From ca8727cf22a445adc20eb1f8b7a12b8eededc32d Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 25 Apr 2013 23:52:58 -0500 Subject: [PATCH 1/1] Win32: Fix, comment capture reparse-point fixups --- src/symlink.c | 14 --------- src/win32.c | 83 ++++++++++++++++++++++++++++++++++++++++----------- 2 files changed, 65 insertions(+), 32 deletions(-) diff --git a/src/symlink.c b/src/symlink.c index 21a564f5..f005cd71 100644 --- a/src/symlink.c +++ b/src/symlink.c @@ -392,12 +392,6 @@ fixup_symlink(tchar *dest, u64 capture_root_ino, u64 capture_root_dev) { tchar *p = dest; -#ifdef __WIN32__ - /* Skip over drive letter */ - if (!is_rp_path_separator(*p)) - p += 2; -#endif - DEBUG("Fixing symlink or junction \"%"TS"\"", dest); for (;;) { tchar save; @@ -424,14 +418,6 @@ fixup_symlink(tchar *dest, u64 capture_root_ino, u64 capture_root_dev) *(p - 1) = RP_PATH_SEPARATOR; while (p - 1 >= dest && is_rp_path_separator(*(p - 1))) p--; - #ifdef __WIN32__ - /* Add back drive letter */ - if (!is_rp_path_separator(*dest)) { - *--p = *(dest + 1); - *--p = *dest; - } - #endif - wimlib_assert(p >= dest); return p; } diff --git a/src/win32.c b/src/win32.c index 0db8c3bf..643832fb 100644 --- a/src/win32.c +++ b/src/win32.c @@ -618,14 +618,47 @@ win32_get_file_and_vol_ids(const wchar_t *path, u64 *ino_ret, u64 *dev_ret) return ret; } +/* Reparse point fixup status code */ enum rp_status { + /* Reparse point corresponded to an absolute symbolic link or junction + * point that pointed outside the directory tree being captured, and + * therefore was excluded. */ RP_EXCLUDED = 0x0, + + /* Reparse point was not fixed as it was either a relative symbolic + * link, a mount point, or something else we could not understand. */ RP_NOT_FIXED = 0x1, + + /* Reparse point corresponded to an absolute symbolic link or junction + * point that pointed inside the directory tree being captured, where + * the target was specified by a "full" \??\ prefixed path, and + * therefore was fixed to be relative to the root of the directory tree + * being captured. */ RP_FIXED_FULLPATH = 0x2, + + /* Same as RP_FIXED_FULLPATH, except the absolute link target did not + * have the \??\ prefix. It may have begun with a drive letter though. + * */ RP_FIXED_ABSPATH = 0x4, + + /* Either RP_FIXED_FULLPATH or RP_FIXED_ABSPATH. */ RP_FIXED = RP_FIXED_FULLPATH | RP_FIXED_ABSPATH, }; +/* Given the "substitute name" target of a Windows reparse point, try doing a + * fixup where we change it to be absolute relative to the root of the directory + * tree being captured. + * + * Note that this is only executed when WIMLIB_ADD_IMAGE_FLAG_RPFIX has been + * set. + * + * @capture_root_ino and @capture_root_dev indicate the inode number and device + * of the root of the directory tree being captured. They are meant to identify + * this directory (as an alternative to its actual path, which could potentially + * be reached via multiple destinations due to other symbolic links). This may + * not work properly on FAT, which doesn't seem to supply proper inode numbers + * or file IDs. However, FAT doesn't support reparse points so this function + * wouldn't even be called anyway. */ static enum rp_status win32_maybe_rpfix_target(wchar_t *target, size_t *target_nchars_p, u64 capture_root_ino, u64 capture_root_dev) @@ -635,11 +668,12 @@ win32_maybe_rpfix_target(wchar_t *target, size_t *target_nchars_p, wchar_t *orig_target; if (target_nchars == 0) + /* Invalid reparse point (empty target) */ return RP_NOT_FIXED; if (target[0] == L'\\') { if (target_nchars >= 2 && target[1] == L'\\') { - /* Probaby a volume. Can't do anything with it. */ + /* Probably a volume. Can't do anything with it. */ DEBUG("Not fixing target (probably a volume)"); return RP_NOT_FIXED; } else if (target_nchars >= 7 && @@ -653,7 +687,7 @@ win32_maybe_rpfix_target(wchar_t *target, size_t *target_nchars_p, DEBUG("Full style path"); /* Full \??\x:\ style path (may be junction or symlink) * */ - stripped_chars = 4; + stripped_chars = 6; } else { DEBUG("Absolute target without drive letter"); /* Absolute target, without drive letter */ @@ -666,7 +700,7 @@ win32_maybe_rpfix_target(wchar_t *target, size_t *target_nchars_p, { DEBUG("Absolute target with drive letter"); /* Absolute target, with drive letter */ - stripped_chars = 0; + stripped_chars = 2; } else { DEBUG("Relative symlink or other link"); /* Relative symlink or other unexpected format */ @@ -675,15 +709,17 @@ win32_maybe_rpfix_target(wchar_t *target, size_t *target_nchars_p, target[target_nchars] = L'\0'; orig_target = target; target = fixup_symlink(target + stripped_chars, capture_root_ino, capture_root_dev); - if (target) { - target_nchars = wcslen(target); - wmemmove(orig_target + stripped_chars, target, target_nchars + 1); - *target_nchars_p = target_nchars + stripped_chars; - DEBUG("Fixed reparse point (new target: \"%ls\")", orig_target); - return stripped_chars ? RP_FIXED_FULLPATH : RP_FIXED_ABSPATH; - } else { + if (!target) return RP_EXCLUDED; - } + + target_nchars = wcslen(target); + wmemmove(orig_target + stripped_chars, target, target_nchars + 1); + *target_nchars_p = target_nchars + stripped_chars; + DEBUG("Fixed reparse point (new target: \"%ls\")", orig_target); + if (stripped_chars == 6) + return RP_FIXED_FULLPATH; + else + return RP_FIXED_ABSPATH; } static enum rp_status @@ -700,21 +736,22 @@ win32_do_capture_rpfix(char *rpbuf, DWORD *rpbuflen_p, u32 rptag; DWORD rpbuflen = *rpbuflen_p; - if (rpbuflen < 16) - return RP_EXCLUDED; + if (rpbuflen < 16) /* Invalid reparse point (length too small) */ + return RP_NOT_FIXED; p_get = get_u32(rpbuf, &rptag); p_get += 4; p_get = get_u16(p_get, &substitute_name_offset); p_get = get_u16(p_get, &substitute_name_len); p_get += 4; - if ((size_t)substitute_name_offset + substitute_name_len > rpbuflen) - return RP_EXCLUDED; if (rptag == WIM_IO_REPARSE_TAG_SYMLINK) { - if (rpbuflen < 20) - return RP_EXCLUDED; + if (rpbuflen < 20) /* Invalid reparse point (length too small) */ + return RP_NOT_FIXED; p_get += 4; } - + if ((DWORD)substitute_name_offset + + substitute_name_len + (p_get - rpbuf) > rpbuflen) + /* Invalid reparse point (length too small) */ + return RP_NOT_FIXED; target = (wchar_t*)&p_get[substitute_name_offset]; target_nchars = substitute_name_len / 2; @@ -729,6 +766,9 @@ win32_do_capture_rpfix(char *rpbuf, DWORD *rpbuflen_p, wchar_t *print_name = target_copy; if (status == RP_FIXED_FULLPATH) { + /* "full path", meaning \??\ prefixed. We should not + * include this prefix in the print name, as it is + * apparently meant for the filesystem driver only. */ print_nbytes -= 8; print_name += 4; } @@ -744,6 +784,9 @@ win32_do_capture_rpfix(char *rpbuf, DWORD *rpbuflen_p, p_put = put_u16(p_put, 0); p_put = put_bytes(p_put, print_nbytes, print_name); p_put = put_u16(p_put, 0); + + /* Wrote the end of the reparse data. Recalculate the length, + * set the length field correctly, and return it. */ rpbuflen = p_put - rpbuf; put_u16(rpbuf + 4, rpbuflen - 8); *rpbuflen_p = rpbuflen; @@ -799,16 +842,20 @@ win32_capture_reparse_point(struct wim_dentry **root_p, (inode->i_reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK || inode->i_reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT)) { + /* Try doing reparse point fixup */ enum rp_status status; status = win32_do_capture_rpfix(reparse_point_buf, &bytesReturned, params->capture_root_ino, params->capture_root_dev); if (status == RP_EXCLUDED) { + /* Absolute path points out of capture tree. Free the + * dentry; we're not including it at all. */ free_dentry(*root_p); *root_p = NULL; return 0; } else if (status & RP_FIXED) { + /* Absolute path fixup was done. */ inode->i_not_rpfixed = 0; } } -- 2.43.0