[Support] Add support for getting file system permissions on Windows and implement sys::fs::set/getPermissions to work with them
This change adds support for functions to set and get file permissions, in a similar manner to the C++17 permissions() function in <filesystem>. The setter uses chmod on Unix systems and SetFileAttributes on Windows, setting the permissions as passed in. The getter simply uses the existing status() function.
Prior to this change, status() would always return an unknown value for the permissions on a Windows file, making it impossible to test the new function on Windows. I have therefore added support for this as well. On Linux, prior to this change, the permissions included the file type, which should actually be accessed via a different member of the file_status class.
Note that on Windows, only the *_write permission bits have any affect - if any are set, the file is writable, and if not, the file is read-only. This is in common with what MSDN describes for their behaviour of std::filesystem::permissions(), and also what boost::filesystem does.
The motivation behind this change is so that we can easily test behaviour on read-only files in LLVM unit tests, but I am sure that others may find it useful in some situations.
Reviewers: zturner, amccarth, aaron.ballman
Differential Revision: https://reviews.llvm.org/D30736
llvm-svn: 297945
diff --git a/llvm/lib/Support/Windows/Path.inc b/llvm/lib/Support/Windows/Path.inc
index d8a14b4..f8a75a2 100644
--- a/llvm/lib/Support/Windows/Path.inc
+++ b/llvm/lib/Support/Windows/Path.inc
@@ -530,13 +530,15 @@
file_type Type = (Info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
? file_type::directory_file
: file_type::regular_file;
- Result =
- file_status(Type, Info.ftLastAccessTime.dwHighDateTime,
- Info.ftLastAccessTime.dwLowDateTime,
- Info.ftLastWriteTime.dwHighDateTime,
- Info.ftLastWriteTime.dwLowDateTime,
- Info.dwVolumeSerialNumber, Info.nFileSizeHigh,
- Info.nFileSizeLow, Info.nFileIndexHigh, Info.nFileIndexLow);
+ perms Permissions = (Info.dwFileAttributes & FILE_ATTRIBUTE_READONLY)
+ ? (all_read | all_exe)
+ : all_all;
+ Result = file_status(
+ Type, Permissions, Info.ftLastAccessTime.dwHighDateTime,
+ Info.ftLastAccessTime.dwLowDateTime,
+ Info.ftLastWriteTime.dwHighDateTime, Info.ftLastWriteTime.dwLowDateTime,
+ Info.dwVolumeSerialNumber, Info.nFileSizeHigh, Info.nFileSizeLow,
+ Info.nFileIndexHigh, Info.nFileIndexLow);
return std::error_code();
}
@@ -589,6 +591,37 @@
return getStatus(FileHandle, Result);
}
+std::error_code setPermissions(const Twine &Path, perms Permissions) {
+ SmallVector<wchar_t, 128> PathUTF16;
+ if (std::error_code EC = widenPath(Path, PathUTF16))
+ return EC;
+
+ DWORD Attributes = ::GetFileAttributesW(PathUTF16.begin());
+ if (Attributes == INVALID_FILE_ATTRIBUTES)
+ return mapWindowsError(GetLastError());
+
+ // There are many Windows file attributes that are not to do with the file
+ // permissions (e.g. FILE_ATTRIBUTE_HIDDEN). We need to be careful to preserve
+ // them.
+ if (Permissions & all_write) {
+ Attributes &= ~FILE_ATTRIBUTE_READONLY;
+ if (Attributes == 0)
+ // FILE_ATTRIBUTE_NORMAL indicates no other attributes are set.
+ Attributes |= FILE_ATTRIBUTE_NORMAL;
+ }
+ else {
+ Attributes |= FILE_ATTRIBUTE_READONLY;
+ // FILE_ATTRIBUTE_NORMAL is not compatible with any other attributes, so
+ // remove it, if it is present.
+ Attributes &= ~FILE_ATTRIBUTE_NORMAL;
+ }
+
+ if (!::SetFileAttributesW(PathUTF16.begin(), Attributes))
+ return mapWindowsError(GetLastError());
+
+ return std::error_code();
+}
+
std::error_code setLastModificationAndAccessTime(int FD, TimePoint<> Time) {
FILETIME FT = toFILETIME(Time);
HANDLE FileHandle = reinterpret_cast<HANDLE>(_get_osfhandle(FD));