fs/squashfs: new filesystem

Add support for SquashFS filesystem. Right now, it does not support
compression but support for zlib will be added in a follow-up commit.

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

1 files changed, 155 insertions, 0 deletions

diff --git a/fs/squashfs/sqfs_inode.c b/fs/squashfs/sqfs_inode.c
new file mode 100644
index 0000000000..b037a9b2ac
--- /dev/null
+++ b/fs/squashfs/sqfs_inode.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#include <asm/unaligned.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "sqfs_decompressor.h"
+#include "sqfs_filesystem.h"
+#include "sqfs_utils.h"
+
+int sqfs_inode_size(struct squashfs_base_inode *inode, u32 blk_size)
+{
+	switch (get_unaligned_le16(&inode->inode_type)) {
+	case SQFS_DIR_TYPE:
+		return sizeof(struct squashfs_dir_inode);
+
+	case SQFS_REG_TYPE: {
+		struct squashfs_reg_inode *reg =
+			(struct squashfs_reg_inode *)inode;
+		u32 fragment = get_unaligned_le32(&reg->fragment);
+		u32 file_size = get_unaligned_le32(&reg->file_size);
+		unsigned int blk_list_size;
+
+		if (SQFS_IS_FRAGMENTED(fragment))
+			blk_list_size = file_size / blk_size;
+		else
+			blk_list_size = DIV_ROUND_UP(file_size, blk_size);
+
+		return sizeof(*reg) + blk_list_size * sizeof(u32);
+	}
+
+	case SQFS_LDIR_TYPE: {
+		struct squashfs_ldir_inode *ldir =
+			(struct squashfs_ldir_inode *)inode;
+		u16 i_count = get_unaligned_le16(&ldir->i_count);
+		unsigned int index_list_size = 0, l = 0;
+		struct squashfs_directory_index *di;
+		u32 sz;
+
+		if (i_count == 0)
+			return sizeof(*ldir);
+
+		di = ldir->index;
+		while (l < i_count + 1) {
+			sz = get_unaligned_le32(&di->size) + 1;
+			index_list_size += sz;
+			di = (void *)di + sizeof(*di) + sz;
+			l++;
+		}
+
+		return sizeof(*ldir) + index_list_size +
+			(i_count + 1) * SQFS_DIR_INDEX_BASE_LENGTH;
+	}
+
+	case SQFS_LREG_TYPE: {
+		struct squashfs_lreg_inode *lreg =
+			(struct squashfs_lreg_inode *)inode;
+		u32 fragment = get_unaligned_le32(&lreg->fragment);
+		u64 file_size = get_unaligned_le64(&lreg->file_size);
+		unsigned int blk_list_size;
+
+		if (fragment == 0xFFFFFFFF)
+			blk_list_size = DIV_ROUND_UP(file_size, blk_size);
+		else
+			blk_list_size = file_size / blk_size;
+
+		return sizeof(*lreg) + blk_list_size * sizeof(u32);
+	}
+
+	case SQFS_SYMLINK_TYPE:
+	case SQFS_LSYMLINK_TYPE: {
+		struct squashfs_symlink_inode *symlink =
+			(struct squashfs_symlink_inode *)inode;
+
+		return sizeof(*symlink) +
+			get_unaligned_le32(&symlink->symlink_size);
+	}
+
+	case SQFS_BLKDEV_TYPE:
+	case SQFS_CHRDEV_TYPE:
+		return sizeof(struct squashfs_dev_inode);
+	case SQFS_LBLKDEV_TYPE:
+	case SQFS_LCHRDEV_TYPE:
+		return sizeof(struct squashfs_ldev_inode);
+	case SQFS_FIFO_TYPE:
+	case SQFS_SOCKET_TYPE:
+		return sizeof(struct squashfs_ipc_inode);
+	case SQFS_LFIFO_TYPE:
+	case SQFS_LSOCKET_TYPE:
+		return sizeof(struct squashfs_lipc_inode);
+	default:
+		printf("Error while searching inode: unknown type.\n");
+		return -EINVAL;
+	}
+}
+
+/*
+ * Given the uncompressed inode table, the inode to be found and the number of
+ * inodes in the table, return inode position in case of success.
+ */
+void *sqfs_find_inode(void *inode_table, int inode_number, __le32 inode_count,
+		      __le32 block_size)
+{
+	struct squashfs_base_inode *base;
+	unsigned int offset = 0, k;
+	int sz;
+
+	if (!inode_table) {
+		printf("%s: Invalid pointer to inode table.\n", __func__);
+		return NULL;
+	}
+
+	for (k = 0; k < le32_to_cpu(inode_count); k++) {
+		base = inode_table + offset;
+		if (get_unaligned_le32(&base->inode_number) == inode_number)
+			return inode_table + offset;
+
+		sz = sqfs_inode_size(base, le32_to_cpu(block_size));
+		if (sz < 0)
+			return NULL;
+
+		offset += sz;
+	}
+
+	printf("Inode not found.\n");
+
+	return NULL;
+}
+
+int sqfs_read_metablock(unsigned char *file_mapping, int offset,
+			bool *compressed, u32 *data_size)
+{
+	unsigned char *data;
+	u16 header;
+
+	data = file_mapping + offset;
+	header = get_unaligned((u16 *)data);
+	*compressed = SQFS_COMPRESSED_METADATA(header);
+	*data_size = SQFS_METADATA_SIZE(header);
+
+	if (*data_size > SQFS_METADATA_BLOCK_SIZE) {
+		printf("Invalid metatada block size: %d bytes.\n", *data_size);
+		return -EINVAL;
+	}
+
+	return 0;
+}