static char argv0_buf[ARGV0_BUF_SIZE] = "btrfs";
+static int rand_seed_initlized = 0;
+static unsigned short rand_seed[3];
+
const char *get_argv0_buf(void)
{
return argv0_buf;
return ret;
}
+
+void init_rand_seed(u64 seed)
+{
+ int i;
+
+ /* only use the last 48 bits */
+ for (i = 0; i < 3; i++) {
+ rand_seed[i] = (unsigned short)(seed ^ (unsigned short)(-1));
+ seed >>= 16;
+ }
+ rand_seed_initlized = 1;
+}
+
+static void __init_seed(void)
+{
+ struct timeval tv;
+ int ret;
+ int fd;
+
+ if(rand_seed_initlized)
+ return;
+ /* Use urandom as primary seed source. */
+ fd = open("/dev/urandom", O_RDONLY);
+ if (fd >= 0) {
+ ret = read(fd, rand_seed, sizeof(rand_seed));
+ close(fd);
+ if (ret < sizeof(rand_seed))
+ goto fallback;
+ } else {
+fallback:
+ /* Use time and pid as fallback seed */
+ warning("failed to read /dev/urandom, use time and pid as random seed");
+ gettimeofday(&tv, 0);
+ rand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
+ rand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
+ rand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
+ }
+ rand_seed_initlized = 1;
+}
+
+u32 rand_u32(void)
+{
+ __init_seed();
+ /*
+ * Don't use nrand48, its range is [0,2^31) The highest bit will alwasy
+ * be 0. Use jrand48 to include the highest bit.
+ */
+ return (u32)jrand48(rand_seed);
+}
+
+unsigned int rand_range(unsigned int upper)
+{
+ __init_seed();
+ /*
+ * Use the full 48bits to mod, which would be more uniformly
+ * distributed
+ */
+ return (unsigned int)(jrand48(rand_seed) % upper);
+}
return 1;
}
+/* Pseudo random number generator wrappers */
+u32 rand_u32(void);
+
+static inline int rand_int(void)
+{
+ return (int)(rand_u32());
+}
+
+static inline u64 rand_u64(void)
+{
+ u64 ret = 0;
+
+ ret += rand_u32();
+ ret <<= 32;
+ ret += rand_u32();
+ return ret;
+}
+
+static inline u16 rand_u16(void)
+{
+ return (u16)(rand_u32());
+}
+
+static inline u8 rand_u8(void)
+{
+ return (u8)(rand_u32());
+}
+
+/* Return random number in range [0, limit) */
+unsigned int rand_range(unsigned int upper);
+
+/* Also allow setting the seed manually */
+void init_rand_seed(u64 seed);
+
#endif