ab843e324
Denys Vlasenko
2018-02-07
Subject
libbb: shrink wget/tftp progress indicator code for 32-bit
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libbb/progress.c+38 -40
| @@ -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; | |