fs/squashfs: Add init and clean-up functions to decompression

Add sqfs_decompressor_init() and sqfs_decompressor_cleanup(). These
functions are called respectively in sqfs_probe() and sqfs_close(). For
now, only ZSTD requires an initialization logic. ZSTD support will be
added in a follow-up commit.

Move squashfs_ctxt definition to sqfs_filesystem.h. This structure is
passed to sqfs_decompressor_init() and sqfs_decompressor_cleanup(), so
it can no longer be local to sqfs.c.

Signed-off-by: Joao Marcos Costa <joaomarcos.costa@bootlin.com>

fs/squashfs/sqfs.c

@@ -23,12 +23,6 @@
 #include "sqfs_filesystem.h"
 #include "sqfs_utils.h"
 
-struct squashfs_ctxt {
-	struct disk_partition cur_part_info;
-	struct blk_desc *cur_dev;
-	struct squashfs_super_block *sblk;
-};
-
 static struct squashfs_ctxt ctxt;
 
 static int sqfs_disk_read(__u32 block, __u32 nr_blocks, void *buf)
@@ -1023,6 +1017,14 @@ int sqfs_probe(struct blk_desc *fs_dev_desc, struct disk_partition *fs_partition
 
 	ctxt.sblk = sblk;
 
+	ret = sqfs_decompressor_init(&ctxt);
+
+	if (ret) {
+		ctxt.cur_dev = NULL;
+		free(ctxt.sblk);
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -1525,6 +1527,7 @@ void sqfs_close(void)
 {
 	free(ctxt.sblk);
 	ctxt.cur_dev = NULL;
+	sqfs_decompressor_cleanup(&ctxt);
 }
 
 void sqfs_closedir(struct fs_dir_stream *dirs)

fs/squashfs/sqfs_decompressor.c

@@ -14,9 +14,37 @@
 #endif
 
 #include "sqfs_decompressor.h"
-#include "sqfs_filesystem.h"
 #include "sqfs_utils.h"
 
+int sqfs_decompressor_init(struct squashfs_ctxt *ctxt)
+{
+	u16 comp_type = get_unaligned_le16(&ctxt->sblk->compression);
+
+	switch (comp_type) {
+#if IS_ENABLED(CONFIG_ZLIB)
+	case SQFS_COMP_ZLIB:
+		break;
+#endif
+	default:
+		printf("Error: unknown compression type.\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+void sqfs_decompressor_cleanup(struct squashfs_ctxt *ctxt)
+{
+	u16 comp_type = get_unaligned_le16(&ctxt->sblk->compression);
+
+	switch (comp_type) {
+#if IS_ENABLED(CONFIG_ZLIB)
+	case SQFS_COMP_ZLIB:
+		break;
+#endif
+	}
+}
+
 #if IS_ENABLED(CONFIG_ZLIB)
 static void zlib_decompression_status(int ret)
 {
@@ -35,14 +63,14 @@ static void zlib_decompression_status(int ret)
 #endif
 
 int sqfs_decompress(u16 comp_type, void *dest, unsigned long *dest_len,
-		    void *source, u32 lenp)
+		    void *source, u32 src_len)
 {
 	int ret = 0;
 
 	switch (comp_type) {
 #if IS_ENABLED(CONFIG_ZLIB)
 	case SQFS_COMP_ZLIB:
-		ret = uncompress(dest, dest_len, source, lenp);
+		ret = uncompress(dest, dest_len, source, src_len);
 		if (ret) {
 			zlib_decompression_status(ret);
 			return -EINVAL;

fs/squashfs/sqfs_decompressor.h

@@ -9,6 +9,7 @@
 #define SQFS_DECOMPRESSOR_H
 
 #include <stdint.h>
+#include "sqfs_filesystem.h"
 
 #define SQFS_COMP_ZLIB 1
 #define SQFS_COMP_LZMA 2
@@ -54,5 +55,7 @@ union squashfs_compression_opts {
 
 int sqfs_decompress(u16 comp_type, void *dest, unsigned long *dest_len,
 		    void *source, u32 lenp);
+int sqfs_decompressor_init(struct squashfs_ctxt *ctxt);
+void sqfs_decompressor_cleanup(struct squashfs_ctxt *ctxt);
 
 #endif /* SQFS_DECOMPRESSOR_H */

fs/squashfs/sqfs_filesystem.h

@@ -9,8 +9,9 @@
 #define SQFS_FILESYSTEM_H
 
 #include <asm/unaligned.h>
-#include <stdint.h>
 #include <fs.h>
+#include <part.h>
+#include <stdint.h>
 
 #define SQFS_UNCOMPRESSED_DATA 0x0002
 #define SQFS_MAGIC_NUMBER 0x73717368
@@ -72,6 +73,12 @@ struct squashfs_super_block {
 	__le64 export_table_start;
 };
 
+struct squashfs_ctxt {
+	struct disk_partition cur_part_info;
+	struct blk_desc *cur_dev;
+	struct squashfs_super_block *sblk;
+};
+
 struct squashfs_directory_index {
 	u32 index;
 	u32 start;