unsquashfs: add support for displaying compression options

Add support to display the compression options used to
compress the filesystem in -stat.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>

3 files changed, 76 insertions, 1 deletions

diff --git a/squashfs-tools/compressor.h b/squashfs-tools/compressor.h
index 4679850..dba6d56 100644
--- a/squashfs-tools/compressor.h
+++ b/squashfs-tools/compressor.h
@@ -31,6 +31,7 @@ struct compressor {
 	int (*options_post)(int);
 	void *(*dump_options)(int, int *);
 	int (*extract_options)(int, void *, int);
+	void (*display_options)(void *, int);
 	void (*usage)();
 };
 
@@ -101,3 +102,11 @@ static inline int compressor_extract_options(struct compressor *comp,
 		return size ? -1 : 0;
 	return comp->extract_options(block_size, buffer, size);
 }
+
+
+static inline void compressor_display_options(struct compressor *comp,
+	void *buffer, int size)
+{
+	if(comp->display_options != NULL)
+		comp->display_options(buffer, size);
+}
diff --git a/squashfs-tools/unsquashfs.c b/squashfs-tools/unsquashfs.c
index 2a0ee0b..f599d74 100644
--- a/squashfs-tools/unsquashfs.c
+++ b/squashfs-tools/unsquashfs.c
@@ -1599,9 +1599,23 @@ void squashfs_stat(char *source)
 		sBlk.s.bytes_used / 1024.0, sBlk.s.bytes_used /
 		(1024.0 * 1024.0));
 
-	if(sBlk.s.s_major == 4)
+	if(sBlk.s.s_major == 4) {
 		printf("Compression %s\n", comp->name);
 
+		if(SQUASHFS_COMP_OPTS(sBlk.s.flags)) {
+			char buffer[SQUASHFS_METADATA_SIZE];
+			int bytes;
+
+			bytes = read_block(fd, sizeof(sBlk.s), NULL, 0, buffer);
+			if(bytes == 0) {
+				ERROR("Failed to read compressor options\n");
+				return;
+			}
+
+			compressor_display_options(comp, buffer, bytes);
+		}
+	}
+
 	printf("Block size %d\n", sBlk.s.block_size);
 	printf("Filesystem is %sexportable via NFS\n",
 		SQUASHFS_EXPORTABLE(sBlk.s.flags) ? "" : "not ");
diff --git a/squashfs-tools/xz_wrapper.c b/squashfs-tools/xz_wrapper.c
index 8c2ab1c..44dfada 100644
--- a/squashfs-tools/xz_wrapper.c
+++ b/squashfs-tools/xz_wrapper.c
@@ -322,6 +322,57 @@ failed:
 }
 
 
+void xz_display_options(void *buffer, int size)
+{
+	struct comp_opts *comp_opts = buffer;
+	int dictionary_size, flags, printed;
+	int i, n;
+
+	/* check passed comp opts struct is of the correct length */
+	if(size != sizeof(comp_opts))
+		goto failed;
+
+	SQUASHFS_INSWAP_COMP_OPTS(comp_opts);
+
+	dictionary_size = comp_opts->dictionary_size;
+	flags = comp_opts->flags;
+
+	/*
+	 * check that the dictionary size seems correct - the dictionary
+	 * size should 2^n or 2^n+2^(n+1)
+	 */
+	n = ffs(dictionary_size) - 1;
+	if(dictionary_size != (1 << n) && 
+			dictionary_size != ((1 << n) + (1 << (n + 1))))
+		goto failed;
+
+	printf("\tDictionary size %d\n", dictionary_size);
+
+	printed = 0;
+	for(i = 0; bcj[i].name; i++) {
+		if((flags >> i) & 1) {
+			if(printed)
+				printf(", ");
+			else
+				printf("\tFilters selected: ");
+			printf("%s", bcj[i].name);
+			printed = 1;
+		}
+	}
+
+	if(!printed)
+		printf("\tNo filters specified\n");
+	else
+		printf("\n");
+
+	return;
+
+failed:
+	fprintf(stderr, "xz: error reading stored compressor options from "
+		"filesystem!\n");
+}	
+
+
 /*
  * This function is called by mksquashfs to initialise the
  * compressor, before compress() is called.
@@ -477,6 +528,7 @@ struct compressor xz_comp_ops = {
 	.options_post = xz_options_post,
 	.dump_options = xz_dump_options,
 	.extract_options = xz_extract_options,
+	.display_options = xz_display_options,
 	.usage = xz_usage,
 	.id = XZ_COMPRESSION,
 	.name = "xz",