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Cygwin: try_to_bin: don't check recycler filename all the time 

So far we check the recycler name all the time, and the last interation
also only managed to handle two ways to write the recycler.  However,
an adventurous user might change the case of the recycler arbitrarily.

Fix this problem by keeping track of the name in a somewhat relaxed
fashion.  Use camel back on drive C by default, all upper case elsewhere.
Only if the rename op fails do we fix the recycler name on the fly
when trying to create it, and it turns out it already existed.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2019-01-09 21:14:58 +01:00
parent b7a6d357ee
commit fbd3835384
1 changed files with 38 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
winsup/cygwin/syscalls.cc
View File

@ -195,6 +195,14 @@ enum bin_status
dir_not_empty
};
/* Typically the recycler on drive C has been created at installation
time. The name is then written in camel back. On any other drive,
the recycler is created on first usage. shell32.dll then creates
the recycler in all upper case. That's only important if the entire
operation is running case sensitive. */
static WCHAR recycler_basename_drive_c[] = L"\\$Recycle.Bin\\";
static WCHAR recycler_basename_other[] = L"\\$RECYCLE.BIN\\";
static bin_status
try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
{
@ -205,6 +213,7 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
HANDLE rootdir = NULL, recyclerdir = NULL, tmp_fh = NULL;
USHORT recycler_base_len = 0, recycler_user_len = 0;
UNICODE_STRING root, recycler, fname;
PWCHAR recycler_basename = NULL;
WCHAR recyclerbuf[NAME_MAX + 1]; /* Enough for recycler + SID + filename */
PFILE_NAME_INFORMATION pfni;
PFILE_INTERNAL_INFORMATION pfii;
@ -217,7 +226,8 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
PBYTE infobuf = (PBYTE) tp.w_get ();
pfni = (PFILE_NAME_INFORMATION) infobuf;
status = NtQueryInformationFile (fh, &io, pfni, 65536, FileNameInformation);
status = NtQueryInformationFile (fh, &io, pfni, NT_MAX_PATH * sizeof (WCHAR),
FileNameInformation);
if (!NT_SUCCESS (status))
{
debug_printf ("NtQueryInformationFile (%S, FileNameInformation) "
@ -236,7 +246,11 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
RtlInitEmptyUnicodeString (&recycler, recyclerbuf, sizeof recyclerbuf);
if (!pc.isremote ())
{
RtlAppendUnicodeToString (&recycler, L"\\$Recycle.Bin\\");
recycler_basename = wcsncmp (pc.get_nt_native_path ()->Buffer,
L"\\??\\C:\\", 7)
? recycler_basename_other
: recycler_basename_drive_c;
RtlAppendUnicodeToString (&recycler, recycler_basename);
RtlInitCountedUnicodeString(&fname, pfni->FileName, pfni->FileNameLength);
/* Is the file a subdir of the recycler? */
if (RtlEqualUnicodePathPrefix (&fname, &recycler, TRUE))
@ -287,36 +301,6 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
recycler.Length -= sizeof (WCHAR);
/* Store length of recycler base dir, if it's necessary to create it. */
recycler_base_len = recycler.Length;
/* The recycler name is $Recycler.Bin by default. If the recycler dir
disappears for some reason, shell32.dll recreates it in all upper
case. So we never know if the dir is written in camel back or in
upper case. That's a problem when using casesensitivity: If the
file handle given to FileRenameInformation has been opened
casesensitive, the call also handles the path to the target dir
casesensitive. Check for the right name here.
Note that, originally, we reopened the file case insensitive instead.
But that's a problem for O_TMPFILE on pre-W10. As soon as the
original HANDLE gets closed, delete-on-close is converted to full
delete disposition and all useful operations on the file cease to
work (STATUS_ACCESS_DENIED or STATUS_FILE_DELETED). */
if (!pc.objcaseinsensitive ())
{
PFILE_BASIC_INFORMATION pfbi;
InitializeObjectAttributes (&attr, &recycler, 0, rootdir, NULL);
pfbi = (PFILE_BASIC_INFORMATION) infobuf;
status = NtQueryAttributesFile (&attr, pfbi);
if (status == STATUS_OBJECT_NAME_NOT_FOUND)
{
wcscpy (recycler.Buffer, L"$RECYCLE.BIN\\");
status = NtQueryAttributesFile (&attr, pfbi);
/* Keep the uppercase name if it exists, otherwise revert to
camel back to create a nicer name than shell32.dll. */
if (status == STATUS_OBJECT_NAME_NOT_FOUND)
wcscpy (recycler.Buffer, L"$Recycle.Bin\\");
}
}
/* On NTFS or ReFS the recycler dir contains user specific subdirs, which
are the actual recycle bins per user. The name of this dir is the
string representation of the user SID. */
@ -376,7 +360,8 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
status = NtSetInformationFile (fh, &io, pfri, frisiz, FileRenameInformation);
if (status == STATUS_OBJECT_PATH_NOT_FOUND && !pc.isremote ())
{
/* Ok, so the recycler and/or the recycler/SID directory don't exist.
/* The recycler and/or the recycler/SID directory don't exist, or the
case of recycler dir has changed and the rename op is case sensitive.
First reopen root dir with permission to create subdirs. */
NtClose (rootdir);
InitializeObjectAttributes (&attr, &root, OBJ_CASE_INSENSITIVE,
@ -412,6 +397,26 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
&recycler, status);
goto out;
}
/* If we opened the recycler (in contrast to creating it) and our
rename op is case sensitive, fetch the actual case of the recycler
and store the name in recycler_basename, as well as in pfri->FileName
for the below 2nd try to rename the file. */
if (io.Information == FILE_OPENED && !pc.objcaseinsensitive ())
{
pfni = (PFILE_NAME_INFORMATION) tp.w_get ();
status = NtQueryInformationFile (recyclerdir, &io, pfni,
NT_MAX_PATH * sizeof (WCHAR),
FileNameInformation);
if (NT_SUCCESS (status))
{
size_t len = pfni->FileNameLength / sizeof (WCHAR) - 1;
PWCHAR p = pfni->FileName + 1;
p[len] = L'\0';
wcpncpy (pfri->FileName, p, len);
wcpncpy (recycler_basename + 1, p, len);
}
}
/* Next, if necessary, check if the recycler/SID dir exists and
create it if not. */
if (fs_has_per_user_recycler)