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