1 /*
2 * link.c --- create links in a ext2fs directory
3 *
4 * Copyright (C) 1993, 1994 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 */
11
12 #include <stdio.h>
13 #include <string.h>
14 #if HAVE_UNISTD_H
15 #include <unistd.h>
16 #endif
17
18 #include "ext2_fs.h"
19 #include "ext2fs.h"
20
21 struct link_struct {
22 ext2_filsys fs;
23 const char *name;
24 int namelen;
25 ext2_ino_t inode;
26 int flags;
27 int done;
28 unsigned int blocksize;
29 errcode_t err;
30 struct ext2_super_block *sb;
31 };
32
link_proc(struct ext2_dir_entry * dirent,int offset,int blocksize,char * buf,void * priv_data)33 static int link_proc(struct ext2_dir_entry *dirent,
34 int offset,
35 int blocksize,
36 char *buf,
37 void *priv_data)
38 {
39 struct link_struct *ls = (struct link_struct *) priv_data;
40 struct ext2_dir_entry *next;
41 unsigned int rec_len, min_rec_len, curr_rec_len;
42 int ret = 0;
43
44 rec_len = EXT2_DIR_REC_LEN(ls->namelen);
45
46 ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
47 if (ls->err)
48 return DIRENT_ABORT;
49
50 /*
51 * See if the following directory entry (if any) is unused;
52 * if so, absorb it into this one.
53 */
54 next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
55 if ((offset + curr_rec_len < blocksize - 8) &&
56 (next->inode == 0) &&
57 (offset + curr_rec_len + next->rec_len <= blocksize)) {
58 curr_rec_len += next->rec_len;
59 ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
60 if (ls->err)
61 return DIRENT_ABORT;
62 ret = DIRENT_CHANGED;
63 }
64
65 /*
66 * If the directory entry is used, see if we can split the
67 * directory entry to make room for the new name. If so,
68 * truncate it and return.
69 */
70 if (dirent->inode) {
71 min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
72 if (curr_rec_len < (min_rec_len + rec_len))
73 return ret;
74 rec_len = curr_rec_len - min_rec_len;
75 ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
76 if (ls->err)
77 return DIRENT_ABORT;
78 next = (struct ext2_dir_entry *) (buf + offset +
79 dirent->rec_len);
80 next->inode = 0;
81 next->name_len = 0;
82 ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
83 if (ls->err)
84 return DIRENT_ABORT;
85 return DIRENT_CHANGED;
86 }
87
88 /*
89 * If we get this far, then the directory entry is not used.
90 * See if we can fit the request entry in. If so, do it.
91 */
92 if (curr_rec_len < rec_len)
93 return ret;
94 dirent->inode = ls->inode;
95 dirent->name_len = ls->namelen;
96 strncpy(dirent->name, ls->name, ls->namelen);
97 if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
98 dirent->name_len |= (ls->flags & 0x7) << 8;
99
100 ls->done++;
101 return DIRENT_ABORT|DIRENT_CHANGED;
102 }
103
104 /*
105 * Note: the low 3 bits of the flags field are used as the directory
106 * entry filetype.
107 */
108 #ifdef __TURBOC__
109 #pragma argsused
110 #endif
ext2fs_link(ext2_filsys fs,ext2_ino_t dir,const char * name,ext2_ino_t ino,int flags)111 errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
112 ext2_ino_t ino, int flags)
113 {
114 errcode_t retval;
115 struct link_struct ls;
116 struct ext2_inode inode;
117
118 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
119
120 if (!(fs->flags & EXT2_FLAG_RW))
121 return EXT2_ET_RO_FILSYS;
122
123 ls.fs = fs;
124 ls.name = name;
125 ls.namelen = name ? strlen(name) : 0;
126 ls.inode = ino;
127 ls.flags = flags;
128 ls.done = 0;
129 ls.sb = fs->super;
130 ls.blocksize = fs->blocksize;
131 ls.err = 0;
132
133 retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
134 0, link_proc, &ls);
135 if (retval)
136 return retval;
137 if (ls.err)
138 return ls.err;
139
140 if (!ls.done)
141 return EXT2_ET_DIR_NO_SPACE;
142
143 if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
144 return retval;
145
146 if (inode.i_flags & EXT2_INDEX_FL) {
147 inode.i_flags &= ~EXT2_INDEX_FL;
148 if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
149 return retval;
150 }
151
152 return 0;
153 }
154