Add lz4 compressor implementation

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

8 files changed, 201 insertions, 1 deletions

diff --git a/README b/README
index a953acf..c81fe46 100644
--- a/README
+++ b/README
@@ -83,5 +83,5 @@ At the moment, the following things are still missing:
  - hard links
  - NFS export tables
  - compressor options
- - compressors other than XZ and GZIP (i.e. lz4, zstd, *maybe* lzma1?)
+ - zstd and *maybe* lzma1 compressors
  - support for extracting SquashFS < 4.0
diff --git a/configure.ac b/configure.ac
index 422a113..b138c6f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -71,15 +71,27 @@ AC_ARG_WITH([lzo],
 	esac],
 	[AM_CONDITIONAL([WITH_LZO], [true])])
 
+AC_ARG_WITH([lz4],
+	[AS_HELP_STRING([--without-lz4],
+			[Build without lz4 compression support])],
+	[case "${withval}" in
+	yes) AM_CONDITIONAL([WITH_LZ4], [true]) ;;
+	no)  AM_CONDITIONAL([WITH_LZ4], [false]) ;;
+	*) AC_MSG_ERROR([bad value ${withval} for --without-lz4]) ;;
+	esac],
+	[AM_CONDITIONAL([WITH_LZ4], [true])])
+
 ##### search for dependencies #####
 
 need_zlib="no"
 need_xz="no"
 need_lzo="no"
+need_lz4="no"
 
 AM_COND_IF([WITH_GZIP], [need_zlib="yes"])
 AM_COND_IF([WITH_XZ], [need_xz="yes"])
 AM_COND_IF([WITH_LZO], [need_lzo="yes"])
+AM_COND_IF([WITH_LZ4], [need_lz4="yes"])
 
 if test "x$need_zlib" = "xyes"; then
 	PKG_CHECK_MODULES(ZLIB, [zlib], [], [AC_MSG_ERROR([cannot find zlib])])
@@ -100,6 +112,11 @@ if test "x$need_lzo" = "xyes"; then
 	)
 fi
 
+if test "x$need_lz4" = "xyes"; then
+	PKG_CHECK_MODULES(LZ4, [liblz4], [],
+			       [AC_MSG_ERROR([cannot lz4 library])])
+fi
+
 ##### generate output #####
 
 AC_CONFIG_HEADERS([config.h])
diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index aacec34..17004bc 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -42,4 +42,11 @@ libcompress_a_CFLAGS += $(LZO_CFLAGS)
 libcompress_a_CPPFLAGS += -DWITH_LZO
 endif
 
+if WITH_LZ4
+libcompress_a_SOURCES += lib/comp/lz4.c
+
+libcompress_a_CFLAGS += $(LZ4_CFLAGS)
+libcompress_a_CPPFLAGS += -DWITH_LZ4
+endif
+
 noinst_LIBRARIES += libfstree.a libcompress.a libutil.a libsquashfs.a
diff --git a/lib/comp/compressor.c b/lib/comp/compressor.c
index 42ebd8b..3b473a3 100644
--- a/lib/comp/compressor.c
+++ b/lib/comp/compressor.c
@@ -1,7 +1,9 @@
 /* SPDX-License-Identifier: GPL-3.0-or-later */
 #include <string.h>
+#include <stdio.h>
 
 #include "internal.h"
+#include "util.h"
 
 typedef compressor_t *(*compressor_fun_t)(bool compress, size_t block_size);
 
@@ -15,8 +17,62 @@ static compressor_fun_t compressors[SQFS_COMP_MAX + 1] = {
 #ifdef WITH_LZO
 	[SQFS_COMP_LZO] = create_lzo_compressor,
 #endif
+#ifdef WITH_LZ4
+	[SQFS_COMP_LZ4] = create_lz4_compressor,
+#endif
 };
 
+int generic_write_options(int fd, const void *data, size_t size)
+{
+	uint8_t buffer[size + 2];
+	ssize_t ret;
+
+	*((uint16_t *)buffer) = htole16(0x8000 | size);
+	memcpy(buffer + 2, data, size);
+
+	ret = write_retry(fd, buffer, sizeof(buffer));
+
+	if (ret < 0) {
+		perror("writing compressor options");
+		return -1;
+	}
+
+	if ((size_t)ret < sizeof(buffer)) {
+		fputs("writing compressor options: truncated write\n", stderr);
+		return -1;
+	}
+
+	return ret;
+}
+
+int generic_read_options(int fd, void *data, size_t size)
+{
+	uint8_t buffer[size + 2];
+	ssize_t ret;
+
+	ret = read_retry(fd, buffer, sizeof(buffer));
+
+	if (ret < 0) {
+		perror("reading compressor options");
+		return -1;
+	}
+
+	if ((size_t)ret < sizeof(buffer)) {
+		fputs("reading compressor options: unexpected end of file\n",
+		      stderr);
+		return -1;
+	}
+
+	if (le16toh(*((uint16_t *)buffer)) != (0x8000 | size)) {
+		fputs("reading compressor options: invalid meta data header\n",
+		      stderr);
+		return -1;
+	}
+
+	memcpy(data, buffer + 2, size);
+	return 0;
+}
+
 bool compressor_exists(E_SQFS_COMPRESSOR id)
 {
 	if (id < SQFS_COMP_MIN || id > SQFS_COMP_MAX)
diff --git a/lib/comp/internal.h b/lib/comp/internal.h
index 3b24af0..863f82b 100644
--- a/lib/comp/internal.h
+++ b/lib/comp/internal.h
@@ -4,10 +4,16 @@
 
 #include "compress.h"
 
+int generic_write_options(int fd, const void *data, size_t size);
+
+int generic_read_options(int fd, void *data, size_t size);
+
 compressor_t *create_xz_compressor(bool compress, size_t block_size);
 
 compressor_t *create_gzip_compressor(bool compress, size_t block_size);
 
 compressor_t *create_lzo_compressor(bool compress, size_t block_size);
 
+compressor_t *create_lz4_compressor(bool compress, size_t block_size);
+
 #endif /* INTERNAL_H */
diff --git a/lib/comp/lz4.c b/lib/comp/lz4.c
new file mode 100644
index 0000000..f9c753d
--- /dev/null
+++ b/lib/comp/lz4.c
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <lz4.h>
+#include <lz4hc.h>
+
+#include "internal.h"
+
+typedef struct {
+	compressor_t base;
+} lz4_compressor_t;
+
+typedef struct {
+	uint32_t version;
+	uint32_t flags;
+} lz4_options;
+
+#define LZ4LEGACY 1
+
+static int lz4_write_options(compressor_t *base, int fd)
+{
+	lz4_options opt = {
+		.version = htole32(LZ4LEGACY),
+		.flags = htole32(0),
+	};
+	(void)base;
+
+	return generic_write_options(fd, &opt, sizeof(opt));
+}
+
+static int lz4_read_options(compressor_t *base, int fd)
+{
+	lz4_options opt;
+	(void)base;
+
+	if (generic_read_options(fd, &opt, sizeof(opt)))
+		return -1;
+
+	opt.version = le32toh(opt.version);
+	opt.flags = le32toh(opt.flags);
+
+	if (opt.version != LZ4LEGACY) {
+		fprintf(stderr, "unsupported lz4 version '%d'\n", opt.version);
+		return -1;
+	}
+
+	return 0;
+}
+
+static ssize_t lz4_comp_block(compressor_t *base, const uint8_t *in,
+			      size_t size, uint8_t *out, size_t outsize)
+{
+	int ret;
+	(void)base;
+
+	ret = LZ4_compress_default((void *)in, (void *)out, size, outsize);
+
+	if (ret < 0) {
+		fputs("internal error in lz4 compressor\n", stderr);
+		return -1;
+	}
+
+	return ret;
+}
+
+static ssize_t lz4_uncomp_block(compressor_t *base, const uint8_t *in,
+				size_t size, uint8_t *out, size_t outsize)
+{
+	int ret;
+	(void)base;
+
+	ret = LZ4_decompress_safe((void *)in, (void *)out, size, outsize);
+
+	if (ret < 0) {
+		fputs("internal error in lz4 decompressor\n", stderr);
+		return -1;
+	}
+
+	return ret;
+}
+
+static void lz4_destroy(compressor_t *base)
+{
+	free(base);
+}
+
+compressor_t *create_lz4_compressor(bool compress, size_t block_size)
+{
+	lz4_compressor_t *lz4 = calloc(1, sizeof(*lz4));
+	compressor_t *base = (compressor_t *)lz4;
+	(void)block_size;
+
+	if (lz4 == NULL) {
+		perror("creating lz4 compressor");
+		return NULL;
+	}
+
+	base->destroy = lz4_destroy;
+	base->do_block = compress ? lz4_comp_block : lz4_uncomp_block;
+	base->write_options = lz4_write_options;
+	base->read_options = lz4_read_options;
+	return base;
+}
diff --git a/mkfs/Makemodule.am b/mkfs/Makemodule.am
index 35e937c..dc105a0 100644
--- a/mkfs/Makemodule.am
+++ b/mkfs/Makemodule.am
@@ -14,4 +14,8 @@ if WITH_LZO
 gensquashfs_LDADD += $(LZO_LIBS)
 endif
 
+if WITH_LZ4
+gensquashfs_LDADD += $(LZ4_LIBS)
+endif
+
 bin_PROGRAMS += gensquashfs
diff --git a/unpack/Makemodule.am b/unpack/Makemodule.am
index c3e61aa..c68a005 100644
--- a/unpack/Makemodule.am
+++ b/unpack/Makemodule.am
@@ -16,4 +16,8 @@ if WITH_LZO
 rdsquashfs_LDADD += $(LZO_LIBS)
 endif
 
+if WITH_LZ4
+rdsquashfs_LDADD += $(LZ4_LIBS)
+endif
+
 bin_PROGRAMS += rdsquashfs