Merge branch 'ps/zlib-ng'

The code paths to interact with zlib has been cleaned up in
preparation for building with zlib-ng.

* ps/zlib-ng:
  ci: make "linux-musl" job use zlib-ng
  ci: switch linux-musl to use Meson
  compat/zlib: allow use of zlib-ng as backend
  git-zlib: cast away potential constness of `next_in` pointer
  compat/zlib: provide stubs for `deflateSetHeader()`
  compat/zlib: provide `deflateBound()` shim centrally
  git-compat-util: move include of "compat/zlib.h" into "git-zlib.h"
  compat: introduce new "zlib.h" header
  git-compat-util: drop `z_const` define
  compat: drop `uncompress2()` compatibility shim

2 files changed, 53 insertions, 96 deletions

diff --git a/compat/zlib-compat.h b/compat/zlib-compat.h
new file mode 100644
index 0000000000..0c60e3af33
--- /dev/null
+++ b/compat/zlib-compat.h
@@ -0,0 +1,53 @@
+#ifndef COMPAT_ZLIB_H
+#define COMPAT_ZLIB_H
+
+#ifdef HAVE_ZLIB_NG
+# include <zlib-ng.h>
+
+# define z_stream zng_stream
+#define gz_header_s zng_gz_header_s
+
+# define crc32(crc, buf, len) zng_crc32(crc, buf, len)
+
+# define inflate(strm, bits) zng_inflate(strm, bits)
+# define inflateEnd(strm) zng_inflateEnd(strm)
+# define inflateInit(strm) zng_inflateInit(strm)
+# define inflateInit2(strm, bits) zng_inflateInit2(strm, bits)
+# define inflateReset(strm) zng_inflateReset(strm)
+
+# define deflate(strm, flush) zng_deflate(strm, flush)
+# define deflateBound(strm, source_len) zng_deflateBound(strm, source_len)
+# define deflateEnd(strm) zng_deflateEnd(strm)
+# define deflateInit(strm, level) zng_deflateInit(strm, level)
+# define deflateInit2(stream, level, method, window_bits, mem_level, strategy) zng_deflateInit2(stream, level, method, window_bits, mem_level, strategy)
+# define deflateReset(strm) zng_deflateReset(strm)
+# define deflateSetHeader(strm, head) zng_deflateSetHeader(strm, head)
+
+#else
+# include <zlib.h>
+
+# if defined(NO_DEFLATE_BOUND) || ZLIB_VERNUM < 0x1200
+#  define deflateBound(c,s)  ((s) + (((s) + 7) >> 3) + (((s) + 63) >> 6) + 11)
+# endif
+
+/*
+ * zlib only gained support for setting up the gzip header in v1.2.2.1. In
+ * Git we only set the header to make archives reproducible across different
+ * operating systems, so it's fine to simply make this a no-op when using a
+ * zlib version that doesn't support this yet.
+ */
+# if ZLIB_VERNUM < 0x1221
+struct gz_header_s {
+	int os;
+};
+
+static int deflateSetHeader(z_streamp strm, struct gz_header_s *head)
+{
+	(void)(strm);
+	(void)(head);
+	return Z_OK;
+}
+# endif
+#endif /* HAVE_ZLIB_NG */
+
+#endif /* COMPAT_ZLIB_H */
diff --git a/compat/zlib-uncompress2.c b/compat/zlib-uncompress2.c
deleted file mode 100644
index 77a1b08048..0000000000
--- a/compat/zlib-uncompress2.c
+++ /dev/null
@@ -1,96 +0,0 @@
-#include "git-compat-util.h"
-
-#if ZLIB_VERNUM < 0x1290
-/* 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
-
-*/
-
-/*
- * Copyright (C) 1995-2003, 2010, 2014, 2016 Jean-loup Gailly, Mark Adler
- * For conditions of distribution and use, see copyright notice in 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;
-}
-#else
-static void *dummy_variable = &dummy_variable;
-#endif