1 /* 2 * namei.c --- ext2fs directory lookup operations 3 * 4 * Copyright (C) 1993, 1994, 1994, 1995 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 /* #define NAMEI_DEBUG */ 20 21 #include "ext2_fs.h" 22 #include "ext2fs.h" 23 #include "ext2fsP.h" 24 25 static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base, 26 const char *pathname, size_t pathlen, int follow, 27 int link_count, char *buf, ext2_ino_t *res_inode); 28 29 static errcode_t follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir, 30 ext2_ino_t inode, int link_count, 31 char *buf, ext2_ino_t *res_inode) 32 { 33 char *pathname; 34 char *buffer = 0; 35 errcode_t retval; 36 struct ext2_inode ei; 37 blk64_t blk; 38 39 #ifdef NAMEI_DEBUG 40 printf("follow_link: root=%lu, dir=%lu, inode=%lu, lc=%d\n", 41 root, dir, inode, link_count); 42 43 #endif 44 retval = ext2fs_read_inode (fs, inode, &ei); 45 if (retval) return retval; 46 if (!LINUX_S_ISLNK (ei.i_mode)) { 47 *res_inode = inode; 48 return 0; 49 } 50 if (link_count++ >= EXT2FS_MAX_NESTED_LINKS) 51 return EXT2_ET_SYMLINK_LOOP; 52 53 if (ext2fs_is_fast_symlink(&ei)) 54 pathname = (char *)&(ei.i_block[0]); 55 else if (ei.i_flags & EXT4_INLINE_DATA_FL) { 56 retval = ext2fs_get_memzero(ei.i_size, &buffer); 57 if (retval) 58 return retval; 59 60 retval = ext2fs_inline_data_get(fs, inode, 61 &ei, buffer, NULL); 62 if (retval) { 63 ext2fs_free_mem(&buffer); 64 return retval; 65 } 66 pathname = buffer; 67 } else { 68 retval = ext2fs_bmap2(fs, inode, &ei, NULL, 0, 0, NULL, &blk); 69 if (retval) 70 return retval; 71 72 retval = ext2fs_get_mem(fs->blocksize, &buffer); 73 if (retval) 74 return retval; 75 76 retval = io_channel_read_blk64(fs->io, blk, 1, buffer); 77 if (retval) { 78 ext2fs_free_mem(&buffer); 79 return retval; 80 } 81 pathname = buffer; 82 } 83 84 retval = open_namei(fs, root, dir, pathname, ei.i_size, 1, 85 link_count, buf, res_inode); 86 if (buffer) 87 ext2fs_free_mem(&buffer); 88 return retval; 89 } 90 91 /* 92 * This routine interprets a pathname in the context of the current 93 * directory and the root directory, and returns the inode of the 94 * containing directory, and a pointer to the filename of the file 95 * (pointing into the pathname) and the length of the filename. 96 */ 97 static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir, 98 const char *pathname, int pathlen, 99 int link_count, char *buf, 100 const char **name, int *namelen, 101 ext2_ino_t *res_inode) 102 { 103 char c; 104 const char *thisname; 105 int len; 106 ext2_ino_t inode; 107 errcode_t retval; 108 109 if ((c = *pathname) == '/') { 110 dir = root; 111 pathname++; 112 pathlen--; 113 } 114 while (1) { 115 thisname = pathname; 116 for (len=0; --pathlen >= 0;len++) { 117 c = *(pathname++); 118 if (c == '/') 119 break; 120 } 121 if (pathlen < 0) 122 break; 123 retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode); 124 if (retval) return retval; 125 retval = follow_link (fs, root, dir, inode, 126 link_count, buf, &dir); 127 if (retval) return retval; 128 } 129 *name = thisname; 130 *namelen = len; 131 *res_inode = dir; 132 return 0; 133 } 134 135 static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base, 136 const char *pathname, size_t pathlen, int follow, 137 int link_count, char *buf, ext2_ino_t *res_inode) 138 { 139 const char *base_name; 140 int namelen; 141 ext2_ino_t dir, inode; 142 errcode_t retval; 143 144 #ifdef NAMEI_DEBUG 145 printf("open_namei: root=%lu, dir=%lu, path=%.*s, lc=%d\n", 146 root, base, pathlen, pathname, link_count); 147 #endif 148 retval = dir_namei(fs, root, base, pathname, pathlen, 149 link_count, buf, &base_name, &namelen, &dir); 150 if (retval) return retval; 151 if (!namelen) { /* special case: '/usr/' etc */ 152 *res_inode=dir; 153 return 0; 154 } 155 retval = ext2fs_lookup (fs, dir, base_name, namelen, buf, &inode); 156 if (retval) 157 return retval; 158 if (follow) { 159 retval = follow_link(fs, root, dir, inode, link_count, 160 buf, &inode); 161 if (retval) 162 return retval; 163 } 164 #ifdef NAMEI_DEBUG 165 printf("open_namei: (link_count=%d) returns %lu\n", 166 link_count, inode); 167 #endif 168 *res_inode = inode; 169 return 0; 170 } 171 172 errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd, 173 const char *name, ext2_ino_t *inode) 174 { 175 char *buf; 176 errcode_t retval; 177 178 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 179 180 retval = ext2fs_get_mem(fs->blocksize, &buf); 181 if (retval) 182 return retval; 183 184 retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0, 185 buf, inode); 186 187 ext2fs_free_mem(&buf); 188 return retval; 189 } 190 191 errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd, 192 const char *name, ext2_ino_t *inode) 193 { 194 char *buf; 195 errcode_t retval; 196 197 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 198 199 retval = ext2fs_get_mem(fs->blocksize, &buf); 200 if (retval) 201 return retval; 202 203 retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0, 204 buf, inode); 205 206 ext2fs_free_mem(&buf); 207 return retval; 208 } 209 210 errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd, 211 ext2_ino_t inode, ext2_ino_t *res_inode) 212 { 213 char *buf; 214 errcode_t retval; 215 216 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); 217 218 retval = ext2fs_get_mem(fs->blocksize, &buf); 219 if (retval) 220 return retval; 221 222 retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode); 223 224 ext2fs_free_mem(&buf); 225 return retval; 226 } 227