LZX, XPRESS decompression: Return 0 bits on overrun

[wimlib] / src / xpress-decompress.c

diff --git a/src/xpress-decompress.c b/src/xpress-decompress.c
index 233e9355b221f65e2c4baad947fb0af6aae21c9c..98ad03d44d0905eb050b19ceb3314c43a768c9ff 100644 (file)
--- a/src/xpress-decompress.c
+++ b/src/xpress-decompress.c
@@ -92,7 +92,6 @@ xpress_decode_match(unsigned sym, input_idx_t window_pos,
 
        u8 len_hdr;
        u8 offset_bsr;
-       int ret;
        u8 *match_dest;
        u8 *match_src;
        unsigned i;
@@ -103,27 +102,15 @@ xpress_decode_match(unsigned sym, input_idx_t window_pos,
        len_hdr = sym & 0xf;
        offset_bsr = sym >> 4;
 
-       if (bitstream_ensure_bits(istream, 16))
-               return -1;
+       bitstream_ensure_bits(istream, 16);
 
        match_offset = (1U << offset_bsr) | bitstream_pop_bits(istream, offset_bsr);
 
        if (len_hdr == 0xf) {
-               ret = bitstream_read_byte(istream);
-               if (ret < 0)
-                       return ret;
-               match_len = ret;
+               match_len = bitstream_read_byte(istream);
                if (unlikely(match_len == 0xff)) {
-                       ret = bitstream_read_byte(istream);
-                       if (ret < 0)
-                               return ret;
-                       match_len = ret;
-
-                       ret = bitstream_read_byte(istream);
-                       if (ret < 0)
-                               return ret;
-
-                       match_len |= (ret << 8);
+                       match_len = bitstream_read_byte(istream);
+                       match_len |= (unsigned)bitstream_read_byte(istream) << 8;
                } else {
                        match_len += 0xf;
                }
@@ -167,14 +154,11 @@ xpress_lz_decode(struct input_bitstream * restrict istream,
                unsigned sym;
                int ret;
 
-               if (unlikely(bitstream_ensure_bits(istream, 16)))
-                       return -1;
-
-               if (unlikely(read_huffsym(istream, decode_table, lens,
-                                         XPRESS_NUM_SYMBOLS, XPRESS_TABLEBITS,
-                                         &sym, XPRESS_MAX_CODEWORD_LEN)))
-                       return -1;
+               bitstream_ensure_bits(istream, 16);
 
+               sym = read_huffsym(istream, decode_table, lens,
+                                  XPRESS_NUM_SYMBOLS, XPRESS_TABLEBITS,
+                                  XPRESS_MAX_CODEWORD_LEN);
                if (sym < XPRESS_NUM_CHARS) {
                        /* Literal  */
                        uncompressed_data[curpos] = sym;