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* fhandler_procsys.cc (fhandler_procsys::exists): Rewrite.

Browse Source 
(fhandler_procsys::fill_filebuf): Fill buffer with valid string even if
	reading the symlink fails.
This commit is contained in:
Corinna Vinschen 2011-03-04 17:51:42 +00:00
parent dfbab84c51
commit d5071ad7f5
2 changed files with 141 additions and 61 deletions
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6
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,9 @@
2011-03-04 Corinna Vinschen <corinna@vinschen.de>
* fhandler_procsys.cc (fhandler_procsys::exists): Rewrite.
(fhandler_procsys::fill_filebuf): Fill buffer with valid string even if
reading the symlink fails.
2011-03-03 Corinna Vinschen <corinna@vinschen.de>
* posix_ipc.cc (ipc_cond_timedwait): If ipc_mutex_unlock fails, return

196
winsup/cygwin/fhandler_procsys.cc
View File

@ -46,78 +46,46 @@ const size_t procsys_len = sizeof (procsys) - 1;
virtual_ftype_t
fhandler_procsys::exists (struct __stat64 *buf)
{
UNICODE_STRING path; \
UNICODE_STRING path;
UNICODE_STRING dir;
OBJECT_ATTRIBUTES attr;
IO_STATUS_BLOCK io;
NTSTATUS status;
HANDLE h;
FILE_BASIC_INFORMATION fbi;
bool internal = false;
bool desperate_parent_check = false;
/* Default device type is character device. */
virtual_ftype_t file_type = virt_chr;
if (strlen (get_name ()) == procsys_len)
return virt_rootdir;
mk_unicode_path (&path);
/* First try to open as file/device to get more info. */
InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL);
status = NtOpenFile (&h, READ_CONTROL | FILE_READ_ATTRIBUTES, &attr, &io,
FILE_SHARE_VALID_FLAGS, FILE_OPEN_FOR_BACKUP_INTENT);
if (status == STATUS_OBJECT_NAME_INVALID)
return virt_none;
/* If no media is found, or we get this dreaded sharing violation, let
the caller immediately try again as normal file. */
if (status == STATUS_NO_MEDIA_IN_DEVICE
|| status == STATUS_SHARING_VIOLATION)
return virt_fsfile; /* Just try again as normal file. */
/* If file or path can't be found, let caller try again as normal file. */
if (status == STATUS_OBJECT_PATH_NOT_FOUND
|| status == STATUS_OBJECT_NAME_NOT_FOUND)
file_type = virt_fsfile;
/* Check for pipe errors, which make a good hint... */
else if (status >= STATUS_PIPE_NOT_AVAILABLE && status <= STATUS_PIPE_BUSY)
file_type = virt_pipe;
else if (status == STATUS_ACCESS_DENIED)
{
/* Check if this is just some file or dir on a real FS to circumvent
most permission problems. */
status = NtQueryAttributesFile (&attr, &fbi);
if (NT_SUCCESS (status))
return (fbi.FileAttributes & FILE_ATTRIBUTE_DIRECTORY)
? virt_fsdir : virt_fsfile;
}
else if (NT_SUCCESS (status))
{
NTSTATUS dev_stat;
FILE_FS_DEVICE_INFORMATION ffdi;
/* If requested, check permissions. */
if (buf)
get_object_attribute (h, &buf->st_uid, &buf->st_gid, &buf->st_mode);
/* Check for the device type. */
dev_stat = NtQueryVolumeInformationFile (h, &io, &ffdi, sizeof ffdi,
FileFsDeviceInformation);
/* And check for file attributes. If we get them, we peeked into
a real FS through /proc/sys. */
status = NtQueryInformationFile (h, &io, &fbi, sizeof fbi,
FileBasicInformation);
/* Try to open parent dir. If it works, the object is definitely
an object within the internal namespace. We don't need to test
it for being a file or dir on the filesystem anymore. If the
error is STATUS_OBJECT_TYPE_MISMATCH, we know that the file
itself is external. Otherwise we don't know. */
RtlSplitUnicodePath (&path, &dir, NULL);
/* RtlSplitUnicodePath preserves the trailing backslash in dir. Don't
preserve it to open the dir, unless it's the object root. */
if (dir.Length > sizeof (WCHAR))
dir.Length -= sizeof (WCHAR);
InitializeObjectAttributes (&attr, &dir, OBJ_CASE_INSENSITIVE, NULL, NULL);
status = NtOpenDirectoryObject (&h, DIRECTORY_QUERY, &attr);
debug_printf ("NtOpenDirectoryObject: %p", status);
if (NT_SUCCESS (status))
{
internal = true;
NtClose (h);
if (NT_SUCCESS (dev_stat))
{
if (ffdi.DeviceType == FILE_DEVICE_NAMED_PIPE)
file_type = NT_SUCCESS (status) ? virt_pipe : virt_blk;
else if (NT_SUCCESS (status))
file_type = (fbi.FileAttributes & FILE_ATTRIBUTE_DIRECTORY)
? virt_fsdir : virt_fsfile;
else if (ffdi.DeviceType == FILE_DEVICE_DISK
|| ffdi.DeviceType == FILE_DEVICE_CD_ROM
|| ffdi.DeviceType == FILE_DEVICE_DFS
|| ffdi.DeviceType == FILE_DEVICE_VIRTUAL_DISK)
file_type = virt_blk;
}
}
/* Then check if it's a symlink. */
/* First check if the object is a symlink. */
InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL);
status = NtOpenSymbolicLinkObject (&h, READ_CONTROL | SYMBOLIC_LINK_QUERY,
&attr);
debug_printf ("NtOpenSymbolicLinkObject: %p", status);
if (NT_SUCCESS (status))
{
/* If requested, check permissions. */
@ -126,8 +94,11 @@ fhandler_procsys::exists (struct __stat64 *buf)
NtClose (h);
return virt_symlink;
}
/* Eventually, test if it's an object directory. */
else if (status == STATUS_ACCESS_DENIED)
return virt_symlink;
/* Then check if it's an object directory. */
status = NtOpenDirectoryObject (&h, READ_CONTROL | DIRECTORY_QUERY, &attr);
debug_printf ("NtOpenDirectoryObject: %p", status);
if (NT_SUCCESS (status))
{
/* If requested, check permissions. */
@ -138,6 +109,101 @@ fhandler_procsys::exists (struct __stat64 *buf)
}
else if (status == STATUS_ACCESS_DENIED)
return virt_directory;
/* Next try to open as file/device. */
status = NtOpenFile (&h, READ_CONTROL | FILE_READ_ATTRIBUTES, &attr, &io,
FILE_SHARE_VALID_FLAGS, FILE_OPEN_FOR_BACKUP_INTENT);
debug_printf ("NtOpenFile: %p", status);
/* Name is invalid, that's nothing. */
if (status == STATUS_OBJECT_NAME_INVALID)
return virt_none;
/* If no media is found, or we get this dreaded sharing violation, let
the caller immediately try again as normal file. */
if (status == STATUS_NO_MEDIA_IN_DEVICE
|| status == STATUS_SHARING_VIOLATION)
return virt_fsfile; /* Just try again as normal file. */
/* If file or path can't be found, let caller try again as normal file. */
if (status == STATUS_OBJECT_PATH_NOT_FOUND
|| status == STATUS_OBJECT_NAME_NOT_FOUND)
return virt_fsfile;
/* Check for pipe errors, which make a good hint... */
if (status >= STATUS_PIPE_NOT_AVAILABLE && status <= STATUS_PIPE_BUSY)
return virt_pipe;
if (status == STATUS_ACCESS_DENIED && !internal)
{
/* Check if this is just some file or dir on a real FS to circumvent
most permission problems. Don't try that on internal objects,
since NtQueryAttributesFile might crash the machine if the underlying
driver is badly written. */
status = NtQueryAttributesFile (&attr, &fbi);
debug_printf ("NtQueryAttributesFile: %p", status);
if (NT_SUCCESS (status))
return (fbi.FileAttributes & FILE_ATTRIBUTE_DIRECTORY)
? virt_fsdir : virt_fsfile;
/* Ok, so we're desperate and the file still maybe on some filesystem.
To check this, we now split the path until we can finally access any
of the parent's. Then we fall through to check the parent type. In
contrast to the first parent check, we now check explicitely with
trailing backslash. This will fail for directories in the internal
namespace, so we won't accidentally test those. */
dir = path;
InitializeObjectAttributes (&attr, &dir, OBJ_CASE_INSENSITIVE,
NULL, NULL);
do
{
RtlSplitUnicodePath (&dir, &dir, NULL);
status = NtOpenFile (&h, READ_CONTROL | FILE_READ_ATTRIBUTES,
&attr, &io, FILE_SHARE_VALID_FLAGS,
FILE_OPEN_FOR_BACKUP_INTENT);
debug_printf ("NtOpenDirectoryObject: %p", status);
if (dir.Length > sizeof (WCHAR))
dir.Length -= sizeof (WCHAR);
}
while (dir.Length > sizeof (WCHAR) && !NT_SUCCESS (status));
desperate_parent_check = true;
}
if (NT_SUCCESS (status))
{
FILE_FS_DEVICE_INFORMATION ffdi;
/* If requested, check permissions. If this is a parent handle from
the above desperate parent check, skip. */
if (buf && !desperate_parent_check)
get_object_attribute (h, &buf->st_uid, &buf->st_gid, &buf->st_mode);
/* Check for the device type. */
status = NtQueryVolumeInformationFile (h, &io, &ffdi, sizeof ffdi,
FileFsDeviceInformation);
debug_printf ("NtQueryVolumeInformationFile: %p", status);
/* Don't call NtQueryInformationFile unless we know it's a safe type.
The call is known to crash machines, if the underlying driver is
badly written. */
if (!NT_SUCCESS (status))
{
NtClose (h);
return file_type;
}
if (ffdi.DeviceType == FILE_DEVICE_NETWORK_FILE_SYSTEM)
file_type = virt_blk;
else if (ffdi.DeviceType == FILE_DEVICE_NAMED_PIPE)
file_type = internal ? virt_blk : virt_pipe;
else if (ffdi.DeviceType == FILE_DEVICE_DISK
|| ffdi.DeviceType == FILE_DEVICE_CD_ROM
|| ffdi.DeviceType == FILE_DEVICE_DFS
|| ffdi.DeviceType == FILE_DEVICE_VIRTUAL_DISK)
{
/* Check for file attributes. If we get them, we peeked
into a real FS through /proc/sys. */
status = NtQueryInformationFile (h, &io, &fbi, sizeof fbi,
FileBasicInformation);
debug_printf ("NtQueryInformationFile: %p", status);
if (!NT_SUCCESS (status))
file_type = virt_blk;
else
file_type = (fbi.FileAttributes & FILE_ATTRIBUTE_DIRECTORY)
? virt_fsdir : virt_fsfile;
}
NtClose (h);
}
/* That's it. Return type we found above. */
return file_type;
}
@ -153,6 +219,8 @@ fhandler_procsys::fhandler_procsys ():
{
}
#define UNREADABLE_SYMLINK_CONTENT "<access denied>"
bool
fhandler_procsys::fill_filebuf ()
{
@ -162,6 +230,7 @@ fhandler_procsys::fill_filebuf ()
NTSTATUS status;
HANDLE h;
tmp_pathbuf tp;
size_t len;
mk_unicode_path (&path);
if (path.Buffer[path.Length / sizeof (WCHAR) - 1] == L'\\')
@ -169,21 +238,26 @@ fhandler_procsys::fill_filebuf ()
InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL);
status = NtOpenSymbolicLinkObject (&h, SYMBOLIC_LINK_QUERY, &attr);
if (!NT_SUCCESS (status))
return false;
goto unreadable;
RtlInitEmptyUnicodeString (&target, tp.w_get (),
(NT_MAX_PATH - 1) * sizeof (WCHAR));
status = NtQuerySymbolicLinkObject (h, &target, NULL);
NtClose (h);
if (!NT_SUCCESS (status))
return false;
size_t len = sys_wcstombs (NULL, 0, target.Buffer,
target.Length / sizeof (WCHAR));
goto unreadable;
len = sys_wcstombs (NULL, 0, target.Buffer, target.Length / sizeof (WCHAR));
filebuf = (char *) crealloc_abort (filebuf, procsys_len + len + 1);
sys_wcstombs (fnamep = stpcpy (filebuf, procsys), len + 1, target.Buffer,
target.Length / sizeof (WCHAR));
while ((fnamep = strchr (fnamep, '\\')))
*fnamep = '/';
return true;
unreadable:
filebuf = (char *) crealloc_abort (filebuf,
sizeof (UNREADABLE_SYMLINK_CONTENT));
strcpy (filebuf, UNREADABLE_SYMLINK_CONTENT);
return false;
}
int