Add uncompress2() function, which returns the input size used.

1 files changed, 25 insertions, 16 deletions

diff --git a/uncompr.c b/uncompr.c
index 50e0d86..834ffc9 100644
--- a/uncompr.c
+++ b/uncompr.c
@@ -1,5 +1,5 @@
 /* uncompr.c -- decompress a memory buffer
- * Copyright (C) 1995-2003, 2010, 2014 Jean-loup Gailly, Mark Adler.
+ * Copyright (C) 1995-2003, 2010, 2014, 2016 Jean-loup Gailly, Mark Adler.
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -9,26 +9,29 @@
 #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.
+     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.
+     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(unsigned char *dest, size_t *destLen, const unsigned char *source, size_t sourceLen) {
+int ZEXPORT uncompress2(unsigned char *dest, size_t *destLen, const unsigned char *source, size_t *sourceLen) {
     z_stream stream;
     int err;
     const unsigned int max = (unsigned int)0 - 1;
-    size_t left;
+    size_t len, left;
     unsigned char buf[1];    /* for detection of incomplete stream when *destLen == 0 */
 
+    len = *sourceLen;
     if (*destLen) {
         left = *destLen;
         *destLen = 0;
@@ -56,12 +59,13 @@ int ZEXPORT uncompress(unsigned char *dest, size_t *destLen, const unsigned char
             left -= stream.avail_out;
         }
         if (stream.avail_in == 0) {
-            stream.avail_in = sourceLen > (unsigned long)max ? max : (unsigned int)sourceLen;
-            sourceLen -= stream.avail_in;
+            stream.avail_in = len > (unsigned long)max ? max : (unsigned int)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)
@@ -73,3 +77,8 @@ int ZEXPORT uncompress(unsigned char *dest, size_t *destLen, const unsigned char
            err == Z_BUF_ERROR && left + stream.avail_out ? Z_DATA_ERROR :
            err;
 }
+
+int ZEXPORT uncompress(unsigned char *dest, size_t *destLen, const unsigned char *source, size_t sourceLen)
+{
+    return uncompress2(dest, destLen, source, &sourceLen);
+}