include/u-boot, lib/zlib: add sources for zlib decompression

Add zlib (v1.2.11) uncompr() function to U-Boot. SquashFS depends on
this function to decompress data from a raw disk image. The actual
support for zlib into SquashFS sources will be added in a follow-up
commit.

Signed-off-by: Joao Marcos Costa <joaomarcos.costa@bootlin.com>

lib/Kconfig

@@ -460,6 +460,13 @@ config GZIP
 	help
 	  This enables support for GZIP compression algorithm.
 
+config ZLIB_UNCOMPRESS
+	bool "Enables zlib's uncompress() functionality"
+	help
+	  This enables an extra zlib functionality: the uncompress() function,
+	  which decompresses data from a buffer into another, knowing their
+	  sizes. Unlike gunzip(), there is no header parsing.
+
 config GZIP_COMPRESSED
 	bool
 	select ZLIB

lib/zlib/uncompr.c

@@ -0,0 +1,97 @@
+/* uncompr.c -- decompress a memory buffer
+ * Copyright (C) 1995-2003, 2010, 2014, 2016 Jean-loup Gailly, Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+/* @(#) $Id$ */
+
+#define ZLIB_INTERNAL
+#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 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 uncompress2(dest, destLen, source, sourceLen)
+	Bytef *dest;
+	uLongf *destLen;
+	const Bytef *source;
+	uLong *sourceLen;
+
+{
+	z_stream stream;
+	int err;
+	const uInt max = (uInt)-1;
+	uLong len, left;
+	/* for detection of incomplete stream when *destLen == 0 */
+	Byte buf[1];
+
+	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;
+
+	stream.next_out = dest;
+	stream.avail_out = 0;
+
+	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);
+}

lib/zlib/zlib.c

@@ -30,3 +30,6 @@
 #include "inflate.c"
 #include "zutil.c"
 #include "adler32.c"
+#if IS_ENABLED(CONFIG_ZLIB_UNCOMPRESS)
+#include "uncompr.c"
+#endif