/* vi: set sw=4 ts=4: */ /* * namei.c --- ext2fs directory lookup operations * * Copyright (C) 1993, 1994, 1994, 1995 Theodore Ts'o. * * %Begin-Header% * This file may be redistributed under the terms of the GNU Public * License. * %End-Header% */ #include <stdio.h> #include <string.h> #if HAVE_UNISTD_H #include <unistd.h> #endif /* #define NAMEI_DEBUG */ #include "ext2_fs.h" #include "ext2fs.h" static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base, const char *pathname, size_t pathlen, int follow, int link_count, char *buf, ext2_ino_t *res_inode); static errcode_t follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir, ext2_ino_t inode, int link_count, char *buf, ext2_ino_t *res_inode) { char *pathname; char *buffer = 0; errcode_t retval; struct ext2_inode ei; #ifdef NAMEI_DEBUG printf("follow_link: root=%lu, dir=%lu, inode=%lu, lc=%d\n", root, dir, inode, link_count); #endif retval = ext2fs_read_inode (fs, inode, &ei); if (retval) return retval; if (!LINUX_S_ISLNK (ei.i_mode)) { *res_inode = inode; return 0; } if (link_count++ > 5) { return EXT2_ET_SYMLINK_LOOP; } if (ext2fs_inode_data_blocks(fs,&ei)) { retval = ext2fs_get_mem(fs->blocksize, &buffer); if (retval) return retval; retval = io_channel_read_blk(fs->io, ei.i_block[0], 1, buffer); if (retval) { ext2fs_free_mem(&buffer); return retval; } pathname = buffer; } else pathname = (char *)&(ei.i_block[0]); retval = open_namei(fs, root, dir, pathname, ei.i_size, 1, link_count, buf, res_inode); ext2fs_free_mem(&buffer); return retval; } /* * This routine interprets a pathname in the context of the current * directory and the root directory, and returns the inode of the * containing directory, and a pointer to the filename of the file * (pointing into the pathname) and the length of the filename. */ static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir, const char *pathname, int pathlen, int link_count, char *buf, const char **name, int *namelen, ext2_ino_t *res_inode) { char c; const char *thisname; int len; ext2_ino_t inode; errcode_t retval; if ((c = *pathname) == '/') { dir = root; pathname++; pathlen--; } while (1) { thisname = pathname; for (len=0; --pathlen >= 0;len++) { c = *(pathname++); if (c == '/') break; } if (pathlen < 0) break; retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode); if (retval) return retval; retval = follow_link (fs, root, dir, inode, link_count, buf, &dir); if (retval) return retval; } *name = thisname; *namelen = len; *res_inode = dir; return 0; } static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base, const char *pathname, size_t pathlen, int follow, int link_count, char *buf, ext2_ino_t *res_inode) { const char *basename; int namelen; ext2_ino_t dir, inode; errcode_t retval; #ifdef NAMEI_DEBUG printf("open_namei: root=%lu, dir=%lu, path=%*s, lc=%d\n", root, base, pathlen, pathname, link_count); #endif retval = dir_namei(fs, root, base, pathname, pathlen, link_count, buf, &basename, &namelen, &dir); if (retval) return retval; if (!namelen) { /* special case: '/usr/' etc */ *res_inode=dir; return 0; } retval = ext2fs_lookup (fs, dir, basename, namelen, buf, &inode); if (retval) return retval; if (follow) { retval = follow_link(fs, root, dir, inode, link_count, buf, &inode); if (retval) return retval; } #ifdef NAMEI_DEBUG printf("open_namei: (link_count=%d) returns %lu\n", link_count, inode); #endif *res_inode = inode; return 0; } errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd, const char *name, ext2_ino_t *inode) { char *buf; errcode_t retval; EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); retval = ext2fs_get_mem(fs->blocksize, &buf); if (retval) return retval; retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0, buf, inode); ext2fs_free_mem(&buf); return retval; } errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd, const char *name, ext2_ino_t *inode) { char *buf; errcode_t retval; EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); retval = ext2fs_get_mem(fs->blocksize, &buf); if (retval) return retval; retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0, buf, inode); ext2fs_free_mem(&buf); return retval; } errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd, ext2_ino_t inode, ext2_ino_t *res_inode) { char *buf; errcode_t retval; EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS); retval = ext2fs_get_mem(fs->blocksize, &buf); if (retval) return retval; retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode); ext2fs_free_mem(&buf); return retval; }