+++ /dev/null
-/*
- * symlink.c
- *
- * Code to read and set symbolic links in WIM files.
- */
-
-/*
- * Copyright (C) 2012, 2013 Eric Biggers
- *
- * This file is part of wimlib, a library for working with WIM files.
- *
- * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free
- * Software Foundation; either version 3 of the License, or (at your option)
- * any later version.
- *
- * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU General Public License for more
- * details.
- *
- * You should have received a copy of the GNU General Public License
- * along with wimlib; if not, see http://www.gnu.org/licenses/.
- */
-
-#include "dentry.h"
-#include "buffer_io.h"
-#include "lookup_table.h"
-#include "sha1.h"
-#include <errno.h>
-
-/* UNIX version of getting and setting the data in reparse points */
-#if !defined(__WIN32__)
-
-#include <sys/stat.h>
-
-#ifdef HAVE_ALLOCA_H
-# include <alloca.h>
-#endif
-
-/*
- * Find the symlink target of a symbolic link or junction point in the WIM.
- *
- * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx for a
- * description of the format of the so-called "reparse point data buffers".
- *
- * But, in the WIM format, the first 8 bytes of the reparse point data buffer
- * are omitted, presumably because we already know the reparse tag from the
- * dentry, and we already know the reparse tag length from the lookup table
- * entry resource length.
- */
-static ssize_t
-get_symlink_name(const void *resource, size_t resource_len, char *buf,
- size_t buf_len, u32 reparse_tag)
-{
- const void *p = resource;
- u16 substitute_name_offset;
- u16 substitute_name_len;
- u16 print_name_offset;
- u16 print_name_len;
- char *link_target;
- char *translated_target;
- size_t link_target_len;
- ssize_t ret;
- unsigned header_size;
- bool translate_slashes;
-
- if (resource_len < 12)
- return -EIO;
- p = get_u16(p, &substitute_name_offset);
- p = get_u16(p, &substitute_name_len);
- p = get_u16(p, &print_name_offset);
- p = get_u16(p, &print_name_len);
-
- wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
- reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
-
- if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT)
- header_size = 8;
- else {
- header_size = 12;
- p += 4;
- }
- if (header_size +
- substitute_name_offset + substitute_name_len > resource_len)
- return -EIO;
-
- ret = utf16le_to_tstr((const utf16lechar*)(p + substitute_name_offset),
- substitute_name_len,
- &link_target, &link_target_len);
- if (ret)
- return -errno;
-
- DEBUG("Interpeting substitute name \"%s\" (ReparseTag=0x%x)",
- link_target, reparse_tag);
- translate_slashes = true;
- translated_target = link_target;
- if (link_target_len >= 7 &&
- translated_target[0] == '\\' &&
- translated_target[1] == '?' &&
- translated_target[2] == '?' &&
- translated_target[3] == '\\' &&
- translated_target[4] != '\0' &&
- translated_target[5] == ':' &&
- translated_target[6] == '\\')
- {
- /* "Full" symlink or junction (\??\x:\ prefixed path) */
- translated_target += 6;
- link_target_len -= 6;
- } else if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT &&
- link_target_len >= 12 &&
- memcmp(translated_target, "\\\\?\\Volume{", 11) == 0 &&
- translated_target[link_target_len - 1] == '\\')
- {
- /* Volume junction. Can't really do anything with it. */
- translate_slashes = false;
- } else if (reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK &&
- link_target_len >= 3 &&
- translated_target[0] != '\0' &&
- translated_target[1] == ':' &&
- translated_target[2] == '\\')
- {
- /* "Absolute" symlink, with drive letter */
- translated_target += 2;
- link_target_len -= 2;
- } else if (reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK &&
- link_target_len >= 1)
- {
- if (translated_target[0] == '\\')
- /* "Absolute" symlink, without drive letter */
- ;
- else
- /* "Relative" symlink, without drive letter */
- ;
- } else {
- ERROR("Invalid reparse point substitute name: \"%s\"", translated_target);
- ret = -EIO;
- goto out;
- }
-
- if (translate_slashes)
- for (size_t i = 0; i < link_target_len; i++)
- if (translated_target[i] == '\\')
- translated_target[i] = '/';
-
- if (link_target_len > buf_len) {
- link_target_len = buf_len;
- ret = -ENAMETOOLONG;
- } else {
- ret = link_target_len;
- }
- memcpy(buf, translated_target, link_target_len);
-out:
- FREE(link_target);
- return ret;
-}
-
-#define SYMBOLIC_LINK_RELATIVE 0x00000001
-
-/* Given a UNIX symlink target, prepare the corresponding symbolic link reparse
- * data buffer. */
-static int
-make_symlink_reparse_data_buf(const char *symlink_target, void *rpdata,
- size_t *rplen_ret)
-{
- int ret;
- utf16lechar *name_utf16le;
- size_t name_utf16le_nbytes;
- size_t substitute_name_nbytes;
- size_t print_name_nbytes;
- static const char abs_subst_name_prefix[12] = "\\\0?\0?\0\\\0C\0:\0";
- static const char abs_print_name_prefix[4] = "C\0:\0";
- u32 flags;
- size_t rplen;
- void *p;
-
- ret = tstr_to_utf16le(symlink_target, strlen(symlink_target),
- &name_utf16le, &name_utf16le_nbytes);
- if (ret)
- return ret;
-
- for (size_t i = 0; i < name_utf16le_nbytes / 2; i++)
- if (name_utf16le[i] == cpu_to_le16('/'))
- name_utf16le[i] = cpu_to_le16('\\');
-
- /* Compatability notes:
- *
- * On UNIX, an absolute symbolic link begins with '/'; everything else
- * is a relative symbolic link. (Quite simple compared to the various
- * ways to provide Windows paths.)
- *
- * To change a UNIX relative symbolic link to Windows format, we only
- * need to translate it to UTF-16LE and replace backslashes with forward
- * slashes. We do not make any attempt to handle filename character
- * problems, such as a link target that itself contains backslashes on
- * UNIX. Then, for these relative links, we set the reparse header
- * @flags field to SYMBOLIC_LINK_RELATIVE.
- *
- * For UNIX absolute symbolic links, we must set the @flags field to 0.
- * Then, there are multiple options as to actually represent the
- * absolute link targets:
- *
- * (1) An absolute path beginning with one backslash character. similar
- * to UNIX-style, just with a different path separator. Print name same
- * as substitute name.
- *
- * (2) Absolute path beginning with drive letter followed by a
- * backslash. Print name same as substitute name.
- *
- * (3) Absolute path beginning with drive letter followed by a
- * backslash; substitute name prefixed with \??\, otherwise same as
- * print name.
- *
- * We choose option (3) here, and we just assume C: for the drive
- * letter. The reasoning for this is:
- *
- * (1) Microsoft imagex.exe has a bug where it does not attempt to do
- * reparse point fixups for these links, even though they are valid
- * absolute links. (Note: in this case prefixing the substitute name
- * with \??\ does not work; it just makes the data unable to be restored
- * at all.)
- * (2) Microsoft imagex.exe will fail when doing reparse point fixups
- * for these. It apparently contains a bug that causes it to create an
- * invalid reparse point, which then cannot be restored.
- * (3) This is the only option I tested for which reparse point fixups
- * worked properly in Microsoft imagex.exe.
- *
- * So option (3) it is.
- */
-
- substitute_name_nbytes = name_utf16le_nbytes;
- print_name_nbytes = name_utf16le_nbytes;
- if (symlink_target[0] == '/') {
- substitute_name_nbytes += sizeof(abs_subst_name_prefix);
- print_name_nbytes += sizeof(abs_print_name_prefix);
- }
-
- rplen = 12 + substitute_name_nbytes + print_name_nbytes +
- 2 * sizeof(utf16lechar);
-
- if (rplen > REPARSE_POINT_MAX_SIZE) {
- ERROR("Symlink \"%s\" is too long!", symlink_target);
- return WIMLIB_ERR_LINK;
- }
-
- p = rpdata;
-
- /* Substitute name offset */
- p = put_u16(p, 0);
-
- /* Substitute name length */
- p = put_u16(p, substitute_name_nbytes);
-
- /* Print name offset */
- p = put_u16(p, substitute_name_nbytes + sizeof(utf16lechar));
-
- /* Print name length */
- p = put_u16(p, print_name_nbytes);
-
- /* Flags */
- flags = 0;
- if (symlink_target[0] != '/')
- flags |= SYMBOLIC_LINK_RELATIVE;
- p = put_u32(p, flags);
-
- /* Substitute name */
- if (symlink_target[0] == '/')
- p = put_bytes(p, sizeof(abs_subst_name_prefix), abs_subst_name_prefix);
- p = put_bytes(p, name_utf16le_nbytes, name_utf16le);
- p = put_u16(p, 0);
-
- /* Print name */
- if (symlink_target[0] == '/')
- p = put_bytes(p, sizeof(abs_print_name_prefix), abs_print_name_prefix);
- p = put_bytes(p, name_utf16le_nbytes, name_utf16le);
- p = put_u16(p, 0);
-
- *rplen_ret = rplen;
- ret = 0;
-out_free_name_utf16le:
- FREE(name_utf16le);
- return ret;
-}
-
-/* Get the symlink target from a WIM inode.
- *
- * The inode may be either a "real" symlink (reparse tag
- * WIM_IO_REPARSE_TAG_SYMLINK), or it may be a junction point (reparse tag
- * WIM_IO_REPARSE_TAG_MOUNT_POINT).
- */
-ssize_t
-inode_readlink(const struct wim_inode *inode, char *buf, size_t buf_len,
- const WIMStruct *w, bool threadsafe)
-{
- const struct wim_lookup_table_entry *lte;
- int ret;
- u8 *res_buf;
-
- wimlib_assert(inode_is_symlink(inode));
-
- lte = inode_unnamed_lte(inode, w->lookup_table);
- if (!lte)
- return -EIO;
-
- if (wim_resource_size(lte) > REPARSE_POINT_MAX_SIZE)
- return -EIO;
-
- res_buf = alloca(wim_resource_size(lte));
- ret = read_full_resource_into_buf(lte, res_buf, threadsafe);
- if (ret)
- return -EIO;
- return get_symlink_name(res_buf, wim_resource_size(lte),
- buf, buf_len, inode->i_reparse_tag);
-}
-
-/*
- * Sets @inode to be a symbolic link pointing to @target.
- *
- * A lookup table entry for the symbolic link data buffer is created and
- * inserted into @lookup_table, unless there is an existing lookup table entry
- * for the exact same data, in which its reference count is incremented.
- *
- * The lookup table entry is returned in @lte_ret.
- *
- * On failure @dentry and @lookup_table are not modified.
- */
-int
-inode_set_symlink(struct wim_inode *inode,
- const char *target,
- struct wim_lookup_table *lookup_table,
- struct wim_lookup_table_entry **lte_ret)
-
-{
- int ret;
-
- /* Buffer for reparse point data */
- u8 rpdata[REPARSE_POINT_MAX_SIZE];
-
- /* Actual length of the reparse point data (to be calculated by
- * make_symlink_reparse_data_buf()) */
- size_t rplen;
-
- DEBUG("Creating reparse point data buffer "
- "for UNIX symlink target \"%s\"", target);
-
- ret = make_symlink_reparse_data_buf(target, rpdata, &rplen);
- if (ret)
- return ret;
-
- ret = inode_set_unnamed_stream(inode, rpdata, rplen, lookup_table);
- if (ret)
- return ret;
-
- if (lte_ret)
- *lte_ret = inode->i_lte;
- return 0;
-}
-
-static int
-unix_get_ino_and_dev(const char *path, u64 *ino_ret, u64 *dev_ret)
-{
- struct stat stbuf;
- if (stat(path, &stbuf)) {
- WARNING_WITH_ERRNO("Failed to stat \"%s\"", path);
- /* Treat as a link pointing outside the capture root (it
- * most likely is). */
- return WIMLIB_ERR_STAT;
- } else {
- *ino_ret = stbuf.st_ino;
- *dev_ret = stbuf.st_dev;
- return 0;
- }
-}
-
-#endif /* !defined(__WIN32__) */
-
-#ifdef __WIN32__
-# include "win32.h"
-# define RP_PATH_SEPARATOR L'\\'
-# define is_rp_path_separator(c) ((c) == L'\\' || (c) == L'/')
-# define os_get_ino_and_dev win32_get_file_and_vol_ids
-#else
-# define RP_PATH_SEPARATOR '/'
-# define is_rp_path_separator(c) ((c) == '/')
-# define os_get_ino_and_dev unix_get_ino_and_dev
-#endif
-
-/* Fix up absolute symbolic link targets--- mostly shared between UNIX and
- * Windows */
-tchar *
-fixup_symlink(tchar *dest, u64 capture_root_ino, u64 capture_root_dev)
-{
- tchar *p = dest;
-
- DEBUG("Fixing symlink or junction \"%"TS"\"", dest);
- for (;;) {
- tchar save;
- int ret;
- u64 ino;
- u64 dev;
-
- while (is_rp_path_separator(*p))
- p++;
-
- save = *p;
- *p = T('\0');
- ret = os_get_ino_and_dev(dest, &ino, &dev);
- *p = save;
-
- if (ret) /* stat() failed before we got to the capture root---
- assume the link points outside it. */
- return NULL;
-
- if (ino == capture_root_ino && dev == capture_root_dev) {
- /* Link points inside capture root. Return abbreviated
- * path. */
- if (*p == T('\0'))
- *(p - 1) = RP_PATH_SEPARATOR;
- while (p - 1 >= dest && is_rp_path_separator(*(p - 1)))
- p--;
- return p;
- }
-
- if (*p == T('\0')) {
- /* Link points outside capture root. */
- return NULL;
- }
-
- do {
- p++;
- } while (!is_rp_path_separator(*p) && *p != T('\0'));
- }
-}
git://wimlib.net / wimlib / blobdiff