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* path.h (path_conv::fs_type): New method.

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* syscalls.cc (rename): Check for cross-device situation before
	touching anything.  Explain why.  Workaround NFS bug in call to
	NtSetInformationFile(FileRenameInformation).
This commit is contained in:
Corinna Vinschen
2013-01-10 15:08:22 +00:00
parent 211f1ec717
commit 34ce80888a
3 changed files with 74 additions and 8 deletions
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7
winsup/cygwin/ChangeLog
View File

@@ -1,3 +1,10 @@
2013-01-10 Corinna Vinschen <corinna@vinschen.de>
* path.h (path_conv::fs_type): New method.
* syscalls.cc (rename): Check for cross-device situation before
touching anything. Explain why. Workaround NFS bug in call to
NtSetInformationFile(FileRenameInformation).
2013-01-09 Corinna Vinschen <corinna@vinschen.de>
* cygerrno.h: Fix copyright.

1
winsup/cygwin/path.h
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@@ -362,6 +362,7 @@ class path_conv
bool fs_is_cifs () const {return fs.is_cifs ();}
bool fs_is_nwfs () const {return fs.is_nwfs ();}
bool fs_is_ncfsd () const {return fs.is_ncfsd ();}
fs_info_type fs_type () const {return fs.what_fs ();}
ULONG fs_serial_number () const {return fs.serial_number ();}
inline const char *set_path (const char *p)
{

74
winsup/cygwin/syscalls.cc
View File

@@ -2297,6 +2297,15 @@ rename (const char *oldpath, const char *newpath)
}
dstpc = (removepc == &newpc) ? &new2pc : &newpc;
/* Check cross-device before touching anything. Otherwise we might end
up with an unlinked target dir even if the actual rename didn't work. */
if (oldpc.fs_type () != dstpc->fs_type ()
|| oldpc.fs_serial_number () != dstpc->fs_serial_number ())
{
set_errno (EXDEV);
goto out;
}
/* Opening the file must be part of the transaction. It's not sufficient
to call only NtSetInformationFile under the transaction. Therefore we
have to start the transaction here, if necessary. */
@@ -2431,17 +2440,66 @@ retry:
}
NtClose (nfh);
}
size = sizeof (FILE_RENAME_INFORMATION)
+ dstpc->get_nt_native_path ()->Length;
if (size > NT_MAX_PATH * sizeof (WCHAR)) /* Hopefully very seldom. */
pfri = (PFILE_RENAME_INFORMATION) alloca (size);
if (oldpc.fs_is_nfs ())
{
/* Workaround depressing NFS bug. FILE_RENAME_INFORMATION.FileName
*must* be relative to the parent directory of the original file,
otherwise NtSetInformationFile returns with STATUS_NOT_SAME_DEVICE.
Neither absolute paths, nor directory handle relative paths work
as expected! */
PWCHAR oldp, dstp;
/* Skip equivalent path prefix. We already know that both paths are
on the same drive anyway. */
for (oldp = oldpc.get_nt_native_path ()->Buffer,
dstp = dstpc->get_nt_native_path ()->Buffer;
*oldp == *dstp; ++oldp, ++dstp)
;
while (oldp[-1] != L'\\')
--oldp, --dstp;
/* Now oldp points to the first path component in oldpc different from
dstpc, vice versa for dstp and oldpc. To create a dstpc path relative
to oldpc, we now have to prepend as many ".." components to dstp, as
are still available in oldp. Example:
oldpc = \??\UNC\server\a\b\c\d\e
dstpc = \??\UNC\server\a\b\f\g
prefix: \??\UNC\server\a\b\
oldp: c\d\e
dstp: f\g
dstp expressed relative to e's parent dir: ..\..\f\g
So what we do here is to count the number of backslashes in oldp and
prepend one "..\" to dstp for each of them. */
PWCHAR newdst = tp.w_get ();
PWCHAR newp = newdst;
while ((oldp = wcschr (++oldp, L'\\')) != NULL)
newp = wcpcpy (newp, L"..\\");
newp = wcpcpy (newp, dstp);
size = sizeof (FILE_RENAME_INFORMATION)
+ (newp - newdst) * sizeof (WCHAR);
if (size > NT_MAX_PATH * sizeof (WCHAR)) /* Hopefully very seldom. */
pfri = (PFILE_RENAME_INFORMATION) alloca (size);
else
pfri = (PFILE_RENAME_INFORMATION) tp.w_get ();
pfri->FileNameLength = (newp - newdst) * sizeof (WCHAR);
memcpy (&pfri->FileName, newdst, pfri->FileNameLength);
}
else
pfri = (PFILE_RENAME_INFORMATION) tp.w_get ();
{
size = sizeof (FILE_RENAME_INFORMATION)
+ dstpc->get_nt_native_path ()->Length;
if (size > NT_MAX_PATH * sizeof (WCHAR)) /* Hopefully very seldom. */
pfri = (PFILE_RENAME_INFORMATION) alloca (size);
else
pfri = (PFILE_RENAME_INFORMATION) tp.w_get ();
pfri->FileNameLength = dstpc->get_nt_native_path ()->Length;
memcpy (&pfri->FileName, dstpc->get_nt_native_path ()->Buffer,
pfri->FileNameLength);
}
pfri->ReplaceIfExists = TRUE;
pfri->RootDirectory = NULL;
pfri->FileNameLength = dstpc->get_nt_native_path ()->Length;
memcpy (&pfri->FileName, dstpc->get_nt_native_path ()->Buffer,
pfri->FileNameLength);
status = NtSetInformationFile (fh, &io, pfri, size, FileRenameInformation);
/* This happens if the access rights don't allow deleting the destination.
Even if the handle to the original file is opened with BACKUP