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