progress bar: better overflow protection; more precise bar

function                                             old     new   delta
bb_progress_update                                   639     749    +110

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 31 insertions, 23 deletions

diff --git a/libbb/progress.c b/libbb/progress.c
index 40608b047..ced04ac32 100644
--- a/libbb/progress.c
+++ b/libbb/progress.c
@@ -62,35 +62,45 @@ void FAST_FUNC bb_progress_init(bb_progress_t *p)
 
 void FAST_FUNC bb_progress_update(bb_progress_t *p,
                 const char *curfile,
-                off_t beg_range,
-                off_t transferred,
-                off_t totalsize)
+                uoff_t beg_range,
+                uoff_t transferred,
+                uoff_t totalsize)
 {
         uoff_t beg_and_transferred;
         unsigned since_last_update, elapsed;
         unsigned ratio;
-        int barlength, i;
+        int barlength;
+        int kiloscale;
 
         /* totalsize == 0 if it is unknown */
 
+        beg_and_transferred = beg_range + transferred;
+
         elapsed = monotonic_sec();
         since_last_update = elapsed - p->lastupdate_sec;
         /* Do not update on every call
          * (we can be called on every network read!) */
-        if (since_last_update == 0 && !totalsize)
+        if (since_last_update == 0 && beg_and_transferred < totalsize)
                 return;
 
-        beg_and_transferred = beg_range + transferred;
-        ratio = 100;
-        if (beg_and_transferred < totalsize) {
-                /* Do not update on every call
-                 * (we can be called on every network read!) */
-                if (since_last_update == 0)
-                        return;
-                /* long long helps to have it working even if !LFS */
-                ratio = 100ULL * beg_and_transferred / (uoff_t)totalsize;
+        /* Scale sizes down if they are close to overflowing.
+         * If off_t is only 32 bits, this allows calculations
+         * like (100 * transferred / totalsize) without risking overflow.
+         * Introduced error is < 0.1%
+         */
+        kiloscale = 0;
+        if (totalsize >= (1 << 20)) {
+                totalsize >>= 10;
+                beg_range >>= 10;
+                transferred >>= 10;
+                beg_and_transferred >>= 10;
+                kiloscale++;
         }
 
+        if (beg_and_transferred >= totalsize)
+                beg_and_transferred = totalsize;
+
+        ratio = 100 * beg_and_transferred / totalsize;
 #if ENABLE_UNICODE_SUPPORT
         init_unicode();
         {
@@ -106,21 +116,20 @@ void FAST_FUNC bb_progress_update(bb_progress_t *p,
         if (barlength > 0) {
                 /* god bless gcc for variable arrays :) */
                 char buf[barlength + 1];
-                unsigned stars = (unsigned)barlength * ratio / (unsigned)100;
+                unsigned stars = (unsigned)barlength * beg_and_transferred / totalsize;
                 memset(buf, ' ', barlength);
                 buf[barlength] = '\0';
                 memset(buf, '*', stars);
                 fprintf(stderr, "|%s|", buf);
         }
 
-        i = 0;
         while (beg_and_transferred >= 100000) {
-                i++;
+                kiloscale++;
                 beg_and_transferred >>= 10;
         }
         /* see http://en.wikipedia.org/wiki/Tera */
-        fprintf(stderr, "%6u%c ", (unsigned)beg_and_transferred, " kMGTPEZY"[i]);
-#define beg_and_transferred dont_use_beg_and_transferred_below
+        fprintf(stderr, "%6u%c ", (unsigned)beg_and_transferred, " kMGTPEZY"[kiloscale]);
+#define beg_and_transferred dont_use_beg_and_transferred_below()
 
         if (transferred > p->lastsize) {
                 p->lastupdate_sec = elapsed;
@@ -137,13 +146,12 @@ void FAST_FUNC bb_progress_update(bb_progress_t *p,
         if (since_last_update >= STALLTIME) {
                 fprintf(stderr, " - stalled -");
         } else {
-                off_t to_download = totalsize - beg_range;
-                if (!totalsize || transferred <= 0 || (int)elapsed <= 0 || transferred > to_download) {
+                uoff_t to_download = totalsize - beg_range;
+                if (!totalsize || (int)elapsed <= 0 || transferred > to_download) {
                         fprintf(stderr, "--:--:-- ETA");
                 } else {
                         /* to_download / (transferred/elapsed) - elapsed: */
-                        /* (long long helps to have working ETA even if !LFS) */
-                        unsigned eta = (unsigned long long)to_download*elapsed/(uoff_t)transferred - elapsed;
+                        unsigned eta = to_download * elapsed / transferred - elapsed;
                         unsigned secs = eta % 3600;
                         unsigned hours = eta / 3600;
                         fprintf(stderr, "%02u:%02u:%02u ETA", hours, secs / 60, secs % 60);