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

2 files changed, 36 insertions, 17 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);
+}
diff --git a/zlib.h b/zlib.h
index 12d5477..73b5624 100644
--- a/zlib.h
+++ b/zlib.h
@@ -1212,7 +1212,7 @@ ZEXTERN int ZEXPORT uncompress(unsigned char *dest, size_t *destLen, const unsig
    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
@@ -1221,6 +1221,16 @@ ZEXTERN int ZEXPORT uncompress(unsigned char *dest, size_t *destLen, const unsig
    buffer with the uncompressed data up to that point.
 */
 
+
+ZEXTERN int ZEXPORT uncompress2 (unsigned char *dest,         size_t *destLen,
+                                 const unsigned char *source, size_t *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.
+*/
+
+
 #ifdef WITH_GZFILEOP
                         /* gzip file access functions */