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authorDenis Vlasenko2008-06-29 02:25:53 +0000
committerDenis Vlasenko2008-06-29 02:25:53 +0000
commitce13b7600277478055de0b7c38b483a76145efd2 (patch)
treeb952e4328f8e182099fb3d72afc5c8978a56ebff
parent540ab7097c2932e8ef9e3bbb6abf5604c05acdde (diff)
downloadbusybox-ce13b7600277478055de0b7c38b483a76145efd2.zip
busybox-ce13b7600277478055de0b7c38b483a76145efd2.tar.gz
libbb: shrink monotonic_XXX functions, introduce monotonic_ns
(unused for now) function old new delta get_mono - 31 +31 sv_main 1228 1234 +6 expand 1693 1697 +4 get_address 178 181 +3 utoa_to_buf 108 110 +2 builtin_exit 46 48 +2 qrealloc 36 33 -3 qgravechar 109 106 -3 ash_main 1383 1380 -3 grep_file 850 846 -4 popstring 140 134 -6 monotonic_us 85 60 -25 monotonic_sec 41 16 -25 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 5/7 up/down: 48/-69) Total: -21 bytes
-rw-r--r--include/libbb.h1
-rw-r--r--libbb/time.c29
-rw-r--r--shell/ash.c12
3 files changed, 31 insertions, 11 deletions
diff --git a/include/libbb.h b/include/libbb.h
index d74f802..7bc0dca 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -237,6 +237,7 @@ extern int *const bb_errno;
#define errno (*bb_errno)
#endif
+unsigned long long monotonic_ns(void) FAST_FUNC;
unsigned long long monotonic_us(void) FAST_FUNC;
unsigned monotonic_sec(void) FAST_FUNC;
diff --git a/libbb/time.c b/libbb/time.c
index 7d3ac91..850ac15 100644
--- a/libbb/time.c
+++ b/libbb/time.c
@@ -10,8 +10,8 @@
#include "libbb.h"
#if ENABLE_MONOTONIC_SYSCALL
-#include <sys/syscall.h>
+#include <sys/syscall.h>
/* Old glibc (< 2.3.4) does not provide this constant. We use syscall
* directly so this definition is safe. */
#ifndef CLOCK_MONOTONIC
@@ -20,30 +20,47 @@
/* libc has incredibly messy way of doing this,
* typically requiring -lrt. We just skip all this mess */
+static void get_mono(struct timespec *ts)
+{
+ if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, ts))
+ bb_error_msg_and_die("clock_gettime(MONOTONIC) failed");
+}
+unsigned long long FAST_FUNC monotonic_ns(void)
+{
+ struct timespec ts;
+ get_mono(&ts);
+ return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
+}
unsigned long long FAST_FUNC monotonic_us(void)
{
struct timespec ts;
- if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts))
- bb_error_msg_and_die("clock_gettime(MONOTONIC) failed");
+ get_mono(&ts);
return ts.tv_sec * 1000000ULL + ts.tv_nsec/1000;
}
unsigned FAST_FUNC monotonic_sec(void)
{
struct timespec ts;
- if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts))
- bb_error_msg_and_die("clock_gettime(MONOTONIC) failed");
+ get_mono(&ts);
return ts.tv_sec;
}
+
#else
+
+unsigned long long FAST_FUNC monotonic_ns(void)
+{
+ struct timeval tv;
+ gettimeofday(&tv, NULL);
+ return tv.tv_sec * 1000000000ULL + tv.tv_usec * 1000;
+}
unsigned long long FAST_FUNC monotonic_us(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec * 1000000ULL + tv.tv_usec;
}
-
unsigned FAST_FUNC monotonic_sec(void)
{
return time(NULL);
}
+
#endif
diff --git a/shell/ash.c b/shell/ash.c
index 9c32162..85064d5 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9615,7 +9615,6 @@ setcmd(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
}
#if ENABLE_ASH_RANDOM_SUPPORT
-/* Roughly copied from bash.. */
static void
change_random(const char *value)
{
@@ -9636,10 +9635,11 @@ change_random(const char *value)
if (random_galois_LFSR < 0) /* if we just shifted 1 out of msb... */
t ^= MASK;
random_galois_LFSR = t;
- /* Both are weak, xoring them gives better randomness
+ /* Both are weak, combining them gives better randomness
* and ~2^64 period. & 0x7fff is probably bash compat
- * for $RANDOM range. */
- t = (t ^ random_LCG) & 0x7fff;
+ * for $RANDOM range. Combining with subtraction is
+ * just for fun. + and ^ would work equally well. */
+ t = (t - random_LCG) & 0x7fff;
/* set without recursion */
setvar(vrandom.text, utoa(t), VNOFUNC);
vrandom.flags &= ~VNOFUNC;
@@ -13432,7 +13432,9 @@ int ash_main(int argc ATTRIBUTE_UNUSED, char **argv)
rootpid = getpid();
#if ENABLE_ASH_RANDOM_SUPPORT
- random_galois_LFSR = random_LCG = rootpid + time(NULL);
+ /* Can use monotonic_ns() for better randomness but for now it is
+ * not used anywhere else in busybox... so avoid bloat */
+ random_galois_LFSR = random_LCG = rootpid + monotonic_us();
#endif
init();
setstackmark(&smark);