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-rw-r--r--ubi-utils/src/common.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/ubi-utils/src/common.c b/ubi-utils/src/common.c
index 3fd470b..da5156d 100644
--- a/ubi-utils/src/common.c
+++ b/ubi-utils/src/common.c
@@ -23,10 +23,13 @@
* Adrian Hunter
*/
+#include <sys/time.h>
+#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
+#include <unistd.h>
#include "common.h"
/**
@@ -175,3 +178,32 @@ void ubiutils_print_text(FILE *stream, const char *text, int width)
++p;
}
}
+
+/**
+ * ubiutils_srand - 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 zero in case of success
+ * and a %-1 in case of error.
+ */
+int ubiutils_srand(void)
+{
+ struct timeval tv;
+ struct timezone tz;
+ unsigned 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 %= RAND_MAX;
+ srand(seed);
+ return 0;
+}