[Cvs-cvs] Changes to ccvs/src/main.c

[Mark D . Baushke]

Index: ccvs/src/main.c
diff -u ccvs/src/main.c:1.257 ccvs/src/main.c:1.258
--- ccvs/src/main.c:1.257       Mon Sep 26 00:33:39 2005
+++ ccvs/src/main.c     Wed Sep 28 23:59:02 2005
@@ -458,6 +458,46 @@
 
 
 
+
+enum {RANDOM_BYTES = 8};
+enum {N = (sizeof(time_t) + RANDOM_BYTES)};
+
+static char const alphabet[62] =
+  "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+/* Divide BUF by D, returning the remainder.  Replace BUF by the
+   quotient.  BUF[0] is the most significant part of BUF.
+   D must not exceed UINT_MAX >> CHAR_BIT.  */
+static unsigned int
+divide_by (unsigned char buf[N], unsigned int d)
+{
+    unsigned int carry = 0;
+    int i;
+    for (i = 0; i < N; i++)
+    {
+       unsigned int byte = buf[i];
+       unsigned int dividend = (carry << CHAR_BIT) + byte;
+       buf[i] = dividend / d;
+       carry = dividend % d;
+    }
+    return carry;
+}
+
+static void
+convert (char const input[N], char *output)
+{
+    static char const zero[N] = { 0, };
+    unsigned char buf[N];
+    size_t o = 0;
+    memcpy (buf, input, N);
+    while (memcmp (buf, zero, N) != 0)
+       output[o++] = alphabet[divide_by (buf, sizeof alphabet)];
+    if (! o)
+       output[o++] = '0';
+    output[o] = '\0';
+}
+
+
 int
 main (int argc, char **argv)
 {
@@ -733,8 +773,29 @@
 
     /* Calculate the cvs global session ID */
 
-    global_session_id = Xasprintf ("%x%08lx%04x", (int)getpid(),
-                                  (long)time (NULL), rand()&0xFFFF);
+    {
+       char buf[N] = { 0, };
+       char out[N*2];
+       ssize_t len = 0;
+       time_t rightnow = time (NULL);
+       unsigned char *p = (unsigned char *) (buf + sizeof (time_t));
+       int fd = open ("/dev/urandom", O_RDONLY, O_NOCTTY);
+       if (fd >= 0) {
+           len = read (fd, buf + sizeof (time_t), RANDOM_BYTES);
+           close (fd);
+       }
+       if (len > 0 && rightnow >= 0) {
+           while (rightnow != 0) {
+               *--p = rightnow % (UCHAR_MAX + 1);
+               rightnow /= UCHAR_MAX + 1;
+           }
+           convert(buf, out);
+           global_session_id = strdup (out);
+       } else
+           global_session_id = Xasprintf ("%x%08lx%04x", (int)getpid(),
+                                          (long)time (NULL), rand()&0xFFFF);
+    }
+
 
     TRACE (TRACE_FUNCTION, "main: Session ID is %s", global_session_id);