3 files changed, 100 insertions, 0 deletions
diff --git a/lib/comp/compressor.c b/lib/comp/compressor.c
index 3b473a3..369cbea 100644
--- a/lib/comp/compressor.c
+++ b/lib/comp/compressor.c
@@ -20,6 +20,9 @@ static compressor_fun_t compressors[SQFS_COMP_MAX + 1] = {
 #ifdef WITH_LZ4
 	[SQFS_COMP_LZ4] = create_lz4_compressor,
 #endif
+#ifdef WITH_ZSTD
+	[SQFS_COMP_ZSTD] = create_zstd_compressor,
+#endif
 };
 
 int generic_write_options(int fd, const void *data, size_t size)
diff --git a/lib/comp/internal.h b/lib/comp/internal.h
index 863f82b..8f880f4 100644
--- a/lib/comp/internal.h
+++ b/lib/comp/internal.h
@@ -16,4 +16,6 @@ compressor_t *create_lzo_compressor(bool compress, size_t block_size);
 
 compressor_t *create_lz4_compressor(bool compress, size_t block_size);
 
+compressor_t *create_zstd_compressor(bool compress, size_t block_size);
+
 #endif /* INTERNAL_H */
diff --git a/lib/comp/zstd.c b/lib/comp/zstd.c
new file mode 100644
index 0000000..6c90505
--- /dev/null
+++ b/lib/comp/zstd.c
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <zstd.h>
+
+#include "internal.h"
+
+#define ZSTD_DEFAULT_COMPRESSION_LEVEL 15
+
+typedef struct {
+	compressor_t base;
+	ZSTD_CCtx *zctx;
+} zstd_compressor_t;
+
+static int zstd_write_options(compressor_t *base, int fd)
+{
+	(void)base; (void)fd;
+	return 0;
+}
+
+static int zstd_read_options(compressor_t *base, int fd)
+{
+	(void)base; (void)fd;
+	fputs("zstd extra options are not yet implemented\n", stderr);
+	return -1;
+}
+
+static ssize_t zstd_comp_block(compressor_t *base, const uint8_t *in,
+			       size_t size, uint8_t *out, size_t outsize)
+{
+	zstd_compressor_t *zstd = (zstd_compressor_t *)base;
+	size_t ret;
+
+	ret = ZSTD_compressCCtx(zstd->zctx, out, outsize, in, size,
+				ZSTD_DEFAULT_COMPRESSION_LEVEL);
+
+	if (ZSTD_isError(ret)) {
+		fputs("internal error in ZSTD compressor\n", stderr);
+		return -1;
+	}
+
+	return ret < size ? ret : 0;
+}
+
+static ssize_t zstd_uncomp_block(compressor_t *base, const uint8_t *in,
+				 size_t size, uint8_t *out, size_t outsize)
+{
+	size_t ret;
+	(void)base;
+
+	ret = ZSTD_decompress(out, outsize, in, size);
+
+	if (ZSTD_isError(ret)) {
+		fputs("error uncompressing ZSTD compressed data", stderr);
+		return -1;
+	}
+
+	return ret;
+}
+
+static void zstd_destroy(compressor_t *base)
+{
+	zstd_compressor_t *zstd = (zstd_compressor_t *)base;
+
+	ZSTD_freeCCtx(zstd->zctx);
+	free(zstd);
+}
+
+compressor_t *create_zstd_compressor(bool compress, size_t block_size)
+{
+	zstd_compressor_t *zstd = calloc(1, sizeof(*zstd));
+	compressor_t *base = (compressor_t *)zstd;
+	(void)block_size;
+
+	if (zstd == NULL) {
+		perror("creating zstd compressor");
+		return NULL;
+	}
+
+	zstd->zctx = ZSTD_createCCtx();
+	if (zstd->zctx == NULL) {
+		fputs("error creating zstd compression context\n", stderr);
+		free(zstd);
+		return NULL;
+	}
+
+	base->destroy = zstd_destroy;
+	base->do_block = compress ? zstd_comp_block : zstd_uncomp_block;
+	base->write_options = zstd_write_options;
+	base->read_options = zstd_read_options;
+	return base;
+}