ubi-test: seed the random genrator in tests

Add a common seed_random_generator() and make tests use it
for seeding the random generator.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

5 files changed, 47 insertions, 14 deletions

diff --git a/tests/ubi-tests/common.c b/tests/ubi-tests/common.c
index b605dd9..05cbecc 100644
--- a/tests/ubi-tests/common.c
+++ b/tests/ubi-tests/common.c
@@ -26,8 +26,10 @@
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
+#include <limits.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/time.h>
 #include <fcntl.h>
 #include "libubi.h"
 #include "common.h"
@@ -332,3 +334,32 @@ close:
 	close(fd);
 	return -1;
 }
+
+/**
+ * seed_random_generator - randomly seed the standard pseudo-random generator.
+ *
+ * This helper function seeds the standard libc pseudo-random generator with a
+ * more or less random value to make sure the 'rand()' call does not return the
+ * same sequence every time UBI utilities run. Returns the random seed in case
+ * of success and a %-1 in case of error.
+ */
+int seed_random_generator(void)
+{
+	struct timeval tv;
+	struct timezone tz;
+	int seed;
+
+	/*
+	 * Just assume that a combination of the PID + current time is a
+	 * reasonably random number.
+	 */
+	if (gettimeofday(&tv, &tz))
+		return -1;
+
+	seed = (unsigned int)tv.tv_sec;
+	seed += (unsigned int)tv.tv_usec;
+	seed *= getpid();
+	seed %= INT_MAX;
+	srand(seed);
+	return seed;
+}
diff --git a/tests/ubi-tests/common.h b/tests/ubi-tests/common.h
index 859af14..88e963f 100644
--- a/tests/ubi-tests/common.h
+++ b/tests/ubi-tests/common.h
@@ -90,19 +90,21 @@ extern "C" {
 	 (s)/5-3, (s)/5-2, (s)/5-1, (s)/5+1, (s)/5+2, (s)/5+3, (s)-17, (s)-9,  \
 	 (s)-8, (s)-6, (s)-4, (s)-1, (s)};
 
+extern int seed_random_generator(void);
+
 extern void __errmsg(const char *test, const char *func, int line,
 		     const char *fmt, ...);
-void __failed(const char *test, const char *func, int line,
-	      const char *failed);
-int __initial_check(const char *test, int argc, char * const argv[]);
-int __check_volume(libubi_t libubi, struct ubi_dev_info *dev_info,
-		   const char *test, const char *func, int line, int vol_id,
-		   const struct ubi_mkvol_request *req);
-int __check_vol_patt(libubi_t libubi, const char *test, const char *func,
-		     int line, const char *node, uint8_t byte);
-int __update_vol_patt(libubi_t libubi, const char *test, const char *func,
-		      int line, const char *node, long long bytes,
-		      uint8_t byte);
+extern void __failed(const char *test, const char *func, int line,
+		     const char *failed);
+extern int __initial_check(const char *test, int argc, char * const argv[]);
+extern int __check_volume(libubi_t libubi, struct ubi_dev_info *dev_info,
+			  const char *test, const char *func, int line,
+			  int vol_id, const struct ubi_mkvol_request *req);
+extern int __check_vol_patt(libubi_t libubi, const char *test, const char *func,
+			    int line, const char *node, uint8_t byte);
+extern int __update_vol_patt(libubi_t libubi, const char *test, const char *func,
+			     int line, const char *node, long long bytes,
+			     uint8_t byte);
 
 #ifdef __cplusplus
 }
diff --git a/tests/ubi-tests/integ.c b/tests/ubi-tests/integ.c
index e0e8bee..f293444 100644
--- a/tests/ubi-tests/integ.c
+++ b/tests/ubi-tests/integ.c
@@ -731,10 +731,8 @@ int main(int argc,char *argv[])
 		return 1;
 	}
 
-	initial_seed = getpid();
+	next_seed = initial_seed = seed_random_generator();
 	printf("Initial seed = %u\n", (unsigned) initial_seed);
-	next_seed = initial_seed;
-	srand(initial_seed);
 	load_ubi();
 
 	libubi = libubi_open();
diff --git a/tests/ubi-tests/io_paral.c b/tests/ubi-tests/io_paral.c
index 3ceda95..9754a0d 100644
--- a/tests/ubi-tests/io_paral.c
+++ b/tests/ubi-tests/io_paral.c
@@ -233,6 +233,7 @@ int main(int argc, char * const argv[])
 	int i, ret;
 	pthread_t threads[THREADS_NUM];
 
+	seed_random_generator();
 	if (initial_check(argc, argv))
 		return 1;
 
diff --git a/tests/ubi-tests/io_update.c b/tests/ubi-tests/io_update.c
index 3b8169d..0259446 100644
--- a/tests/ubi-tests/io_update.c
+++ b/tests/ubi-tests/io_update.c
@@ -267,6 +267,7 @@ remove:
 
 int main(int argc, char * const argv[])
 {
+	seed_random_generator();
 	if (initial_check(argc, argv))
 		return 1;