From 5986f1d2b002d4f7f7144239a2c39b8aa39ac874 Mon Sep 17 00:00:00 2001
From: Sean Purcell <me@seanp.xyz>
Date: Mon, 27 Mar 2017 14:42:40 -0700
Subject: [PATCH] Add zstd compression support

---
 CONFIGURATION |  1 +
 Makefile.am   |  4 ++--
 configure.ac  |  1 +
 decompress.c  | 21 ++++++++++++++++++++-
 squashfs_fs.h |  1 +
 5 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/CONFIGURATION b/CONFIGURATION
index c172c3e1..044c67a3 100644
--- a/CONFIGURATION
+++ b/CONFIGURATION
@@ -14,5 +14,6 @@ These are the most useful options to ./configure:
   --with-xz=PREFIX
   --with-lzo=PREFIX
   --with-lz4=PREFIX
+  --with-zstd=PREFIX
   
 More options are available in `./configure --help'
diff --git a/Makefile.am b/Makefile.am
index e84534e4..8e61e21b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,4 @@
-COMPRESSION_LIBS = $(ZLIB_LIBS) $(XZ_LIBS) $(LZO_LIBS) $(LZ4_LIBS)
+COMPRESSION_LIBS = $(ZLIB_LIBS) $(XZ_LIBS) $(LZO_LIBS) $(LZ4_LIBS) $(ZSTD_LIBS)
 
 ACLOCAL_AMFLAGS = -I m4 --install
 
@@ -23,7 +23,7 @@ libsquashfuse_la_SOURCES = swap.c cache.c table.c dir.c file.c fs.c \
 	dir.h file.h decompress.h xattr.h squashfuse.h hash.h stack.h traverse.h \
 	util.h fs.h
 libsquashfuse_la_CPPFLAGS = $(ZLIB_CPPFLAGS) $(XZ_CPPFLAGS) $(LZO_CPPFLAGS) \
-	$(LZ4_CPPFLAGS)
+	$(LZ4_CPPFLAGS) $(ZSTD_CPPFLAGS)
 libsquashfuse_la_LIBADD =
 
 # Helper for FUSE clients: libfuseprivate
diff --git a/configure.ac b/configure.ac
index 36ffb51b..f3b55eb8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -31,6 +31,7 @@ SQ_CHECK_DECOMPRESS([ZLIB],[z],[uncompress],[zlib.h])
 SQ_CHECK_DECOMPRESS([XZ],[lzma],[lzma_stream_buffer_decode],[lzma.h],[liblzma])
 SQ_CHECK_DECOMPRESS([LZO],[lzo2],[lzo1x_decompress_safe],[lzo/lzo1x.h])
 SQ_CHECK_DECOMPRESS([LZ4],[lz4],[LZ4_decompress_safe],[lz4.h])
+SQ_CHECK_DECOMPRESS([ZSTD],[zstd],[ZSTD_decompress],[zstd.h])
 AS_IF([test "x$sq_decompressors" = x],
 	[AC_MSG_FAILURE([At least one decompression library must exist])])
 
diff --git a/decompress.c b/decompress.c
index d8a677ef..80344f05 100644
--- a/decompress.c
+++ b/decompress.c
@@ -98,6 +98,19 @@ static sqfs_err sqfs_decompressor_lz4(void *in, size_t insz,
 #endif
 
 
+#ifdef HAVE_ZSTD_H
+#include <zstd.h>
+static sqfs_err sqfs_decompressor_zstd(void *in, size_t insz,
+        void *out, size_t *outsz) {
+	const size_t zstdout = ZSTD_decompress(out, *outsz, in, insz);
+	if (ZSTD_isError(zstdout))
+		return SQFS_ERR;
+	*outsz = zstdout;
+	return SQFS_OK;
+}
+#define CAN_DECOMPRESS_ZSTD 1
+#endif
+
 sqfs_decompressor sqfs_decompressor_get(sqfs_compression_type type) {
 	switch (type) {
 #ifdef CAN_DECOMPRESS_ZLIB
@@ -111,13 +124,16 @@ sqfs_decompressor sqfs_decompressor_get(sqfs_compression_type type) {
 #endif
 #ifdef CAN_DECOMPRESS_LZ4
 		case LZ4_COMPRESSION: return &sqfs_decompressor_lz4;
+#endif
+#ifdef CAN_DECOMPRESS_ZSTD
+		case ZSTD_COMPRESSION: return &sqfs_decompressor_zstd;
 #endif
 		default: return NULL;
 	}
 }
 
 static char *const sqfs_compression_names[SQFS_COMP_MAX] = {
-	NULL, "zlib", "lzma", "lzo", "xz", "lz4",
+	NULL, "zlib", "lzma", "lzo", "xz", "lz4", "zstd",
 };
 
 char *sqfs_compression_name(sqfs_compression_type type) {
@@ -141,4 +157,7 @@ void sqfs_compression_supported(sqfs_compression_type *types) {
 #ifdef CAN_DECOMPRESS_LZ4
 	types[i++] = LZ4_COMPRESSION;
 #endif
+#ifdef CAN_DECOMPRESS_ZSTD
+	types[i++] = ZSTD_COMPRESSION;
+#endif
 }
diff --git a/squashfs_fs.h b/squashfs_fs.h
index 7269c1f7..e0ab1f4e 100644
--- a/squashfs_fs.h
+++ b/squashfs_fs.h
@@ -126,6 +126,7 @@
 #define LZO_COMPRESSION		3
 #define XZ_COMPRESSION		4
 #define LZ4_COMPRESSION		5
+#define ZSTD_COMPRESSION	6
 
 struct squashfs_super_block {
 	__le32			s_magic;