725,10 +4725,12 @@ forkshell(struct job *jp, union node *n, int mode) freejob(jp); ash_msg_and_raise_error("can't fork"); } - if (pid == 0) + if (pid == 0) { + CLEAR_RANDOM_T(&random_gen); /* or else $RANDOM repeats in child */ forkchild(jp, n, mode); - else + } else { forkparent(jp, n, mode, pid); + } return pid; } @@ -10079,12 +10081,6 @@ setcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM) static void FAST_FUNC change_random(const char *value) { - /* Galois LFSR parameter */ - /* Taps at 32 31 29 1: */ - enum { MASK = 0x8000000b }; - /* Another example - taps at 32 31 30 10: */ - /* MASK = 0x00400007 */ - uint32_t t; if (value == NULL) { @@ -13268,11 +13264,6 @@ int ash_main(int argc UNUSED_PARAM, char **argv) #endif rootpid = getpid(); -#if ENABLE_ASH_RANDOM_SUPPORT - /* Can use monotonic_ns() for better randomness but for now it is - * not used anywhere else in busybox... so avoid bloat */ - INIT_RANDOM_T(&random_gen, rootpid, monotonic_us()); -#endif init(); setstackmark(&smark); procargs(argv); diff --git a/shell/hush.c b/shell/hush.c index d105029ff..21f3edcac 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -88,6 +88,8 @@ #include "match.h" #if ENABLE_HUSH_RANDOM_SUPPORT # include "random.h" +#else +# define CLEAR_RANDOM_T(rnd) ((void)0) #endif #ifndef PIPE_BUF # define PIPE_BUF 4096 /* amount of buffering in a pipe */ @@ -1319,8 +1321,6 @@ static const char *get_local_var_value(const char *name) // bash compat: UID? EUID? #if ENABLE_HUSH_RANDOM_SUPPORT if (strcmp(name, "RANDOM") == 0) { - if (G.random_gen.galois_LFSR == 0) - INIT_RANDOM_T(&G.random_gen, G.root_pid, monotonic_us()); return utoa(next_random(&G.random_gen)); } #endif @@ -4000,6 +4000,7 @@ static NOINLINE int run_pipe(struct pipe *pi) if (!command->pid) { /* child */ #if ENABLE_HUSH_JOB disable_restore_tty_pgrp_on_exit(); + CLEAR_RANDOM_T(&G.random_gen); /* or else $RANDOM repeats in child */ /* Every child adds itself to new process group * with pgid == pid_of_first_child_in_pipe */ @@ -5207,6 +5208,7 @@ static FILE *generate_stream_from_string(const char *s) + (1 << SIGTTIN) + (1 << SIGTTOU) , SIG_IGN); + CLEAR_RANDOM_T(&G.random_gen); /* or else $RANDOM repeats in child */ close(channel[0]); /* NB: close _first_, then move fd! */ xmove_fd(channel[1], 1); /* Prevent it from trying to handle ctrl-z etc */ diff --git a/shell/math.c b/shell/math.c index 3791b84bc..fc20def62 100644 --- a/shell/math.c +++ b/shell/math.c @@ -258,7 +258,7 @@ static int arith_lookup_val(v_n_t *t, a_e_h_t *math_hooks) { if (t->var) { - const char * p = lookupvar(t->var); + const char *p = lookupvar(t->var); if (p) { int errcode; diff --git a/shell/random.c b/shell/random.c index cca9d120d..7f5821cbc 100644 --- a/shell/random.c +++ b/shell/random.c @@ -20,6 +20,13 @@ next_random(random_t *rnd) uint32_t t; + if (UNINITED_RANDOM_T(rnd)) { + /* Can use monotonic_ns() for better randomness but for now + * it is not used anywhere else in busybox... so avoid bloat + */ + INIT_RANDOM_T(rnd, getpid(), monotonic_us()); + } + /* LCG has period of 2^32 and alternating lowest bit */ rnd->LCG = 1664525 * rnd->LCG + 1013904223; /* Galois LFSR has period of 2^32-1 = 3 * 5 * 17 * 257 * 65537 */ diff --git a/shell/random.h b/shell/random.h index 8667e1c99..e22a2e88b 100644 --- a/shell/random.h +++ b/shell/random.h @@ -13,7 +13,13 @@ typedef struct random_t { uint32_t LCG; /* LCG (fast but weak) */ } random_t; +#define UNINITED_RANDOM_T(rnd) \ + ((rnd)->galois_LFSR == 0) + #define INIT_RANDOM_T(rnd, nonzero, v) \ ((rnd)->galois_LFSR = (nonzero), (rnd)->LCG = (v)) +#define CLEAR_RANDOM_T(rnd) \ + ((rnd)->galois_LFSR = 0) + uint32_t next_random(random_t *rnd) FAST_FUNC; -- 2.25.1