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//! This file contains thin wrappers around OS-specific APIs, with these
//! specific goals in mind:
//! * Convert "errno"-style error codes into Zig errors.
//! * When null-terminated byte buffers are required, provide APIs which accept
//! slices as well as APIs which accept null-terminated byte buffers. Same goes
//! for UTF-16LE encoding.
//! * Where operating systems share APIs, e.g. POSIX, these thin wrappers provide
//! cross platform abstracting.
//! * When there exists a corresponding libc function and linking libc, the libc
//! implementation is used. Exceptions are made for known buggy areas of libc.
//! On Linux libc can be side-stepped by using `std.os.linux` directly.
//! * For Windows, this file represents the API that libc would provide for
//! Windows. For thin wrappers around Windows-specific APIs, see `std.os.windows`.
//! Note: The Zig standard library does not support POSIX thread cancellation, and
//! in general EINTR is handled by trying again.
const root = @import("root");
const std = @import("std.zig");
const builtin = @import("builtin");
const assert = std.debug.assert;
const math = std.math;
const mem = std.mem;
const elf = std.elf;
const fs = std.fs;
const dl = @import("dynamic_library.zig");
const MAX_PATH_BYTES = std.fs.MAX_PATH_BYTES;
const is_windows = builtin.os.tag == .windows;
const Allocator = std.mem.Allocator;
const Preopen = std.fs.wasi.Preopen;
const PreopenList = std.fs.wasi.PreopenList;
pub const darwin = @import("os/darwin.zig");
pub const dragonfly = std.c;
pub const freebsd = std.c;
pub const haiku = std.c;
pub const netbsd = std.c;
pub const openbsd = std.c;
pub const solaris = std.c;
pub const linux = @import("os/linux.zig");
pub const plan9 = @import("os/plan9.zig");
pub const uefi = @import("os/uefi.zig");
pub const wasi = @import("os/wasi.zig");
pub const windows = @import("os/windows.zig");
pub const posix_spawn = @import("os/posix_spawn.zig");
comptime {
assert(@import("std") == std); // std lib tests require --zig-lib-dir
}
test {
_ = darwin;
_ = linux;
_ = uefi;
_ = wasi;
_ = windows;
_ = posix_spawn;
_ = @import("os/test.zig");
}
/// Applications can override the `system` API layer in their root source file.
/// Otherwise, when linking libc, this is the C API.
/// When not linking libc, it is the OS-specific system interface.
pub const system = if (@hasDecl(root, "os") and root.os != @This())
root.os.system
else if (builtin.link_libc or is_windows)
std.c
else switch (builtin.os.tag) {
.linux => linux,
.wasi => wasi,
.uefi => uefi,
else => struct {},
};
pub const AF = system.AF;
pub const AF_SUN = system.AF_SUN;
pub const ARCH = system.ARCH;
pub const AT = system.AT;
pub const AT_SUN = system.AT_SUN;
pub const CLOCK = system.CLOCK;
pub const CPU_COUNT = system.CPU_COUNT;
pub const CTL = system.CTL;
pub const DT = system.DT;
pub const E = system.E;
pub const Elf_Symndx = system.Elf_Symndx;
pub const F = system.F;
pub const FD_CLOEXEC = system.FD_CLOEXEC;
pub const Flock = system.Flock;
pub const HOST_NAME_MAX = system.HOST_NAME_MAX;
pub const IFNAMESIZE = system.IFNAMESIZE;
pub const IOV_MAX = system.IOV_MAX;
pub const IPPROTO = system.IPPROTO;
pub const KERN = system.KERN;
pub const Kevent = system.Kevent;
pub const LOCK = system.LOCK;
pub const MADV = system.MADV;
pub const MAP = system.MAP;
pub const MSF = system.MSF;
pub const MAX_ADDR_LEN = system.MAX_ADDR_LEN;
pub const MMAP2_UNIT = system.MMAP2_UNIT;
pub const MSG = system.MSG;
pub const NAME_MAX = system.NAME_MAX;
pub const O = switch (builtin.os.tag) {
// We want to expose the POSIX-like OFLAGS, so we use std.c.wasi.O instead
// of std.os.wasi.O, which is for non-POSIX-like `wasi.path_open`, etc.
.wasi => std.c.O,
else => system.O,
};
pub const PATH_MAX = system.PATH_MAX;
pub const POLL = system.POLL;
pub const POSIX_FADV = system.POSIX_FADV;
pub const PR = system.PR;
pub const PROT = system.PROT;
pub const REG = system.REG;
pub const RIGHT = system.RIGHT;
pub const RLIM = system.RLIM;
pub const RR = system.RR;
pub const S = system.S;
pub const SA = system.SA;
pub const SC = system.SC;
pub const _SC = system._SC;
pub const SEEK = system.SEEK;
pub const SHUT = system.SHUT;
pub const SIG = system.SIG;
pub const SIOCGIFINDEX = system.SIOCGIFINDEX;
pub const SO = system.SO;
pub const SOCK = system.SOCK;
pub const SOL = system.SOL;
pub const STDERR_FILENO = system.STDERR_FILENO;
pub const STDIN_FILENO = system.STDIN_FILENO;
pub const STDOUT_FILENO = system.STDOUT_FILENO;
pub const SYS = system.SYS;
pub const Sigaction = system.Sigaction;
pub const Stat = system.Stat;
pub const TCSA = system.TCSA;
pub const TCP = system.TCP;
pub const VDSO = system.VDSO;
pub const W = system.W;
pub const addrinfo = system.addrinfo;
pub const blkcnt_t = system.blkcnt_t;
pub const blksize_t = system.blksize_t;
pub const clock_t = system.clock_t;
pub const cpu_set_t = system.cpu_set_t;
pub const dev_t = system.dev_t;
pub const dl_phdr_info = system.dl_phdr_info;
pub const empty_sigset = system.empty_sigset;
pub const fd_t = system.fd_t;
pub const fdflags_t = system.fdflags_t;
pub const fdstat_t = system.fdstat_t;
pub const gid_t = system.gid_t;
pub const ifreq = system.ifreq;
pub const ino_t = system.ino_t;
pub const lookupflags_t = system.lookupflags_t;
pub const mcontext_t = system.mcontext_t;
pub const mode_t = system.mode_t;
pub const msghdr = system.msghdr;
pub const msghdr_const = system.msghdr_const;
pub const nfds_t = system.nfds_t;
pub const nlink_t = system.nlink_t;
pub const off_t = system.off_t;
pub const oflags_t = system.oflags_t;
pub const pid_t = system.pid_t;
pub const pollfd = system.pollfd;
pub const port_t = system.port_t;
pub const port_event = system.port_event;
pub const port_notify = system.port_notify;
pub const file_obj = system.file_obj;
pub const rights_t = system.rights_t;
pub const rlim_t = system.rlim_t;
pub const rlimit = system.rlimit;
pub const rlimit_resource = system.rlimit_resource;
pub const rusage = system.rusage;
pub const sa_family_t = system.sa_family_t;
pub const siginfo_t = system.siginfo_t;
pub const sigset_t = system.sigset_t;
pub const sockaddr = system.sockaddr;
pub const socklen_t = system.socklen_t;
pub const stack_t = system.stack_t;
pub const tcflag_t = system.tcflag_t;
pub const termios = system.termios;
pub const time_t = system.time_t;
pub const timespec = system.timespec;
pub const timestamp_t = system.timestamp_t;
pub const timeval = system.timeval;
pub const timezone = system.timezone;
pub const ucontext_t = system.ucontext_t;
pub const uid_t = system.uid_t;
pub const user_desc = system.user_desc;
pub const utsname = system.utsname;
pub const F_OK = system.F_OK;
pub const R_OK = system.R_OK;
pub const W_OK = system.W_OK;
pub const X_OK = system.X_OK;
pub const iovec = extern struct {
iov_base: [*]u8,
iov_len: usize,
};
pub const iovec_const = extern struct {
iov_base: [*]const u8,
iov_len: usize,
};
pub const LOG = struct {
/// system is unusable
pub const EMERG = 0;
/// action must be taken immediately
pub const ALERT = 1;
/// critical conditions
pub const CRIT = 2;
/// error conditions
pub const ERR = 3;
/// warning conditions
pub const WARNING = 4;
/// normal but significant condition
pub const NOTICE = 5;
/// informational
pub const INFO = 6;
/// debug-level messages
pub const DEBUG = 7;
};
/// An fd-relative file path
///
/// This is currently only used for WASI-specific functionality, but the concept
/// is the same as the dirfd/pathname pairs in the `*at(...)` POSIX functions.
pub const RelativePathWasi = struct {
/// Handle to directory
dir_fd: fd_t,
/// Path to resource within `dir_fd`.
relative_path: []const u8,
};
pub const socket_t = if (builtin.os.tag == .windows) windows.ws2_32.SOCKET else fd_t;
/// See also `getenv`. Populated by startup code before main().
/// TODO this is a footgun because the value will be undefined when using `zig build-lib`.
/// https://github.com/ziglang/zig/issues/4524
pub var environ: [][*:0]u8 = undefined;
/// Populated by startup code before main().
/// Not available on WASI or Windows without libc. See `std.process.argsAlloc`
/// or `std.process.argsWithAllocato
10BC8
r` for a cross-platform alternative.
pub var argv: [][*:0]u8 = if (builtin.link_libc) undefined else switch (builtin.os.tag) {
.windows => @compileError("argv isn't supported on Windows: use std.process.argsAlloc instead"),
.wasi => @compileError("argv isn't supported on WASI: use std.process.argsAlloc instead"),
else => undefined,
};
/// To obtain errno, call this function with the return value of the
/// system function call. For some systems this will obtain the value directly
/// from the return code; for others it will use a thread-local errno variable.
/// Therefore, this function only returns a well-defined value when it is called
/// directly after the system function call which one wants to learn the errno
/// value of.
pub const errno = system.getErrno;
/// Closes the file descriptor.
/// This function is not capable of returning any indication of failure. An
/// application which wants to ensure writes have succeeded before closing
/// must call `fsync` before `close`.
/// Note: The Zig standard library does not support POSIX thread cancellation.
pub fn close(fd: fd_t) void {
if (builtin.os.tag == .windows) {
return windows.CloseHandle(fd);
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
_ = wasi.fd_close(fd);
return;
}
if (comptime builtin.target.isDarwin()) {
// This avoids the EINTR problem.
switch (darwin.getErrno(darwin.@"close$NOCANCEL"(fd))) {
.BADF => unreachable, // Always a race condition.
else => return,
}
}
switch (errno(system.close(fd))) {
.BADF => unreachable, // Always a race condition.
.INTR => return, // This is still a success. See https://github.com/ziglang/zig/issues/2425
else => return,
}
}
pub const FChmodError = error{
AccessDenied,
InputOutput,
SymLinkLoop,
FileNotFound,
SystemResources,
ReadOnlyFileSystem,
} || UnexpectedError;
/// Changes the mode of the file referred to by the file descriptor.
/// The process must have the correct privileges in order to do this
/// successfully, or must have the effective user ID matching the owner
/// of the file.
pub fn fchmod(fd: fd_t, mode: mode_t) FChmodError!void {
if (builtin.os.tag == .windows or builtin.os.tag == .wasi)
@compileError("Unsupported OS");
while (true) {
const res = system.fchmod(fd, mode);
switch (system.getErrno(res)) {
.SUCCESS => return,
.INTR => continue,
.BADF => unreachable, // Can be reached if the fd refers to a directory opened without `OpenDirOptions{ .iterate = true }`
.FAULT => unreachable,
.INVAL => unreachable,
.ACCES => return error.AccessDenied,
.IO => return error.InputOutput,
.LOOP => return error.SymLinkLoop,
.NOENT => return error.FileNotFound,
.NOMEM => return error.SystemResources,
.NOTDIR => return error.FileNotFound,
.PERM => return error.AccessDenied,
.ROFS => return error.ReadOnlyFileSystem,
else => |err| return unexpectedErrno(err),
}
}
}
pub const FChownError = error{
AccessDenied,
InputOutput,
SymLinkLoop,
FileNotFound,
SystemResources,
ReadOnlyFileSystem,
} || UnexpectedError;
/// Changes the owner and group of the file referred to by the file descriptor.
/// The process must have the correct privileges in order to do this
/// successfully. The group may be changed by the owner of the directory to
/// any group of which the owner is a member. If the owner or group is
/// specified as `null`, the ID is not changed.
pub fn fchown(fd: fd_t, owner: ?uid_t, group: ?gid_t) FChownError!void {
if (builtin.os.tag == .windows or builtin.os.tag == .wasi)
@compileError("Unsupported OS");
while (true) {
const res = system.fchown(fd, owner orelse @as(u32, 0) -% 1, group orelse @as(u32, 0) -% 1);
switch (system.getErrno(res)) {
.SUCCESS => return,
.INTR => continue,
.BADF => unreachable, // Can be reached if the fd refers to a directory opened without `OpenDirOptions{ .iterate = true }`
.FAULT => unreachable,
.INVAL => unreachable,
.ACCES => return error.AccessDenied,
.IO => return error.InputOutput,
.LOOP => return error.SymLinkLoop,
.NOENT => return error.FileNotFound,
.NOMEM => return error.SystemResources,
.NOTDIR => return error.FileNotFound,
.PERM => return error.AccessDenied,
.ROFS => return error.ReadOnlyFileSystem,
else => |err| return unexpectedErrno(err),
}
}
}
pub const GetRandomError = OpenError;
/// Obtain a series of random bytes. These bytes can be used to seed user-space
/// random number generators or for cryptographic purposes.
/// When linking against libc, this calls the
/// appropriate OS-specific library call. Otherwise it uses the zig standard
/// library implementation.
pub fn getrandom(buffer: []u8) GetRandomError!void {
if (builtin.os.tag == .windows) {
return windows.RtlGenRandom(buffer);
}
if (builtin.os.tag == .linux or builtin.os.tag == .freebsd) {
var buf = buffer;
const use_c = builtin.os.tag != .linux or
std.c.versionCheck(std.builtin.Version{ .major = 2, .minor = 25, .patch = 0 }).ok;
while (buf.len != 0) {
const res = if (use_c) blk: {
const rc = std.c.getrandom(buf.ptr, buf.len, 0);
break :blk .{
.num_read = @bitCast(usize, rc),
.err = std.c.getErrno(rc),
};
} else blk: {
const rc = linux.getrandom(buf.ptr, buf.len, 0);
break :blk .{
.num_read = rc,
.err = linux.getErrno(rc),
};
};
switch (res.err) {
.SUCCESS => buf = buf[res.num_read..],
.INVAL => unreachable,
.FAULT => unreachable,
.INTR => continue,
.NOSYS => return getRandomBytesDevURandom(buf),
else => return unexpectedErrno(res.err),
}
}
return;
}
switch (builtin.os.tag) {
.netbsd, .openbsd, .macos, .ios, .tvos, .watchos => {
system.arc4random_buf(buffer.ptr, buffer.len);
return;
},
.wasi => switch (wasi.random_get(buffer.ptr, buffer.len)) {
.SUCCESS => return,
else => |err| return unexpectedErrno(err),
},
else => return getRandomBytesDevURandom(buffer),
}
}
fn getRandomBytesDevURandom(buf: []u8) !void {
const fd = try openZ("/dev/urandom", O.RDONLY | O.CLOEXEC, 0);
defer close(fd);
const st = try fstat(fd);
if (!S.ISCHR(st.mode)) {
return error.NoDevice;
}
const file = std.fs.File{
.handle = fd,
.capable_io_mode = .blocking,
.intended_io_mode = .blocking,
};
const stream = file.reader();
stream.readNoEof(buf) catch return error.Unexpected;
}
/// Causes abnormal process termination.
/// If linking against libc, this calls the abort() libc function. Otherwise
/// it raises SIGABRT followed by SIGKILL and finally lo
pub fn abort() noreturn {
@setCold(true);
// MSVCRT abort() sometimes opens a popup window which is undesirable, so
// even when linking libc on Windows we use our own abort implementation.
// See https://github.com/ziglang/zig/issues/2071 for more details.
if (builtin.os.tag == .windows) {
if (builtin.mode == .Debug) {
@breakpoint();
}
windows.kernel32.ExitProcess(3);
}
if (!builtin.link_libc and builtin.os.tag == .linux) {
raise(SIG.ABRT) catch {};
// TODO the rest of the implementation of abort() from musl libc here
raise(SIG.KILL) catch {};
exit(127);
}
if (builtin.os.tag == .uefi) {
exit(0); // TODO choose appropriate exit code
}
if (builtin.os.tag == .wasi) {
@breakpoint();
exit(1);
}
system.abort();
}
pub const RaiseError = UnexpectedError;
pub fn raise(sig: u8) RaiseError!void {
if (builtin.link_libc) {
switch (errno(system.raise(sig))) {
.SUCCESS => return,
else => |err| return unexpectedErrno(err),
}
}
if (builtin.os.tag == .linux) {
var set: sigset_t = undefined;
// block application signals
_ = linux.sigprocmask(SIG.BLOCK, &linux.app_mask, &set);
const tid = linux.gettid();
const rc = linux.tkill(tid, sig);
// restore signal mask
_ = linux.sigprocmask(SIG.SETMASK, &set, null);
switch (errno(rc)) {
.SUCCESS => return,
else => |err| return unexpectedErrno(err),
}
}
@compileError("std.os.raise unimplemented for this target");
}
pub const KillError = error{PermissionDenied} || UnexpectedError;
pub fn kill(pid: pid_t, sig: u8) KillError!void {
switch (errno(system.kill(pid, sig))) {
.SUCCESS => return,
.INVAL => unreachable, // invalid signal
.PERM => return error.PermissionDenied,
.SRCH => unreachable, // always a race condition
else => |err| return unexpectedErrno(err),
}
}
/// Exits the program cleanly with the specified status code.
pub fn exit(status: u8) noreturn {
if (builtin.link_libc) {
system.exit(status);
}
if (builtin.os.tag == .windows) {
windows.kernel32.ExitProcess(status);
}
if (builtin.os.tag == .wasi) {
wasi.proc_exit(status);
}
if (builtin.os.tag == .linux and !builtin.single_threaded) {
linux.exit_group(status);
}
if (builtin.os.tag == .uefi) {
// exit() is only avaliable if exitBootServices() has not been called yet.
// This call to exit should not fail, so we don't care about its return value.
if (uefi.system_table.boot_services) |bs| {
_ = bs.exit(uefi.handle, @intToEnum(uefi.Status, status), 0, null);
}
// If we can't exit, reboot the system instead.
uefi.system_table.runtime_services.resetSystem(uefi.tables.ResetType.ResetCold, @intToEnum(uefi.Status, status), 0, null);
}
system.exit(status);
}
pub const ReadError = error{
InputOutput,
SystemResources,
IsDir,
OperationAborted,
BrokenPipe,
ConnectionResetByPeer,
ConnectionTimedOut,
NotOpenForReading,
/// This error occurs when no global event loop is configured,
/// and reading from the file descriptor would block.
WouldBlock,
/// In WASI, this error occurs when the file descriptor does
/// not hold the required rights to read from it.
AccessDenied,
} || UnexpectedError;
/// Returns the number of bytes that were read, which can be less than
/// buf.len. If 0 bytes were read, that means EOF.
/// If `fd` is opened in non blocking mode, the function will return error.WouldBlock
/// when EAGAIN is received.
///
/// Linux has a limit on how many bytes may be transferred in one `read` call, which is `0x7ffff000`
/// on both 64-bit and 32-bit systems. This is due to using a signed C int as the return value, as
/// well as stuffing the errno codes into the last `4096` values. This is noted on the `read` man page.
/// The limit on Darwin is `0x7fffffff`, trying to read more than that returns EINVAL.
/// The corresponding POSIX limit is `math.maxInt(isize)`.
pub fn read(fd: fd_t, buf: []u8) ReadError!usize {
if (builtin.os.tag == .windows) {
return windows.ReadFile(fd, buf, null, std.io.default_mode);
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
const iovs = [1]iovec{iovec{
.iov_base = buf.ptr,
.iov_len = buf.len,
}};
var nread: usize = undefined;
switch (wasi.fd_read(fd, &iovs, iovs.len, &nread)) {
.SUCCESS => return nread,
.INTR => unreachable,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => unreachable,
.BADF => return error.NotOpenForReading, // Can be a race condition.
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.CONNRESET => return error.ConnectionResetByPeer,
.TIMEDOUT => return error.ConnectionTimedOut,
.NOTCAPABLE => return error.AccessDenied,
else => |err| return unexpectedErrno(err),
}
}
// Prevents EINVAL.
const max_count = switch (builtin.os.tag) {
.linux => 0x7ffff000,
.macos, .ios, .watchos, .tvos => math.maxInt(i32),
else => math.maxInt(isize),
};
const adjusted_len = @minimum(max_count, buf.len);
while (true) {
const rc = system.read(fd, buf.ptr, adjusted_len);
switch (errno(rc)) {
.SUCCESS => return @intCast(usize, rc),
.INTR => continue,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForReading, // Can be a race condition.
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.CONNRESET => return error.ConnectionResetByPeer,
.TIMEDOUT => return error.ConnectionTimedOut,
else => |err| return unexpectedErrno(err),
}
}
}
/// Number of bytes read is returned. Upon reading end-of-file, zero is returned.
///
/// For POSIX systems, if `fd` is opened in non blocking mode, the function will
/// return error.WouldBlock when EAGAIN is received.
/// On Windows, if the application has a global event loop enabled, I/O Completion Ports are
/// used to perform the I/O. `error.WouldBlock` is not possible on Windows.
///
/// This operation is non-atomic on the following systems:
/// * Windows
/// On these systems, the read races with concurrent writes to the same file descriptor.
pub fn readv(fd: fd_t, iov: []const iovec) ReadError!usize {
if (builtin.os.tag == .windows) {
// TODO improve this to use ReadFileScatter
if (iov.len == 0) return @as(usize, 0);
const first = iov[0];
return read(fd, first.iov_base[0..first.iov_len]);
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
var nread: usize = undefined;
switch (wasi.fd_read(fd, iov.ptr, iov.len, &nread)) {
.SUCCESS => return nread,
.INTR => unreachable,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => unreachable, // currently not support in WASI
.BADF => return error.NotOpenForReading, // can be a race condition
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.NOTCAPABLE => return error.AccessDenied,
else => |err| return unexpectedErrno(err),
}
}
const iov_count = math.cast(u31, iov.len) catch math.maxInt(u31);
while (true) {
// TODO handle the case when iov_len is too large and get rid of this @intCast
const rc = system.readv(fd, iov.ptr, iov_count);
switch (errno(rc)) {
.SUCCESS => return @intCast(usize, rc),
.INTR => continue,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForReading, // can be a race condition
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
else => |err| return unexpectedErrno(err),
}
}
}
pub const PReadError = ReadError || error{Unseekable};
/// Number of bytes read is returned. Upon reading end-of-file, zero is returned.
///
/// Retries when interrupted by a signal.
///
/// For POSIX systems, if `fd` is opened in non blocking mode, the function will
/// return error.WouldBlock when EAGAIN is received.
/// On Windows, if the application has a global event loop enabled, I/O Completion Ports are
/// used to perform the I/O. `error.WouldBlock` is not possible on Windows.
///
/// Linux has a limit on how many bytes may be transferred in one `pread` call, which is `0x7ffff000`
/// on both 64-bit and 32-bit systems. This is due to using a signed C int as the return value, as
/// well as stuffing the errno codes into the last `4096` values. This is noted on the `read` man page.
/// The limit on Darwin is `0x7fffffff`, trying to read more than that returns EINVAL.
/// The corresponding POSIX limit is `math.maxInt(isize)`.
pub fn pread(fd: fd_t, buf: []u8, offset: u64) PReadError!usize {
if (builtin.os.tag == .windows) {
return windows.ReadFile(fd, buf, offset, std.io.default_mode);
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
const iovs = [1]iovec{iovec{
.iov_base = buf.ptr,
.iov_len = buf.len,
}};
var nread: usize = undefined;
switch (wasi.fd_pread(fd, &iovs, iovs.len, offset, &nread)) {
.SUCCESS => return nread,
.INTR => unreachable,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => unreachable,
.BADF => return error.NotOpenForReading, // Can be a race condition.
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.CONNRESET => return error.ConnectionResetByPeer,
.NXIO => return error.Unseekable,
.SPIPE => return error.Unseekable,
.OVERFLOW => return error.Unseekable,
.NOTCAPABLE => return error.AccessDenied,
else => |err| return unexpectedErrno(err),
}
}
// Prevent EINVAL.
const max_count = switch (builtin.os.tag) {
.linux => 0x7ffff000,
.macos, .ios, .watchos, .tvos => math.maxInt(i32),
else => math.maxInt(isize),
};
const adjusted_len = @minimum(max_count, buf.len);
const pread_sym = if (builtin.os.tag == .linux and builtin.link_libc)
system.pread64
else
system.pread;
const ioffset = @bitCast(i64, offset); // the OS treats this as unsigned
while (true) {
const rc = pread_sym(fd, buf.ptr, adjusted_len, ioffset);
switch (errno(rc)) {
.SUCCESS => return @intCast(usize, rc),
.INTR => continue,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForReading, // Can be a race condition.
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.CONNRESET => return error.ConnectionResetByPeer,
.NXIO => return error.Unseekable,
.SPIPE => return error.Unseekable,
.OVERFLOW => return error.Unseekable,
else => |err| return unexpectedErrno(err),
}
}
}
pub const TruncateError = error{
FileTooBig,
InputOutput,
FileBusy,
/// In WASI, this error occurs when the file descriptor does
/// not hold the required rights to call `ftruncate` on it.
AccessDenied,
} || UnexpectedError;
pub fn ftruncate(fd: fd_t, length: u64) TruncateError!void {
if (builtin.os.tag == .windows) {
var io_status_block: windows.IO_STATUS_BLOCK = undefined;
var eof_info = windows.FILE_END_OF_FILE_INFORMATION{
.EndOfFile = @bitCast(windows.LARGE_INTEGER, length),
};
const rc = windows.ntdll.NtSetInformationFile(
fd,
&io_status_block,
&eof_info,
@sizeOf(windows.FILE_END_OF_FILE_INFORMATION),
.FileEndOfFileInformation,
);
switch (rc) {
.SUCCESS => return,
.INVALID_HANDLE => unreachable, // Handle not open for writing
.ACCESS_DENIED => return error.AccessDenied,
else => return windows.unexpectedStatus(rc),
}
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
switch (wasi.fd_filestat_set_size(fd, length)) {
.SUCCESS => return,
.INTR => unreachable,
.FBIG => return error.FileTooBig,
.IO => return error.InputOutput,
.PERM => return error.AccessDenied,
.TXTBSY => return error.FileBusy,
.BADF => unreachable, // Handle not open for writing
.INVAL => unreachable, // Handle not open for writing
.NOTCAPABLE => return error.AccessDenied,
else => |err| return unexpectedErrno(err),
}
}
while (true) {
const ftruncate_sym = if (builtin.os.tag == .linux and builtin.link_libc)
system.ftruncate64
else
system.ftruncate;
const ilen = @bitCast(i64, length); // the OS treats this as unsigned
switch (errno(ftruncate_sym(fd, ilen))) {
.SUCCESS => return,
.INTR => continue,
.FBIG => return error.FileTooBig,
.IO => return error.InputOutput,
.PERM => return error.AccessDenied,
.TXTBSY => return error.FileBusy,
.BADF => unreachable, // Handle not open for writing
.INVAL => unreachable, // Handle not open for writing
else => |err| return unexpectedErrno(err),
}
}
}
/// Number of bytes read is returned. Upon reading end-of-file, zero is returned.
///
/// Retries when interrupted by a signal.
///
/// For POSIX systems, if `fd` is opened in non blocking mode, the function will
/// return error.WouldBlock when EAGAIN is received.
/// On Windows, if the application has a global event loop enabled, I/O Completion Ports are
/// used to perform the I/O. `error.WouldBlock` is not possible on Windows.
///
/// This operation is non-atomic on the following systems:
/// * Darwin
/// * Windows
/// On these systems, the read races with concurrent writes to the same file descriptor.
pub fn preadv(fd: fd_t, iov: []const iovec, offset: u64) PReadError!usize {
const have_pread_but_not_preadv = switch (builtin.os.tag) {
.windows, .macos, .ios, .watchos, .tvos, .haiku => true,
else => false,
};
if (have_pread_but_not_preadv) {
// We could loop here; but proper usage of `preadv` must handle partial reads anyway.
// So we simply read into the first vector only.
if (iov.len == 0) return @as(usize, 0);
const first = iov[0];
return pread(fd, first.iov_base[0..first.iov_len], offset);
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
var nread: usize = undefined;
switch (wasi.fd_pread(fd, iov.ptr, iov.len, offset, &nread)) {
.SUCCESS => return nread,
.INTR => unreachable,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => unreachable,
.BADF => return error.NotOpenForReading, // can be a race condition
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.NXIO => return error.Unseekable,
.SPIPE => return error.Unseekable,
.OVERFLOW => return error.Unseekable,
.NOTCAPABLE => return error.AccessDenied,
else => |err| return unexpectedErrno(err),
}
}
const iov_count = math.cast(u31, iov.len) catch math.maxInt(u31);
const preadv_sym = if (builtin.os.tag == .linux and builtin.link_libc)
system.preadv64
else
system.preadv;
const ioffset = @bitCast(i64, offset); // the OS treats this as unsigned
while (true) {
const rc = preadv_sym(fd, iov.ptr, iov_count, ioffset);
switch (errno(rc)) {
.SUCCESS => return @bitCast(usize, rc),
.INTR => continue,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForReading, // can be a race condition
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.NXIO => return error.Unseekable,
.SPIPE => return error.Unseekable,
.OVERFLOW => return error.Unseekable,
else => |err| return unexpectedErrno(err),
}
}
}
pub const WriteError = error{
DiskQuota,
FileTooBig,
InputOutput,
NoSpaceLeft,
/// In WASI, this error may occur when the file descriptor does
/// not hold the required rights to write to it.
AccessDenied,
BrokenPipe,
SystemResources,
OperationAborted,
NotOpenForWriting,
/// This error occurs when no global event loop is configured,
/// and reading from the file descriptor would block.
WouldBlock,
/// Connection reset by peer.
ConnectionResetByPeer,
} || UnexpectedError;
/// Write to a file descriptor.
/// Retries when interrupted by a signal.
/// Returns the number of bytes written. If nonzero bytes were supplied, this will be nonzero.
///
/// Note that a successful write() may transfer fewer than count bytes. Such partial writes can
/// occur for various reasons; for example, because there was insufficient space on the disk
/// device to write all of the requested bytes, or because a blocked write() to a socket, pipe, or
/// similar was interrupted by a signal handler after it had transferred some, but before it had
/// transferred all of the requested bytes. In the event of a partial write, the caller can make
/// another write() call to transfer the remaining bytes. The subsequent call will either
/// transfer further bytes or may result in an error (e.g., if the disk is now full).
///
/// For POSIX systems, if `fd` is opened in non blocking mode, the function will
/// return error.WouldBlock when EAGAIN is received.
/// On Windows, if the application has a global event loop enabled, I/O Completion Ports are
/// used to perform the I/O. `error.WouldBlock` is not possible on Windows.
///
/// Linux has a limit on how many bytes may be transferred in one `write` call, which is `0x7ffff000`
/// on both 64-bit and 32-bit systems. This is due to using a signed C int as the return value, as
/// well as stuffing the errno codes into the last `4096` values. This is noted on the `write` man page.
/// The limit on Darwin is `0x7fffffff`, trying to read more than that returns EINVAL.
/// The corresponding POSIX limit is `math.maxInt(isize)`.
pub fn write(fd: fd_t, bytes: []const u8) WriteError!usize {
if (builtin.os.tag == .windows) {
return windows.WriteFile(fd, bytes, null, std.io.default_mode);
}
if (builtin.os.tag == .wasi and !builtin.link_libc) {
const ciovs = [_]iovec_const{iovec_const{
.iov_base = bytes.ptr,
.iov_len = bytes.len,
}};
var nwritten: usize = undefined;
switch (wasi.fd_write(fd, &ciovs, ciovs.len, &nwritten)) {
.SUCCESS => return nwritten,
.INTR => unreachable,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => unreachable,
.BADF => return error.NotOpenForWriting, // can be a race condition.
.DESTADDRREQ => unreachable, // `connect` was never called.
.DQUOT => return error.DiskQuota,
.FBIG => return error.FileTooBig,
.IO => return error.InputOutput,
.NOSPC => return error.NoSpaceLeft,
.PERM => return error.AccessDenied,
.PIPE => return error.BrokenPipe,
.NOTCAPABLE => return error.AccessDenied,
else => |err| return unexpectedErrno(err),
}
}
const max_count = switch (builtin.os.tag) {
.linux => 0x7ffff000,
.macos, .ios, .watchos, .tvos => math.maxInt(i32),
else => math.maxInt(isize),
};
const adjusted_len = @minimum(max_count, bytes.len);
while (true) {
const rc = system.write(fd, bytes.ptr, adjusted_len);
switch (errno(rc)) {
.SUCCESS => return @intCast(usize, rc),
.INTR => continue,
.INVAL => unreachable,
.FAULT => unreachable,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForWriting, // can be a race condition.
.DESTADDRREQ => unreachable, // `connect` was never called.
.DQUOT => return error.DiskQuota,
.FBIG => return error.FileTooBig,