2 * symlink.c --- make a symlink in the filesystem, based on mkdir.c
4 * Copyright (c) 2012, Intel Corporation.
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
25 #include <sys/types.h>
33 * Incredibly, libc5 doesn't appear to have strnlen. So we have to
36 static int my_strnlen(const char * s, int count)
40 while (count-- && *cp)
44 #define strnlen(str, x) my_strnlen((str),(x))
47 errcode_t ext2fs_symlink(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t ino,
48 const char *name, const char *target)
51 struct ext2_inode inode;
52 ext2_ino_t scratch_ino;
54 int fastlink, inlinelink;
55 unsigned int target_len;
58 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
61 * The Linux kernel doesn't allow for links longer than a block
62 * (counting the NUL terminator)
64 target_len = strnlen(target, fs->blocksize + 1);
65 if (target_len >= fs->blocksize) {
66 retval = EXT2_ET_INVALID_ARGUMENT;
71 * Allocate a data block for slow links
73 retval = ext2fs_get_mem(fs->blocksize, &block_buf);
76 memset(block_buf, 0, fs->blocksize);
77 strncpy(block_buf, target, fs->blocksize);
79 memset(&inode, 0, sizeof(struct ext2_inode));
80 fastlink = (target_len < sizeof(inode.i_block));
82 retval = ext2fs_new_block2(fs, ext2fs_find_inode_goal(fs, ino,
91 * Allocate an inode, if necessary
94 retval = ext2fs_new_inode(fs, parent, LINUX_S_IFLNK | 0755,
101 * Create the inode structure....
103 inode.i_mode = LINUX_S_IFLNK | 0777;
104 inode.i_uid = inode.i_gid = 0;
105 inode.i_links_count = 1;
106 ext2fs_inode_size_set(fs, &inode, target_len);
107 /* The time fields are set by ext2fs_write_new_inode() */
109 inlinelink = !fastlink && ext2fs_has_feature_inline_data(fs->super);
111 /* Fast symlinks, target stored in inode */
112 strcpy((char *)&inode.i_block, target);
113 } else if (inlinelink) {
114 /* Try inserting an inline data symlink */
115 inode.i_flags |= EXT4_INLINE_DATA_FL;
116 retval = ext2fs_write_new_inode(fs, ino, &inode);
119 retval = ext2fs_inline_data_set(fs, ino, &inode, block_buf,
122 inode.i_flags &= ~EXT4_INLINE_DATA_FL;
126 retval = ext2fs_read_inode(fs, ino, &inode);
131 /* Slow symlinks, target stored in the first block */
132 ext2fs_iblk_set(fs, &inode, 1);
133 if (ext2fs_has_feature_extents(fs->super)) {
135 * The extent bmap is setup after the inode and block
136 * have been written out below.
138 inode.i_flags |= EXT4_EXTENTS_FL;
143 * Write out the inode and inode data block. The inode generation
144 * number is assigned by write_new_inode, which means that the
145 * operations using ino must come after it.
148 retval = ext2fs_write_inode(fs, ino, &inode);
150 retval = ext2fs_write_new_inode(fs, ino, &inode);
154 if (!fastlink && !inlinelink) {
155 retval = ext2fs_bmap2(fs, ino, &inode, NULL, BMAP_SET, 0, NULL,
160 retval = io_channel_write_blk64(fs->io, blk, 1, block_buf);
166 * Link the symlink into the filesystem hierarchy
169 retval = ext2fs_lookup(fs, parent, name, strlen(name), 0,
172 retval = EXT2_ET_FILE_EXISTS;
175 if (retval != EXT2_ET_FILE_NOT_FOUND)
177 retval = ext2fs_link(fs, parent, name, ino, EXT2_FT_SYMLINK);
183 * Update accounting....
185 if (!fastlink && !inlinelink)
186 ext2fs_block_alloc_stats2(fs, blk, +1);
187 ext2fs_inode_alloc_stats2(fs, ino, +1, 0);
191 ext2fs_free_mem(&block_buf);
196 * Test whether an inode is a fast symlink.
198 * A fast symlink has its symlink data stored in inode->i_block.
200 int ext2fs_is_fast_symlink(struct ext2_inode *inode)
202 return LINUX_S_ISLNK(inode->i_mode) && EXT2_I_SIZE(inode) &&
203 EXT2_I_SIZE(inode) < sizeof(inode->i_block);