From 71cfbce655bcfa6d3e0154d441a33d3bfd1dca57 Mon Sep 17 00:00:00 2001 From: Natanael Copa Date: Wed, 3 Aug 2016 16:21:52 +0200 Subject: [PATCH] gzip: fix compression level bug. Closes 9131 fix broken logic to get the gzip_level_config value from options -1 to -9. This fixes an off-by-one bug that caused gzip -9 output bigger files than the other compression levels. It fixes so that compression level 1 to 3 are actually mapped to level 4 as comments say. It also fixes that levels -4 to -9 is mapped to correct level and avoids out-of-bounds access. Signed-off-by: Natanael Copa Signed-off-by: Denys Vlasenko --- archival/gzip.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/archival/gzip.c b/archival/gzip.c index 8f1e4ff29..9e0bee815 100644 --- a/archival/gzip.c +++ b/archival/gzip.c @@ -2220,10 +2220,7 @@ int gzip_main(int argc UNUSED_PARAM, char **argv) opt >>= ENABLE_GUNZIP ? 7 : 5; /* drop cfv[dt]qn bits */ if (opt == 0) opt = 1 << 6; /* default: 6 */ - /* Map 1..3 to 4 */ - if (opt & 0x7) - opt |= 1 << 4; - opt = ffs(opt >> 3); + opt = ffs(opt >> 4); /* Maps -1..-4 to [0], -5 to [1] ... -9 to [5] */ max_chain_length = 1 << gzip_level_config[opt].chain_shift; good_match = gzip_level_config[opt].good; max_lazy_match = gzip_level_config[opt].lazy2 * 2; -- 2.25.1