1 files changed, 61 insertions, 0 deletions
diff --git a/lib/zstd/zstd.c b/lib/zstd/zstd.c
new file mode 100644
index 00000000000..14bde369068
--- /dev/null
+++ b/lib/zstd/zstd.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2021 Google LLC
+ */
+
+#define LOG_CATEGORY	LOGC_BOOT
+
+#include <abuf.h>
+#include <log.h>
+#include <malloc.h>
+#include <linux/errno.h>
+#include <linux/zstd.h>
+
+int zstd_decompress(struct abuf *in, struct abuf *out)
+{
+	zstd_dctx *ctx;
+	size_t wsize, len;
+	void *workspace;
+	int ret;
+
+	wsize = zstd_dctx_workspace_bound();
+	workspace = malloc(wsize);
+	if (!workspace) {
+		debug("%s: cannot allocate workspace of size %zu\n", __func__,
+			wsize);
+		return -ENOMEM;
+	}
+
+	ctx = zstd_init_dctx(workspace, wsize);
+	if (!ctx) {
+		log_err("%s: zstd_init_dctx() failed\n", __func__);
+		ret = -EPERM;
+		goto do_free;
+	}
+
+	/*
+	 * Find out how large the frame actually is, there may be junk at
+	 * the end of the frame that zstd_decompress_dctx() can't handle.
+	 */
+	len = zstd_find_frame_compressed_size(abuf_data(in), abuf_size(in));
+	if (zstd_is_error(len)) {
+		log_err("%s: failed to detect compressed size: %d\n", __func__,
+			zstd_get_error_code(len));
+		ret = -EINVAL;
+		goto do_free;
+	}
+
+	len = zstd_decompress_dctx(ctx, abuf_data(out), abuf_size(out),
+				   abuf_data(in), len);
+	if (zstd_is_error(len)) {
+		log_err("%s: failed to decompress: %d\n", __func__,
+			zstd_get_error_code(len));
+		ret = -EINVAL;
+		goto do_free;
+	}
+
+	ret = len;
+do_free:
+	free(workspace);
+	return ret;
+}