Ensure validity of max_search_depth

[wimlib] / src / lzx_compress.c

diff --git a/src/lzx_compress.c b/src/lzx_compress.c
index 88ac8fac7b2a72aa31df2a32754fa04d085747ef..0db8f10877f2f4c1fca9bb3eac1c9732d7003235 100644 (file)
--- a/src/lzx_compress.c
+++ b/src/lzx_compress.c
@@ -2062,9 +2062,13 @@ lzx_create_compressor(size_t max_bufsize, unsigned compression_level,
 
                c->impl = lzx_compress_lazy;
                c->max_search_depth = (36 * compression_level) / 20;
-               c->nice_match_length = min((72 * compression_level) / 20,
-                                          LZX_MAX_MATCH_LEN);
+               c->nice_match_length = (72 * compression_level) / 20;
 
+               /* lzx_compress_lazy() needs max_search_depth >= 2 because it
+                * halves the max_search_depth when attempting a lazy match, and
+                * max_search_depth cannot be 0.  */
+               if (c->max_search_depth < 2)
+                       c->max_search_depth = 2;
        } else {
 
                /* Normal / high compression: Use near-optimal parsing.  */
@@ -2074,8 +2078,7 @@ lzx_create_compressor(size_t max_bufsize, unsigned compression_level,
                /* Scale nice_match_length and max_search_depth with the
                 * compression level.  */
                c->max_search_depth = (24 * compression_level) / 50;
-               c->nice_match_length = min((32 * compression_level) / 50,
-                                          LZX_MAX_MATCH_LEN);
+               c->nice_match_length = (32 * compression_level) / 50;
 
                /* Set a number of optimization passes appropriate for the
                 * compression level.  */
@@ -2101,6 +2104,13 @@ lzx_create_compressor(size_t max_bufsize, unsigned compression_level,
                }
        }
 
+       /* max_search_depth == 0 is invalid.  */
+       if (c->max_search_depth < 1)
+               c->max_search_depth = 1;
+
+       if (c->nice_match_length > LZX_MAX_MATCH_LEN)
+               c->nice_match_length = LZX_MAX_MATCH_LEN;
+
        lzx_init_offset_slot_fast(c);
        *c_ret = c;
        return 0;