zig/std/fs/file.zig

const std = @import("../std.zig");
const builtin = @import("builtin");
const os = std.os;
const io = std.io;
const mem = std.mem;
const math = std.math;
const assert = std.debug.assert;
const windows = os.windows;
const Os = builtin.Os;
const maxInt = std.math.maxInt;

pub const File = struct {
    /// The OS-specific file descriptor or file handle.
    handle: os.fd_t,

    pub const Mode = switch (builtin.os) {
        Os.windows => void,
        else => u32,
    };

    pub const default_mode = switch (builtin.os) {
        Os.windows => {},
        else => 0o666,
    };

    pub const OpenError = windows.CreateFileError || os.OpenError;

    /// Call close to clean up.
    pub fn openRead(path: []const u8) OpenError!File {
        if (windows.is_the_target and !builtin.link_libc) {
            const path_w = try windows.sliceToPrefixedFileW(path);
            return openReadW(&path_w);
        }
        const path_c = try os.toPosixPath(path);
        return openReadC(&path_c);
    }

    /// `openRead` except with a null terminated path
    pub fn openReadC(path: [*]const u8) OpenError!File {
        if (windows.is_the_target and !builtin.link_libc) {
            const path_w = try windows.cStrToPrefixedFileW(path);
            return openReadW(&path_w);
        }
        const flags = os.O_LARGEFILE | os.O_RDONLY;
        const fd = try os.openC(path, flags, 0);
        return openHandle(fd);
    }

    /// `openRead` except with a null terminated UTF16LE encoded path
    pub fn openReadW(path_w: [*]const u16) OpenError!File {
        const handle = try windows.CreateFileW(
            path_w,
            windows.GENERIC_READ,
            windows.FILE_SHARE_READ,
            windows.OPEN_EXISTING,
            windows.FILE_ATTRIBUTE_NORMAL,
        );
        return openHandle(handle);
    }

    /// Calls `openWriteMode` with `default_mode` for the mode.
    pub fn openWrite(path: []const u8) OpenError!File {
        return openWriteMode(path, default_mode);
    }

    /// If the path does not exist it will be created.
    /// If a file already exists in the destination it will be truncated.
    /// Call close to clean up.
    pub fn openWriteMode(path: []const u8, file_mode: Mode) OpenError!File {
        if (windows.is_the_target and !builtin.link_libc) {
            const path_w = try windows.sliceToPrefixedFileW(path);
            return openWriteModeW(&path_w, file_mode);
        }
        const path_c = try os.toPosixPath(path);
        return openWriteModeC(&path_c, file_mode);
    }

    /// Same as `openWriteMode` except `path` is null-terminated.
    pub fn openWriteModeC(path: [*]const u8, file_mode: Mode) OpenError!File {
        if (windows.is_the_target and !builtin.link_libc) {
            const path_w = try windows.cStrToPrefixedFileW(path);
            return openWriteModeW(&path_w, file_mode);
        }
        const flags = os.O_LARGEFILE | os.O_WRONLY | os.O_CREAT | os.O_CLOEXEC | os.O_TRUNC;
        const fd = try os.openC(path, flags, file_mode);
        return openHandle(fd);
    }

    /// Same as `openWriteMode` except `path` is null-terminated and UTF16LE encoded
    pub fn openWriteModeW(path_w: [*]const u16, file_mode: Mode) OpenError!File {
        const handle = try windows.CreateFileW(
            path_w,
            windows.GENERIC_WRITE,
            windows.FILE_SHARE_WRITE | windows.FILE_SHARE_READ | windows.FILE_SHARE_DELETE,
            windows.CREATE_ALWAYS,
            windows.FILE_ATTRIBUTE_NORMAL,
        );
        return openHandle(handle);
    }

    /// If the path does not exist it will be created.
    /// If a file already exists in the destination this returns OpenError.PathAlreadyExists
    /// Call close to clean up.
    pub fn openWriteNoClobber(path: []const u8, file_mode: Mode) OpenError!File {
        if (windows.is_the_target and !builtin.link_libc) {
            const path_w = try windows.sliceToPrefixedFileW(path);
            return openWriteNoClobberW(&path_w, file_mode);
        }
        const path_c = try os.toPosixPath(path);
        return openWriteNoClobberC(&path_c, file_mode);
    }

    pub fn openWriteNoClobberC(path: [*]const u8, file_mode: Mode) OpenError!File {
        if (windows.is_the_target and !builtin.link_libc) {
            const path_w = try windows.cStrToPrefixedFileW(path);
            return openWriteNoClobberW(&path_w, file_mode);
        }
        const flags = os.O_LARGEFILE | os.O_WRONLY | os.O_CREAT | os.O_CLOEXEC | os.O_EXCL;
        const fd = try os.openC(path, flags, file_mode);
        return openHandle(fd);
    }

    pub fn openWriteNoClobberW(path_w: [*]const u16, file_mode: Mode) OpenError!File {
        const handle = try windows.CreateFileW(
            path_w,
            windows.GENERIC_WRITE,
            windows.FILE_SHARE_WRITE | windows.FILE_SHARE_READ | windows.FILE_SHARE_DELETE,
            windows.CREATE_NEW,
            windows.FILE_ATTRIBUTE_NORMAL,
        );
        return openHandle(handle);
    }

    pub fn openHandle(handle: os.fd_t) File {
        return File{ .handle = handle };
    }

    /// Test for the existence of `path`.
    /// `path` is UTF8-encoded.
    pub fn exists(path: []const u8) !void {
        return os.access(path, os.F_OK);
    }

    /// Same as `exists` except the parameter is null-terminated.
    pub fn existsC(path: [*]const u8) !void {
        return os.accessC(path, os.F_OK);
    }

    /// Same as `exists` except the parameter is null-terminated UTF16LE-encoded.
    pub fn existsW(path: [*]const u16) !void {
        return os.accessW(path, os.F_OK);
    }

    /// Upon success, the stream is in an uninitialized state. To continue using it,
    /// you must use the open() function.
    pub fn close(self: File) void {
        os.close(self.handle);
    }

    /// Test whether the file refers to a terminal.
    /// See also `supportsAnsiEscapeCodes`.
    pub fn isTty(self: File) bool {
        return os.isatty(self.handle);
    }

    /// Test whether ANSI escape codes will be treated as such.
    pub fn supportsAnsiEscapeCodes(self: File) bool {
        if (windows.is_the_target) {
            return os.isCygwinPty(self.handle);
        }
        return self.isTty();
    }

    pub const SeekError = os.SeekError;

    /// Repositions read/write file offset relative to the current offset.
    pub fn seekBy(self: File, offset: i64) SeekError!void {
        return os.lseek_CUR(self.handle, offset);
    }

    /// Repositions read/write file offset relative to the end.
    pub fn seekFromEnd(self: File, offset: i64) SeekError!void {
        return os.lseek_END(self.handle, offset);
    }

    /// Repositions read/write file offset relative to the beginning.
    pub fn seekTo(self: File, offset: u64) SeekError!void {
        return os.lseek_SET(self.handle, offset);
    }

    pub const GetPosError = os.SeekError || os.FStatError;

    pub fn getPos(self: File) GetPosError!u64 {
        return os.lseek_CUR_get(self.handle);
    }

    pub fn getEndPos(self: File) GetPosError!u64 {
        if (windows.is_the_target and !builtin.link_libc) {
            return windows.GetFileSizeEx(self.handle);
        }
        const stat = try os.fstat(self.handle);
        return @bitCast(u64, stat.size);
    }

    pub const ModeError = os.FStatError;

    pub fn mode(self: File) ModeError!Mode {
        if (windows.is_the_target and !builtin.link_libc) {
            return {};
        }
        const stat = try os.fstat(self.handle);
        // TODO: we should be able to cast u16 to ModeError!u32, making this
        // explicit cast not necessary
        return Mode(stat.mode);
    }

    pub const ReadError = os.ReadError;

    pub fn read(self: File, buffer: []u8) ReadError!usize {
        return os.read(self.handle, buffer);
    }

    pub const WriteError = os.WriteError;

    pub fn write(self: File, bytes: []const u8) WriteError!void {
        return os.write(self.handle, bytes);
    }

    pub fn inStream(file: File) InStream {
        return InStream{
            .file = file,
            .stream = InStream.Stream{ .readFn = InStream.readFn },
        };
    }

    pub fn outStream(file: File) OutStream {
        return OutStream{
            .file = file,
            .stream = OutStream.Stream{ .writeFn = OutStream.writeFn },
        };
    }

    pub fn seekableStream(file: File) SeekableStream {
        return SeekableStream{
            .file = file,
            .stream = SeekableStream.Stream{
                .seekToFn = SeekableStream.seekToFn,
                .seekByFn = SeekableStream.seekByFn,
                .getPosFn = SeekableStream.getPosFn,
                .getEndPosFn = SeekableStream.getEndPosFn,
            },
        };
    }

    /// Implementation of io.InStream trait for File
    pub const InStream = struct {
        file: File,
        stream: Stream,

        pub const Error = ReadError;
        pub const Stream = io.InStream(Error);

        fn readFn(in_stream: *Stream, buffer: []u8) Error!usize {
            const self = @fieldParentPtr(InStream, "stream", in_stream);
            return self.file.read(buffer);
        }
    };

    /// Implementation of io.OutStream trait for File
    pub const OutStream = struct {
        file: File,
        stream: Stream,

        pub const Error = WriteError;
        pub const Stream = io.OutStream(Error);

        fn writeFn(out_stream: *Stream, bytes: []const u8) Error!void {
            const self = @fieldParentPtr(OutStream, "stream", out_stream);
            return self.file.write(bytes);
        }
    };

    /// Implementation of io.SeekableStream trait for File
    pub const SeekableStream = struct {
        file: File,
        stream: Stream,

        pub const Stream = io.SeekableStream(SeekError, GetPosError);

        pub fn seekToFn(seekable_stream: *Stream, pos: u64) SeekError!void {
            const self = @fieldParentPtr(SeekableStream, "stream", seekable_stream);
            return self.file.seekTo(pos);
        }

        pub fn seekByFn(seekable_stream: *Stream, amt: i64) SeekError!void {
            const self = @fieldParentPtr(SeekableStream, "stream", seekable_stream);
            return self.file.seekBy(amt);
        }

        pub fn getEndPosFn(seekable_stream: *Stream) GetPosError!u64 {
            const self = @fieldParentPtr(SeekableStream, "stream", seekable_stream);
            return self.file.getEndPos();
        }

        pub fn getPosFn(seekable_stream: *Stream) GetPosError!u64 {
            const self = @fieldParentPtr(SeekableStream, "stream", seekable_stream);
            return self.file.getPos();
        }
    };
};