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 "config.h" 13 #include <stdio.h> 14 #include <string.h> 15 #if HAVE_UNISTD_H 16 #include <unistd.h> 17 #endif 18 19 #include "ext2_fs.h" 20 #include "ext2fs.h" 21 22 struct link_struct { 23 ext2_filsys fs; 24 const char *name; 25 int namelen; 26 ext2_ino_t inode; 27 int flags; 28 int done; 29 unsigned int blocksize; 30 errcode_t err; 31 struct ext2_super_block *sb; 32 }; 33 34 static int link_proc(struct ext2_dir_entry *dirent, 35 int offset, 36 int blocksize, 37 char *buf, 38 void *priv_data) 39 { 40 struct link_struct *ls = (struct link_struct *) priv_data; 41 struct ext2_dir_entry *next; 42 unsigned int rec_len, min_rec_len, curr_rec_len; 43 int ret = 0; 44 int csum_size = 0; 45 struct ext2_dir_entry_tail *t; 46 47 if (ls->done) 48 return DIRENT_ABORT; 49 50 rec_len = EXT2_DIR_REC_LEN(ls->namelen); 51 52 ls->err = ext2fs_get_rec_len(ls->fs, dirent, &curr_rec_len); 53 if (ls->err) 54 return DIRENT_ABORT; 55 56 if (ext2fs_has_feature_metadata_csum(ls->fs->super)) 57 csum_size = sizeof(struct ext2_dir_entry_tail); 58 /* 59 * See if the following directory entry (if any) is unused; 60 * if so, absorb it into this one. 61 */ 62 next = (struct ext2_dir_entry *) (buf + offset + curr_rec_len); 63 if ((offset + (int) curr_rec_len < blocksize - (8 + csum_size)) && 64 (next->inode == 0) && 65 (offset + (int) curr_rec_len + (int) next->rec_len <= blocksize)) { 66 curr_rec_len += next->rec_len; 67 ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent); 68 if (ls->err) 69 return DIRENT_ABORT; 70 ret = DIRENT_CHANGED; 71 } 72 73 /* 74 * Since ext2fs_link blows away htree data, we need to be 75 * careful -- if metadata_csum is enabled and we're passed in 76 * a dirent that contains htree data, we need to create the 77 * fake entry at the end of the block that hides the checksum. 78 */ 79 80 /* De-convert a dx_node block */ 81 if (csum_size && 82 curr_rec_len == ls->fs->blocksize && 83 !dirent->inode) { 84 curr_rec_len -= csum_size; 85 ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent); 86 if (ls->err) 87 return DIRENT_ABORT; 88 t = EXT2_DIRENT_TAIL(buf, ls->fs->blocksize); 89 ext2fs_initialize_dirent_tail(ls->fs, t); 90 ret = DIRENT_CHANGED; 91 } 92 93 /* De-convert a dx_root block */ 94 if (csum_size && 95 curr_rec_len == ls->fs->blocksize - EXT2_DIR_REC_LEN(1) && 96 offset == EXT2_DIR_REC_LEN(1) && 97 dirent->name[0] == '.' && dirent->name[1] == '.') { 98 curr_rec_len -= csum_size; 99 ls->err = ext2fs_set_rec_len(ls->fs, curr_rec_len, dirent); 100 if (ls->err) 101 return DIRENT_ABORT; 102 t = EXT2_DIRENT_TAIL(buf, ls->fs->blocksize); 103 ext2fs_initialize_dirent_tail(ls->fs, t); 104 ret = DIRENT_CHANGED; 105 } 106 107 /* 108 * If the directory entry is used, see if we can split the 109 * directory entry to make room for the new name. If so, 110 * truncate it and return. 111 */ 112 if (dirent->inode) { 113 min_rec_len = EXT2_DIR_REC_LEN(ext2fs_dirent_name_len(dirent)); 114 if (curr_rec_len < (min_rec_len + rec_len)) 115 return ret; 116 rec_len = curr_rec_len - min_rec_len; 117 ls->err = ext2fs_set_rec_len(ls->fs, min_rec_len, dirent); 118 if (ls->err) 119 return DIRENT_ABORT; 120 next = (struct ext2_dir_entry *) (buf + offset + 121 dirent->rec_len); 122 next->inode = 0; 123 ext2fs_dirent_set_name_len(next, 0); 124 ext2fs_dirent_set_file_type(next, 0); 125 ls->err = ext2fs_set_rec_len(ls->fs, rec_len, next); 126 if (ls->err) 127 return DIRENT_ABORT; 128 return DIRENT_CHANGED; 129 } 130 131 /* 132 * If we get this far, then the directory entry is not used. 133 * See if we can fit the request entry in. If so, do it. 134 */ 135 if (curr_rec_len < rec_len) 136 return ret; 137 dirent->inode = ls->inode; 138 ext2fs_dirent_set_name_len(dirent, ls->namelen); 139 strncpy(dirent->name, ls->name, ls->namelen); 140 if (ext2fs_has_feature_filetype(ls->sb)) 141 ext2fs_dirent_set_file_type(dirent, ls->flags & 0x7); 142 143 ls->done++; 144 return DIRENT_ABORT|DIRENT_CHANGED; 145 } 146 147 /* 148 * Note: the low 3 bits of the flags field are used as the directory 149 * entry filetype. 150 */ 151 #ifdef __TURBOC__ 152 #pragma argsused 153 #endif 154 errcode_t ext2fs_link(ext2_filsys fs, ext2_ino_t dir, const char *name, 155 ext2_ino_t ino, int flags) 156 { 157 errcode_t retval; 158 struct link_struct ls; 159 struct ext2_inode inode; 160 161 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 162 163 if (!(fs->flags & EXT2_FLAG_RW)) 164 return EXT2_ET_RO_FILSYS; 165 166 ls.fs = fs; 167 ls.name = name; 168 ls.namelen = name ? strlen(name) : 0; 169 ls.inode = ino; 170 ls.flags = flags; 171 ls.done = 0; 172 ls.sb = fs->super; 173 ls.blocksize = fs->blocksize; 174 ls.err = 0; 175 176 retval = ext2fs_dir_iterate(fs, dir, DIRENT_FLAG_INCLUDE_EMPTY, 177 0, link_proc, &ls); 178 if (retval) 179 return retval; 180 if (ls.err) 181 return ls.err; 182 183 if (!ls.done) 184 return EXT2_ET_DIR_NO_SPACE; 185 186 if ((retval = ext2fs_read_inode(fs, dir, &inode)) != 0) 187 return retval; 188 189 /* 190 * If this function changes to preserve the htree, remove the 191 * two hunks in link_proc that shove checksum tails into the 192 * former dx_root/dx_node blocks. 193 */ 194 if (inode.i_flags & EXT2_INDEX_FL) { 195 inode.i_flags &= ~EXT2_INDEX_FL; 196 if ((retval = ext2fs_write_inode(fs, dir, &inode)) != 0) 197 return retval; 198 } 199 200 return 0; 201 } 202
