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authorDenys Vlasenko <vda.linux@googlemail.com>2009-10-12 13:25:01 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2009-10-12 13:25:01 (GMT)
commit76ace254e171ee9ca7a13f36335ccad9cc6ae6e1 (patch)
tree47b017524b61e217e1dce1a82f3111b97a49425f
parent3c39e702d02600e9023f2f87f6e7c2c62aa27587 (diff)
downloadbusybox-76ace254e171ee9ca7a13f36335ccad9cc6ae6e1.tar.gz
busybox-76ace254e171ee9ca7a13f36335ccad9cc6ae6e1.tar.bz2
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 <vda.linux@googlemail.com>
-rw-r--r--shell/ash.c17
-rw-r--r--shell/hush.c6
-rw-r--r--shell/math.c2
-rw-r--r--shell/random.c7
-rw-r--r--shell/random.h6
5 files changed, 22 insertions, 16 deletions
diff --git a/shell/ash.c b/shell/ash.c
index cc26771..d81dbd3 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 d105029..21f3edc 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 3791b84..fc20def 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 cca9d12..7f5821c 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 8667e1c..e22a2e8 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;