1 files changed, 265 insertions, 0 deletions
diff --git a/squashfs-tools/zstd_wrapper.c b/squashfs-tools/zstd_wrapper.c
new file mode 100644
index 0000000..3fa8676
--- /dev/null
+++ b/squashfs-tools/zstd_wrapper.c
@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 2017, 2021, 2022
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * zstd_wrapper.c
+ *
+ * Support for ZSTD compression http://zstd.net
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <zstd.h>
+#include <zstd_errors.h>
+
+#include "squashfs_fs.h"
+#include "zstd_wrapper.h"
+#include "compressor.h"
+
+static int compression_level = ZSTD_DEFAULT_COMPRESSION_LEVEL;
+
+/*
+ * This function is called by the options parsing code in mksquashfs.c
+ * to parse any -X compressor option.
+ *
+ * This function returns:
+ *	>=0 (number of additional args parsed) on success
+ *	-1 if the option was unrecognised, or
+ *	-2 if the option was recognised, but otherwise bad in
+ *	   some way (e.g. invalid parameter)
+ *
+ * Note: this function sets internal compressor state, but does not
+ * pass back the results of the parsing other than success/failure.
+ * The zstd_dump_options() function is called later to get the options in
+ * a format suitable for writing to the filesystem.
+ */
+static int zstd_options(char *argv[], int argc)
+{
+	if (strcmp(argv[0], "-Xcompression-level") == 0) {
+		if (argc < 2) {
+			fprintf(stderr, "zstd: -Xcompression-level missing "
+				"compression level\n");
+			fprintf(stderr, "zstd: -Xcompression-level it should "
+				"be 1 <= n <= %d\n", ZSTD_maxCLevel());
+			goto failed;
+		}
+
+		compression_level = atoi(argv[1]);
+		if (compression_level < 1 ||
+		    compression_level > ZSTD_maxCLevel()) {
+			fprintf(stderr, "zstd: -Xcompression-level invalid, it "
+				"should be 1 <= n <= %d\n", ZSTD_maxCLevel());
+			goto failed;
+		}
+
+		return 1;
+	}
+
+	return -1;
+failed:
+	return -2;
+}
+
+/*
+ * This function is called by mksquashfs to dump the parsed
+ * compressor options in a format suitable for writing to the
+ * compressor options field in the filesystem (stored immediately
+ * after the superblock).
+ *
+ * This function returns a pointer to the compression options structure
+ * to be stored (and the size), or NULL if there are no compression
+ * options.
+ */
+static void *zstd_dump_options(int block_size, int *size)
+{
+	static struct zstd_comp_opts comp_opts;
+
+	/* don't return anything if the options are all default */
+	if (compression_level == ZSTD_DEFAULT_COMPRESSION_LEVEL)
+		return NULL;
+
+	comp_opts.compression_level = compression_level;
+
+	SQUASHFS_INSWAP_COMP_OPTS(&comp_opts);
+
+	*size = sizeof(comp_opts);
+	return &comp_opts;
+}
+
+/*
+ * This function is a helper specifically for the append mode of
+ * mksquashfs.  Its purpose is to set the internal compressor state
+ * to the stored compressor options in the passed compressor options
+ * structure.
+ *
+ * In effect this function sets up the compressor options
+ * to the same state they were when the filesystem was originally
+ * generated, this is to ensure on appending, the compressor uses
+ * the same compression options that were used to generate the
+ * original filesystem.
+ *
+ * Note, even if there are no compressor options, this function is still
+ * called with an empty compressor structure (size == 0), to explicitly
+ * set the default options, this is to ensure any user supplied
+ * -X options on the appending mksquashfs command line are over-ridden.
+ *
+ * This function returns 0 on sucessful extraction of options, and -1 on error.
+ */
+static int zstd_extract_options(int block_size, void *buffer, int size)
+{
+	struct zstd_comp_opts *comp_opts = buffer;
+
+	if (size == 0) {
+		/* Set default values */
+		compression_level = ZSTD_DEFAULT_COMPRESSION_LEVEL;
+		return 0;
+	}
+
+	/* we expect a comp_opts structure of sufficient size to be present */
+	if (size < sizeof(*comp_opts))
+		goto failed;
+
+	SQUASHFS_INSWAP_COMP_OPTS(comp_opts);
+
+	if (comp_opts->compression_level < 1 ||
+	    comp_opts->compression_level > ZSTD_maxCLevel()) {
+		fprintf(stderr, "zstd: bad compression level in compression "
+			"options structure\n");
+		goto failed;
+	}
+
+	compression_level = comp_opts->compression_level;
+
+	return 0;
+
+failed:
+	fprintf(stderr, "zstd: error reading stored compressor options from "
+		"filesystem!\n");
+
+	return -1;
+}
+
+static void zstd_display_options(void *buffer, int size)
+{
+	struct zstd_comp_opts *comp_opts = buffer;
+
+	/* we expect a comp_opts structure of sufficient size to be present */
+	if (size < sizeof(*comp_opts))
+		goto failed;
+
+	SQUASHFS_INSWAP_COMP_OPTS(comp_opts);
+
+	if (comp_opts->compression_level < 1 ||
+	    comp_opts->compression_level > ZSTD_maxCLevel()) {
+		fprintf(stderr, "zstd: bad compression level in compression "
+			"options structure\n");
+		goto failed;
+	}
+
+	printf("\tcompression-level %d\n", comp_opts->compression_level);
+
+	return;
+
+failed:
+	fprintf(stderr, "zstd: error reading stored compressor options from "
+		"filesystem!\n");
+}
+
+/*
+ * This function is called by mksquashfs to initialise the
+ * compressor, before compress() is called.
+ *
+ * This function returns 0 on success, and -1 on error.
+ */
+static int zstd_init(void **strm, int block_size, int datablock)
+{
+	ZSTD_CCtx *cctx = ZSTD_createCCtx();
+
+	if (!cctx) {
+		fprintf(stderr, "zstd: failed to allocate compression "
+			"context!\n");
+		return -1;
+	}
+
+	*strm = cctx;
+	return 0;
+}
+
+static int zstd_compress(void *strm, void *dest, void *src, int size,
+			 int block_size, int *error)
+{
+	const size_t res = ZSTD_compressCCtx((ZSTD_CCtx*)strm, dest, block_size,
+					     src, size, compression_level);
+
+	if (ZSTD_isError(res)) {
+		/* FIXME:
+		 * zstd does not expose stable error codes. The error enum may
+		 * change between versions. Until upstream zstd stablizes the
+		 * error codes, we have no way of knowing why the error occurs.
+		 * zstd shouldn't fail to compress any input unless there isn't
+		 * enough output space. We assume that is the cause and return
+		 * the special error code for not enough output space.
+		 */
+		return 0;
+	}
+
+	return (int)res;
+}
+
+static int zstd_uncompress(void *dest, void *src, int size, int outsize,
+			   int *error)
+{
+	const size_t res = ZSTD_decompress(dest, outsize, src, size);
+
+	if (ZSTD_isError(res)) {
+		fprintf(stderr, "\t%d %d\n", outsize, size);
+
+		*error = (int)ZSTD_getErrorCode(res);
+		return -1;
+	}
+
+	return (int)res;
+}
+
+static void zstd_usage(FILE *stream)
+{
+	fprintf(stream, "\t  -Xcompression-level <compression-level>\n");
+	fprintf(stream, "\t\t<compression-level> should be 1 .. %d (default "
+		"%d)\n", ZSTD_maxCLevel(), ZSTD_DEFAULT_COMPRESSION_LEVEL);
+}
+
+
+static int option_args(char *option)
+{
+	if(strcmp(option, "-Xcompression-level") == 0)
+		return 1;
+
+	return 0;
+}
+
+
+struct compressor zstd_comp_ops = {
+	.init = zstd_init,
+	.compress = zstd_compress,
+	.uncompress = zstd_uncompress,
+	.options = zstd_options,
+	.dump_options = zstd_dump_options,
+	.extract_options = zstd_extract_options,
+	.display_options = zstd_display_options,
+	.usage = zstd_usage,
+	.option_args = option_args,
+	.id = ZSTD_COMPRESSION,
+	.name = "zstd",
+	.supported = 1
+};