libbb: shrink wget/tftp progress indicator code for 32-bit

function                                             old     new   delta
bb_progress_update                                   756     654    -102

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

1 files changed, 38 insertions, 40 deletions

diff --git a/libbb/progress.c b/libbb/progress.c
index 64e6529ac..17272fd17 100644
--- a/libbb/progress.c
+++ b/libbb/progress.c
@@ -71,7 +71,7 @@ void FAST_FUNC bb_progress_update(bb_progress_t *p,
                 uoff_t transferred,
                 uoff_t totalsize)
 {
-        uoff_t beg_and_transferred;
+        unsigned beg_and_transferred; /* does not need uoff_t, see scaling code below */
         unsigned since_last_update, elapsed;
         int notty;
         int kiloscale;
@@ -102,33 +102,24 @@ void FAST_FUNC bb_progress_update(bb_progress_t *p,
          * without risking overflow: we guarantee 10 highest bits to be 0.
          * Introduced error is less than 1 / 2^12 ~= 0.025%
          */
-        if (ULONG_MAX > 0xffffffff || sizeof(off_t) == 4 || sizeof(off_t) != 8) {
-                /*
-                 * 64-bit CPU || small off_t: in either case,
-                 * >> is cheap, single-word operation.
-                 * ... || strange off_t: also use this code
-                 * (it is safe, just suboptimal wrt code size),
-                 * because 32/64 optimized one works only for 64-bit off_t.
-                 */
-                if (totalsize >= (1 << 22)) {
-                        totalsize >>= 10;
-                        beg_size >>= 10;
-                        transferred >>= 10;
-                        kiloscale = 1;
-                }
-        } else {
-                /* 32-bit CPU and 64-bit off_t.
-                 * Use a 40-bit shift, it is easier to do on 32-bit CPU.
-                 */
-/* ONE suppresses "warning: shift count >= width of type" */
-#define ONE (sizeof(off_t) > 4)
-                if (totalsize >= (uoff_t)(1ULL << 54*ONE)) {
-                        totalsize = (uint32_t)(totalsize >> 32*ONE) >> 8;
-                        beg_size = (uint32_t)(beg_size >> 32*ONE) >> 8;
-                        transferred = (uint32_t)(transferred >> 32*ONE) >> 8;
-                        kiloscale = 4;
-                }
+        while (totalsize >= (1 << 22)) {
+                totalsize >>= 10;
+                beg_size >>= 10;
+                transferred >>= 10;
+                kiloscale++;
         }
+        /* If they were huge, now they are scaled down to [4194303,4096] range.
+         * (N * totalsize) won't overflow 32 bits for N up to 1024.
+         * The downside is that files larger than 4194303 kbytes (>4GB)
+         * never show kbytes download size, they show "0M","1M"... right away
+         * since kiloscale is already >1.
+         */
+#if ULONG_MAX == 0xffffffff
+/* 32-bit CPU, uoff_t arithmetic is complex on it, cast variables to narrower types */
+# define totalsize   ((unsigned)totalsize)
+# define beg_size    ((unsigned)beg_size)
+# define transferred ((unsigned)transferred)
+#endif
 
         notty = !isatty(STDERR_FILENO);
 
@@ -146,13 +137,18 @@ void FAST_FUNC bb_progress_update(bb_progress_t *p,
 
                 barlength = get_terminal_width(2) - 49;
                 if (barlength > 0) {
-                        /* god bless gcc for variable arrays :) */
-                        char buf[barlength + 1];
-                        unsigned stars = (unsigned)barlength * beg_and_transferred / totalsize;
-                        memset(buf, ' ', barlength);
-                        buf[barlength] = '\0';
-                        memset(buf, '*', stars);
-                        fprintf(stderr, " |%s|", buf);
+                        if (barlength > 999)
+                                barlength = 999;
+                        {
+                                /* god bless gcc for variable arrays :) */
+                                char buf[barlength + 1];
+                                unsigned stars = (unsigned)barlength * beg_and_transferred / totalsize;
+                                /* can't overflow ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */
+                                memset(buf, ' ', barlength);
+                                buf[barlength] = '\0';
+                                memset(buf, '*', stars);
+                                fprintf(stderr, " |%s|", buf);
+                        }
                 }
         }
 
@@ -184,16 +180,18 @@ void FAST_FUNC bb_progress_update(bb_progress_t *p,
                 fprintf(stderr, " --:--:-- ETA");
         } else {
                 unsigned eta, secs, hours;
+                unsigned bytes;
 
-                totalsize -= beg_size; /* now it's "total to upload" */
+                bytes = totalsize - beg_size;
 
                 /* Estimated remaining time =
-                 * estimated_sec_to_dl_totalsize_bytes - elapsed_sec =
-                 * totalsize / average_bytes_sec_so_far - elapsed =
-                 * totalsize / (transferred/elapsed) - elapsed =
-                 * totalsize * elapsed / transferred - elapsed
+                 * estimated_sec_to_dl_bytes - elapsed_sec =
+                 * bytes / average_bytes_sec_so_far - elapsed =
+                 * bytes / (transferred/elapsed) - elapsed =
+                 * bytes * elapsed / transferred - elapsed
                  */
-                eta = totalsize * elapsed / transferred - elapsed;
+                eta = (unsigned long)bytes * elapsed / transferred - elapsed;
+                /* if 32bit, can overflow ^^^^^^^^^^, but this would only show bad ETA */
                 if (eta >= 1000*60*60)
                         eta = 1000*60*60 - 1;
                 secs = eta % 3600;