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Return WTF-16 from W-suffixed functions instead of converting to WTF-8 #23657

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Return WTF-16 from W-suffixed functions instead of converting to WTF-8 #23657

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7049a07
Return WTF16LE encoded path from realpathW
mpfaff Apr 26, 2025
381ccb9
Improve documentation on Dir.realpathW
mpfaff Apr 23, 2025
471c985
Reuse pathname_w buffer as out_buffer when calling realpathW
mpfaff Apr 23, 2025
d2554d4
Fix realpathW out_buffer size
mpfaff Apr 26, 2025
fcf8123
Deprecate old realpathW correctly
mpfaff Apr 26, 2025
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13 changes: 11 additions & 2 deletions lib/std/fs.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ pub const wasi = @import("fs/wasi.zig");
pub const realpath = posix.realpath;
pub const realpathZ = posix.realpathZ;
pub const realpathW = posix.realpathW;
pub const realpathW2 = posix.realpathW2;

pub const getAppDataDir = @import("fs/get_app_data_dir.zig").getAppDataDir;
pub const GetAppDataDirError = @import("fs/get_app_data_dir.zig").GetAppDataDirError;
Expand Down Expand Up @@ -651,11 +652,19 @@ pub fn selfExePath(out_buffer: []u8) SelfExePathError![]u8 {
// If ImagePathName is a symlink, then it will contain the path of the
// symlink, not the path that the symlink points to. We want the path
// that the symlink points to, though, so we need to get the realpath.
const pathname_w = try windows.wToPrefixedFileW(null, image_path_name);
return std.fs.cwd().realpathW(pathname_w.span(), out_buffer) catch |err| switch (err) {
var pathname_w = try windows.wToPrefixedFileW(null, image_path_name);

const wide_slice = std.fs.cwd().realpathW2(pathname_w.span(), &pathname_w.data) catch |err| switch (err) {
error.InvalidWtf8 => unreachable,
else => |e| return e,
};

const len = std.unicode.calcWtf8Len(wide_slice);
if (len > out_buffer.len)
return error.NameTooLong;

const end_index = std.unicode.wtf16LeToWtf8(out_buffer, wide_slice);
return out_buffer[0..end_index];
},
else => @compileError("std.fs.selfExePath not supported for this target"),
}
Expand Down
56 changes: 45 additions & 11 deletions lib/std/fs/Dir.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -1282,8 +1282,16 @@ pub fn realpath(self: Dir, pathname: []const u8, out_buffer: []u8) RealPathError
@compileError("realpath is not available on WASI");
}
if (native_os == .windows) {
const pathname_w = try windows.sliceToPrefixedFileW(self.fd, pathname);
return self.realpathW(pathname_w.span(), out_buffer);
var pathname_w = try windows.sliceToPrefixedFileW(self.fd, pathname);

const wide_slice = try self.realpathW2(pathname_w.span(), &pathname_w.data);

const len = std.unicode.calcWtf8Len(wide_slice);
if (len > out_buffer.len)
return error.NameTooLong;

const end_index = std.unicode.wtf16LeToWtf8(out_buffer, wide_slice);
return out_buffer[0..end_index];
}
const pathname_c = try posix.toPosixPath(pathname);
return self.realpathZ(&pathname_c, out_buffer);
Expand All @@ -1293,8 +1301,16 @@ pub fn realpath(self: Dir, pathname: []const u8, out_buffer: []u8) RealPathError
/// See also `Dir.realpath`, `realpathZ`.
pub fn realpathZ(self: Dir, pathname: [*:0]const u8, out_buffer: []u8) RealPathError![]u8 {
if (native_os == .windows) {
const pathname_w = try windows.cStrToPrefixedFileW(self.fd, pathname);
return self.realpathW(pathname_w.span(), out_buffer);
var pathname_w = try windows.cStrToPrefixedFileW(self.fd, pathname);

const wide_slice = try self.realpathW2(pathname_w.span(), &pathname_w.data);

const len = std.unicode.calcWtf8Len(wide_slice);
if (len > out_buffer.len)
return error.NameTooLong;

const end_index = std.unicode.wtf16LeToWtf8(out_buffer, wide_slice);
return out_buffer[0..end_index];
}

var flags: posix.O = .{};
Expand Down Expand Up @@ -1323,10 +1339,34 @@ pub fn realpathZ(self: Dir, pathname: [*:0]const u8, out_buffer: []u8) RealPathE
return result;
}

/// Deprecated: use `realpathW2`.
///
/// Windows-only. Same as `Dir.realpath` except `pathname` is WTF16 LE encoded.
/// The result is encoded as [WTF-8](https://simonsapin.github.io/wtf-8/).
/// See also `Dir.realpath`, `realpathW`.
pub fn realpathW(self: Dir, pathname: []const u16, out_buffer: []u8) RealPathError![]u8 {
var wide_buf: [std.os.windows.PATH_MAX_WIDE]u16 = undefined;

const wide_slice = try self.realpathW2(pathname, &wide_buf);

var big_out_buf: [fs.max_path_bytes]u8 = undefined;
const end_index = std.unicode.wtf16LeToWtf8(&big_out_buf, wide_slice);
if (end_index > out_buffer.len)
return error.NameTooLong;
const result = out_buffer[0..end_index];
@memcpy(result, big_out_buf[0..end_index]);
return result;
}

/// Windows-only. Same as `Dir.realpath` except
/// * `pathname` and the result are WTF-16 LE encoded
/// * `pathname` is relative or has the NT namespace prefix. See `windows.wToPrefixedFileW` for details.
///
/// Additionally, `pathname` will never be accessed after `out_buffer` has been written to, so it
/// is safe to reuse a single buffer for both.
///
/// See also `Dir.realpath`, `realpathW`.
pub fn realpathW2(self: Dir, pathname: []const u16, out_buffer: []u16) RealPathError![]u16 {
const w = windows;

const access_mask = w.GENERIC_READ | w.SYNCHRONIZE;
Expand All @@ -1347,13 +1387,7 @@ pub fn realpathW(self: Dir, pathname: []const u16, out_buffer: []u8) RealPathErr
};
defer w.CloseHandle(h_file);

var wide_buf: [w.PATH_MAX_WIDE]u16 = undefined;
const wide_slice = try w.GetFinalPathNameByHandle(h_file, .{}, &wide_buf);
const len = std.unicode.calcWtf8Len(wide_slice);
if (len > out_buffer.len)
return error.NameTooLong;
const end_index = std.unicode.wtf16LeToWtf8(out_buffer, wide_slice);
return out_buffer[0..end_index];
return w.GetFinalPathNameByHandle(h_file, .{}, out_buffer);
}

pub const RealPathAllocError = RealPathError || Allocator.Error;
Expand Down
48 changes: 23 additions & 25 deletions lib/std/posix.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -5533,8 +5533,12 @@ pub const RealPathError = error{
/// Calling this function is usually a bug.
pub fn realpath(pathname: []const u8, out_buffer: *[max_path_bytes]u8) RealPathError![]u8 {
if (native_os == .windows) {
const pathname_w = try windows.sliceToPrefixedFileW(null, pathname);
return realpathW(pathname_w.span(), out_buffer);
var pathname_w = try windows.sliceToPrefixedFileW(null, pathname);

const wide_slice = try realpathW2(pathname_w.span(), &pathname_w.data);

const end_index = std.unicode.wtf16LeToWtf8(out_buffer, wide_slice);
return out_buffer[0..end_index];
} else if (native_os == .wasi and !builtin.link_libc) {
@compileError("WASI does not support os.realpath");
}
Expand All @@ -5547,8 +5551,12 @@ pub fn realpath(pathname: []const u8, out_buffer: *[max_path_bytes]u8) RealPathE
/// Calling this function is usually a bug.
pub fn realpathZ(pathname: [*:0]const u8, out_buffer: *[max_path_bytes]u8) RealPathError![]u8 {
if (native_os == .windows) {
const pathname_w = try windows.cStrToPrefixedFileW(null, pathname);
return realpathW(pathname_w.span(), out_buffer);
var pathname_w = try windows.cStrToPrefixedFileW(null, pathname);

const wide_slice = try realpathW2(pathname_w.span(), &pathname_w.data);

const end_index = std.unicode.wtf16LeToWtf8(out_buffer, wide_slice);
return out_buffer[0..end_index];
} else if (native_os == .wasi and !builtin.link_libc) {
return realpath(mem.sliceTo(pathname, 0), out_buffer);
}
Expand Down Expand Up @@ -5592,34 +5600,24 @@ pub fn realpathZ(pathname: [*:0]const u8, out_buffer: *[max_path_bytes]u8) RealP
return mem.sliceTo(result_path, 0);
}

/// Deprecated: use `realpathW2`.
///
/// Same as `realpath` except `pathname` is WTF16LE-encoded.
///
/// The result is encoded as [WTF-8](https://simonsapin.github.io/wtf-8/).
///
/// Calling this function is usually a bug.
pub fn realpathW(pathname: []const u16, out_buffer: *[max_path_bytes]u8) RealPathError![]u8 {
const w = windows;

const dir = fs.cwd().fd;
const access_mask = w.GENERIC_READ | w.SYNCHRONIZE;
const share_access = w.FILE_SHARE_READ | w.FILE_SHARE_WRITE | w.FILE_SHARE_DELETE;
const creation = w.FILE_OPEN;
const h_file = blk: {
const res = w.OpenFile(pathname, .{
.dir = dir,
.access_mask = access_mask,
.share_access = share_access,
.creation = creation,
.filter = .any,
}) catch |err| switch (err) {
error.WouldBlock => unreachable,
else => |e| return e,
};
break :blk res;
};
defer w.CloseHandle(h_file);
return fs.cwd().realpathW(pathname, out_buffer);
}

return std.os.getFdPath(h_file, out_buffer);
/// Same as `realpath` except `pathname` is WTF16LE-encoded.
///
/// The result is encoded as WTF16LE.
///
/// Calling this function is usually a bug.
pub fn realpathW2(pathname: []const u16, out_buffer: *[std.os.windows.PATH_MAX_WIDE]u16) RealPathError![]u16 {
return fs.cwd().realpathW2(pathname, out_buffer);
}

/// Spurious wakeups are possible and no precision of timing is guaranteed.
Expand Down