From: Eric Biggers <ebiggers3@gmail.com>
Date: Mon, 12 Jan 2015 02:06:41 +0000 (-0600)
Subject: Ensure validity of max_search_depth
X-Git-Tag: v1.8.0~62
X-Git-Url: https://wimlib.net/git/?p=wimlib;a=commitdiff_plain;h=917100f2f08773e5b6c7a479a095b499fab848b8

Ensure validity of max_search_depth
---

diff --git a/include/wimlib/bt_matchfinder.h b/include/wimlib/bt_matchfinder.h
index 1d30e362..78ecdd75 100644
--- a/include/wimlib/bt_matchfinder.h
+++ b/include/wimlib/bt_matchfinder.h
@@ -127,8 +127,9 @@ bt_right_child(struct bt_matchfinder *mf, pos_t node)
  *	The maximum permissible match length at this position.
  * @nice_len
  *	Stop searching if a match of at least this length is found.
+ *	Must be <= @max_len.
  * @max_search_depth
- *	Limit on the number of potential matches to consider.
+ *	Limit on the number of potential matches to consider.  Must be >= 1.
  * @next_hash
  *	Pointer to the hash code for the current sequence, which was computed
  *	one position in advance so that the binary tree root could be
diff --git a/include/wimlib/hc_matchfinder.h b/include/wimlib/hc_matchfinder.h
index 1403a157..a5cca95e 100644
--- a/include/wimlib/hc_matchfinder.h
+++ b/include/wimlib/hc_matchfinder.h
@@ -145,8 +145,9 @@ hc_matchfinder_init(struct hc_matchfinder *mf)
  *	The maximum permissible match length at this position.
  * @nice_len
  *	Stop searching if a match of at least this length is found.
+ *	Must be <= @max_len.
  * @max_search_depth
- *	Limit on the number of potential matches to consider.
+ *	Limit on the number of potential matches to consider.  Must be >= 1.
  * @offset_ret
  *	If a match is found, its offset is returned in this location.
  *
diff --git a/src/lzx_compress.c b/src/lzx_compress.c
index 88ac8fac..0db8f108 100644
--- 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;
diff --git a/src/xpress_compress.c b/src/xpress_compress.c
index 65c4b026..1c824a57 100644
--- a/src/xpress_compress.c
+++ b/src/xpress_compress.c
@@ -1088,6 +1088,13 @@ xpress_create_compressor(size_t max_bufsize, unsigned compression_level,
 			c->impl = xpress_compress_lazy;
 			c->max_search_depth = (compression_level * 24) / 32;
 			c->nice_match_length = (compression_level * 48) / 32;
+
+			/* xpress_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;
 		}
 	}
 #if SUPPORT_NEAR_OPTIMAL_PARSING
@@ -1113,6 +1120,10 @@ xpress_create_compressor(size_t max_bufsize, unsigned compression_level,
 	}
 #endif /* SUPPORT_NEAR_OPTIMAL_PARSING */
 
+	/* max_search_depth == 0 is invalid.  */
+	if (c->max_search_depth < 1)
+		c->max_search_depth = 1;
+
 	*c_ret = c;
 	return 0;