1 /*
2 * symlink.c --- make a symlink in the filesystem, based on mkdir.c
3 *
4 * Copyright (c) 2012, Intel Corporation.
5 * All Rights Reserved.
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
10 * %End-Header%
11 */
12
13 #include <stdio.h>
14 #include <string.h>
15 #if HAVE_UNISTD_H
16 #include <unistd.h>
17 #endif
18 #include <fcntl.h>
19 #include <time.h>
20 #if HAVE_SYS_STAT_H
21 #include <sys/stat.h>
22 #endif
23 #if HAVE_SYS_TYPES_H
24 #include <sys/types.h>
25 #endif
26
27 #include "ext2_fs.h"
28 #include "ext2fs.h"
29
ext2fs_symlink(ext2_filsys fs,ext2_ino_t parent,ext2_ino_t ino,const char * name,char * target)30 errcode_t ext2fs_symlink(ext2_filsys fs, ext2_ino_t parent, ext2_ino_t ino,
31 const char *name, char *target)
32 {
33 ext2_extent_handle_t handle;
34 errcode_t retval;
35 struct ext2_inode inode;
36 ext2_ino_t scratch_ino;
37 blk64_t blk;
38 int fastlink;
39 unsigned int target_len;
40 char *block_buf = 0;
41
42 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
43
44 /* The Linux kernel doesn't allow for links longer than a block */
45 target_len = strlen(target);
46 if (target_len > fs->blocksize) {
47 retval = EXT2_ET_INVALID_ARGUMENT;
48 goto cleanup;
49 }
50
51 /*
52 * Allocate a data block for slow links
53 */
54 fastlink = (target_len < sizeof(inode.i_block));
55 if (!fastlink) {
56 retval = ext2fs_new_block2(fs, 0, 0, &blk);
57 if (retval)
58 goto cleanup;
59 retval = ext2fs_get_mem(fs->blocksize, &block_buf);
60 if (retval)
61 goto cleanup;
62 }
63
64 /*
65 * Allocate an inode, if necessary
66 */
67 if (!ino) {
68 retval = ext2fs_new_inode(fs, parent, LINUX_S_IFLNK | 0755,
69 0, &ino);
70 if (retval)
71 goto cleanup;
72 }
73
74 /*
75 * Create the inode structure....
76 */
77 memset(&inode, 0, sizeof(struct ext2_inode));
78 inode.i_mode = LINUX_S_IFLNK | 0777;
79 inode.i_uid = inode.i_gid = 0;
80 ext2fs_iblk_set(fs, &inode, fastlink ? 0 : 1);
81 inode.i_links_count = 1;
82 inode.i_size = target_len;
83 /* The time fields are set by ext2fs_write_new_inode() */
84
85 if (fastlink) {
86 /* Fast symlinks, target stored in inode */
87 strcpy((char *)&inode.i_block, target);
88 } else {
89 /* Slow symlinks, target stored in the first block */
90 memset(block_buf, 0, fs->blocksize);
91 strcpy(block_buf, target);
92 if (fs->super->s_feature_incompat &
93 EXT3_FEATURE_INCOMPAT_EXTENTS) {
94 /*
95 * The extent bmap is setup after the inode and block
96 * have been written out below.
97 */
98 inode.i_flags |= EXT4_EXTENTS_FL;
99 }
100 }
101
102 /*
103 * Write out the inode and inode data block. The inode generation
104 * number is assigned by write_new_inode, which means that the
105 * operations using ino must come after it.
106 */
107 retval = ext2fs_write_new_inode(fs, ino, &inode);
108 if (retval)
109 goto cleanup;
110
111 if (!fastlink) {
112 retval = ext2fs_bmap2(fs, ino, &inode, NULL, BMAP_SET, 0, NULL,
113 &blk);
114 if (retval)
115 goto cleanup;
116
117 retval = io_channel_write_blk64(fs->io, blk, 1, block_buf);
118 if (retval)
119 goto cleanup;
120 }
121
122 /*
123 * Link the symlink into the filesystem hierarchy
124 */
125 if (name) {
126 retval = ext2fs_lookup(fs, parent, name, strlen(name), 0,
127 &scratch_ino);
128 if (!retval) {
129 retval = EXT2_ET_FILE_EXISTS;
130 goto cleanup;
131 }
132 if (retval != EXT2_ET_FILE_NOT_FOUND)
133 goto cleanup;
134 retval = ext2fs_link(fs, parent, name, ino, EXT2_FT_SYMLINK);
135 if (retval)
136 goto cleanup;
137 }
138
139 /*
140 * Update accounting....
141 */
142 if (!fastlink)
143 ext2fs_block_alloc_stats2(fs, blk, +1);
144 ext2fs_inode_alloc_stats2(fs, ino, +1, 0);
145
146 cleanup:
147 if (block_buf)
148 ext2fs_free_mem(&block_buf);
149 return retval;
150 }
151