zig/lib/std/fs/file.zig

685 lines
27 KiB
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;
const is_windows = std.Target.current.os.tag == .windows;
pub const File = struct {
/// The OS-specific file descriptor or file handle.
handle: os.fd_t,
/// On some systems, such as Linux, file system file descriptors are incapable of non-blocking I/O.
/// This forces us to perform asynchronous I/O on a dedicated thread, to achieve non-blocking
/// file-system I/O. To do this, `File` must be aware of whether it is a file system file descriptor,
/// or, more specifically, whether the I/O is always blocking.
capable_io_mode: io.ModeOverride = io.default_mode,
/// Furthermore, even when `std.io.mode` is async, it is still sometimes desirable to perform blocking I/O,
/// although not by default. For example, when printing a stack trace to stderr.
/// This field tracks both by acting as an overriding I/O mode. When not building in async I/O mode,
/// the type only has the `.blocking` tag, making it a zero-bit type.
intended_io_mode: io.ModeOverride = io.default_mode,
pub const Mode = os.mode_t;
pub const INode = os.ino_t;
pub const default_mode = switch (builtin.os.tag) {
.windows => 0,
.wasi => 0,
else => 0o666,
};
pub const OpenError = windows.CreateFileError || os.OpenError || os.FlockError;
pub const Lock = enum { None, Shared, Exclusive };
/// TODO https://github.com/ziglang/zig/issues/3802
pub const OpenFlags = struct {
read: bool = true,
write: bool = false,
/// Open the file with a lock to prevent other processes from accessing it at the
/// same time. An exclusive lock will prevent other processes from acquiring a lock.
/// A shared lock will prevent other processes from acquiring a exclusive lock, but
/// doesn't prevent other process from getting their own shared locks.
///
/// Note that the lock is only advisory on Linux, except in very specific cirsumstances[1].
/// This means that a process that does not respect the locking API can still get access
/// to the file, despite the lock.
///
/// Windows' file locks are mandatory, and any process attempting to access the file will
/// receive an error.
///
/// [1]: https://www.kernel.org/doc/Documentation/filesystems/mandatory-locking.txt
lock: Lock = .None,
/// Sets whether or not to wait until the file is locked to return. If set to true,
/// `error.WouldBlock` will be returned. Otherwise, the file will wait until the file
/// is available to proceed.
/// In async I/O mode, non-blocking at the OS level is
/// determined by `intended_io_mode`, and `true` means `error.WouldBlock` is returned,
/// and `false` means `error.WouldBlock` is handled by the event loop.
lock_nonblocking: bool = false,
/// Setting this to `.blocking` prevents `O_NONBLOCK` from being passed even
/// if `std.io.is_async`. It allows the use of `nosuspend` when calling functions
/// related to opening the file, reading, writing, and locking.
intended_io_mode: io.ModeOverride = io.default_mode,
};
/// TODO https://github.com/ziglang/zig/issues/3802
pub const CreateFlags = struct {
/// Whether the file will be created with read access.
read: bool = false,
/// If the file already exists, and is a regular file, and the access
/// mode allows writing, it will be truncated to length 0.
truncate: bool = true,
/// Ensures that this open call creates the file, otherwise causes
/// `error.FileAlreadyExists` to be returned.
exclusive: bool = false,
/// Open the file with a lock to prevent other processes from accessing it at the
/// same time. An exclusive lock will prevent other processes from acquiring a lock.
/// A shared lock will prevent other processes from acquiring a exclusive lock, but
/// doesn't prevent other process from getting their own shared locks.
///
/// Note that the lock is only advisory on Linux, except in very specific cirsumstances[1].
/// This means that a process that does not respect the locking API can still get access
/// to the file, despite the lock.
///
/// Windows's file locks are mandatory, and any process attempting to access the file will
/// receive an error.
///
/// [1]: https://www.kernel.org/doc/Documentation/filesystems/mandatory-locking.txt
lock: Lock = .None,
/// Sets whether or not to wait until the file is locked to return. If set to true,
/// `error.WouldBlock` will be returned. Otherwise, the file will wait until the file
/// is available to proceed.
/// In async I/O mode, non-blocking at the OS level is
/// determined by `intended_io_mode`, and `true` means `error.WouldBlock` is returned,
/// and `false` means `error.WouldBlock` is handled by the event loop.
lock_nonblocking: bool = false,
/// For POSIX systems this is the file system mode the file will
/// be created with.
mode: Mode = default_mode,
/// Setting this to `.blocking` prevents `O_NONBLOCK` from being passed even
/// if `std.io.is_async`. It allows the use of `nosuspend` when calling functions
/// related to opening the file, reading, writing, and locking.
intended_io_mode: io.ModeOverride = io.default_mode,
};
/// 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 {
if (is_windows) {
windows.CloseHandle(self.handle);
} else if (self.capable_io_mode != self.intended_io_mode) {
std.event.Loop.instance.?.close(self.handle);
} else {
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 (builtin.os.tag == .windows) {
return os.isCygwinPty(self.handle);
}
if (builtin.os.tag == .wasi) {
// WASI sanitizes stdout when fd is a tty so ANSI escape codes
// will not be interpreted as actual cursor commands, and
// stderr is always sanitized.
return false;
}
if (self.isTty()) {
if (self.handle == os.STDOUT_FILENO or self.handle == os.STDERR_FILENO) {
// Use getenvC to workaround https://github.com/ziglang/zig/issues/3511
if (os.getenvZ("TERM")) |term| {
if (std.mem.eql(u8, term, "dumb"))
return false;
}
}
return true;
}
return false;
}
pub const SetEndPosError = os.TruncateError;
/// Shrinks or expands the file.
/// The file offset after this call is left unchanged.
pub fn setEndPos(self: File, length: u64) SetEndPosError!void {
try os.ftruncate(self.handle, length);
}
pub const SeekError = os.SeekError;
/// Repositions read/write file offset relative to the current offset.
/// TODO: integrate with async I/O
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.
/// TODO: integrate with async I/O
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.
/// TODO: integrate with async I/O
pub fn seekTo(self: File, offset: u64) SeekError!void {
return os.lseek_SET(self.handle, offset);
}
pub const GetPosError = os.SeekError || os.FStatError;
/// TODO: integrate with async I/O
pub fn getPos(self: File) GetPosError!u64 {
return os.lseek_CUR_get(self.handle);
}
/// TODO: integrate with async I/O
pub fn getEndPos(self: File) GetPosError!u64 {
if (builtin.os.tag == .windows) {
return windows.GetFileSizeEx(self.handle);
}
return (try self.stat()).size;
}
pub const ModeError = os.FStatError;
/// TODO: integrate with async I/O
pub fn mode(self: File) ModeError!Mode {
if (builtin.os.tag == .windows) {
return {};
}
return (try self.stat()).mode;
}
pub const Stat = struct {
/// A number that the system uses to point to the file metadata. This number is not guaranteed to be
/// unique across time, as some file systems may reuse an inode after its file has been deleted.
/// Some systems may change the inode of a file over time.
///
/// On Linux, the inode _is_ structure that stores the metadata, and the inode _number_ is what
/// you see here: the index number of the inode.
///
/// The FileIndex on Windows is similar. It is a number for a file that is unique to each filesystem.
inode: INode,
size: u64,
mode: Mode,
/// Access time in nanoseconds, relative to UTC 1970-01-01.
atime: i128,
/// Last modification time in nanoseconds, relative to UTC 1970-01-01.
mtime: i128,
/// Creation time in nanoseconds, relative to UTC 1970-01-01.
ctime: i128,
};
pub const StatError = os.FStatError;
/// TODO: integrate with async I/O
pub fn stat(self: File) StatError!Stat {
if (builtin.os.tag == .windows) {
var io_status_block: windows.IO_STATUS_BLOCK = undefined;
var info: windows.FILE_ALL_INFORMATION = undefined;
const rc = windows.ntdll.NtQueryInformationFile(self.handle, &io_status_block, &info, @sizeOf(windows.FILE_ALL_INFORMATION), .FileAllInformation);
switch (rc) {
.SUCCESS => {},
.BUFFER_OVERFLOW => {},
.INVALID_PARAMETER => unreachable,
.ACCESS_DENIED => return error.AccessDenied,
else => return windows.unexpectedStatus(rc),
}
return Stat{
.inode = info.InternalInformation.IndexNumber,
.size = @bitCast(u64, info.StandardInformation.EndOfFile),
.mode = 0,
.atime = windows.fromSysTime(info.BasicInformation.LastAccessTime),
.mtime = windows.fromSysTime(info.BasicInformation.LastWriteTime),
.ctime = windows.fromSysTime(info.BasicInformation.CreationTime),
};
}
const st = try os.fstat(self.handle);
const atime = st.atime();
const mtime = st.mtime();
const ctime = st.ctime();
return Stat{
.inode = st.ino,
.size = @bitCast(u64, st.size),
.mode = st.mode,
.atime = @as(i128, atime.tv_sec) * std.time.ns_per_s + atime.tv_nsec,
.mtime = @as(i128, mtime.tv_sec) * std.time.ns_per_s + mtime.tv_nsec,
.ctime = @as(i128, ctime.tv_sec) * std.time.ns_per_s + ctime.tv_nsec,
};
}
pub const UpdateTimesError = os.FutimensError || windows.SetFileTimeError;
/// The underlying file system may have a different granularity than nanoseconds,
/// and therefore this function cannot guarantee any precision will be stored.
/// Further, the maximum value is limited by the system ABI. When a value is provided
/// that exceeds this range, the value is clamped to the maximum.
/// TODO: integrate with async I/O
pub fn updateTimes(
self: File,
/// access timestamp in nanoseconds
atime: i128,
/// last modification timestamp in nanoseconds
mtime: i128,
) UpdateTimesError!void {
if (builtin.os.tag == .windows) {
const atime_ft = windows.nanoSecondsToFileTime(atime);
const mtime_ft = windows.nanoSecondsToFileTime(mtime);
return windows.SetFileTime(self.handle, null, &atime_ft, &mtime_ft);
}
const times = [2]os.timespec{
os.timespec{
.tv_sec = math.cast(isize, @divFloor(atime, std.time.ns_per_s)) catch maxInt(isize),
.tv_nsec = math.cast(isize, @mod(atime, std.time.ns_per_s)) catch maxInt(isize),
},
os.timespec{
.tv_sec = math.cast(isize, @divFloor(mtime, std.time.ns_per_s)) catch maxInt(isize),
.tv_nsec = math.cast(isize, @mod(mtime, std.time.ns_per_s)) catch maxInt(isize),
},
};
try os.futimens(self.handle, &times);
}
pub const ReadError = os.ReadError;
pub const PReadError = os.PReadError;
pub fn read(self: File, buffer: []u8) ReadError!usize {
if (is_windows) {
return windows.ReadFile(self.handle, buffer, null, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.read(self.handle, buffer);
} else {
return os.read(self.handle, buffer);
}
}
/// Returns the number of bytes read. If the number read is smaller than `buffer.len`, it
/// means the file reached the end. Reaching the end of a file is not an error condition.
pub fn readAll(self: File, buffer: []u8) ReadError!usize {
var index: usize = 0;
while (index != buffer.len) {
const amt = try self.read(buffer[index..]);
if (amt == 0) break;
index += amt;
}
return index;
}
pub fn pread(self: File, buffer: []u8, offset: u64) PReadError!usize {
if (is_windows) {
return windows.ReadFile(self.handle, buffer, offset, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.pread(self.handle, buffer, offset);
} else {
return os.pread(self.handle, buffer, offset);
}
}
/// Returns the number of bytes read. If the number read is smaller than `buffer.len`, it
/// means the file reached the end. Reaching the end of a file is not an error condition.
pub fn preadAll(self: File, buffer: []u8, offset: u64) PReadError!usize {
var index: usize = 0;
while (index != buffer.len) {
const amt = try self.pread(buffer[index..], offset + index);
if (amt == 0) break;
index += amt;
}
return index;
}
pub fn readv(self: File, iovecs: []const os.iovec) ReadError!usize {
if (is_windows) {
// TODO improve this to use ReadFileScatter
if (iovecs.len == 0) return @as(usize, 0);
const first = iovecs[0];
return windows.ReadFile(self.handle, first.iov_base[0..first.iov_len], null, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.readv(self.handle, iovecs);
} else {
return os.readv(self.handle, iovecs);
}
}
/// Returns the number of bytes read. If the number read is smaller than the total bytes
/// from all the buffers, it means the file reached the end. Reaching the end of a file
/// is not an error condition.
/// The `iovecs` parameter is mutable because this function needs to mutate the fields in
/// order to handle partial reads from the underlying OS layer.
pub fn readvAll(self: File, iovecs: []os.iovec) ReadError!usize {
if (iovecs.len == 0) return;
var i: usize = 0;
var off: usize = 0;
while (true) {
var amt = try self.readv(iovecs[i..]);
var eof = amt == 0;
off += amt;
while (amt >= iovecs[i].iov_len) {
amt -= iovecs[i].iov_len;
i += 1;
if (i >= iovecs.len) return off;
eof = false;
}
if (eof) return off;
iovecs[i].iov_base += amt;
iovecs[i].iov_len -= amt;
}
}
pub fn preadv(self: File, iovecs: []const os.iovec, offset: u64) PReadError!usize {
if (is_windows) {
// TODO improve this to use ReadFileScatter
if (iovecs.len == 0) return @as(usize, 0);
const first = iovecs[0];
return windows.ReadFile(self.handle, first.iov_base[0..first.iov_len], offset, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.preadv(self.handle, iovecs, offset);
} else {
return os.preadv(self.handle, iovecs, offset);
}
}
/// Returns the number of bytes read. If the number read is smaller than the total bytes
/// from all the buffers, it means the file reached the end. Reaching the end of a file
/// is not an error condition.
/// The `iovecs` parameter is mutable because this function needs to mutate the fields in
/// order to handle partial reads from the underlying OS layer.
pub fn preadvAll(self: File, iovecs: []const os.iovec, offset: u64) PReadError!void {
if (iovecs.len == 0) return;
var i: usize = 0;
var off: usize = 0;
while (true) {
var amt = try self.preadv(iovecs[i..], offset + off);
var eof = amt == 0;
off += amt;
while (amt >= iovecs[i].iov_len) {
amt -= iovecs[i].iov_len;
i += 1;
if (i >= iovecs.len) return off;
eof = false;
}
if (eof) return off;
iovecs[i].iov_base += amt;
iovecs[i].iov_len -= amt;
}
}
pub const WriteError = os.WriteError;
pub const PWriteError = os.PWriteError;
pub fn write(self: File, bytes: []const u8) WriteError!usize {
if (is_windows) {
return windows.WriteFile(self.handle, bytes, null, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.write(self.handle, bytes);
} else {
return os.write(self.handle, bytes);
}
}
pub fn writeAll(self: File, bytes: []const u8) WriteError!void {
var index: usize = 0;
while (index < bytes.len) {
index += try self.write(bytes[index..]);
}
}
pub fn pwrite(self: File, bytes: []const u8, offset: u64) PWriteError!usize {
if (is_windows) {
return windows.WriteFile(self.handle, bytes, offset, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.pwrite(self.handle, bytes, offset);
} else {
return os.pwrite(self.handle, bytes, offset);
}
}
pub fn pwriteAll(self: File, bytes: []const u8, offset: u64) PWriteError!void {
var index: usize = 0;
while (index < bytes.len) {
index += try self.pwrite(bytes[index..], offset + index);
}
}
pub fn writev(self: File, iovecs: []const os.iovec_const) WriteError!usize {
if (is_windows) {
// TODO improve this to use WriteFileScatter
if (iovecs.len == 0) return @as(usize, 0);
const first = iovecs[0];
return windows.WriteFile(self.handle, first.iov_base[0..first.iov_len], null, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.writev(self.handle, iovecs);
} else {
return os.writev(self.handle, iovecs);
}
}
/// The `iovecs` parameter is mutable because this function needs to mutate the fields in
/// order to handle partial writes from the underlying OS layer.
pub fn writevAll(self: File, iovecs: []os.iovec_const) WriteError!void {
if (iovecs.len == 0) return;
var i: usize = 0;
while (true) {
var amt = try self.writev(iovecs[i..]);
while (amt >= iovecs[i].iov_len) {
amt -= iovecs[i].iov_len;
i += 1;
if (i >= iovecs.len) return;
}
iovecs[i].iov_base += amt;
iovecs[i].iov_len -= amt;
}
}
pub fn pwritev(self: File, iovecs: []os.iovec_const, offset: usize) PWriteError!usize {
if (is_windows) {
// TODO improve this to use WriteFileScatter
if (iovecs.len == 0) return @as(usize, 0);
const first = iovecs[0];
return windows.WriteFile(self.handle, first.iov_base[0..first.iov_len], offset, self.intended_io_mode);
} else if (self.capable_io_mode != self.intended_io_mode) {
return std.event.Loop.instance.?.pwritev(self.handle, iovecs, offset);
} else {
return os.pwritev(self.handle, iovecs, offset);
}
}
/// The `iovecs` parameter is mutable because this function needs to mutate the fields in
/// order to handle partial writes from the underlying OS layer.
pub fn pwritevAll(self: File, iovecs: []os.iovec_const, offset: usize) PWriteError!void {
if (iovecs.len == 0) return;
var i: usize = 0;
var off: usize = 0;
while (true) {
var amt = try self.pwritev(iovecs[i..], offset + off);
off += amt;
while (amt >= iovecs[i].iov_len) {
amt -= iovecs[i].iov_len;
i += 1;
if (i >= iovecs.len) return;
}
iovecs[i].iov_base += amt;
iovecs[i].iov_len -= amt;
}
}
pub const CopyRangeError = PWriteError || PReadError;
pub fn copyRange(in: File, in_offset: u64, out: File, out_offset: u64, len: usize) CopyRangeError!usize {
// TODO take advantage of copy_file_range OS APIs
var buf: [8 * 4096]u8 = undefined;
const adjusted_count = math.min(buf.len, len);
const amt_read = try in.pread(buf[0..adjusted_count], in_offset);
if (amt_read == 0) return @as(usize, 0);
return out.pwrite(buf[0..amt_read], out_offset);
}
/// Returns the number of bytes copied. If the number read is smaller than `buffer.len`, it
/// means the in file reached the end. Reaching the end of a file is not an error condition.
pub fn copyRangeAll(in: File, in_offset: u64, out: File, out_offset: u64, len: usize) CopyRangeError!usize {
var total_bytes_copied: usize = 0;
var in_off = in_offset;
var out_off = out_offset;
while (total_bytes_copied < len) {
const amt_copied = try copyRange(in, in_off, out, out_off, len - total_bytes_copied);
if (amt_copied == 0) return total_bytes_copied;
total_bytes_copied += amt_copied;
in_off += amt_copied;
out_off += amt_copied;
}
return total_bytes_copied;
}
pub const WriteFileOptions = struct {
in_offset: u64 = 0,
/// `null` means the entire file. `0` means no bytes from the file.
/// When this is `null`, trailers must be sent in a separate writev() call
/// due to a flaw in the BSD sendfile API. Other operating systems, such as
/// Linux, already do this anyway due to API limitations.
/// If the size of the source file is known, passing the size here will save one syscall.
in_len: ?u64 = null,
headers_and_trailers: []os.iovec_const = &[0]os.iovec_const{},
/// The trailer count is inferred from `headers_and_trailers.len - header_count`
header_count: usize = 0,
};
pub const WriteFileError = os.SendFileError;
/// TODO integrate with async I/O
pub fn writeFileAll(self: File, in_file: File, args: WriteFileOptions) WriteFileError!void {
const count = blk: {
if (args.in_len) |l| {
if (l == 0) {
return self.writevAll(args.headers_and_trailers);
} else {
break :blk l;
}
} else {
break :blk 0;
}
};
const headers = args.headers_and_trailers[0..args.header_count];
const trailers = args.headers_and_trailers[args.header_count..];
const zero_iovec = &[0]os.iovec_const{};
// When reading the whole file, we cannot put the trailers in the sendfile() syscall,
// because we have no way to determine whether a partial write is past the end of the file or not.
const trls = if (count == 0) zero_iovec else trailers;
const offset = args.in_offset;
const out_fd = self.handle;
const in_fd = in_file.handle;
const flags = 0;
var amt: usize = 0;
hdrs: {
var i: usize = 0;
while (i < headers.len) {
amt = try os.sendfile(out_fd, in_fd, offset, count, headers[i..], trls, flags);
while (amt >= headers[i].iov_len) {
amt -= headers[i].iov_len;
i += 1;
if (i >= headers.len) break :hdrs;
}
headers[i].iov_base += amt;
headers[i].iov_len -= amt;
}
}
if (count == 0) {
var off: u64 = amt;
while (true) {
amt = try os.sendfile(out_fd, in_fd, offset + off, 0, zero_iovec, zero_iovec, flags);
if (amt == 0) break;
off += amt;
}
} else {
var off: u64 = amt;
while (off < count) {
amt = try os.sendfile(out_fd, in_fd, offset + off, count - off, zero_iovec, trailers, flags);
off += amt;
}
amt = @intCast(usize, off - count);
}
var i: usize = 0;
while (i < trailers.len) {
while (amt >= headers[i].iov_len) {
amt -= trailers[i].iov_len;
i += 1;
if (i >= trailers.len) return;
}
trailers[i].iov_base += amt;
trailers[i].iov_len -= amt;
amt = try os.writev(self.handle, trailers[i..]);
}
}
pub const Reader = io.Reader(File, ReadError, read);
/// Deprecated: use `Reader`
pub const InStream = Reader;
pub fn reader(file: File) io.Reader(File, ReadError, read) {
return .{ .context = file };
}
/// Deprecated: use `reader`
pub fn inStream(file: File) io.InStream(File, ReadError, read) {
return .{ .context = file };
}
pub const Writer = io.Writer(File, WriteError, write);
/// Deprecated: use `Writer`
pub const OutStream = Writer;
pub fn writer(file: File) Writer {
return .{ .context = file };
}
/// Deprecated: use `writer`
pub fn outStream(file: File) Writer {
return .{ .context = file };
}
pub const SeekableStream = io.SeekableStream(
File,
SeekError,
GetPosError,
seekTo,
seekBy,
getPos,
getEndPos,
);
pub fn seekableStream(file: File) SeekableStream {
return .{ .context = file };
}
};