FIX: failed decompress when input data was not at head

Oldes · Sep 23, 2021 · 552ec9b · 552ec9b
1 parent 9f15dac
commit 552ec9b
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Showing 2 changed files with 13 additions and 2 deletions.
diff --git a/src/core/u-compress.c b/src/core/u-compress.c
@@ -181,7 +181,7 @@ void Trap_ZStream_Error(z_stream *stream, int err, REBOOL while_compression)
 	} else {
 		// Get the uncompressed size from last 4 source data bytes.
 		if (len < 4) Trap0(RE_PAST_END); // !!! better msg needed
-		size = cast(REBU64, Bytes_To_REBCNT(BIN_SKIP(input, len) - sizeof(REBCNT)));
+		size = cast(REBU64, Bytes_To_REBCNT(BIN_SKIP(input, index + len) - sizeof(REBCNT)));
 		if (size > (uLongf)len * 14) Trap_Num(RE_SIZE_LIMIT, size); // check for a realistic limit
 	}
 
@@ -322,7 +322,7 @@ static const ISzAlloc g_Alloc = { SzAlloc, SzFree };
 		destLen = limit;
 	} else {
 		// Get the uncompressed size from last 4 source data bytes.
-		destLen = cast(REBU64, Bytes_To_REBCNT(BIN_SKIP(input, in_len) - sizeof(REBCNT)));
+		destLen = cast(REBU64, Bytes_To_REBCNT(BIN_SKIP(input, index + in_len) - sizeof(REBCNT)));
 	}
 
 	output = Make_Binary(destLen);

diff --git a/src/tests/units/compress-test.r3 b/src/tests/units/compress-test.r3
@@ -39,16 +39,24 @@ data: "test test test"
 		--assert  #{74657374} = decompress compress/part skip data 5 4
 		--assert  #{74657374} = decompress compress/part tail data -4
 
+	--test-- "decompress when not at head"
+		--assert data = to string! decompress next join #{00} compress data
+
 ===end-group===
 
 ===start-group=== "GZIP compression / decompression"
 
 	--test-- "DEFLATE decompress"
 		--assert #{74657374} = decompress/deflate #{2B492D2E01000C7E7FD804}
+	--test-- "DEFLATE decompress when not at head"
+		--assert #{74657374} = decompress/deflate next #{002B492D2E01000C7E7FD804}
 
 	--test-- "GZIP compress/decompress"
 		--assert  data = to string! decompress/gzip compress/gzip data
 
+	--test-- "GZIP decompress when not at head"
+		--assert data = to string! decompress/gzip next join #{00} compress/gzip data
+
 	--test-- "GZIP compress/decompress while specifing level of compression"
 		--assert (skip compress/gzip/level ""   0 10) =
 			#{010000FFFF0000000000000000}
@@ -116,6 +124,9 @@ data: "test test test"
 			--assert  #{74657374} = decompress/lzma compress/lzma/part data 4
 			--assert  #{74657374} = decompress/lzma compress/lzma/part skip data 5 4
 			--assert  #{74657374} = decompress/lzma compress/lzma/part tail data -4
+
+		--test-- "LZMA decompress when not at head"
+			--assert data = to string! decompress/lzma next join #{00} compress/lzma data
 	]
 ===end-group===