Fix tv_divide().

The old code contained an integer overflow which caused the mp3 audio
format handler to compute the chunk of large mp3 files incorrectly.

Moreover, the code was more complicated than necessary. So replace it
by a simple calculation which just transforms the given struct timeval
into its number of microseconds, does the division and transforms
the quotient back to a struct timeval.

Thanks to Gerrit Renker for pointing out the problem.

diff --git a/time.c b/time.c
index b77138295c2ded13d8890cf3e626a7a8a0df3494..155e11d86e99dcbdef2535108c5602fa1752efc5 100644 (file)
--- a/time.c
+++ b/time.c
@@ -121,17 +121,10 @@ void tv_scale(const unsigned long mult, const struct timeval *tv,
 void tv_divide(const unsigned long divisor, const struct timeval *tv,
        struct timeval *result)
 {
-       long unsigned q;
+       uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) / divisor;
 
-       q = tv->tv_usec / divisor;
-       result->tv_sec = tv->tv_sec / divisor;
-       result->tv_usec = (tv->tv_sec - result->tv_sec * divisor)
-               * 1000 * 1000 / divisor;
-       if (result->tv_usec + q >= 1000 * 1000) {
-               result->tv_sec++;
-               result->tv_usec = 1000 * 1000 - result->tv_usec - q;
-       } else
-               result->tv_usec += q;
+       result->tv_sec = x / 1000 / 1000;
+       result->tv_usec = x % (1000 * 1000);
 }
 
 /**