dump.f2fs: Dump symlinks as symlinks

Previously, dumped symlinks would always create regular files instead.
This allows symlinks to be dumped as symlinks with the -L option.

The i_name field's name may not be the same as the actual name from the
dirent, so we use the dirent name when available.

Currently hardlinks aren't detected, so print a warning if we notice a
nondirectory with a link count over 1.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fsck/dump.c

@@ -253,20 +253,27 @@ static void dump_folder_contents(struct f2fs_sb_info *sbi, u8 *bitmap,
 {
 	int i;
 	int name_len;
+	char name[F2FS_NAME_LEN + 1] = {0};
 
 	for (i = 0; i < max; i++) {
 		if (test_bit_le(i, bitmap) == 0)
 			continue;
 		name_len = le16_to_cpu(dentry[i].name_len);
+		if (name_len == 0 || name_len > F2FS_NAME_LEN) {
+			MSG(c.force, "Wrong name info\n\n");
+			ASSERT(name_len == 0 || name_len > F2FS_NAME_LEN);
+		}
 		if (name_len == 1 && filenames[i][0] == '.')
 			continue;
 		if (name_len == 2 && filenames[i][0] == '.' && filenames[i][1] == '.')
 			continue;
-		dump_node(sbi, le32_to_cpu(dentry[i].ino), 1, NULL, 0, 1);
+		strncpy(name, (const char *)filenames[i], name_len);
+		name[name_len] = 0;
+		dump_node(sbi, le32_to_cpu(dentry[i].ino), 1, NULL, 0, 1, name);
 	}
 }
 
-static void dump_data_blk(struct f2fs_sb_info *sbi, __u64 offset, u32 blkaddr, bool is_folder)
+static void dump_data_blk(struct f2fs_sb_info *sbi, __u64 offset, u32 blkaddr, int type)
 {
 	char buf[F2FS_BLKSIZE];
 
@@ -307,11 +314,15 @@ static void dump_data_blk(struct f2fs_sb_info *sbi, __u64 offset, u32 blkaddr, b
 		ASSERT(ret >= 0);
 	}
 
-	if (is_folder) {
+	if (S_ISDIR(type)) {
 		struct f2fs_dentry_block *d = (struct f2fs_dentry_block *) buf;
 
 		dump_folder_contents(sbi, d->dentry_bitmap, F2FS_DENTRY_BLOCK_DENTRIES(d),
 					F2FS_DENTRY_BLOCK_FILENAMES(d), NR_DENTRY_IN_BLOCK);
+#if !defined(__MINGW32__)
+	} if (S_ISLNK(type)) {
+		dev_write_symlink(buf, c.dump_sym_target_len);
+#endif
 	} else {
 		/* write blkaddr */
 		dev_write_dump(buf, offset, F2FS_BLKSIZE);
@@ -319,7 +330,7 @@ static void dump_data_blk(struct f2fs_sb_info *sbi, __u64 offset, u32 blkaddr, b
 }
 
 static void dump_node_blk(struct f2fs_sb_info *sbi, int ntype,
-				u32 nid, u32 addr_per_block, u64 *ofs, int is_dir)
+				u32 nid, u32 addr_per_block, u64 *ofs, int type)
 {
 	struct node_info ni;
 	struct f2fs_node *node_blk;
@@ -356,20 +367,20 @@ static void dump_node_blk(struct f2fs_sb_info *sbi, int ntype,
 		switch (ntype) {
 		case TYPE_DIRECT_NODE:
 			dump_data_blk(sbi, *ofs * F2FS_BLKSIZE,
-					le32_to_cpu(node_blk->dn.addr[i]), is_dir);
+					le32_to_cpu(node_blk->dn.addr[i]), type);
 			(*ofs)++;
 			break;
 		case TYPE_INDIRECT_NODE:
 			dump_node_blk(sbi, TYPE_DIRECT_NODE,
 					le32_to_cpu(node_blk->in.nid[i]),
 					addr_per_block,
-					ofs, is_dir);
+					ofs, type);
 			break;
 		case TYPE_DOUBLE_INDIRECT_NODE:
 			dump_node_blk(sbi, TYPE_INDIRECT_NODE,
 					le32_to_cpu(node_blk->in.nid[i]),
 					addr_per_block,
-					ofs, is_dir);
+					ofs, type);
 			break;
 		}
 	}
@@ -377,7 +388,7 @@ static void dump_node_blk(struct f2fs_sb_info *sbi, int ntype,
 }
 
 #ifdef HAVE_FSETXATTR
-static void dump_xattr(struct f2fs_sb_info *sbi, struct f2fs_node *node_blk, int is_dir)
+static void dump_xattr(struct f2fs_sb_info *sbi, struct f2fs_node *node_blk, int type)
 {
 	void *xattr;
 	void *last_base_addr;
@@ -431,19 +442,26 @@ static void dump_xattr(struct f2fs_sb_info *sbi, struct f2fs_node *node_blk, int
 
 		DBG(1, "fd %d xattr_name %s\n", c.dump_fd, xattr_name);
 #if defined(__linux__)
-		if (is_dir) {
+		if (S_ISDIR(type)) {
 			ret = setxattr(".", xattr_name, value,
 							le16_to_cpu(ent->e_value_size), 0);
+		} if (S_ISLNK(type) && c.preserve_symlinks) {
+			ret = lsetxattr(c.dump_symlink, xattr_name, value,
+							le16_to_cpu(ent->e_value_size), 0);
 		} else {
 			ret = fsetxattr(c.dump_fd, xattr_name, value,
 							le16_to_cpu(ent->e_value_size), 0);
 		}
 
 #elif defined(__APPLE__)
-		if (is_dir) {
+		if (S_ISDIR(type)) {
 			ret = setxattr(".", xattr_name, value,
 					le16_to_cpu(ent->e_value_size), 0,
 					XATTR_CREATE);
+		} if (S_ISLNK(type) && c.preserve_symlinks) {
+			ret = lsetxattr(c.dump_symlink, xattr_name, value,
+					le16_to_cpu(ent->e_value_size), 0,
+					XATTR_CREATE);
 		} else {
 			ret = fsetxattr(c.dump_fd, xattr_name, value,
 					le16_to_cpu(ent->e_value_size), 0,
@@ -473,14 +491,21 @@ static int dump_inode_blk(struct f2fs_sb_info *sbi, u32 nid,
 	u32 i = 0;
 	u64 ofs = 0;
 	u32 addr_per_block;
-	bool is_dir = S_ISDIR(le16_to_cpu(node_blk->i.i_mode));
+	u16 type = le16_to_cpu(node_blk->i.i_mode);
 	int ret = 0;
 
 	if ((node_blk->i.i_inline & F2FS_INLINE_DATA)) {
 		DBG(3, "ino[0x%x] has inline data!\n", nid);
 		/* recover from inline data */
-		dev_write_dump(inline_data_addr(node_blk),
+#if !defined(__MINGW32__)
+		if (S_ISLNK(type) && c.preserve_symlinks) {
+			dev_write_symlink(inline_data_addr(node_blk), c.dump_sym_target_len);
+		} else
+#endif
+		{
+			dev_write_dump(inline_data_addr(node_blk),
 						0, MAX_INLINE_DATA(node_blk));
+		}
 		ret = -1;
 		goto dump_xattr;
 	}
@@ -504,7 +529,7 @@ static int dump_inode_blk(struct f2fs_sb_info *sbi, u32 nid,
 	/* check data blocks in inode */
 	for (i = 0; i < ADDRS_PER_INODE(&node_blk->i); i++, ofs++)
 		dump_data_blk(sbi, ofs * F2FS_BLKSIZE, le32_to_cpu(
-			node_blk->i.i_addr[get_extra_isize(node_blk) + i]), is_dir);
+			node_blk->i.i_addr[get_extra_isize(node_blk) + i]), type);
 
 	/* check node blocks in inode */
 	for (i = 0; i < 5; i++) {
@@ -513,26 +538,26 @@ static int dump_inode_blk(struct f2fs_sb_info *sbi, u32 nid,
 					le32_to_cpu(F2FS_INODE_I_NID(&node_blk->i, i)),
 					addr_per_block,
 					&ofs,
-					is_dir);
+					type);
 		else if (i == 2 || i == 3)
 			dump_node_blk(sbi, TYPE_INDIRECT_NODE,
 					le32_to_cpu(F2FS_INODE_I_NID(&node_blk->i, i)),
 					addr_per_block,
 					&ofs,
-					is_dir);
+					type);
 		else if (i == 4)
 			dump_node_blk(sbi, TYPE_DOUBLE_INDIRECT_NODE,
 					le32_to_cpu(F2FS_INODE_I_NID(&node_blk->i, i)),
 					addr_per_block,
 					&ofs,
-					is_dir);
+					type);
 		else
 			ASSERT(0);
 	}
 	/* last block in extent cache */
 	print_extent(true);
 dump_xattr:
-	dump_xattr(sbi, node_blk, is_dir);
+	dump_xattr(sbi, node_blk, type);
 	return ret;
 }
 
@@ -555,6 +580,23 @@ static void dump_file(struct f2fs_sb_info *sbi, struct node_info *ni,
 	close(c.dump_fd);
 }
 
+static void dump_link(struct f2fs_sb_info *sbi, struct node_info *ni,
+				struct f2fs_node *node_blk, char *name)
+{
+#if defined(__MINGW32__)
+	dump_file(sbi, ni, node_blk, name);
+#else
+	struct f2fs_inode *inode = &node_blk->i;
+	int len = le64_to_cpu(inode->i_size);
+
+	if (!c.preserve_symlinks)
+		return dump_file(sbi, ni, node_blk, name);
+	c.dump_symlink = name;
+	c.dump_sym_target_len = len + 1;
+	dump_inode_blk(sbi, ni->ino, node_blk);
+#endif
+}
+
 static void dump_folder(struct f2fs_sb_info *sbi, struct node_info *ni,
 				struct f2fs_node *node_blk, char *path, int is_root)
 {
@@ -580,18 +622,24 @@ static void dump_folder(struct f2fs_sb_info *sbi, struct node_info *ni,
 
 static int dump_filesystem(struct f2fs_sb_info *sbi, struct node_info *ni,
 				struct f2fs_node *node_blk, int force, char *base_path,
-				bool is_base, bool allow_folder)
+				bool is_base, bool allow_folder, char *dirent_name)
 {
 	struct f2fs_inode *inode = &node_blk->i;
 	u32 imode = le16_to_cpu(inode->i_mode);
-	u32 namelen = le32_to_cpu(inode->i_namelen);
-	char name[F2FS_NAME_LEN + 1] = {0};
+	u32 ilinks = le32_to_cpu(inode->i_links);
+	u32 i_namelen = le32_to_cpu(inode->i_namelen);
+	char i_name[F2FS_NAME_LEN + 1] = {0};
+	char *name = NULL;
 	char path[1024] = {0};
 	char ans[255] = {0};
 	int is_encrypted = file_is_encrypt(inode);
 	int is_root = sbi->root_ino_num == ni->nid;
 	int ret;
 
+	if (!S_ISDIR(imode) && ilinks != 1) {
+		MSG(force, "Warning: Hard link detected. Dumped files may be duplicated\n");
+	}
+
 	if (is_encrypted) {
 		MSG(force, "File is encrypted\n");
 		return -1;
@@ -601,7 +649,7 @@ static int dump_filesystem(struct f2fs_sb_info *sbi, struct node_info *ni,
 		MSG(force, "Not a valid file type\n\n");
 		return -1;
 	}
-	if (!is_root && (namelen == 0 || namelen > F2FS_NAME_LEN)) {
+	if (!is_root && !dirent_name && (i_namelen == 0 || i_namelen > F2FS_NAME_LEN)) {
 		MSG(force, "Wrong name info\n\n");
 		return -1;
 	}
@@ -614,7 +662,7 @@ static int dump_filesystem(struct f2fs_sb_info *sbi, struct node_info *ni,
 		return dump_inode_blk(sbi, ni->ino, node_blk);
 
 	printf("Do you want to dump this %s into %s/? [Y/N] ",
-			S_ISREG(imode) || S_ISLNK(imode) ? "file" : "folder",
+			S_ISDIR(imode) ? "folder" : "file",
 			base_path);
 	ret = scanf("%s", ans);
 	ASSERT(ret >= 0);
@@ -635,23 +683,34 @@ dump:
 
 		/* make a file */
 		if (!is_root) {
-			strncpy(name, (const char *)inode->i_name, namelen);
-			name[namelen] = 0;
+			/* The i_name name may be out of date. Prefer dirent_name */
+			if (dirent_name) {
+				name = dirent_name;
+			} else  {
+				strncpy(i_name, (const char *)inode->i_name, i_namelen);
+				i_name[i_namelen] = 0;
+				name = i_name;
+			}
 		}
 
-		if (S_ISREG(imode) || S_ISLNK(imode)) {
+		if (S_ISREG(imode)) {
 			dump_file(sbi, ni, node_blk, name);
-		} else {
+		} else if (S_ISDIR(imode)) {
 			dump_folder(sbi, ni, node_blk, name, is_root);
+		} else {
+			dump_link(sbi, ni, node_blk, name);
 		}
 
 #if !defined(__MINGW32__)
 		/* fix up mode/owner */
 		if (c.preserve_perms) {
-			if (is_root)
+			if (is_root) {
+				name = i_name;
 				strncpy(name, ".", 2);
-			ASSERT(chmod(name, imode) == 0);
-			ASSERT(chown(name, inode->i_uid, inode->i_gid) == 0);
+			}
+			if (!S_ISLNK(imode))
+				ASSERT(chmod(name, imode) == 0);
+			ASSERT(lchown(name, inode->i_uid, inode->i_gid) == 0);
 		}
 #endif
 		if (is_base)
@@ -705,7 +764,7 @@ void dump_node_scan_disk(struct f2fs_sb_info *sbi, nid_t nid)
 	free(node_blk);
 }
 
-int dump_node(struct f2fs_sb_info *sbi, nid_t nid, int force, char *base_path, int base, int allow_folder)
+int dump_node(struct f2fs_sb_info *sbi, nid_t nid, int force, char *base_path, int base, int allow_folder, char *dirent_name)
 {
 	struct node_info ni;
 	struct f2fs_node *node_blk;
@@ -740,7 +799,7 @@ int dump_node(struct f2fs_sb_info *sbi, nid_t nid, int force, char *base_path, i
 			print_node_info(sbi, node_blk, force);
 
 		if (ni.ino == ni.nid)
-			ret = dump_filesystem(sbi, &ni, node_blk, force, base_path, base, allow_folder);
+			ret = dump_filesystem(sbi, &ni, node_blk, force, base_path, base, allow_folder, dirent_name);
 	} else {
 		print_node_info(sbi, node_blk, force);
 		MSG(force, "Invalid (i)node block\n\n");

fsck/fsck.c

@@ -1651,7 +1651,7 @@ static void print_dentry(struct f2fs_sb_info *sbi, __u8 *name,
 			d = d->next;
 		}
 		printf("/%s", new);
-		if (dump_node(sbi, le32_to_cpu(dentry[idx].ino), 0, NULL, 0, 0))
+		if (dump_node(sbi, le32_to_cpu(dentry[idx].ino), 0, NULL, 0, 0, NULL))
 			printf("\33[2K\r");
 	} else {
 		for (i = 1; i < depth; i++)
@@ -3632,7 +3632,7 @@ int fsck_verify(struct f2fs_sb_info *sbi)
 		if (!strcasecmp(ans, "y")) {
 			for (i = 0; i < fsck->nr_nat_entries; i++) {
 				if (f2fs_test_bit(i, fsck->nat_area_bitmap))
-					dump_node(sbi, i, 1, NULL, 1, 0);
+					dump_node(sbi, i, 1, NULL, 1, 0, NULL);
 			}
 		}
 	}

fsck/fsck.h

@@ -277,7 +277,7 @@ struct dump_option {
 extern void nat_dump(struct f2fs_sb_info *, nid_t, nid_t);
 extern void sit_dump(struct f2fs_sb_info *, unsigned int, unsigned int);
 extern void ssa_dump(struct f2fs_sb_info *, int, int);
-extern int dump_node(struct f2fs_sb_info *, nid_t, int, char *, int, int);
+extern int dump_node(struct f2fs_sb_info *, nid_t, int, char *, int, int, char *);
 extern int dump_info_from_blkaddr(struct f2fs_sb_info *, u32);
 extern unsigned int start_bidx_of_node(unsigned int, struct f2fs_node *);
 extern void dump_node_scan_disk(struct f2fs_sb_info *sbi, nid_t nid);

fsck/main.c

@@ -102,6 +102,7 @@ void dump_usage()
 	MSG(0, "  -y alias for -f\n");
 	MSG(0, "  -o dump inodes to the given path\n");
 	MSG(0, "  -P preserve mode/owner/group for dumped inode\n");
+	MSG(0, "  -L Preserves symlinks. Otherwise symlinks are dumped as regular files.\n");
 	MSG(0, "  -V print the version number and exit\n");
 
 	exit(1);
@@ -389,7 +390,7 @@ void f2fs_parse_options(int argc, char *argv[])
 		}
 	} else if (!strcmp("dump.f2fs", prog)) {
 #ifdef WITH_DUMP
-		const char *option_string = "d:fi:I:n:Mo:Prs:Sa:b:Vy";
+		const char *option_string = "d:fi:I:n:LMo:Prs:Sa:b:Vy";
 		static struct dump_option dump_opt = {
 			.nid = 0,	/* default root ino */
 			.start_nat = -1,
@@ -479,6 +480,14 @@ void f2fs_parse_options(int argc, char *argv[])
 				err = EWRONG_OPT;
 #else
 				c.preserve_perms = 1;
+#endif
+				break;
+			case 'L':
+#if defined(__MINGW32__)
+				MSG(0, "-L not supported for Windows\n");
+				err = EWRONG_OPT;
+#else
+				c.preserve_symlinks = 1;
 #endif
 				break;
 			case 'V':
@@ -957,7 +966,7 @@ static void do_dump(struct f2fs_sb_info *sbi)
 	if (opt->blk_addr != -1)
 		dump_info_from_blkaddr(sbi, opt->blk_addr);
 	if (opt->nid)
-		dump_node(sbi, opt->nid, c.force, opt->base_path, 1, 1);
+		dump_node(sbi, opt->nid, c.force, opt->base_path, 1, 1, NULL);
 	if (opt->scan_nid)
 		dump_node_scan_disk(sbi, opt->scan_nid);
 

include/f2fs_fs.h

@@ -1478,6 +1478,8 @@ struct f2fs_configuration {
 	uint16_t s_encoding_flags;
 	int32_t kd;
 	int32_t dump_fd;
+	char *dump_symlink;
+	int dump_sym_target_len;
 	struct device_info devices[MAX_DEVICES];
 	int ndevs;
 	char *extension_list[2];
@@ -1540,7 +1542,10 @@ struct f2fs_configuration {
 	struct selinux_opt seopt_file[8];
 	int nr_opt;
 #endif
+
+	/* dump parameters */
 	int preserve_perms;
+	int preserve_symlinks;
 
 	/* resize parameters */
 	int safe_resize;
@@ -1614,6 +1619,9 @@ extern int dev_readahead(__u64, size_t UNUSED(len));
 extern int dev_write(void *, __u64, size_t);
 extern int dev_write_block(void *, __u64);
 extern int dev_write_dump(void *, __u64, size_t);
+#if !defined(__MINGW32__)
+extern int dev_write_symlink(char *, size_t);
+#endif
 /* All bytes in the buffer must be 0 use dev_fill(). */
 extern int dev_fill(void *, __u64, size_t);
 extern int dev_fill_block(void *, __u64);

lib/libf2fs_io.c

@@ -598,6 +598,16 @@ int dev_write_dump(void *buf, __u64 offset, size_t len)
 	return 0;
 }
 
+#if !defined(__MINGW32__)
+int dev_write_symlink(char *buf, size_t len)
+{
+	buf[len] = 0;
+	if (symlink(buf, c.dump_symlink))
+		return -1;
+	return 0;
+}
+#endif
+
 int dev_fill(void *buf, __u64 offset, size_t len)
 {
 	int fd;

man/dump.f2fs.8

@@ -71,6 +71,9 @@ Dump inodes to the given path
 .BI \-P
 Preserve mode/owner/group for dumped inode
 .TP
+.BI \-L
+Preserves symlinks. Otherwise symlinks are dumped as regular files.
+.TP
 .BI \-I " inode number"
 Specify an inode number and scan full disk to dump out, include history inode block
 .TP