public inbox for cygwin-cvs@sourceware.org
help / color / mirror / Atom feed
* [newlib-cygwin] Cygwin: path handling: never substitute virtual drive with target path
@ 2022-12-12 20:59 Corinna Vinschen
0 siblings, 0 replies; only message in thread
From: Corinna Vinschen @ 2022-12-12 20:59 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5ba5e09b9d39feaedc9be0dcd88d085b256c5d40
commit 5ba5e09b9d39feaedc9be0dcd88d085b256c5d40
Author: Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Mon Dec 12 21:56:14 2022 +0100
Commit: Corinna Vinschen <corinna@vinschen.de>
CommitDate: Mon Dec 12 21:56:14 2022 +0100
Cygwin: path handling: never substitute virtual drive with target path
Move the drive substitution code after the call to
GetFinalPathNameByHandleW into a local function revert_virtual_drive
and add code to handle non-remote virtual drives, i. e., those
created with the subst command. (Try to) make sure that virtual
drives are never treated like symlinks.
Fixes: 19d59ce75d53 ("Cygwin: path_conv: Rework handling native symlinks as inner path components")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Diff:
---
winsup/cygwin/path.cc | 149 +++++++++++++++++++++++++++++---------------------
1 file changed, 87 insertions(+), 62 deletions(-)
diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index e7619270a269..c044d5295ed5 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -3024,6 +3024,65 @@ symlink_info::parse_device (const char *contents)
return isdevice = true;
}
+/* Probably we have a virtual drive input path and the resulting full path
+ starts with the substitution. Retrieve the target path of the virtual
+ drive and try to revert what GetFinalPathNameByHandleW did to the
+ drive letter. */
+static bool
+revert_virtual_drive (PUNICODE_STRING upath, PUNICODE_STRING fpath,
+ bool is_remote, ULONG ci_flag)
+{
+ /* Get the drive's target path. */
+ WCHAR drive[3] = {(WCHAR) towupper (upath->Buffer[4]), L':', L'\0'};
+ WCHAR target[MAX_PATH];
+ UNICODE_STRING tpath;
+ WCHAR *p;
+
+ DWORD remlen = QueryDosDeviceW (drive, target, MAX_PATH);
+ if (remlen < 3)
+ return false;
+ remlen -= 2; /* Two L'\0' */
+
+ if (target[remlen - 1] == L'\\')
+ remlen--;
+ RtlInitCountedUnicodeString (&tpath, target, remlen * sizeof (WCHAR));
+
+ const USHORT uncp_len = is_remote ? ro_u_uncp.Length / sizeof (WCHAR) - 1 : 0;
+
+ if (is_remote)
+ {
+ /* target path starts with \??\UNC\. */
+ if (RtlEqualUnicodePathPrefix (&tpath, &ro_u_uncp, TRUE))
+ {
+ remlen -= uncp_len;
+ p = target + uncp_len;
+ }
+ /* target path starts with \Device\<redirector>. */
+ else if ((p = wcschr (target, L';'))
+ && p + 3 < target + remlen
+ && wcsncmp (p + 1, drive, 2) == 0
+ && (p = wcschr (p + 3, L'\\')))
+ remlen -= p - target;
+ else
+ return false;
+ if (wcsncasecmp (fpath->Buffer + uncp_len, p, remlen))
+ return false;
+ }
+ else if (!RtlEqualUnicodePathPrefix (fpath, &tpath, TRUE))
+ return false;
+ /* Replace fpath with source drive letter and append reminder of
+ final path after skipping target path */
+ fpath->Buffer[4] = drive[0]; /* Drive letter */
+ fpath->Buffer[5] = L':';
+ WCHAR *to = fpath->Buffer + 6; /* Next to L':' */
+ WCHAR *from = fpath->Buffer + uncp_len + remlen;
+ memmove (to, from, (wcslen (from) + 1) * sizeof (WCHAR));
+ fpath->Length -= (from - to) * sizeof (WCHAR);
+ if (RtlEqualUnicodeString (upath, fpath, !!ci_flag))
+ return false;
+ return true;
+}
+
/* Check if PATH is a symlink. PATH must be a valid Win32 path name.
If PATH is a symlink, put the value of the symlink--the file to
@@ -3343,6 +3402,14 @@ restart:
continue;
}
+ /* Consider the situation where a virtual drive points to a native
+ symlink. Opening the virtual drive with FILE_OPEN_REPARSE_POINT
+ actually opens the symlink. If this symlink points to another
+ directory using a relative path, symlink evaluation goes totally
+ awry. We never want a virtual drive evaluated as symlink. */
+ if (upath.Length <= 14)
+ goto file_not_symlink;
+
/* Reparse points are potentially symlinks. This check must be
performed before checking the SYSTEM attribute for sysfile
symlinks, since reparse points can have this flag set, too. */
@@ -3490,80 +3557,38 @@ restart:
RtlInitCountedUnicodeString (&fpath, fpbuf, ret * sizeof (WCHAR));
if (!RtlEqualUnicodeString (&upath, &fpath, !!ci_flag))
{
- /* Check if the final path is an UNC path and the incoming
- path isn't. If so... */
- if (RtlEqualUnicodePathPrefix (&fpath, &ro_u_uncp, TRUE)
- && !RtlEqualUnicodePathPrefix (&upath, &ro_u_uncp, TRUE))
+ /* If the incoming path is a local drive letter path... */
+ if (!RtlEqualUnicodePathPrefix (&upath, &ro_u_uncp, TRUE))
{
- /* ...get the remote path, replace remote path
- with drive letter, check again. */
- WCHAR drive[3] =
- {(WCHAR) towupper (upath.Buffer[4]), L':', L'\0'};
- WCHAR remote[MAX_PATH];
-
- DWORD remlen = QueryDosDeviceW (drive, remote, MAX_PATH);
- if (remlen < 3)
- goto file_not_symlink; /* fallback */
- remlen -= 2; /* Two L'\0' */
-
- if (remote[remlen - 1] == L'\\')
- remlen--;
- WCHAR *p;
- UNICODE_STRING rpath;
- RtlInitCountedUnicodeString (&rpath, remote,
- remlen * sizeof (WCHAR));
- const USHORT uncp_len =
- ro_u_uncp.Length / sizeof (WCHAR) - 1;
- if (RtlEqualUnicodePathPrefix (&rpath, &ro_u_uncp, TRUE))
+ /* ...and the final path is an UNC path, revert to the
+ drive letter path syntax. */
+ if (RtlEqualUnicodePathPrefix (&fpath, &ro_u_uncp, TRUE))
+ {
+ if (!revert_virtual_drive (&upath, &fpath, true,
+ ci_flag))
+ goto file_not_symlink;
+ }
+ /* ...otherwise, if the final path changes the drive
+ letter, let revert_virtual_drive check for a
+ virtual drive and revert that. */
+ else if (upath.Buffer[5] == L':'
+ && (WCHAR) towupper (upath.Buffer[4])
+ != (WCHAR) towupper (fpath.Buffer[4]))
{
- remlen -= uncp_len;
- p = remote + uncp_len;
+ if (!revert_virtual_drive (&upath, &fpath, false,
+ ci_flag))
+ goto file_not_symlink;
}
- else if ((p = wcschr (remote, L';'))
- && p + 3 < remote + remlen
- && wcsncmp (p + 1, drive, 2) == 0
- && (p = wcschr (p + 3, L'\\')))
- remlen -= p - remote;
- else
- goto file_not_symlink; /* fallback */
- if (wcsncasecmp (fpath.Buffer + uncp_len, p, remlen))
- goto file_not_symlink; /* fallback (not expected) */
- /* Hackfest */
- fpath.Buffer[4] = drive[0]; /* Drive letter */
- fpath.Buffer[5] = L':';
- WCHAR *to = fpath.Buffer + 6; /* Next to L':' */
- WCHAR *from = fpath.Buffer + uncp_len + remlen;
- memmove (to, from,
- (wcslen (from) + 1) * sizeof (WCHAR));
- fpath.Length -= (from - to) * sizeof (WCHAR);
- if (RtlEqualUnicodeString (&upath, &fpath, !!ci_flag))
- goto file_not_symlink;
}
issymlink = true;
/* upath.Buffer is big enough and unused from this point on.
Reuse it here, avoiding yet another buffer allocation. */
char *nfpath = (char *) upath.Buffer;
sys_wcstombs (nfpath, NT_MAX_PATH, fpbuf);
- res = posixify (nfpath);
-
- /* If the incoming path consisted of a drive prefix only,
- we just handle a virtual drive, created with, e.g.
-
- subst X: C:\foo\bar
-
- Treat it like a symlink. This is required to tell an
- lstat caller that the "drive" is actually pointing
- somewhere else, thus, it's a symlink in POSIX speak. */
- if (upath.Length == 14) /* \??\X:\ */
- {
- fileattr &= ~FILE_ATTRIBUTE_DIRECTORY;
- path_flags |= PATH_SYMLINK;
- }
/* For final paths differing in inner path components return
length as negative value. This informs path_conv::check
to skip realpath handling on the last path component. */
- else
- res = -res;
+ res = -posixify (nfpath);
break;
}
}
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2022-12-12 20:59 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-12-12 20:59 [newlib-cygwin] Cygwin: path handling: never substitute virtual drive with target path Corinna Vinschen
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).