Provide zlib's uncompress2 from compat/zlib-compat.c

This will be needed for reading reflog blocks in reftable.

Helped-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -256,6 +256,8 @@ all::
 #
 # Define NO_DEFLATE_BOUND if your zlib does not have deflateBound.
 #
+# Define NO_UNCOMPRESS2 if your zlib does not have uncompress2.
+#
 # Define NO_NORETURN if using buggy versions of gcc 4.6+ and profile feedback,
 # as the compiler can crash (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49299)
 #
@@ -1738,6 +1740,11 @@ ifdef NO_DEFLATE_BOUND
 	BASIC_CFLAGS += -DNO_DEFLATE_BOUND
 endif
 
+ifdef NO_UNCOMPRESS2
+	BASIC_CFLAGS += -DNO_UNCOMPRESS2
+	REFTABLE_OBJS += compat/zlib-uncompress2.o
+endif
+
 ifdef NO_POSIX_GOODIES
 	BASIC_CFLAGS += -DNO_POSIX_GOODIES
 endif

ci/lib.sh

@@ -224,6 +224,7 @@ linux-gcc-default)
 	;;
 Linux32)
 	CC=gcc
+	MAKEFLAGS="$MAKEFLAGS NO_UNCOMPRESS2=1"
 	;;
 linux-musl)
 	CC=gcc

compat/.gitattributes

@@ -0,0 +1 @@
+/zlib-uncompress2.c	whitespace=-indent-with-non-tab,-trailing-space

compat/zlib-uncompress2.c

@@ -0,0 +1,95 @@
+/* taken from zlib's uncompr.c
+
+   commit cacf7f1d4e3d44d871b605da3b647f07d718623f
+   Author: Mark Adler <madler@alumni.caltech.edu>
+   Date:   Sun Jan 15 09:18:46 2017 -0800
+
+       zlib 1.2.11
+
+*/
+
+#include "../reftable/system.h"
+#define z_const
+
+/*
+ * Copyright (C) 1995-2003, 2010, 2014, 2016 Jean-loup Gailly, Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include <zlib.h>
+
+/* clang-format off */
+
+/* ===========================================================================
+     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 (
+    Bytef *dest,
+    uLongf *destLen,
+    const Bytef *source,
+    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 */
+
+    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;
+}

config.mak.uname

@@ -258,6 +258,10 @@ ifeq ($(uname_S),FreeBSD)
 	FILENO_IS_A_MACRO = UnfortunatelyYes
 endif
 ifeq ($(uname_S),OpenBSD)
+	# Versions < 7.0 need compatibility layer
+	ifeq ($(shell expr "$(uname_R)" : "[1-6]\."),2)
+		NO_UNCOMPRESS2 = UnfortunatelyYes
+	endif
 	NO_STRCASESTR = YesPlease
 	NO_MEMMEM = YesPlease
 	USE_ST_TIMESPEC = YesPlease
@@ -513,6 +517,7 @@ ifeq ($(uname_S),Interix)
 	endif
 endif
 ifeq ($(uname_S),Minix)
+	NO_UNCOMPRESS2 = YesPlease
 	NO_IPV6 = YesPlease
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
 	NO_NSEC = YesPlease

configure.ac

@@ -672,9 +672,22 @@ AC_LINK_IFELSE([ZLIBTEST_SRC],
 	NO_DEFLATE_BOUND=yes])
 LIBS="$old_LIBS"
 
+AC_DEFUN([ZLIBTEST_UNCOMPRESS2_SRC], [
+AC_LANG_PROGRAM([#include <zlib.h>],
+ [uncompress2(NULL,NULL,NULL,NULL);])])
+AC_MSG_CHECKING([for uncompress2 in -lz])
+old_LIBS="$LIBS"
+LIBS="$LIBS -lz"
+AC_LINK_IFELSE([ZLIBTEST_UNCOMPRESS2_SRC],
+	[AC_MSG_RESULT([yes])],
+	[AC_MSG_RESULT([no])
+	NO_UNCOMPRESS2=yes])
+LIBS="$old_LIBS"
+
 GIT_UNSTASH_FLAGS($ZLIB_PATH)
 
 GIT_CONF_SUBST([NO_DEFLATE_BOUND])
+GIT_CONF_SUBST([NO_UNCOMPRESS2])
 
 #
 # Define NEEDS_SOCKET if linking with libc is not enough (SunOS,