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 Library
8 * General Public License, version 2.
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 if (ls->done)
45 return DIRENT_ABORT;
46
47 rec_len = EXT2_DIR_REC_LEN(ls->namelen);
48
49 ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len);
50 if (ls->err)
51 return DIRENT_ABORT;
52
53 /*
54 * See if the following directory entry (if any) is unused;
55 * if so, absorb it into this one.
56 */
57 next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len);
58 if ((offset + (int) curr_rec_len < blocksize - 8) &&
59 (next->inode == 0) &&
60 (offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) {
61 curr_rec_len += next->rec_len;
62 ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent);
63 if (ls->err)
64 return DIRENT_ABORT;
65 ret = DIRENT_CHANGED;
66 }
67
68 /*
69 * If the directory entry is used, see if we can split the
70 * directory entry to make room for the new name. If so,
71 * truncate it and return.
72 */
73 if (dirent->inode) {
74 min_rec_len = EXT2_DIR_REC_LEN(dirent->name_len & 0xFF);
75 if (curr_rec_len < (min_rec_len + rec_len))
76 return ret;
77 rec_len = curr_rec_len - min_rec_len;
78 ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent);
79 if (ls->err)
80 return DIRENT_ABORT;
81 next = (struct ext2_dir_entry *) (buf + offset +
82 dirent->rec_len);
83 next->inode = 0;
84 next->name_len = 0;
85 ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next);
86 if (ls->err)
87 return DIRENT_ABORT;
88 return DIRENT_CHANGED;
89 }
90
91 /*
92 * If we get this far, then the directory entry is not used.
93 * See if we can fit the request entry in. If so, do it.
94 */
95 if (curr_rec_len < rec_len)
96 return ret;
97 dirent->inode = ls->inode;
98 dirent->name_len = ls->namelen;
99 strncpy(dirent->name, ls->name, ls->namelen);
100 if (ls->sb->s_feature_incompat & EXT2_FEATURE_INCOMPAT_FILETYPE)
101 dirent->name_len |= (ls->flags & 0x7) << 8;
102
103 ls->done++;
104 return DIRENT_ABORT|DIRENT_CHANGED;
105 }
106
107 /*
108 * Note: the low 3 bits of the flags field are used as the directory
109 * entry filetype.
110 */
111 #ifdef __TURBOC__
112 #pragma argsused
113 #endif
ext2fs_link(ext2_filsys fs,ext2_ino_t dir,const char * name,ext2_ino_t ino,int flags)114 errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name,
115 ext2_ino_t ino, int flags)
116 {
117 errcode_t retval;
118 struct link_struct ls;
119 struct ext2_inode inode;
120
121 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
122
123 if (!(fs->flags & EXT2_FLAG_RW))
124 return EXT2_ET_RO_FILSYS;
125
126 ls.fs = fs;
127 ls.name = name;
128 ls.namelen = name ? strlen(name) : 0;
129 ls.inode = ino;
130 ls.flags = flags;
131 ls.done = 0;
132 ls.sb = fs->super;
133 ls.blocksize = fs->blocksize;
134 ls.err = 0;
135
136 retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY,
137 0, link_proc, &ls);
138 if (retval)
139 return retval;
140 if (ls.err)
141 return ls.err;
142
143 if (!ls.done)
144 return EXT2_ET_DIR_NO_SPACE;
145
146 if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0)
147 return retval;
148
149 if (inode.i_flags & EXT2_INDEX_FL) {
150 inode.i_flags &= ~EXT2_INDEX_FL;
151 if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0)
152 return retval;
153 }
154
155 return 0;
156 }
157