zstd: Create a function for use from U-Boot

The existing zstd API requires the same sequence of calls to perform its
task. Create a helper for U-Boot, to avoid code duplication, as is done
with other compression algorithms. Make use of of this from the image
code.

Note that the zstd code lacks a test in test/compression.c and this should
be added by the maintainer.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/image.c

@@ -22,6 +22,7 @@
 #include <status_led.h>
 #endif
 
+#include <abuf.h>
 #include <rtc.h>
 
 #include <gzip.h>
@@ -527,50 +528,17 @@ int image_decomp(int comp, ulong load, ulong image_start, int type,
 #ifndef USE_HOSTCC
 #if CONFIG_IS_ENABLED(ZSTD)
 	case IH_COMP_ZSTD: {
-		size_t size = unc_len;
-		ZSTD_DStream *dstream;
-		ZSTD_inBuffer in_buf;
-		ZSTD_outBuffer out_buf;
-		void *workspace;
-		size_t wsize;
+		struct abuf in, out;
 
-		wsize = ZSTD_DStreamWorkspaceBound(image_len);
-		workspace = malloc(wsize);
-		if (!workspace) {
-			debug("%s: cannot allocate workspace of size %zu\n", __func__,
-			      wsize);
-			return -1;
+		abuf_init_set(&in, image_buf, image_len);
+		abuf_init_set(&in, load_buf, unc_len);
+		ret = zstd_decompress(&in, &out);
+		if (ret < 0) {
+			printf("ZSTD decompression failed\n");
+			return ret;
 		}
 
-		dstream = ZSTD_initDStream(image_len, workspace, wsize);
-		if (!dstream) {
-			printf("%s: ZSTD_initDStream failed\n", __func__);
-			return ZSTD_getErrorCode(ret);
-		}
-
-		in_buf.src = image_buf;
-		in_buf.pos = 0;
-		in_buf.size = image_len;
-
-		out_buf.dst = load_buf;
-		out_buf.pos = 0;
-		out_buf.size = size;
-
-		while (1) {
-			size_t ret;
-
-			ret = ZSTD_decompressStream(dstream, &out_buf, &in_buf);
-			if (ZSTD_isError(ret)) {
-				printf("%s: ZSTD_decompressStream error %d\n", __func__,
-				       ZSTD_getErrorCode(ret));
-				return ZSTD_getErrorCode(ret);
-			}
-
-			if (in_buf.pos >= image_len || !ret)
-				break;
-		}
-
-		image_len = out_buf.pos;
+		image_len = ret;
 
 		break;
 	}

include/linux/zstd.h

@@ -1144,4 +1144,15 @@ size_t ZSTD_decompressBlock(ZSTD_DCtx *dctx, void *dst, size_t dstCapacity,
 size_t ZSTD_insertBlock(ZSTD_DCtx *dctx, const void *blockStart,
 	size_t blockSize);
 
+struct abuf;
+
+/**
+ * zstd_decompress() - Decompress Zstandard data
+ *
+ * @in: Input buffer to decompress
+ * @out: Output buffer to hold the results (must be large enough)
+ * @return size of the decompressed data, or -ve on error
+ */
+int zstd_decompress(struct abuf *in, struct abuf *out);
+
 #endif  /* ZSTD_H */

lib/zstd/Makefile

@@ -1,4 +1,4 @@
 obj-y += zstd_decompress.o
 
 zstd_decompress-y := huf_decompress.o decompress.o \
-		     entropy_common.o fse_decompress.o zstd_common.o
+		     entropy_common.o fse_decompress.o zstd_common.o zstd.o

lib/zstd/zstd.c

@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2021 Google LLC
+ */
+
+#define LOG_CATEGORY	LOGC_BOOT
+
+#include <common.h>
+#include <abuf.h>
+#include <log.h>
+#include <malloc.h>
+#include <linux/zstd.h>
+
+int zstd_decompress(struct abuf *in, struct abuf *out)
+{
+	ZSTD_DStream *dstream;
+	ZSTD_inBuffer in_buf;
+	ZSTD_outBuffer out_buf;
+	void *workspace;
+	size_t wsize;
+	int ret;
+
+	wsize = ZSTD_DStreamWorkspaceBound(abuf_size(in));
+	workspace = malloc(wsize);
+	if (!workspace) {
+		debug("%s: cannot allocate workspace of size %zu\n", __func__,
+			wsize);
+		return -ENOMEM;
+	}
+
+	dstream = ZSTD_initDStream(abuf_size(in), workspace, wsize);
+	if (!dstream) {
+		log_err("%s: ZSTD_initDStream failed\n", __func__);
+		ret = -EPERM;
+		goto do_free;
+	}
+
+	in_buf.src = abuf_data(in);
+	in_buf.pos = 0;
+	in_buf.size = abuf_size(in);
+
+	out_buf.dst = abuf_data(out);
+	out_buf.pos = 0;
+	out_buf.size = abuf_size(out);
+
+	while (1) {
+		size_t res;
+
+		res = ZSTD_decompressStream(dstream, &out_buf, &in_buf);
+		if (ZSTD_isError(res)) {
+			ret = ZSTD_getErrorCode(res);
+			log_err("ZSTD_decompressStream error %d\n", ret);
+			goto do_free;
+		}
+
+		if (in_buf.pos >= abuf_size(in) || !res)
+			break;
+	}
+
+	ret = out_buf.pos;
+do_free:
+	free(workspace);
+	return ret;
+}