hdparm: more robust (re overflows) code. +38 bytes.

diff --git a/miscutils/hdparm.c b/miscutils/hdparm.c
index 1f85644d642af6eae2e1db90106f911c37a827c1..906dd7a0c2beef51836c2c368d94f32b84aec504 100644 (file)
--- a/miscutils/hdparm.c
+++ b/miscutils/hdparm.c
@@ -1353,35 +1353,34 @@ static void read_big_block(/*int fd,*/ char *buf)
                buf[i] &= 1;
 }
 
-static unsigned long long dev_size_mb(/*int fd*/ void)
+static unsigned dev_size_mb(/*int fd*/ void)
 {
        union {
                unsigned long long blksize64;
                unsigned blksize32;
        } u;
 
-       if (0 == ioctl(fd, BLKGETSIZE64, &u.blksize64)) { // returns bytes
-               return u.blksize64 / (1024 * 1024);
+       if (0 == ioctl(fd, BLKGETSIZE64, &u.blksize64)) { // bytes
+               u.blksize64 /= (1024 * 1024);
+       } else {
+               xioctl(fd, BLKGETSIZE, &u.blksize32); // sectors
+               u.blksize64 = u.blksize32 / (2 * 1024);
        }
-       xioctl(fd, BLKGETSIZE, &u.blksize32); // returns sectors
-       return u.blksize32 / (2 * 1024);
+       if (u.blksize64 > UINT_MAX)
+               return UINT_MAX;
+       return u.blksize64;
 }
 
-static void print_timing(unsigned long m, unsigned elapsed_us)
+static void print_timing(unsigned m, unsigned elapsed_us)
 {
        unsigned sec = elapsed_us / 1000000;
        unsigned hs = (elapsed_us % 1000000) / 10000;
 
-       printf("%5lu MB in %u.%02u seconds = %lu kB/s\n",
+       printf("%5u MB in %u.%02u seconds = %u kB/s\n",
                m, sec, hs,
-               /* Trying to not overflow 32-bit arith in m * CONST
-                * by keeping CONST not so big. But elapsed_us / CONST2 
-                * also should not introduce big errors. Currently,
-                * 16000us is ~1.6% of 1 second.
-                * "+ 1" prevents div-by-0. */
-               (m * (1024 * 1000000 / (16*1024))) / (elapsed_us / (16*1024) + 1)
-               // ~= (m * 1024 * 1000000) / elapsed_us
-               // = (m * 1024) / (elapsed_us / 1000000)
+               /* + 1 prevents div-by-0 */
+               (unsigned) ((unsigned long long)m * (1024 * 1000000) / (elapsed_us + 1))
+               // ~= (m * 1024) / (elapsed_us / 1000000)
                // = kb / elapsed_sec
        );
 }
@@ -1392,19 +1391,14 @@ static void do_time(int cache /*,int fd*/)
  */
 {
        unsigned max_iterations, iterations;
-       unsigned start; /* don't need to be long long */
+       unsigned start; /* doesn't need to be long long */
        unsigned elapsed, elapsed2;
-       unsigned long total_MB;
+       unsigned total_MB;
        char *buf = xmalloc(TIMING_BUF_BYTES);
 
        if (mlock(buf, TIMING_BUF_BYTES))
                bb_perror_msg_and_die("mlock");
 
-       /* Don't want to read past the end! */
-       max_iterations = UINT_MAX;
-       if (!cache)
-               max_iterations = dev_size_mb() / TIMING_BUF_MB;
-
        /* Clear out the device request queues & give them time to complete.
         * NB: *small* delay. User is expected to have a clue and to not run
         * heavy io in parallel with measurements. */
@@ -1422,10 +1416,14 @@ static void do_time(int cache /*,int fd*/)
        /* Now do the timing */
        iterations = 0;
        /* Max time to run (small for cache, avoids getting
-        * huge total_MB which can overlow on print_timing) */
+        * huge total_MB which can overlow unsigned type) */
        elapsed2 = 510000; /* cache */
-       if (!cache)
+       max_iterations = UINT_MAX;
+       if (!cache) {
                elapsed2 = 3000000; /* not cache */
+               /* Don't want to read past the end! */
+               max_iterations = dev_size_mb() / TIMING_BUF_MB;
+       }
        start = monotonic_us();
        do {
                if (cache)
@@ -1434,7 +1432,7 @@ static void do_time(int cache /*,int fd*/)
                elapsed = (unsigned)monotonic_us() - start;
                ++iterations;
        } while (elapsed < elapsed2 && iterations < max_iterations);
-       total_MB = (unsigned long)iterations * TIMING_BUF_MB;
+       total_MB = iterations * TIMING_BUF_MB;
        //printf(" elapsed:%u iterations:%u ", elapsed, iterations);
        if (cache) {
                /* Cache: remove lseek() and monotonic_us() overheads