Add compressor library

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 108 insertions, 0 deletions

diff --git a/lib/comp/zlib.c b/lib/comp/zlib.c
new file mode 100644
index 0000000..d3bfe70
--- /dev/null
+++ b/lib/comp/zlib.c
@@ -0,0 +1,108 @@
+/* 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;
+	uint8_t buffer[];
+} zlib_compressor_t;
+
+static void zlib_destroy(compressor_t *base)
+{
+	zlib_compressor_t *zlib = (zlib_compressor_t *)base;
+
+	if (zlib->compress) {
+		deflateEnd(&zlib->strm);
+	} else {
+		inflateEnd(&zlib->strm);
+	}
+
+	free(zlib);
+}
+
+static ssize_t zlib_do_block(compressor_t *base, uint8_t *block, size_t size)
+{
+	zlib_compressor_t *zlib = (zlib_compressor_t *)base;
+	size_t written;
+	int ret;
+
+	if (zlib->compress) {
+		ret = deflateReset(&zlib->strm);
+	} else {
+		ret = inflateReset(&zlib->strm);
+	}
+
+	if (ret != Z_OK) {
+		fputs("resetting zlib stream failed\n", stderr);
+		return -1;
+	}
+
+	zlib->strm.next_in = (void *)block;
+	zlib->strm.avail_in = size;
+	zlib->strm.next_out = zlib->buffer;
+	zlib->strm.avail_out = zlib->block_size;
+
+	if (zlib->compress) {
+		ret = deflate(&zlib->strm, Z_FINISH);
+	} else {
+		ret = inflate(&zlib->strm, Z_FINISH);
+	}
+
+	if (ret == Z_STREAM_END) {
+		written = zlib->strm.total_out;
+
+		if (zlib->compress && written >= size)
+			return 0;
+
+		memcpy(block, zlib->buffer, written);
+		return (ssize_t)written;
+	}
+
+	if (ret != Z_OK) {
+		fputs("zlib block processing failed\n", stderr);
+		return -1;
+	}
+
+	return 0;
+}
+
+compressor_t *create_zlib_compressor(bool compress, size_t block_size)
+{
+	zlib_compressor_t *zlib = calloc(1, sizeof(*zlib) + block_size);
+	compressor_t *base = (compressor_t *)zlib;
+	int ret;
+
+	if (zlib == NULL) {
+		perror("creating zlib stream");
+		return NULL;
+	}
+
+	zlib->compress = compress;
+	zlib->block_size = block_size;
+	base->do_block = zlib_do_block;
+	base->destroy = zlib_destroy;
+
+	if (compress) {
+		ret = deflateInit(&zlib->strm, Z_BEST_COMPRESSION);
+	} else {
+		ret = inflateInit(&zlib->strm);
+	}
+
+	if (ret != Z_OK) {
+		fputs("internal error creating zlib stream\n", stderr);
+		free(zlib);
+		return NULL;
+	}
+
+	return base;
+}