From: Davidlohr Bueso <dave@xxxxxxx>
Add a random number(s) generator specific file. The intial functions are based
on what libuuid provide. I did some modifications like avoid WIN32 checks - this
is util-LINUX.
Signed-off-by: Davidlohr Bueso <dave@xxxxxxx>
---
include/randutils.h | 19 +++++++++
lib/Makefile.am | 2 +
lib/randutils.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 125 insertions(+), 0 deletions(-)
create mode 100644 include/randutils.h
create mode 100644 lib/randutils.c
diff --git a/include/randutils.h b/include/randutils.h
new file mode 100644
index 0000000..8c1a447
--- /dev/null
+++ b/include/randutils.h
@@ -0,0 +1,19 @@
+#ifndef UTIL_LINUX_RANDUTILS
+#define UTIL_LINUX_RANDUTILS
+
+#include <sys/syscall.h>
+
+#ifdef HAVE_SRANDOM
+#define srand(x) srandom(x)
+#define rand() random()
+#endif
+
+#if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
+#define DO_JRAND_MIX
+static unsigned short jrand_seed[3];
+#endif
+
+int random_get_fd(void);
+void random_get_bytes(void *buf, int nbytes);
+
+#endif
diff --git a/lib/Makefile.am b/lib/Makefile.am
index c34481d..fc967fc 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -10,6 +10,7 @@ noinst_PROGRAMS = \
test_ismounted \
test_mangle \
test_procutils \
+ test_randutils \
test_strutils \
test_tt \
test_wholedisk
@@ -30,6 +31,7 @@ test_at_SOURCES = at.c
test_at_CFLAGS = -DTEST_PROGRAM_AT
test_strutils_SOURCES = strutils.c
+test_randutils_SOURCES = randutils.c
test_procutils_SOURCES = procutils.c
if LINUX
diff --git a/lib/randutils.c b/lib/randutils.c
new file mode 100644
index 0000000..7bc78a3
--- /dev/null
+++ b/lib/randutils.c
@@ -0,0 +1,104 @@
+/*
+ * General purpose random utilities
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+
+#include "randutils.h"
+
+int random_get_fd(void)
+{
+ int i, fd;
+ struct timeval tv;
+
+ gettimeofday(&tv, 0);
+ fd = open("/dev/urandom", O_RDONLY);
+ if (fd == -1)
+ fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
+ if (fd >= 0) {
+ i = fcntl(fd, F_GETFD);
+ if (i >= 0)
+ fcntl(fd, F_SETFD, i | FD_CLOEXEC);
+ }
+ srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
+
+#ifdef DO_JRAND_MIX
+ jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
+ jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
+ jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
+#endif
+ /* Crank the random number generator a few times */
+ gettimeofday(&tv, 0);
+ for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
+ rand();
+ return fd;
+}
+
+
+/*
+ * Generate a stream of random nbytes into buf.
+ * Use /dev/urandom if possible, and if not,
+ * use glibc pseudo-random functions.
+ */
+void random_get_bytes(void *buf, int nbytes)
+{
+ int i, n = nbytes, fd = random_get_fd();
+ int lose_counter = 0;
+ unsigned char *cp = (unsigned char *) buf;
+
+ if (fd >= 0) {
+ while (n > 0) {
+ i = read(fd, cp, n);
+ if (i <= 0) {
+ if (lose_counter++ > 16)
+ break;
+ continue;
+ }
+ n -= i;
+ cp += i;
+ lose_counter = 0;
+ }
+ }
+
+ /*
+ * We do this all the time, but this is the only source of
+ * randomness if /dev/random/urandom is out to lunch.
+ */
+ for (cp = buf, i = 0; i < nbytes; i++)
+ *cp++ ^= (rand() >> 7) & 0xFF;
+
+#ifdef DO_JRAND_MIX
+ {
+ unsigned short tmp_seed[3];
+
+ memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
+ jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
+ for (cp = buf, i = 0; i < nbytes; i++)
+ *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
+ memcpy(jrand_seed, tmp_seed,
+ sizeof(jrand_seed)-sizeof(unsigned short));
+ }
+#endif
+
+ return;
+}
+
+#ifdef TEST_PROGRAM
+int main(int argc, char *argv[])
+{
+ unsigned int v, i;
+
+ /* generate and print 10 random numbers */
+ for (i = 0; i < 10; i++) {
+ random_get_bytes(&v, sizeof(v));
+ printf("%d\n", v);
+ }
+
+ return EXIT_SUCCESS;
+}
+#endif /* TEST_PROGRAM */
--
1.7.4.1
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