1 files changed, 107 insertions, 0 deletions
diff --git a/lib/comp/gzip.c b/lib/comp/gzip.c
new file mode 100644
index 0000000..ea634b8
--- /dev/null
+++ b/lib/comp/gzip.c
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <zlib.h>
+
+#include "internal.h"
+
+typedef struct {
+	compressor_t base;
+
+	z_stream strm;
+	bool compress;
+
+	size_t block_size;
+} gzip_compressor_t;
+
+static void gzip_destroy(compressor_t *base)
+{
+	gzip_compressor_t *gzip = (gzip_compressor_t *)base;
+
+	if (gzip->compress) {
+		deflateEnd(&gzip->strm);
+	} else {
+		inflateEnd(&gzip->strm);
+	}
+
+	free(gzip);
+}
+
+static ssize_t gzip_do_block(compressor_t *base, const uint8_t *in,
+			     size_t size, uint8_t *out, size_t outsize)
+{
+	gzip_compressor_t *gzip = (gzip_compressor_t *)base;
+	size_t written;
+	int ret;
+
+	if (gzip->compress) {
+		ret = deflateReset(&gzip->strm);
+	} else {
+		ret = inflateReset(&gzip->strm);
+	}
+
+	if (ret != Z_OK) {
+		fputs("resetting zlib stream failed\n", stderr);
+		return -1;
+	}
+
+	gzip->strm.next_in = (void *)in;
+	gzip->strm.avail_in = size;
+	gzip->strm.next_out = out;
+	gzip->strm.avail_out = outsize;
+
+	if (gzip->compress) {
+		ret = deflate(&gzip->strm, Z_FINISH);
+	} else {
+		ret = inflate(&gzip->strm, Z_FINISH);
+	}
+
+	if (ret == Z_STREAM_END) {
+		written = gzip->strm.total_out;
+
+		if (gzip->compress && written >= size)
+			return 0;
+
+		return (ssize_t)written;
+	}
+
+	if (ret != Z_OK) {
+		fputs("gzip block processing failed\n", stderr);
+		return -1;
+	}
+
+	return 0;
+}
+
+compressor_t *create_gzip_compressor(bool compress, size_t block_size)
+{
+	gzip_compressor_t *gzip = calloc(1, sizeof(*gzip));
+	compressor_t *base = (compressor_t *)gzip;
+	int ret;
+
+	if (gzip == NULL) {
+		perror("creating gzip compressor");
+		return NULL;
+	}
+
+	gzip->compress = compress;
+	gzip->block_size = block_size;
+	base->do_block = gzip_do_block;
+	base->destroy = gzip_destroy;
+
+	if (compress) {
+		ret = deflateInit(&gzip->strm, Z_BEST_COMPRESSION);
+	} else {
+		ret = inflateInit(&gzip->strm);
+	}
+
+	if (ret != Z_OK) {
+		fputs("internal error creating zlib stream\n", stderr);
+		free(gzip);
+		return NULL;
+	}
+
+	return base;
+}