Port uncompress2() function and use it for uncompress() function.

Co-authored-by: Mark Adler <[email protected]>

uncompr.c

@@ -9,51 +9,84 @@
 #include "zlib.h"
 
 /* ===========================================================================
-     Decompresses the source buffer into the destination buffer.  sourceLen is
-   the byte length of the source buffer. Upon entry, destLen is the total
-   size of the destination buffer, which must be large enough to hold the
-   entire uncompressed data. (The size of the uncompressed data must have
-   been saved previously by the compressor and transmitted to the decompressor
-   by some mechanism outside the scope of this compression library.)
-   Upon exit, destLen is the actual size of the compressed buffer.
-
-     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
-   enough memory, Z_BUF_ERROR if there was not enough room in the output
-   buffer, or Z_DATA_ERROR if the input data was corrupted.
+     Decompresses the source buffer into the destination buffer.  *sourceLen is
+   the byte length of the source buffer. Upon entry, *destLen is the total size
+   of the destination buffer, which must be large enough to hold the entire
+   uncompressed data. (The size of the uncompressed data must have been saved
+   previously by the compressor and transmitted to the decompressor by some
+   mechanism outside the scope of this compression library.) Upon exit,
+   *destLen is the size of the decompressed data and *sourceLen is the number
+   of source bytes consumed. Upon return, source + *sourceLen points to the
+   first unused input byte.
+     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not enough
+   memory, Z_BUF_ERROR if there was not enough room in the output buffer, or
+   Z_DATA_ERROR if the input data was corrupted, including if the input data is
+   an incomplete zlib stream.
 */
-int ZEXPORT uncompress (dest, destLen, source, sourceLen)
+int ZEXPORT uncompress2(dest, destLen, source, sourceLen)
     Bytef *dest;
     uLongf *destLen;
     const Bytef *source;
-    uLong sourceLen;
+    uLong *sourceLen;
 {
     z_stream stream;
     int err;
+    const uInt max = (uInt)-1;
+    uLong len, left;
+    Byte buf[1];    /* for detection of incomplete stream when *destLen == 0 */
 
-    stream.next_in = (z_const Bytef *)source;
-    stream.avail_in = (uInt)sourceLen;
-    /* Check for source > 64K on 16-bit machine: */
-    if ((uLong)stream.avail_in != sourceLen) return Z_BUF_ERROR;
-
-    stream.next_out = dest;
-    stream.avail_out = (uInt)*destLen;
-    if ((uLong)stream.avail_out != *destLen) return Z_BUF_ERROR;
+    len = *sourceLen;
+    if (*destLen) {
+        left = *destLen;
+        *destLen = 0;
+    }
+    else {
+        left = 1;
+        dest = buf;
+    }
 
+    stream.next_in = (z_const Bytef *)source;
+    stream.avail_in = 0;
     stream.zalloc = (alloc_func)0;
     stream.zfree = (free_func)0;
+    stream.opaque = (voidpf)0;
 
     err = inflateInit(&stream);
     if (err != Z_OK) return err;
 
-    err = inflate(&stream, Z_FINISH);
-    if (err != Z_STREAM_END) {
-        inflateEnd(&stream);
-        if (err == Z_NEED_DICT || (err == Z_BUF_ERROR && stream.avail_in == 0))
-            return Z_DATA_ERROR;
-        return err;
-    }
-    *destLen = stream.total_out;
+    stream.next_out = dest;
+    stream.avail_out = 0;
 
-    err = inflateEnd(&stream);
-    return err;
+    do {
+        if (stream.avail_out == 0) {
+            stream.avail_out = left > (uLong)max ? max : (uInt)left;
+            left -= stream.avail_out;
+        }
+        if (stream.avail_in == 0) {
+            stream.avail_in = len > (uLong)max ? max : (uInt)len;
+            len -= stream.avail_in;
+        }
+        err = inflate(&stream, Z_NO_FLUSH);
+    } while (err == Z_OK);
+
+    *sourceLen -= len + stream.avail_in;
+    if (dest != buf)
+        *destLen = stream.total_out;
+    else if (stream.total_out && err == Z_BUF_ERROR)
+        left = 1;
+
+    inflateEnd(&stream);
+    return err == Z_STREAM_END ? Z_OK :
+           err == Z_NEED_DICT ? Z_DATA_ERROR  :
+           err == Z_BUF_ERROR && left + stream.avail_out ? Z_DATA_ERROR :
+           err;
+}
+
+int ZEXPORT uncompress(dest, destLen, source, sourceLen)
+    Bytef *dest;
+    uLongf *destLen;
+    const Bytef *source;
+    uLong sourceLen;
+{
+    return uncompress2(dest, destLen, source, &sourceLen);
 }

zlib.h

@@ -1204,7 +1204,7 @@ ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
    uncompressed data.  (The size of the uncompressed data must have been saved
    previously by the compressor and transmitted to the decompressor by some
    mechanism outside the scope of this compression library.) Upon exit, destLen
-   is the actual size of the uncompressed buffer.
+   is the actual size of the uncompressed data.
 
      uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
    enough memory, Z_BUF_ERROR if there was not enough room in the output
@@ -1213,6 +1213,14 @@ ZEXTERN int ZEXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
    buffer with the uncompressed data up to that point.
 */
 
+ZEXTERN int ZEXPORT uncompress2 OF((Bytef *dest,   uLongf *destLen,
+                                    const Bytef *source, uLong *sourceLen));
+/*
+     Same as uncompress, except that sourceLen is a pointer, where the
+   length of the source is *sourceLen.  On return, *sourceLen is the number of
+   source bytes consumed.
+*/
+
                         /* gzip file access functions */
 
 /*