X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Fxpress-decompress.c;h=6756b159465d13e72ce5b071ce3531df7c74ef20;hb=9eb3ffad2c12ed8e5b3d8864f5db173961af953a;hp=87205543022ed76c041b6a5f9f5714ddeeaf4ee0;hpb=40beb80283a2df7af88c8359ca41adb814585e9a;p=wimlib

diff --git a/src/xpress-decompress.c b/src/xpress-decompress.c
index 87205543..6756b159 100644
--- a/src/xpress-decompress.c
+++ b/src/xpress-decompress.c
@@ -6,7 +6,7 @@
 
 /*
  *
- * Copyright (C) 2012 Eric Biggers
+ * Copyright (C) 2012, 2013 Eric Biggers
  *
  * This file is part of wimlib, a library for working with WIM files.
  *
@@ -88,10 +88,13 @@
  *
  * Note: taking the low 8 bits of the symbol is the same as subtracting 256, the
  * number of symbols reserved for literals.
+ *
+ * Returns the match length, or -1 on error.
  */
-static int xpress_decode_match(int huffsym, unsigned window_pos,
-			       unsigned window_len, u8 window[],
-			       struct input_bitstream *istream)
+static int
+xpress_decode_match(unsigned huffsym, unsigned window_pos,
+		    unsigned window_len, u8 window[],
+		    struct input_bitstream *istream)
 {
 	unsigned match_len;
 	unsigned match_offset;
@@ -105,27 +108,25 @@ static int xpress_decode_match(int huffsym, unsigned window_pos,
 
 	ret = bitstream_read_bits(istream, offset_bsr, &match_offset);
 	if (ret != 0)
-		return -1;
+		return ret;
 	match_offset |= (1 << offset_bsr);
 
 	if (len_hdr == 0xf) {
 		ret = bitstream_read_byte(istream);
-		if (ret == -1)
-			return -1;
+		if (ret < 0)
+			return ret;
 		match_len = ret;
 		if (match_len == 0xff) {
 			ret = bitstream_read_byte(istream);
-			if (ret == -1)
-				return -1;
+			if (ret < 0)
+				return ret;
 			match_len = ret;
 
 			ret = bitstream_read_byte(istream);
-			if (ret == -1)
-				return -1;
+			if (ret < 0)
+				return ret;
 
 			match_len |= (ret << 8);
-			if (match_len < 0xf)
-				return -1;
 		} else {
 			match_len += 0xf;
 		}
@@ -142,15 +143,15 @@ static int xpress_decode_match(int huffsym, unsigned window_pos,
 	match_src = match_dest - match_offset;
 
 	if (window_pos + match_len > window_len) {
-		ERROR("XPRESS decompression error: match of length %d "
+		ERROR("XPRESS decompression error: match of length %u "
 		      "bytes overflows window", match_len);
 		return -1;
 	}
 
 	if (match_src < window) {
-		ERROR("XPRESS decompression error: match of length %d bytes "
-		      "references data before window (match_offset = %d, "
-		      "window_pos = %d)", match_len, match_offset, window_pos);
+		ERROR("XPRESS decompression error: match of length %u bytes "
+		      "references data before window (match_offset = %u, "
+		      "window_pos = %u)", match_len, match_offset, window_pos);
 		return -1;
 	}
 
@@ -162,23 +163,25 @@ static int xpress_decode_match(int huffsym, unsigned window_pos,
 
 /* Decodes the Huffman-encoded matches and literal bytes in a block of
  * XPRESS-encoded data. */
-static int xpress_decompress_literals(struct input_bitstream *istream,
-				      u8 uncompressed_data[],
-				      unsigned uncompressed_len,
-				      const u8 lens[],
-				      const u16 decode_table[])
+static int
+xpress_decompress_block(struct input_bitstream *istream,
+			u8 uncompressed_data[],
+			unsigned uncompressed_len,
+			const u8 lens[],
+			const u16 decode_table[])
 {
-	unsigned curpos = 0;
+	unsigned curpos;
 	unsigned huffsym;
+	int ret;
 	int match_len;
-	int ret = 0;
 
+	curpos = 0;
 	while (curpos < uncompressed_len) {
 		ret = read_huffsym(istream, decode_table, lens,
 				   XPRESS_NUM_SYMBOLS, XPRESS_TABLEBITS,
 				   &huffsym, XPRESS_MAX_CODEWORD_LEN);
-		if (ret != 0)
-			break;
+		if (ret)
+			return ret;
 
 		if (huffsym < XPRESS_NUM_CHARS) {
 			uncompressed_data[curpos++] = huffsym;
@@ -188,19 +191,19 @@ static int xpress_decompress_literals(struct input_bitstream *istream,
 							uncompressed_len,
 							uncompressed_data,
 							istream);
-			if (match_len == -1) {
-				ret = 1;
-				break;
-			}
+			if (match_len < 0)
+				return match_len;
 			curpos += match_len;
 		}
 	}
-	return ret;
+	return 0;
 }
 
 
-int xpress_decompress(const void *__compressed_data, unsigned compressed_len,
-		      void *uncompressed_data, unsigned uncompressed_len)
+/* Documented in wimlib.h */
+WIMLIBAPI int
+wimlib_xpress_decompress(const void *__compressed_data, unsigned compressed_len,
+			 void *uncompressed_data, unsigned uncompressed_len)
 {
 	u8 lens[XPRESS_NUM_SYMBOLS];
 	u16 decode_table[(1 << XPRESS_TABLEBITS) + 2 * XPRESS_NUM_SYMBOLS];
@@ -220,8 +223,10 @@ int xpress_decompress(const void *__compressed_data, unsigned compressed_len,
 	 * code lengths of these symbols are given literally as 4-bit integers
 	 * in the first 256 bytes of the compressed data.
 	 */
-	if (compressed_len < XPRESS_NUM_SYMBOLS / 2)
-		return WIMLIB_ERR_DECOMPRESSION;
+	if (compressed_len < XPRESS_NUM_SYMBOLS / 2) {
+		ERROR("xpress_decompress(): Compressed length too short!");
+		return -1;
+	}
 
 	for (i = 0; i < XPRESS_NUM_SYMBOLS / 2; i++) {
 		*lens_p++ = compressed_data[i] & 0xf;
@@ -231,13 +236,13 @@ int xpress_decompress(const void *__compressed_data, unsigned compressed_len,
 	ret = make_huffman_decode_table(decode_table, XPRESS_NUM_SYMBOLS,
 					XPRESS_TABLEBITS, lens,
 					XPRESS_MAX_CODEWORD_LEN);
-	if (ret != 0)
+	if (ret)
 		return ret;
 
 	init_input_bitstream(&istream, compressed_data + XPRESS_NUM_SYMBOLS / 2,
 			     compressed_len - XPRESS_NUM_SYMBOLS / 2);
 
-	return xpress_decompress_literals(&istream, uncompressed_data,
-					  uncompressed_len, lens,
-					  decode_table);
+	return xpress_decompress_block(&istream, uncompressed_data,
+				       uncompressed_len, lens,
+				       decode_table);
 }