package/utils/busybox/patches/000-busybox-1.25.0-gzip.patch

   1 gzip: fix compression level bug. Closes 9131
   2 fix broken logic to get the gzip_level_config value from options -1 to
   3 -9.
   4
   5 This fixes an off-by-one bug that caused gzip -9 output bigger files
   6 than the other compression levels.
   7
   8 It fixes so that compression level 1 to 3 are actually mapped to level 4
   9 as comments say.
  10
  11 It also fixes that levels -4 to -9 is mapped to correct level and avoids
  12 out-of-bounds access.
  13
  14 Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
  15 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
  16
  17 --- a/archival/gzip.c
  18 +++ b/archival/gzip.c
  19 @@ -2220,10 +2220,7 @@ int gzip_main(int argc UNUSED_PARAM, cha
  20         opt >>= ENABLE_GUNZIP ? 7 : 5; /* drop cfv[dt]qn bits */
  21         if (opt == 0)
  22                 opt = 1 << 6; /* default: 6 */
  23 -       /* Map 1..3 to 4 */
  24 -       if (opt & 0x7)
  25 -               opt |= 1 << 4;
  26 -       opt = ffs(opt >> 3);
  27 +       opt = ffs(opt >> 4); /* Maps -1..-4 to [0], -5 to [1] ... -9 to [5] */
  28         max_chain_length = 1 << gzip_level_config[opt].chain_shift;
  29         good_match       = gzip_level_config[opt].good;
  30         max_lazy_match   = gzip_level_config[opt].lazy2 * 2;