use zlib internally to decompress

1 files changed, 93 insertions, 0 deletions

diff --git a/src/gunzip.c b/src/gunzip.c
new file mode 100644
index 0000000..f488fa4
--- /dev/null
+++ b/src/gunzip.c
@@ -0,0 +1,93 @@
+/* gunzip.c - Alpine Package Keeper (APK)
+ *
+ * Copyright (C) 2008 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it 
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <malloc.h>
+#include <zlib.h>
+
+#include "apk_defines.h"
+#include "apk_io.h"
+
+struct apk_gzip_istream {
+	struct apk_istream is;
+	struct apk_bstream *bs;
+	z_stream zs;
+	int z_err;
+};
+
+static size_t gz_read(void *stream, void *ptr, size_t size)
+{
+	struct apk_gzip_istream *gis =
+		container_of(stream, struct apk_gzip_istream, is);
+
+	if (gis->z_err == Z_DATA_ERROR || gis->z_err == Z_ERRNO)
+		return -1;
+	if (gis->z_err == Z_STREAM_END)
+		return 0;
+
+	if (ptr == NULL)
+		return apk_istream_skip(&gis->is, size);
+
+	gis->zs.avail_out = size;
+	gis->zs.next_out  = ptr;
+
+	while (gis->zs.avail_out != 0 && gis->z_err == Z_OK) {
+		if (gis->zs.avail_in == 0) {
+			gis->zs.avail_in = gis->bs->read(gis->bs, (void **) &gis->zs.next_in);
+			if (gis->zs.avail_in < 0) {
+				gis->z_err = Z_DATA_ERROR;
+				return size - gis->zs.avail_out;
+			}
+		}
+
+		gis->z_err = inflate(&gis->zs, Z_NO_FLUSH);
+	}
+
+	if (gis->z_err != Z_OK && gis->z_err != Z_STREAM_END)
+		return -1;
+
+	return size - gis->zs.avail_out;
+}
+
+static void gz_close(void *stream)
+{
+	struct apk_gzip_istream *gis =
+		container_of(stream, struct apk_gzip_istream, is);
+
+	inflateEnd(&gis->zs);
+	free(gis);
+}
+
+struct apk_istream *apk_gunzip_bstream(struct apk_bstream *bs)
+{
+	struct apk_gzip_istream *gis;
+
+	gis = malloc(sizeof(struct apk_gzip_istream));
+	if (gis == NULL)
+		return NULL;
+
+	*gis = (struct apk_gzip_istream) {
+		.is.read = gz_read,
+		.is.splice = apk_istream_splice,
+		.is.close = gz_close,
+		.bs = bs,
+		.z_err = 0,
+	};
+
+	if (inflateInit2(&gis->zs, 15+32) != Z_OK) {
+		free(gis);
+		return NULL;
+	}
+
+	return &gis->is;
+}
+