X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/05dcfac6f90b695d4e238f9f15fab1cb5d011967..026a72d4f3e7d69c31c9523aa08554d159e21e1a:/server/choose.c

diff --git a/server/choose.c b/server/choose.c
index dbb962c..c39e27b 100644
--- a/server/choose.c
+++ b/server/choose.c
@@ -56,6 +56,7 @@
 #include "trackname.h"
 #include "queue.h"
 #include "server-queue.h"
+#include "random.h"
 
 #define BASE_WEIGHT 90000
 
@@ -189,42 +190,13 @@ static unsigned long compute_weight(const char *track,
   return BASE_WEIGHT;
 }
 
-static unsigned char random_buffer[4096];
-static size_t random_left;
-
-/** @brief Fill [buf, buf+n) with random bytes */
-static void random_bytes(unsigned char *buf, size_t n) {
-  while(n > 0) {
-    if(random_left > 0) {
-      const size_t this_time = n > random_left ? random_left : n;
-
-      memcpy(buf, random_buffer + random_left - this_time, this_time);
-      n -= this_time;
-      random_left -= this_time;
-    } else {
-      static int fd = -1;
-      int r;
-
-      if(fd < 0) {
-        if((fd = open("/dev/urandom", O_RDONLY)) < 0)
-          fatal(errno, "opening /dev/urandom");
-      }
-      if((r = read(fd, random_buffer, sizeof random_buffer)) < 0)
-        fatal(errno, "reading /dev/urandom");
-      if((size_t)r < sizeof random_buffer)
-        fatal(0, "short read from /dev/urandom");
-      random_left = sizeof random_buffer;
-    }
-  }
-}
-
 /** @brief Pick a random integer uniformly from [0, limit) */
 static unsigned long long pick_weight(unsigned long long limit) {
   unsigned char buf[(sizeof(unsigned long long) * CHAR_BIT + 7)/8], m;
   unsigned long long t, r, slop;
   int i, nby, nbi;
 
-  //info("pick_weight: limit = %llu", limit);
+  D(("pick_weight: limit = %#016llx", limit));
 
   /* First, decide how many bits of output we actually need; do bytes first
    * (they're quicker) and then bits.
@@ -241,7 +213,7 @@ static unsigned long long pick_weight(unsigned long long limit) {
   if (t >> 2) { t >>= 2; nbi += 2; }
   if (t >> 1) { t >>= 1; nbi += 1; }
   nbi++;
-  //info("nby = %d; nbi = %d", nby, nbi);
+  D(("nby = %d; nbi = %d", nby, nbi));
 
   /* Main randomness collection loop.  We read a number of bytes from the
    * randomness source, and glue them together into an integer (dropping
@@ -255,14 +227,14 @@ static unsigned long long pick_weight(unsigned long long limit) {
    * limit > 0; if r < slop then we try again, otherwise r - slop is our
    * winner.
    */
-  slop = (2 << (nbi - 1)) - limit;
+  slop = ((unsigned long long)2 << (nbi - 1)) - limit;
   m = nbi & 7 ? (1 << (nbi & 7)) - 1 : 0xff;
-  //info("slop = %llu", slop);
-  //info("m = 0x%02x", m);
+  D(("slop = %#016llx", slop));
+  D(("m = 0x%02x", m));
 
   do {
     /* Actually get some random data. */
-    random_bytes(buf, nby);
+    random_get(buf, nby);
 
     /* Clobber the top byte.  */
     buf[0] &= m;
@@ -270,9 +242,10 @@ static unsigned long long pick_weight(unsigned long long limit) {
     /* Turn it into an integer.  */
     for (r = 0, i = 0; i < nby; i++)
       r = (r << 8) | buf[i];
-    //info("r = %llu", r);
+    D(("r = %#016llx", r));
   } while (r < slop);
 
+  D(("  result=%#016llx", r - slop));
   return r - slop;
 }
 
@@ -307,6 +280,7 @@ static int collect_tracks_callback(const char *track,
    * choose thing i, for 0 <= i < n - 1, is w_i/c_{n-1} (induction
    * hypothesis); undoing the conditioning gives the desired result.
    */
+  D(("consider %s", track));
   if(weight) {
     total_weight += weight;
     if (pick_weight(total_weight) < weight)
@@ -358,7 +332,7 @@ int main(int argc, char **argv) {
   trackdb_commit_transaction(global_tid);
   trackdb_close();
   trackdb_deinit();
-  //info("ntracks=%ld total_weight=%lld", ntracks, total_weight);
+  D(("ntracks=%ld total_weight=%lld", ntracks, total_weight));
   if(!total_weight)
     fatal(0, "no tracks match random choice criteria");
   if(!winning)