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

1 files changed, 23 insertions, 25 deletions

diff --git a/miscutils/hdparm.c b/miscutils/hdparm.c
index 1f85644d6..906dd7a0c 100644
--- 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