SIGN IN SIGN UP
const std = @import("../std.zig");
const builtin = @import("builtin");
const unicode = std.unicode;
const fs = std.fs;
const process = std.process;
const File = std.fs.File;
const windows = std.os.windows;
const linux = std.os.linux;
const posix = std.posix;
const mem = std.mem;
const EnvMap = std.process.EnvMap;
const maxInt = std.math.maxInt;
const assert = std.debug.assert;
const native_os = builtin.os.tag;
const Allocator = std.mem.Allocator;
const ChildProcess = @This();
pub const Id = switch (native_os) {
.windows => windows.HANDLE,
.wasi => void,
else => posix.pid_t,
};
/// Available after calling `spawn()`. This becomes `undefined` after calling `wait()`.
/// On Windows this is the hProcess.
/// On POSIX this is the pid.
id: Id,
thread_handle: if (native_os == .windows) windows.HANDLE else void,
allocator: mem.Allocator,
/// The writing end of the child process's standard input pipe.
/// Usage requires `stdin_behavior == StdIo.Pipe`.
/// Available after calling `spawn()`.
stdin: ?File,
/// The reading end of the child process's standard output pipe.
/// Usage requires `stdout_behavior == StdIo.Pipe`.
/// Available after calling `spawn()`.
stdout: ?File,
/// The reading end of the child process's standard error pipe.
/// Usage requires `stderr_behavior == StdIo.Pipe`.
/// Available after calling `spawn()`.
stderr: ?File,
/// Terminated state of the child process.
/// Available after calling `wait()`.
term: ?(SpawnError!Term),
argv: []const []const u8,
/// Leave as null to use the current env map using the supplied allocator.
env_map: ?*const EnvMap,
stdin_behavior: StdIo,
stdout_behavior: StdIo,
stderr_behavior: StdIo,
/// Set to change the user id when spawning the child process.
uid: if (native_os == .windows or native_os == .wasi) void else ?posix.uid_t,
/// Set to change the group id when spawning the child process.
gid: if (native_os == .windows or native_os == .wasi) void else ?posix.gid_t,
/// Set to change the process group id when spawning the child process.
pgid: if (native_os == .windows or native_os == .wasi) void else ?posix.pid_t,
/// Set to change the current working directory when spawning the child process.
cwd: ?[]const u8,
/// Set to change the current working directory when spawning the child process.
/// This is not yet implemented for Windows. See https://github.com/ziglang/zig/issues/5190
/// Once that is done, `cwd` will be deprecated in favor of this field.
cwd_dir: ?fs.Dir = null,
err_pipe: if (native_os == .windows) void else ?posix.fd_t,
expand_arg0: Arg0Expand,
/// Darwin-only. Disable ASLR for the child process.
disable_aslr: bool = false,
/// Darwin and Windows only. Start child process in suspended state. For Darwin it's started
/// as if SIGSTOP was sent.
start_suspended: bool = false,
/// Windows-only. Sets the CREATE_NO_WINDOW flag in CreateProcess.
create_no_window: bool = false,
/// Set to true to obtain rusage information for the child process.
/// Depending on the target platform and implementation status, the
/// requested statistics may or may not be available. If they are
/// available, then the `resource_usage_statistics` field will be populated
/// after calling `wait`.
/// On Linux and Darwin, this obtains rusage statistics from wait4().
request_resource_usage_statistics: bool = false,
/// This is available after calling wait if
/// `request_resource_usage_statistics` was set to `true` before calling
/// `spawn`.
resource_usage_statistics: ResourceUsageStatistics = .{},
/// When populated, a pipe will be created for the child process to
/// communicate progress back to the parent. The file descriptor of the
/// write end of the pipe will be specified in the `ZIG_PROGRESS`
/// environment variable inside the child process. The progress reported by
/// the child will be attached to this progress node in the parent process.
///
/// The child's progress tree will be grafted into the parent's progress tree,
/// by substituting this node with the child's root node.
progress_node: std.Progress.Node = std.Progress.Node.none,
pub const ResourceUsageStatistics = struct {
rusage: @TypeOf(rusage_init) = rusage_init,
/// Returns the peak resident set size of the child process, in bytes,
/// if available.
pub inline fn getMaxRss(rus: ResourceUsageStatistics) ?usize {
switch (native_os) {
.linux => {
if (rus.rusage) |ru| {
return @as(usize, @intCast(ru.maxrss)) * 1024;
} else {
return null;
}
},
.windows => {
if (rus.rusage) |ru| {
return ru.PeakWorkingSetSize;
} else {
return null;
}
},
.macos, .ios => {
if (rus.rusage) |ru| {
// Darwin oddly reports in bytes instead of kilobytes.
return @as(usize, @intCast(ru.maxrss));
} else {
return null;
}
},
else => return null,
}
}
const rusage_init = switch (native_os) {
.linux, .macos, .ios => @as(?posix.rusage, null),
.windows => @as(?windows.VM_COUNTERS, null),
else => {},
};
};
pub const Arg0Expand = posix.Arg0Expand;
pub const SpawnError = error{
OutOfMemory,
/// POSIX-only. `StdIo.Ignore` was selected and opening `/dev/null` returned ENODEV.
NoDevice,
/// Windows-only. `cwd` or `argv` was provided and it was invalid WTF-8.
/// https://simonsapin.github.io/wtf-8/
InvalidWtf8,
/// Windows-only. `cwd` was provided, but the path did not exist when spawning the child process.
CurrentWorkingDirectoryUnlinked,
/// Windows-only. NUL (U+0000), LF (U+000A), CR (U+000D) are not allowed
/// within arguments when executing a `.bat`/`.cmd` script.
/// - NUL/LF signifiies end of arguments, so anything afterwards
/// would be lost after execution.
/// - CR is stripped by `cmd.exe`, so any CR codepoints
/// would be lost after execution.
InvalidBatchScriptArg,
} ||
posix.ExecveError ||
posix.SetIdError ||
posix.SetPgidError ||
posix.ChangeCurDirError ||
windows.CreateProcessError ||
windows.GetProcessMemoryInfoError ||
windows.WaitForSingleObjectError;
pub const Term = union(enum) {
Exited: u8,
Signal: u32,
Stopped: u32,
Unknown: u32,
};
/// Behavior of the child process's standard input, output, and error
/// streams.
pub const StdIo = enum {
/// Inherit the stream from the parent process.
Inherit,
/// Pass a null stream to the child process.
/// This is /dev/null on POSIX and NUL on Windows.
Ignore,
/// Create a pipe for the stream.
/// The corresponding field (`stdout`, `stderr`, or `stdin`)
/// will be assigned a `File` object that can be used
/// to read from or write to the pipe.
Pipe,
/// Close the stream after the child process spawns.
Close,
};
/// First argument in argv is the executable.
pub fn init(argv: []const []const u8, allocator: mem.Allocator) ChildProcess {
return .{
.allocator = allocator,
.argv = argv,
.id = undefined,
.thread_handle = undefined,
.err_pipe = if (native_os == .windows) {} else null,
.term = null,
.env_map = null,
.cwd = null,
.uid = if (native_os == .windows or native_os == .wasi) {} else null,
.gid = if (native_os == .windows or native_os == .wasi) {} else null,
.pgid = if (native_os == .windows or native_os == .wasi) {} else null,
.stdin = null,
.stdout = null,
.stderr = null,
.stdin_behavior = .Inherit,
.stdout_behavior = .Inherit,
.stderr_behavior = .Inherit,
.expand_arg0 = .no_expand,
};
}
pub fn setUserName(self: *ChildProcess, name: []const u8) !void {
const user_info = try process.getUserInfo(name);
self.uid = user_info.uid;
self.gid = user_info.gid;
}
/// On success must call `kill` or `wait`.
/// After spawning the `id` is available.
pub fn spawn(self: *ChildProcess) SpawnError!void {
if (!process.can_spawn) {
@compileError("the target operating system cannot spawn processes");
}
if (native_os == .windows) {
return self.spawnWindows();
} else {
return self.spawnPosix();
}
}
pub fn spawnAndWait(self: *ChildProcess) SpawnError!Term {
try self.spawn();
return self.wait();
}
/// Forcibly terminates child process and then cleans up all resources.
pub fn kill(self: *ChildProcess) !Term {
if (native_os == .windows) {
return self.killWindows(1);
} else {
return self.killPosix();
}
}
pub fn killWindows(self: *ChildProcess, exit_code: windows.UINT) !Term {
if (self.term) |term| {
self.cleanupStreams();
return term;
}
windows.TerminateProcess(self.id, exit_code) catch |err| switch (err) {
error.AccessDenied => {
// Usually when TerminateProcess triggers a ACCESS_DENIED error, it
// indicates that the process has already exited, but there may be
// some rare edge cases where our process handle no longer has the
// PROCESS_TERMINATE access right, so let's do another check to make
// sure the process is really no longer running:
windows.WaitForSingleObjectEx(self.id, 0, false) catch return err;
return error.AlreadyTerminated;
},
else => return err,
};
try self.waitUnwrappedWindows();
return self.term.?;
}
pub fn killPosix(self: *ChildProcess) !Term {
if (self.term) |term| {
self.cleanupStreams();
return term;
}
posix.kill(self.id, posix.SIG.TERM) catch |err| switch (err) {
error.ProcessNotFound => return error.AlreadyTerminated,
else => return err,
};
self.waitUnwrappedPosix();
return self.term.?;
}
pub const WaitError = SpawnError || std.os.windows.GetProcessMemoryInfoError;
/// On some targets, `spawn` may not report all spawn errors, such as `error.InvalidExe`.
/// This function will block until any spawn errors can be reported, and return them.
pub fn waitForSpawn(self: *ChildProcess) SpawnError!void {
if (native_os == .windows) return; // `spawn` reports everything
if (self.term) |term| {
_ = term catch |spawn_err| return spawn_err;
return;
}
const err_pipe = self.err_pipe orelse return;
self.err_pipe = null;
// Wait for the child to report any errors in or before `execvpe`.
if (readIntFd(err_pipe)) |child_err_int| {
posix.close(err_pipe);
const child_err: SpawnError = @errorCast(@errorFromInt(child_err_int));
self.term = child_err;
return child_err;
} else |_| {
// Write end closed by CLOEXEC at the time of the `execvpe` call, indicating success!
posix.close(err_pipe);
}
}
/// Blocks until child process terminates and then cleans up all resources.
pub fn wait(self: *ChildProcess) WaitError!Term {
try self.waitForSpawn(); // report spawn errors
if (self.term) |term| {
self.cleanupStreams();
return term;
}
switch (native_os) {
.windows => try self.waitUnwrappedWindows(),
else => self.waitUnwrappedPosix(),
}
self.id = undefined;
return self.term.?;
}
pub const RunResult = struct {
term: Term,
stdout: []u8,
stderr: []u8,
};
fn writeFifoDataToArrayList(allocator: Allocator, list: *std.ArrayListUnmanaged(u8), fifo: *std.io.PollFifo) !void {
if (fifo.head != 0) fifo.realign();
if (list.capacity == 0) {
list.* = .{
.items = fifo.buf[0..fifo.count],
.capacity = fifo.buf.len,
};
fifo.* = std.io.PollFifo.init(fifo.allocator);
} else {
try list.appendSlice(allocator, fifo.buf[0..fifo.count]);
}
}
/// Collect the output from the process's stdout and stderr. Will return once all output
/// has been collected. This does not mean that the process has ended. `wait` should still
/// be called to wait for and clean up the process.
///
/// The process must be started with stdout_behavior and stderr_behavior == .Pipe
pub fn collectOutput(
child: ChildProcess,
/// Used for `stdout` and `stderr`.
allocator: Allocator,
stdout: *std.ArrayListUnmanaged(u8),
stderr: *std.ArrayListUnmanaged(u8),
max_output_bytes: usize,
) !void {
assert(child.stdout_behavior == .Pipe);
assert(child.stderr_behavior == .Pipe);
var poller = std.io.poll(allocator, enum { stdout, stderr }, .{
.stdout = child.stdout.?,
.stderr = child.stderr.?,
});
defer poller.deinit();
while (try poller.poll()) {
if (poller.fifo(.stdout).count > max_output_bytes)
return error.StdoutStreamTooLong;
if (poller.fifo(.stderr).count > max_output_bytes)
return error.StderrStreamTooLong;
}
try writeFifoDataToArrayList(allocator, stdout, poller.fifo(.stdout));
try writeFifoDataToArrayList(allocator, stderr, poller.fifo(.stderr));
}
pub const RunError = posix.GetCwdError || posix.ReadError || SpawnError || posix.PollError || error{
StdoutStreamTooLong,
StderrStreamTooLong,
};
/// Spawns a child process, waits for it, collecting stdout and stderr, and then returns.
/// If it succeeds, the caller owns result.stdout and result.stderr memory.
pub fn run(args: struct {
allocator: mem.Allocator,
argv: []const []const u8,
cwd: ?[]const u8 = null,
cwd_dir: ?fs.Dir = null,
env_map: ?*const EnvMap = null,
max_output_bytes: usize = 50 * 1024,
expand_arg0: Arg0Expand = .no_expand,
progress_node: std.Progress.Node = std.Progress.Node.none,
}) RunError!RunResult {
var child = ChildProcess.init(args.argv, args.allocator);
child.stdin_behavior = .Ignore;
child.stdout_behavior = .Pipe;
child.stderr_behavior = .Pipe;
child.cwd = args.cwd;
child.cwd_dir = args.cwd_dir;
child.env_map = args.env_map;
child.expand_arg0 = args.expand_arg0;
child.progress_node = args.progress_node;
var stdout: std.ArrayListUnmanaged(u8) = .empty;
errdefer stdout.deinit(args.allocator);
var stderr: std.ArrayListUnmanaged(u8) = .empty;
errdefer stderr.deinit(args.allocator);
try child.spawn();
errdefer {
_ = child.kill() catch {};
}
try child.collectOutput(args.allocator, &stdout, &stderr, args.max_output_bytes);
return RunResult{
.stdout = try stdout.toOwnedSlice(args.allocator),
.stderr = try stderr.toOwnedSlice(args.allocator),
.term = try child.wait(),
};
}
fn waitUnwrappedWindows(self: *ChildProcess) WaitError!void {
const result = windows.WaitForSingleObjectEx(self.id, windows.INFINITE, false);
self.term = @as(SpawnError!Term, x: {
var exit_code: windows.DWORD = undefined;
if (windows.kernel32.GetExitCodeProcess(self.id, &exit_code) == 0) {
break :x Term{ .Unknown = 0 };
} else {
break :x Term{ .Exited = @as(u8, @truncate(exit_code)) };
}
});
if (self.request_resource_usage_statistics) {
self.resource_usage_statistics.rusage = try windows.GetProcessMemoryInfo(self.id);
}
posix.close(self.id);
posix.close(self.thread_handle);
self.cleanupStreams();
return result;
}
fn waitUnwrappedPosix(self: *ChildProcess) void {
const res: posix.WaitPidResult = res: {
if (self.request_resource_usage_statistics) {
switch (native_os) {
.linux, .macos, .ios => {
var ru: posix.rusage = undefined;
const res = posix.wait4(self.id, 0, &ru);
self.resource_usage_statistics.rusage = ru;
break :res res;
},
else => {},
}
}
break :res posix.waitpid(self.id, 0);
};
const status = res.status;
self.cleanupStreams();
self.handleWaitResult(status);
}
fn handleWaitResult(self: *ChildProcess, status: u32) void {
self.term = statusToTerm(status);
}
fn cleanupStreams(self: *ChildProcess) void {
if (self.stdin) |*stdin| {
stdin.close();
self.stdin = null;
}
if (self.stdout) |*stdout| {
stdout.close();
self.stdout = null;
}
if (self.stderr) |*stderr| {
stderr.close();
self.stderr = null;
}
}
fn statusToTerm(status: u32) Term {
return if (posix.W.IFEXITED(status))
Term{ .Exited = posix.W.EXITSTATUS(status) }
else if (posix.W.IFSIGNALED(status))
Term{ .Signal = posix.W.TERMSIG(status) }
else if (posix.W.IFSTOPPED(status))
Term{ .Stopped = posix.W.STOPSIG(status) }
else
Term{ .Unknown = status };
}
fn spawnPosix(self: *ChildProcess) SpawnError!void {
// The child process does need to access (one end of) these pipes. However,
// we must initially set CLOEXEC to avoid a race condition. If another thread
// is racing to spawn a different child process, we don't want it to inherit
// these FDs in any scenario; that would mean that, for instance, calls to
// `poll` from the parent would not report the child's stdout as closing when
// expected, since the other child may retain a reference to the write end of
// the pipe. So, we create the pipes with CLOEXEC initially. After fork, we
// need to do something in the new child to make sure we preserve the reference
// we want. We could use `fcntl` to remove CLOEXEC from the FD, but as it
// turns out, we `dup2` everything anyway, so there's no need!
const pipe_flags: posix.O = .{ .CLOEXEC = true };
const stdin_pipe = if (self.stdin_behavior == .Pipe) try posix.pipe2(pipe_flags) else undefined;
errdefer if (self.stdin_behavior == .Pipe) {
destroyPipe(stdin_pipe);
};
const stdout_pipe = if (self.stdout_behavior == .Pipe) try posix.pipe2(pipe_flags) else undefined;
errdefer if (self.stdout_behavior == .Pipe) {
destroyPipe(stdout_pipe);
};
const stderr_pipe = if (self.stderr_behavior == .Pipe) try posix.pipe2(pipe_flags) else undefined;
errdefer if (self.stderr_behavior == .Pipe) {
destroyPipe(stderr_pipe);
};
const any_ignore = (self.stdin_behavior == .Ignore or self.stdout_behavior == .Ignore or self.stderr_behavior == .Ignore);
const dev_null_fd = if (any_ignore)
posix.openZ("/dev/null", .{ .ACCMODE = .RDWR }, 0) catch |err| switch (err) {
error.PathAlreadyExists => unreachable,
error.NoSpaceLeft => unreachable,
error.FileTooBig => unreachable,
error.DeviceBusy => unreachable,
error.FileLocksNotSupported => unreachable,
error.BadPathName => unreachable, // Windows-only
error.WouldBlock => unreachable,
error.NetworkNotFound => unreachable, // Windows-only
else => |e| return e,
}
else
undefined;
defer {
if (any_ignore) posix.close(dev_null_fd);
}
const prog_pipe: [2]posix.fd_t = p: {
if (self.progress_node.index == .none) {
break :p .{ -1, -1 };
} else {
// We use CLOEXEC for the same reason as in `pipe_flags`.
break :p try posix.pipe2(.{ .NONBLOCK = true, .CLOEXEC = true });
}
};
errdefer destroyPipe(prog_pipe);
var arena_allocator = std.heap.ArenaAllocator.init(self.allocator);
defer arena_allocator.deinit();
const arena = arena_allocator.allocator();
// The POSIX standard does not allow malloc() between fork() and execve(),
// and `self.allocator` may be a libc allocator.
// I have personally observed the child process deadlocking when it tries
// to call malloc() due to a heap allocation between fork() and execve(),
// in musl v1.1.24.
// Additionally, we want to reduce the number of possible ways things
// can fail between fork() and execve().
// Therefore, we do all the allocation for the execve() before the fork().
// This means we must do the null-termination of argv and env vars here.
const argv_buf = try arena.allocSentinel(?[*:0]const u8, self.argv.len, null);
for (self.argv, 0..) |arg, i| argv_buf[i] = (try arena.dupeZ(u8, arg)).ptr;
const prog_fileno = 3;
comptime assert(@max(posix.STDIN_FILENO, posix.STDOUT_FILENO, posix.STDERR_FILENO) + 1 == prog_fileno);
const envp: [*:null]const ?[*:0]const u8 = m: {
const prog_fd: i32 = if (prog_pipe[1] == -1) -1 else prog_fileno;
if (self.env_map) |env_map| {
break :m (try process.createEnvironFromMap(arena, env_map, .{
.zig_progress_fd = prog_fd,
})).ptr;
} else if (builtin.link_libc) {
break :m (try process.createEnvironFromExisting(arena, std.c.environ, .{
.zig_progress_fd = prog_fd,
})).ptr;
} else if (builtin.output_mode == .Exe) {
// Then we have Zig start code and this works.
// TODO type-safety for null-termination of `os.environ`.
break :m (try process.createEnvironFromExisting(arena, @ptrCast(std.os.environ.ptr), .{
.zig_progress_fd = prog_fd,
})).ptr;
} else {
// TODO come up with a solution for this.
@compileError("missing std lib enhancement: ChildProcess implementation has no way to collect the environment variables to forward to the child process");
}
};
// This pipe communicates to the parent errors in the child between `fork` and `execvpe`.
// It is closed by the child (via CLOEXEC) without writing if `execvpe` succeeds.
const err_pipe: [2]posix.fd_t = try posix.pipe2(.{ .CLOEXEC = true });
errdefer destroyPipe(err_pipe);
const pid_result = try posix.fork();
if (pid_result == 0) {
// we are the child
setUpChildIo(self.stdin_behavior, stdin_pipe[0], posix.STDIN_FILENO, dev_null_fd) catch |err| forkChildErrReport(err_pipe[1], err);
setUpChildIo(self.stdout_behavior, stdout_pipe[1], posix.STDOUT_FILENO, dev_null_fd) catch |err| forkChildErrReport(err_pipe[1], err);
setUpChildIo(self.stderr_behavior, stderr_pipe[1], posix.STDERR_FILENO, dev_null_fd) catch |err| forkChildErrReport(err_pipe[1], err);
if (self.cwd_dir) |cwd| {
posix.fchdir(cwd.fd) catch |err| forkChildErrReport(err_pipe[1], err);
} else if (self.cwd) |cwd| {
posix.chdir(cwd) catch |err| forkChildErrReport(err_pipe[1], err);
}
// Must happen after fchdir above, the cwd file descriptor might be
// equal to prog_fileno and be clobbered by this dup2 call.
if (prog_pipe[1] != -1) posix.dup2(prog_pipe[1], prog_fileno) catch |err| forkChildErrReport(err_pipe[1], err);
if (self.gid) |gid| {
posix.setregid(gid, gid) catch |err| forkChildErrReport(err_pipe[1], err);
}
if (self.uid) |uid| {
posix.setreuid(uid, uid) catch |err| forkChildErrReport(err_pipe[1], err);
}
if (self.pgid) |pid| {
posix.setpgid(0, pid) catch |err| forkChildErrReport(err_pipe[1], err);
}
const err = switch (self.expand_arg0) {
.expand => posix.execvpeZ_expandArg0(.expand, argv_buf.ptr[0].?, argv_buf.ptr, envp),
.no_expand => posix.execvpeZ_expandArg0(.no_expand, argv_buf.ptr[0].?, argv_buf.ptr, envp),
};
forkChildErrReport(err_pipe[1], err);
}
// we are the parent
errdefer comptime unreachable; // The child is forked; we must not error from now on
posix.close(err_pipe[1]); // make sure only the child holds the write end open
self.err_pipe = err_pipe[0];
const pid: i32 = @intCast(pid_result);
if (self.stdin_behavior == .Pipe) {
self.stdin = .{ .handle = stdin_pipe[1] };
} else {
self.stdin = null;
}
if (self.stdout_behavior == .Pipe) {
self.stdout = .{ .handle = stdout_pipe[0] };
} else {
self.stdout = null;
}
if (self.stderr_behavior == .Pipe) {
self.stderr = .{ .handle = stderr_pipe[0] };
} else {
self.stderr = null;
}
self.id = pid;
self.term = null;
if (self.stdin_behavior == .Pipe) {
posix.close(stdin_pipe[0]);
}
if (self.stdout_behavior == .Pipe) {
posix.close(stdout_pipe[1]);
}
if (self.stderr_behavior == .Pipe) {
posix.close(stderr_pipe[1]);
}
if (prog_pipe[1] != -1) {
posix.close(prog_pipe[1]);
}
self.progress_node.setIpcFd(prog_pipe[0]);
}
fn spawnWindows(self: *ChildProcess) SpawnError!void {
var saAttr = windows.SECURITY_ATTRIBUTES{
.nLength = @sizeOf(windows.SECURITY_ATTRIBUTES),
.bInheritHandle = windows.TRUE,
.lpSecurityDescriptor = null,
};
const any_ignore = (self.stdin_behavior == StdIo.Ignore or self.stdout_behavior == StdIo.Ignore or self.stderr_behavior == StdIo.Ignore);
const nul_handle = if (any_ignore)
// "\Device\Null" or "\??\NUL"
windows.OpenFile(&[_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'N', 'u', 'l', 'l' }, .{
.access_mask = windows.GENERIC_READ | windows.GENERIC_WRITE | windows.SYNCHRONIZE,
.share_access = windows.FILE_SHARE_READ | windows.FILE_SHARE_WRITE | windows.FILE_SHARE_DELETE,
.sa = &saAttr,
.creation = windows.OPEN_EXISTING,
}) catch |err| switch (err) {
error.PathAlreadyExists => return error.Unexpected, // not possible for "NUL"
error.PipeBusy => return error.Unexpected, // not possible for "NUL"
error.NoDevice => return error.Unexpected, // not possible for "NUL"
error.FileNotFound => return error.Unexpected, // not possible for "NUL"
error.AccessDenied => return error.Unexpected, // not possible for "NUL"
error.NameTooLong => return error.Unexpected, // not possible for "NUL"
error.WouldBlock => return error.Unexpected, // not possible for "NUL"
error.NetworkNotFound => return error.Unexpected, // not possible for "NUL"
error.AntivirusInterference => return error.Unexpected, // not possible for "NUL"
else => |e| return e,
}
else
undefined;
defer {
if (any_ignore) posix.close(nul_handle);
}
var g_hChildStd_IN_Rd: ?windows.HANDLE = null;
var g_hChildStd_IN_Wr: ?windows.HANDLE = null;
switch (self.stdin_behavior) {
StdIo.Pipe => {
try windowsMakePipeIn(&g_hChildStd_IN_Rd, &g_hChildStd_IN_Wr, &saAttr);
},
StdIo.Ignore => {
g_hChildStd_IN_Rd = nul_handle;
},
StdIo.Inherit => {
g_hChildStd_IN_Rd = windows.GetStdHandle(windows.STD_INPUT_HANDLE) catch null;
},
StdIo.Close => {
g_hChildStd_IN_Rd = null;
},
}
errdefer if (self.stdin_behavior == StdIo.Pipe) {
windowsDestroyPipe(g_hChildStd_IN_Rd, g_hChildStd_IN_Wr);
};
var g_hChildStd_OUT_Rd: ?windows.HANDLE = null;
var g_hChildStd_OUT_Wr: ?windows.HANDLE = null;
switch (self.stdout_behavior) {
StdIo.Pipe => {
try windowsMakeAsyncPipe(&g_hChildStd_OUT_Rd, &g_hChildStd_OUT_Wr, &saAttr);
},
StdIo.Ignore => {
g_hChildStd_OUT_Wr = nul_handle;
},
StdIo.Inherit => {
g_hChildStd_OUT_Wr = windows.GetStdHandle(windows.STD_OUTPUT_HANDLE) catch null;
},
StdIo.Close => {
g_hChildStd_OUT_Wr = null;
},
}
errdefer if (self.stdout_behavior == StdIo.Pipe) {
windowsDestroyPipe(g_hChildStd_OUT_Rd, g_hChildStd_OUT_Wr);
};
var g_hChildStd_ERR_Rd: ?windows.HANDLE = null;
var g_hChildStd_ERR_Wr: ?windows.HANDLE = null;
switch (self.stderr_behavior) {
StdIo.Pipe => {
try windowsMakeAsyncPipe(&g_hChildStd_ERR_Rd, &g_hChildStd_ERR_Wr, &saAttr);
},
StdIo.Ignore => {
g_hChildStd_ERR_Wr = nul_handle;
},
StdIo.Inherit => {
g_hChildStd_ERR_Wr = windows.GetStdHandle(windows.STD_ERROR_HANDLE) catch null;
},
StdIo.Close => {
g_hChildStd_ERR_Wr = null;
},
}
errdefer if (self.stderr_behavior == StdIo.Pipe) {
windowsDestroyPipe(g_hChildStd_ERR_Rd, g_hChildStd_ERR_Wr);
};
var siStartInfo = windows.STARTUPINFOW{
.cb = @sizeOf(windows.STARTUPINFOW),
.hStdError = g_hChildStd_ERR_Wr,
.hStdOutput = g_hChildStd_OUT_Wr,
.hStdInput = g_hChildStd_IN_Rd,
.dwFlags = windows.STARTF_USESTDHANDLES,
.lpReserved = null,
.lpDesktop = null,
.lpTitle = null,
.dwX = 0,
.dwY = 0,
.dwXSize = 0,
.dwYSize = 0,
.dwXCountChars = 0,
.dwYCountChars = 0,
.dwFillAttribute = 0,
.wShowWindow = 0,
.cbReserved2 = 0,
.lpReserved2 = null,
};
var piProcInfo: windows.PROCESS_INFORMATION = undefined;
const cwd_w = if (self.cwd) |cwd| try unicode.wtf8ToWtf16LeAllocZ(self.allocator, cwd) else null;
defer if (cwd_w) |cwd| self.allocator.free(cwd);
const cwd_w_ptr = if (cwd_w) |cwd| cwd.ptr else null;
const maybe_envp_buf = if (self.env_map) |env_map| try process.createWindowsEnvBlock(self.allocator, env_map) else null;
defer if (maybe_envp_buf) |envp_buf| self.allocator.free(envp_buf);
const envp_ptr = if (maybe_envp_buf) |envp_buf| envp_buf.ptr else null;
const app_name_wtf8 = self.argv[0];
const app_name_is_absolute = fs.path.isAbsolute(app_name_wtf8);
// the cwd set in ChildProcess is in effect when choosing the executable path
// to match posix semantics
var cwd_path_w_needs_free = false;
const cwd_path_w = x: {
// If the app name is absolute, then we need to use its dirname as the cwd
if (app_name_is_absolute) {
cwd_path_w_needs_free = true;
const dir = fs.path.dirname(app_name_wtf8).?;
break :x try unicode.wtf8ToWtf16LeAllocZ(self.allocator, dir);
} else if (self.cwd) |cwd| {
cwd_path_w_needs_free = true;
break :x try unicode.wtf8ToWtf16LeAllocZ(self.allocator, cwd);
} else {
break :x &[_:0]u16{}; // empty for cwd
}
};
defer if (cwd_path_w_needs_free) self.allocator.free(cwd_path_w);
// If the app name has more than just a filename, then we need to separate that
// into the basename and dirname and use the dirname as an addition to the cwd
// path. This is because NtQueryDirectoryFile cannot accept FileName params with
// path separators.
const app_basename_wtf8 = fs.path.basename(app_name_wtf8);
// If the app name is absolute, then the cwd will already have the app's dirname in it,
// so only populate app_dirname if app name is a relative path with > 0 path separators.
const maybe_app_dirname_wtf8 = if (!app_name_is_absolute) fs.path.dirname(app_name_wtf8) else null;
const app_dirname_w: ?[:0]u16 = x: {
if (maybe_app_dirname_wtf8) |app_dirname_wtf8| {
break :x try unicode.wtf8ToWtf16LeAllocZ(self.allocator, app_dirname_wtf8);
}
break :x null;
};
defer if (app_dirname_w != null) self.allocator.free(app_dirname_w.?);
const app_name_w = try unicode.wtf8ToWtf16LeAllocZ(self.allocator, app_basename_wtf8);
defer self.allocator.free(app_name_w);
const flags: windows.CreateProcessFlags = .{
.create_suspended = self.start_suspended,
.create_unicode_environment = true,
.create_no_window = self.create_no_window,
};
run: {
const PATH: [:0]const u16 = process.getenvW(unicode.utf8ToUtf16LeStringLiteral("PATH")) orelse &[_:0]u16{};
const PATHEXT: [:0]const u16 = process.getenvW(unicode.utf8ToUtf16LeStringLiteral("PATHEXT")) orelse &[_:0]u16{};
// In case the command ends up being a .bat/.cmd script, we need to escape things using the cmd.exe rules
// and invoke cmd.exe ourselves in order to mitigate arbitrary command execution from maliciously
// constructed arguments.
//
// We'll need to wait until we're actually trying to run the command to know for sure
// if the resolved command has the `.bat` or `.cmd` extension, so we defer actually
// serializing the command line until we determine how it should be serialized.
var cmd_line_cache = WindowsCommandLineCache.init(self.allocator, self.argv);
defer cmd_line_cache.deinit();
var app_buf: std.ArrayListUnmanaged(u16) = .empty;
defer app_buf.deinit(self.allocator);
try app_buf.appendSlice(self.allocator, app_name_w);
var dir_buf: std.ArrayListUnmanaged(u16) = .empty;
defer dir_buf.deinit(self.allocator);
if (cwd_path_w.len > 0) {
try dir_buf.appendSlice(self.allocator, cwd_path_w);
}
if (app_dirname_w) |app_dir| {
if (dir_buf.items.len > 0) try dir_buf.append(self.allocator, fs.path.sep);
try dir_buf.appendSlice(self.allocator, app_dir);
}
if (dir_buf.items.len > 0) {
// Need to normalize the path, openDirW can't handle things like double backslashes
const normalized_len = windows.normalizePath(u16, dir_buf.items) catch return error.BadPathName;
dir_buf.shrinkRetainingCapacity(normalized_len);
}
windowsCreateProcessPathExt(self.allocator, &dir_buf, &app_buf, PATHEXT, &cmd_line_cache, envp_ptr, cwd_w_ptr, flags, &siStartInfo, &piProcInfo) catch |no_path_err| {
const original_err = switch (no_path_err) {
// argv[0] contains unsupported characters that will never resolve to a valid exe.
error.InvalidArg0 => return error.FileNotFound,
error.FileNotFound, error.InvalidExe, error.AccessDenied => |e| e,
error.UnrecoverableInvalidExe => return error.InvalidExe,
else => |e| return e,
};
// If the app name had path separators, that disallows PATH searching,
// and there's no need to search the PATH if the app name is absolute.
// We still search the path if the cwd is absolute because of the
// "cwd set in ChildProcess is in effect when choosing the executable path
// to match posix semantics" behavior--we don't want to skip searching
// the PATH just because we were trying to set the cwd of the child process.
if (app_dirname_w != null or app_name_is_absolute) {
return original_err;
}
var it = mem.tokenizeScalar(u16, PATH, ';');
while (it.next()) |search_path| {
dir_buf.clearRetainingCapacity();
try dir_buf.appendSlice(self.allocator, search_path);
// Need to normalize the path, some PATH values can contain things like double
// backslashes which openDirW can't handle
const normalized_len = windows.normalizePath(u16, dir_buf.items) catch continue;
dir_buf.shrinkRetainingCapacity(normalized_len);
if (windowsCreateProcessPathExt(self.allocator, &dir_buf, &app_buf, PATHEXT, &cmd_line_cache, envp_ptr, cwd_w_ptr, flags, &siStartInfo, &piProcInfo)) {
break :run;
} else |err| switch (err) {
// argv[0] contains unsupported characters that will never resolve to a valid exe.
error.InvalidArg0 => return error.FileNotFound,
error.FileNotFound, error.AccessDenied, error.InvalidExe => continue,
error.UnrecoverableInvalidExe => return error.InvalidExe,
else => |e| return e,
}
} else {
return original_err;
}
};
}
if (g_hChildStd_IN_Wr) |h| {
self.stdin = File{ .handle = h };
} else {
self.stdin = null;
}
if (g_hChildStd_OUT_Rd) |h| {
self.stdout = File{ .handle = h };
} else {
self.stdout = null;
}
if (g_hChildStd_ERR_Rd) |h| {
self.stderr = File{ .handle = h };
} else {
self.stderr = null;
}
self.id = piProcInfo.hProcess;
self.thread_handle = piProcInfo.hThread;
self.term = null;
if (self.stdin_behavior == StdIo.Pipe) {
posix.close(g_hChildStd_IN_Rd.?);
}
if (self.stderr_behavior == StdIo.Pipe) {
posix.close(g_hChildStd_ERR_Wr.?);
}
if (self.stdout_behavior == StdIo.Pipe) {
posix.close(g_hChildStd_OUT_Wr.?);
}
}
fn setUpChildIo(stdio: StdIo, pipe_fd: i32, std_fileno: i32, dev_null_fd: i32) !void {
switch (stdio) {
.Pipe => try posix.dup2(pipe_fd, std_fileno),
.Close => posix.close(std_fileno),
.Inherit => {},
.Ignore => try posix.dup2(dev_null_fd, std_fileno),
}
}
fn destroyPipe(pipe: [2]posix.fd_t) void {
if (pipe[0] != -1) posix.close(pipe[0]);
if (pipe[0] != pipe[1]) posix.close(pipe[1]);
}
// Child of fork calls this to report an error to the fork parent.
// Then the child exits.
fn forkChildErrReport(fd: i32, err: ChildProcess.SpawnError) noreturn {
writeIntFd(fd, @as(ErrInt, @intFromError(err))) catch {};
// If we're linking libc, some naughty applications may have registered atexit handlers
// which we really do not want to run in the fork child. I caught LLVM doing this and
// it caused a deadlock instead of doing an exit syscall. In the words of Avril Lavigne,
// "Why'd you have to go and make things so complicated?"
if (builtin.link_libc) {
// The _exit(2) function does nothing but make the exit syscall, unlike exit(3)
std.c._exit(1);
}
posix.exit(1);
}
fn writeIntFd(fd: i32, value: ErrInt) !void {
const file: File = .{ .handle = fd };
file.writer().writeInt(u64, @intCast(value), .little) catch return error.SystemResources;
}
fn readIntFd(fd: i32) !ErrInt {
const file: File = .{ .handle = fd };
return @intCast(file.reader().readInt(u64, .little) catch return error.SystemResources);
}
const ErrInt = std.meta.Int(.unsigned, @sizeOf(anyerror) * 8);
/// Expects `app_buf` to contain exactly the app name, and `dir_buf` to contain exactly the dir path.
/// After return, `app_buf` will always contain exactly the app name and `dir_buf` will always contain exactly the dir path.
/// Note: `app_buf` should not contain any leading path separators.
/// Note: If the dir is the cwd, dir_buf should be empty (len = 0).
fn windowsCreateProcessPathExt(
allocator: mem.Allocator,
dir_buf: *std.ArrayListUnmanaged(u16),
app_buf: *std.ArrayListUnmanaged(u16),
pathext: [:0]const u16,
cmd_line_cache: *WindowsCommandLineCache,
envp_ptr: ?[*]u16,
cwd_ptr: ?[*:0]u16,
flags: windows.CreateProcessFlags,
lpStartupInfo: *windows.STARTUPINFOW,
lpProcessInformation: *windows.PROCESS_INFORMATION,
) !void {
const app_name_len = app_buf.items.len;
const dir_path_len = dir_buf.items.len;
if (app_name_len == 0) return error.FileNotFound;
defer app_buf.shrinkRetainingCapacity(app_name_len);
defer dir_buf.shrinkRetainingCapacity(dir_path_len);
// The name of the game here is to avoid CreateProcessW calls at all costs,
// and only ever try calling it when we have a real candidate for execution.
// Secondarily, we want to minimize the number of syscalls used when checking
// for each PATHEXT-appended version of the app name.
//
// An overview of the technique used:
// - Open the search directory for iteration (either cwd or a path from PATH)
// - Use NtQueryDirectoryFile with a wildcard filename of `<app name>*` to
// check if anything that could possibly match either the unappended version
// of the app name or any of the versions with a PATHEXT value appended exists.
// - If the wildcard NtQueryDirectoryFile call found nothing, we can exit early
// without needing to use PATHEXT at all.
//
// This allows us to use a <open dir, NtQueryDirectoryFile, close dir> sequence
// for any directory that doesn't contain any possible matches, instead of having
// to use a separate look up for each individual filename combination (unappended +
// each PATHEXT appended). For directories where the wildcard *does* match something,
// we iterate the matches and take note of any that are either the unappended version,
// or a version with a supported PATHEXT appended. We then try calling CreateProcessW
// with the found versions in the appropriate order.
var dir = dir: {
// needs to be null-terminated
try dir_buf.append(allocator, 0);
defer dir_buf.shrinkRetainingCapacity(dir_path_len);
const dir_path_z = dir_buf.items[0 .. dir_buf.items.len - 1 :0];
const prefixed_path = try windows.wToPrefixedFileW(null, dir_path_z);
break :dir fs.cwd().openDirW(prefixed_path.span().ptr, .{ .iterate = true }) catch
return error.FileNotFound;
};
defer dir.close();
// Add wildcard and null-terminator
try app_buf.append(allocator, '*');
try app_buf.append(allocator, 0);
const app_name_wildcard = app_buf.items[0 .. app_buf.items.len - 1 :0];
// This 2048 is arbitrary, we just want it to be large enough to get multiple FILE_DIRECTORY_INFORMATION entries
// returned per NtQueryDirectoryFile call.
var file_information_buf: [2048]u8 align(@alignOf(windows.FILE_DIRECTORY_INFORMATION)) = undefined;
const file_info_maximum_single_entry_size = @sizeOf(windows.FILE_DIRECTORY_INFORMATION) + (windows.NAME_MAX * 2);
if (file_information_buf.len < file_info_maximum_single_entry_size) {
@compileError("file_information_buf must be large enough to contain at least one maximum size FILE_DIRECTORY_INFORMATION entry");
}
var io_status: windows.IO_STATUS_BLOCK = undefined;
const num_supported_pathext = @typeInfo(WindowsExtension).@"enum".fields.len;
var pathext_seen = [_]bool{false} ** num_supported_pathext;
var any_pathext_seen = false;
var unappended_exists = false;
// Fully iterate the wildcard matches via NtQueryDirectoryFile and take note of all versions
// of the app_name we should try to spawn.
// Note: This is necessary because the order of the files returned is filesystem-dependent:
// On NTFS, `blah.exe*` will always return `blah.exe` first if it exists.
// On FAT32, it's possible for something like `blah.exe.obj` to be returned first.
while (true) {
const app_name_len_bytes = std.math.cast(u16, app_name_wildcard.len * 2) orelse return error.NameTooLong;
var app_name_unicode_string = windows.UNICODE_STRING{
.Length = app_name_len_bytes,
.MaximumLength = app_name_len_bytes,
.Buffer = @constCast(app_name_wildcard.ptr),
};
const rc = windows.ntdll.NtQueryDirectoryFile(
dir.fd,
null,
null,
null,
&io_status,
&file_information_buf,
file_information_buf.len,
.FileDirectoryInformation,
windows.FALSE, // single result
&app_name_unicode_string,
windows.FALSE, // restart iteration
);
// If we get nothing with the wildcard, then we can just bail out
// as we know appending PATHEXT will not yield anything.
switch (rc) {
.SUCCESS => {},
.NO_SUCH_FILE => return error.FileNotFound,
.NO_MORE_FILES => break,
.ACCESS_DENIED => return error.AccessDenied,
else => return windows.unexpectedStatus(rc),
}
// According to the docs, this can only happen if there is not enough room in the
// buffer to write at least one complete FILE_DIRECTORY_INFORMATION entry.
// Therefore, this condition should not be possible to hit with the buffer size we use.
std.debug.assert(io_status.Information != 0);
var it = windows.FileInformationIterator(windows.FILE_DIRECTORY_INFORMATION){ .buf = &file_information_buf };
while (it.next()) |info| {
// Skip directories
if (info.FileAttributes & windows.FILE_ATTRIBUTE_DIRECTORY != 0) continue;
const filename = @as([*]u16, @ptrCast(&info.FileName))[0 .. info.FileNameLength / 2];
// Because all results start with the app_name since we're using the wildcard `app_name*`,
// if the length is equal to app_name then this is an exact match
if (filename.len == app_name_len) {
// Note: We can't break early here because it's possible that the unappended version
// fails to spawn, in which case we still want to try the PATHEXT appended versions.
unappended_exists = true;
} else if (windowsCreateProcessSupportsExtension(filename[app_name_len..])) |pathext_ext| {
pathext_seen[@intFromEnum(pathext_ext)] = true;
any_pathext_seen = true;
}
}
}
const unappended_err = unappended: {
if (unappended_exists) {
if (dir_path_len != 0) switch (dir_buf.items[dir_buf.items.len - 1]) {
'/', '\\' => {},
else => try dir_buf.append(allocator, fs.path.sep),
};
try dir_buf.appendSlice(allocator, app_buf.items[0..app_name_len]);
try dir_buf.append(allocator, 0);
const full_app_name = dir_buf.items[0 .. dir_buf.items.len - 1 :0];
const is_bat_or_cmd = bat_or_cmd: {
const app_name = app_buf.items[0..app_name_len];
const ext_start = std.mem.lastIndexOfScalar(u16, app_name, '.') orelse break :bat_or_cmd false;
const ext = app_name[ext_start..];
const ext_enum = windowsCreateProcessSupportsExtension(ext) orelse break :bat_or_cmd false;
switch (ext_enum) {
.cmd, .bat => break :bat_or_cmd true,
else => break :bat_or_cmd false,
}
};
const cmd_line_w = if (is_bat_or_cmd)
try cmd_line_cache.scriptCommandLine(full_app_name)
else
try cmd_line_cache.commandLine();
const app_name_w = if (is_bat_or_cmd)
try cmd_line_cache.cmdExePath()
else
full_app_name;
if (windowsCreateProcess(app_name_w.ptr, cmd_line_w.ptr, envp_ptr, cwd_ptr, flags, lpStartupInfo, lpProcessInformation)) |_| {
return;
} else |err| switch (err) {
error.FileNotFound,
error.AccessDenied,
=> break :unappended err,
error.InvalidExe => {
// On InvalidExe, if the extension of the app name is .exe then
// it's treated as an unrecoverable error. Otherwise, it'll be
// skipped as normal.
const app_name = app_buf.items[0..app_name_len];
const ext_start = std.mem.lastIndexOfScalar(u16, app_name, '.') orelse break :unappended err;
const ext = app_name[ext_start..];
if (windows.eqlIgnoreCaseWTF16(ext, unicode.utf8ToUtf16LeStringLiteral(".EXE"))) {
return error.UnrecoverableInvalidExe;
}
break :unappended err;
},
else => return err,
}
}
break :unappended error.FileNotFound;
};
if (!any_pathext_seen) return unappended_err;
// Now try any PATHEXT appended versions that we've seen
var ext_it = mem.tokenizeScalar(u16, pathext, ';');
while (ext_it.next()) |ext| {
const ext_enum = windowsCreateProcessSupportsExtension(ext) orelse continue;
if (!pathext_seen[@intFromEnum(ext_enum)]) continue;
dir_buf.shrinkRetainingCapacity(dir_path_len);
if (dir_path_len != 0) switch (dir_buf.items[dir_buf.items.len - 1]) {
'/', '\\' => {},
else => try dir_buf.append(allocator, fs.path.sep),
};
try dir_buf.appendSlice(allocator, app_buf.items[0..app_name_len]);
try dir_buf.appendSlice(allocator, ext);
try dir_buf.append(allocator, 0);
const full_app_name = dir_buf.items[0 .. dir_buf.items.len - 1 :0];
const is_bat_or_cmd = switch (ext_enum) {
.cmd, .bat => true,
else => false,
};
const cmd_line_w = if (is_bat_or_cmd)
try cmd_line_cache.scriptCommandLine(full_app_name)
else
try cmd_line_cache.commandLine();
const app_name_w = if (is_bat_or_cmd)
try cmd_line_cache.cmdExePath()
else
full_app_name;
if (windowsCreateProcess(app_name_w.ptr, cmd_line_w.ptr, envp_ptr, cwd_ptr, flags, lpStartupInfo, lpProcessInformation)) |_| {
return;
} else |err| switch (err) {
error.FileNotFound => continue,
error.AccessDenied => continue,
error.InvalidExe => {
// On InvalidExe, if the extension of the app name is .exe then
// it's treated as an unrecoverable error. Otherwise, it'll be
// skipped as normal.
if (windows.eqlIgnoreCaseWTF16(ext, unicode.utf8ToUtf16LeStringLiteral(".EXE"))) {
return error.UnrecoverableInvalidExe;
}
continue;
},
else => return err,
}
}
return unappended_err;
}
fn windowsCreateProcess(
app_name: [*:0]u16,
cmd_line: [*:0]u16,
envp_ptr: ?[*]u16,
cwd_ptr: ?[*:0]u16,
flags: windows.CreateProcessFlags,
lpStartupInfo: *windows.STARTUPINFOW,
lpProcessInformation: *windows.PROCESS_INFORMATION,
) !void {
// TODO the docs for environment pointer say:
// > A pointer to the environment block for the new process. If this parameter
// > is NULL, the new process uses the environment of the calling process.
// > ...
// > An environment block can contain either Unicode or ANSI characters. If
// > the environment block pointed to by lpEnvironment contains Unicode
// > characters, be sure that dwCreationFlags includes CREATE_UNICODE_ENVIRONMENT.
// > If this parameter is NULL and the environment block of the parent process
// > contains Unicode characters, you must also ensure that dwCreationFlags
// > includes CREATE_UNICODE_ENVIRONMENT.
// This seems to imply that we have to somehow know whether our process parent passed
// CREATE_UNICODE_ENVIRONMENT if we want to pass NULL for the environment parameter.
// Since we do not know this information that would imply that we must not pass NULL
// for the parameter.
// However this would imply that programs compiled with -DUNICODE could not pass
// environment variables to programs that were not, which seems unlikely.
// More investigation is needed.
return windows.CreateProcessW(
app_name,
cmd_line,
null,
null,
windows.TRUE,
flags,
@as(?*anyopaque, @ptrCast(envp_ptr)),
cwd_ptr,
lpStartupInfo,
lpProcessInformation,
);
}
fn windowsMakePipeIn(rd: *?windows.HANDLE, wr: *?windows.HANDLE, sattr: *const windows.SECURITY_ATTRIBUTES) !void {
var rd_h: windows.HANDLE = undefined;
var wr_h: windows.HANDLE = undefined;
try windows.CreatePipe(&rd_h, &wr_h, sattr);
errdefer windowsDestroyPipe(rd_h, wr_h);
try windows.SetHandleInformation(wr_h, windows.HANDLE_FLAG_INHERIT, 0);
rd.* = rd_h;
wr.* = wr_h;
}
fn windowsDestroyPipe(rd: ?windows.HANDLE, wr: ?windows.HANDLE) void {
if (rd) |h| posix.close(h);
if (wr) |h| posix.close(h);
}
fn windowsMakeAsyncPipe(rd: *?windows.HANDLE, wr: *?windows.HANDLE, sattr: *const windows.SECURITY_ATTRIBUTES) !void {
var tmp_bufw: [128]u16 = undefined;
// Anonymous pipes are built upon Named pipes.
// https://docs.microsoft.com/en-us/windows/win32/api/namedpipeapi/nf-namedpipeapi-createpipe
// Asynchronous (overlapped) read and write operations are not supported by anonymous pipes.
// https://docs.microsoft.com/en-us/windows/win32/ipc/anonymous-pipe-operations
const pipe_path = blk: {
var tmp_buf: [128]u8 = undefined;
// Forge a random path for the pipe.
const pipe_path = std.fmt.bufPrintZ(
&tmp_buf,
"\\\\.\\pipe\\zig-childprocess-{d}-{d}",
.{ windows.GetCurrentProcessId(), pipe_name_counter.fetchAdd(1, .monotonic) },
) catch unreachable;
const len = std.unicode.wtf8ToWtf16Le(&tmp_bufw, pipe_path) catch unreachable;
tmp_bufw[len] = 0;
break :blk tmp_bufw[0..len :0];
};
// Create the read handle that can be used with overlapped IO ops.
const read_handle = windows.kernel32.CreateNamedPipeW(
pipe_path.ptr,
windows.PIPE_ACCESS_INBOUND | windows.FILE_FLAG_OVERLAPPED,
windows.PIPE_TYPE_BYTE,
1,
4096,
4096,
0,
sattr,
);
if (read_handle == windows.INVALID_HANDLE_VALUE) {
switch (windows.GetLastError()) {
else => |err| return windows.unexpectedError(err),
}
}
errdefer posix.close(read_handle);
var sattr_copy = sattr.*;
const write_handle = windows.kernel32.CreateFileW(
pipe_path.ptr,
windows.GENERIC_WRITE,
0,
&sattr_copy,
windows.OPEN_EXISTING,
windows.FILE_ATTRIBUTE_NORMAL,
null,
);
if (write_handle == windows.INVALID_HANDLE_VALUE) {
switch (windows.GetLastError()) {
else => |err| return windows.unexpectedError(err),
}
}
errdefer posix.close(write_handle);
try windows.SetHandleInformation(read_handle, windows.HANDLE_FLAG_INHERIT, 0);
rd.* = read_handle;
wr.* = write_handle;
}
var pipe_name_counter = std.atomic.Value(u32).init(1);
/// File name extensions supported natively by `CreateProcess()` on Windows.
// Should be kept in sync with `windowsCreateProcessSupportsExtension`.
pub const WindowsExtension = enum {
bat,
cmd,
com,
exe,
};
/// Case-insensitive WTF-16 lookup
fn windowsCreateProcessSupportsExtension(ext: []const u16) ?WindowsExtension {
if (ext.len != 4) return null;
const State = enum {
start,
dot,
b,
ba,
c,
cm,
co,
e,
ex,
};
var state: State = .start;
for (ext) |c| switch (state) {
.start => switch (c) {
'.' => state = .dot,
else => return null,
},
.dot => switch (c) {
'b', 'B' => state = .b,
'c', 'C' => state = .c,
'e', 'E' => state = .e,
else => return null,
},
.b => switch (c) {
'a', 'A' => state = .ba,
else => return null,
},
.c => switch (c) {
'm', 'M' => state = .cm,
'o', 'O' => state = .co,
else => return null,
},
.e => switch (c) {
'x', 'X' => state = .ex,
else => return null,
},
.ba => switch (c) {
't', 'T' => return .bat,
else => return null,
},
.cm => switch (c) {
'd', 'D' => return .cmd,
else => return null,
},
.co => switch (c) {
'm', 'M' => return .com,
else => return null,
},
.ex => switch (c) {
'e', 'E' => return .exe,
else => return null,
},
};
return null;
}
test windowsCreateProcessSupportsExtension {
try std.testing.expectEqual(WindowsExtension.exe, windowsCreateProcessSupportsExtension(&[_]u16{ '.', 'e', 'X', 'e' }).?);
try std.testing.expect(windowsCreateProcessSupportsExtension(&[_]u16{ '.', 'e', 'X', 'e', 'c' }) == null);
}
/// Serializes argv into a WTF-16 encoded command-line string for use with CreateProcessW.
///
/// Serialization is done on-demand and the result is cached in order to allow for:
/// - Only serializing the particular type of command line needed (`.bat`/`.cmd`
/// command line serialization is different from `.exe`/etc)
/// - Reusing the serialized command lines if necessary (i.e. if the execution
/// of a command fails and the PATH is going to be continued to be searched
/// for more candidates)
const WindowsCommandLineCache = struct {
cmd_line: ?[:0]u16 = null,
script_cmd_line: ?[:0]u16 = null,
cmd_exe_path: ?[:0]u16 = null,
argv: []const []const u8,
allocator: mem.Allocator,
fn init(allocator: mem.Allocator, argv: []const []const u8) WindowsCommandLineCache {
return .{
.allocator = allocator,
.argv = argv,
};
}
fn deinit(self: *WindowsCommandLineCache) void {
if (self.cmd_line) |cmd_line| self.allocator.free(cmd_line);
if (self.script_cmd_line) |script_cmd_line| self.allocator.free(script_cmd_line);
if (self.cmd_exe_path) |cmd_exe_path| self.allocator.free(cmd_exe_path);
}
fn commandLine(self: *WindowsCommandLineCache) ![:0]u16 {
if (self.cmd_line == null) {
self.cmd_line = try argvToCommandLineWindows(self.allocator, self.argv);
}
return self.cmd_line.?;
}
/// Not cached, since the path to the batch script will change during PATH searching.
/// `script_path` should be as qualified as possible, e.g. if the PATH is being searched,
/// then script_path should include both the search path and the script filename
/// (this allows avoiding cmd.exe having to search the PATH again).
fn scriptCommandLine(self: *WindowsCommandLineCache, script_path: []const u16) ![:0]u16 {
if (self.script_cmd_line) |v| self.allocator.free(v);
self.script_cmd_line = try argvToScriptCommandLineWindows(
self.allocator,
script_path,
self.argv[1..],
);
return self.script_cmd_line.?;
}
fn cmdExePath(self: *WindowsCommandLineCache) ![:0]u16 {
if (self.cmd_exe_path == null) {
self.cmd_exe_path = try windowsCmdExePath(self.allocator);
}
return self.cmd_exe_path.?;
}
};
/// Returns the absolute path of `cmd.exe` within the Windows system directory.
/// The caller owns the returned slice.
fn windowsCmdExePath(allocator: mem.Allocator) error{ OutOfMemory, Unexpected }![:0]u16 {
var buf = try std.ArrayListUnmanaged(u16).initCapacity(allocator, 128);
errdefer buf.deinit(allocator);
while (true) {
const unused_slice = buf.unusedCapacitySlice();
// TODO: Get the system directory from PEB.ReadOnlyStaticServerData
const len = windows.kernel32.GetSystemDirectoryW(@ptrCast(unused_slice), @intCast(unused_slice.len));
if (len == 0) {
switch (windows.GetLastError()) {
else => |err| return windows.unexpectedError(err),
}
}
if (len > unused_slice.len) {
try buf.ensureUnusedCapacity(allocator, len);
} else {
buf.items.len = len;
break;
}
}
switch (buf.items[buf.items.len - 1]) {
'/', '\\' => {},
else => try buf.append(allocator, fs.path.sep),
}
try buf.appendSlice(allocator, unicode.utf8ToUtf16LeStringLiteral("cmd.exe"));
return try buf.toOwnedSliceSentinel(allocator, 0);
}
const ArgvToCommandLineError = error{ OutOfMemory, InvalidWtf8, InvalidArg0 };
/// Serializes `argv` to a Windows command-line string suitable for passing to a child process and
/// parsing by the `CommandLineToArgvW` algorithm. The caller owns the returned slice.
///
/// To avoid arbitrary command execution, this function should not be used when spawning `.bat`/`.cmd` scripts.
/// https://flatt.tech/research/posts/batbadbut-you-cant-securely-execute-commands-on-windows/
///
/// When executing `.bat`/`.cmd` scripts, use `argvToScriptCommandLineWindows` instead.
fn argvToCommandLineWindows(
allocator: mem.Allocator,
argv: []const []const u8,
) ArgvToCommandLineError![:0]u16 {
var buf = std.ArrayList(u8).init(allocator);
defer buf.deinit();
if (argv.len != 0) {
const arg0 = argv[0];
// The first argument must be quoted if it contains spaces or ASCII control characters
// (excluding DEL). It also follows special quoting rules where backslashes have no special
// interpretation, which makes it impossible to pass certain first arguments containing
// double quotes to a child process without characters from the first argument leaking into
// subsequent ones (which could have security implications).
//
// Empty arguments technically don't need quotes, but we quote them anyway for maximum
// compatibility with different implementations of the 'CommandLineToArgvW' algorithm.
//
// Double quotes are illegal in paths on Windows, so for the sake of simplicity we reject
// all first arguments containing double quotes, even ones that we could theoretically
// serialize in unquoted form.
var needs_quotes = arg0.len == 0;
for (arg0) |c| {
if (c <= ' ') {
needs_quotes = true;
} else if (c == '"') {
return error.InvalidArg0;
}
}
if (needs_quotes) {
try buf.append('"');
try buf.appendSlice(arg0);
try buf.append('"');
} else {
try buf.appendSlice(arg0);
}
for (argv[1..]) |arg| {
try buf.append(' ');
// Subsequent arguments must be quoted if they contain spaces, tabs or double quotes,
// or if they are empty. For simplicity and for maximum compatibility with different
// implementations of the 'CommandLineToArgvW' algorithm, we also quote all ASCII
// control characters (again, excluding DEL).
needs_quotes = for (arg) |c| {
if (c <= ' ' or c == '"') {
break true;
}
} else arg.len == 0;
if (!needs_quotes) {
try buf.appendSlice(arg);
continue;
}
try buf.append('"');
var backslash_count: usize = 0;
for (arg) |byte| {
switch (byte) {
'\\' => {
backslash_count += 1;
},
'"' => {
try buf.appendNTimes('\\', backslash_count * 2 + 1);
try buf.append('"');
backslash_count = 0;
},
else => {
try buf.appendNTimes('\\', backslash_count);
try buf.append(byte);
backslash_count = 0;
},
}
}
try buf.appendNTimes('\\', backslash_count * 2);
try buf.append('"');
}
}
return try unicode.wtf8ToWtf16LeAllocZ(allocator, buf.items);
}
test argvToCommandLineWindows {
const t = testArgvToCommandLineWindows;
try t(&.{
\\C:\Program Files\zig\zig.exe
,
\\run
,
\\.\src\main.zig
,
\\-target
,
\\x86_64-windows-gnu
,
\\-O
,
\\ReleaseSafe
,
\\--
,
\\--emoji=🗿
,
\\--eval=new Regex("Dwayne \"The Rock\" Johnson")
,
},
\\"C:\Program Files\zig\zig.exe" run .\src\main.zig -target x86_64-windows-gnu -O ReleaseSafe -- --emoji=🗿 "--eval=new Regex(\"Dwayne \\\"The Rock\\\" Johnson\")"
);
try t(&.{}, "");
try t(&.{""}, "\"\"");
try t(&.{" "}, "\" \"");
try t(&.{"\t"}, "\"\t\"");
try t(&.{"\x07"}, "\"\x07\"");
try t(&.{"🦎"}, "🦎");
try t(
&.{ "zig", "aa aa", "bb\tbb", "cc\ncc", "dd\r\ndd", "ee\x7Fee" },
"zig \"aa aa\" \"bb\tbb\" \"cc\ncc\" \"dd\r\ndd\" ee\x7Fee",
);
try t(
&.{ "\\\\foo bar\\foo bar\\", "\\\\zig zag\\zig zag\\" },
"\"\\\\foo bar\\foo bar\\\" \"\\\\zig zag\\zig zag\\\\\"",
);
try std.testing.expectError(
error.InvalidArg0,
argvToCommandLineWindows(std.testing.allocator, &.{"\"quotes\"quotes\""}),
);
try std.testing.expectError(
error.InvalidArg0,
argvToCommandLineWindows(std.testing.allocator, &.{"quotes\"quotes"}),
);
try std.testing.expectError(
error.InvalidArg0,
argvToCommandLineWindows(std.testing.allocator, &.{"q u o t e s \" q u o t e s"}),
);
}
fn testArgvToCommandLineWindows(argv: []const []const u8, expected_cmd_line: []const u8) !void {
const cmd_line_w = try argvToCommandLineWindows(std.testing.allocator, argv);
defer std.testing.allocator.free(cmd_line_w);
const cmd_line = try unicode.wtf16LeToWtf8Alloc(std.testing.allocator, cmd_line_w);
defer std.testing.allocator.free(cmd_line);
try std.testing.expectEqualStrings(expected_cmd_line, cmd_line);
}
const ArgvToScriptCommandLineError = error{
OutOfMemory,
InvalidWtf8,
/// NUL (U+0000), LF (U+000A), CR (U+000D) are not allowed
/// within arguments when executing a `.bat`/`.cmd` script.
/// - NUL/LF signifiies end of arguments, so anything afterwards
/// would be lost after execution.
/// - CR is stripped by `cmd.exe`, so any CR codepoints
/// would be lost after execution.
InvalidBatchScriptArg,
};
/// Serializes `argv` to a Windows command-line string that uses `cmd.exe /c` and `cmd.exe`-specific
/// escaping rules. The caller owns the returned slice.
///
/// Escapes `argv` using the suggested mitigation against arbitrary command execution from:
/// https://flatt.tech/research/posts/batbadbut-you-cant-securely-execute-commands-on-windows/
///
/// The return of this function will look like
/// `cmd.exe /d /e:ON /v:OFF /c "<escaped command line>"`
/// and should be used as the `lpCommandLine` of `CreateProcessW`, while the
/// return of `windowsCmdExePath` should be used as `lpApplicationName`.
///
/// Should only be used when spawning `.bat`/`.cmd` scripts, see `argvToCommandLineWindows` otherwise.
/// The `.bat`/`.cmd` file must be known to both have the `.bat`/`.cmd` extension and exist on the filesystem.
fn argvToScriptCommandLineWindows(
allocator: mem.Allocator,
/// Path to the `.bat`/`.cmd` script. If this path is relative, it is assumed to be relative to the CWD.
/// The script must have been verified to exist at this path before calling this function.
script_path: []const u16,
/// Arguments, not including the script name itself. Expected to be encoded as WTF-8.
script_args: []const []const u8,
) ArgvToScriptCommandLineError![:0]u16 {
var buf = try std.ArrayList(u8).initCapacity(allocator, 64);
defer buf.deinit();
// `/d` disables execution of AutoRun commands.
// `/e:ON` and `/v:OFF` are needed for BatBadBut mitigation:
// > If delayed expansion is enabled via the registry value DelayedExpansion,
// > it must be disabled by explicitly calling cmd.exe with the /V:OFF option.
// > Escaping for % requires the command extension to be enabled.
// > If its disabled via the registry value EnableExtensions, it must be enabled with the /E:ON option.
// https://flatt.tech/research/posts/batbadbut-you-cant-securely-execute-commands-on-windows/
buf.appendSliceAssumeCapacity("cmd.exe /d /e:ON /v:OFF /c \"");
// Always quote the path to the script arg
buf.appendAssumeCapacity('"');
// We always want the path to the batch script to include a path separator in order to
// avoid cmd.exe searching the PATH for the script. This is not part of the arbitrary
// command execution mitigation, we just know exactly what script we want to execute
// at this point, and potentially making cmd.exe re-find it is unnecessary.
//
// If the script path does not have a path separator, then we know its relative to CWD and
// we can just put `.\` in the front.
if (mem.indexOfAny(u16, script_path, &[_]u16{ mem.nativeToLittle(u16, '\\'), mem.nativeToLittle(u16, '/') }) == null) {
try buf.appendSlice(".\\");
}
// Note that we don't do any escaping/mitigations for this argument, since the relevant
// characters (", %, etc) are illegal in file paths and this function should only be called
// with script paths that have been verified to exist.
try unicode.wtf16LeToWtf8ArrayList(&buf, script_path);
buf.appendAssumeCapacity('"');
for (script_args) |arg| {
// Literal carriage returns get stripped when run through cmd.exe
// and NUL/newlines act as 'end of command.' Because of this, it's basically
// always a mistake to include these characters in argv, so it's
// an error condition in order to ensure that the return of this
// function can always roundtrip through cmd.exe.
if (std.mem.indexOfAny(u8, arg, "\x00\r\n") != null) {
return error.InvalidBatchScriptArg;
}
// Separate args with a space.
try buf.append(' ');
// Need to quote if the argument is empty (otherwise the arg would just be lost)
// or if the last character is a `\`, since then something like "%~2" in a .bat
// script would cause the closing " to be escaped which we don't want.
var needs_quotes = arg.len == 0 or arg[arg.len - 1] == '\\';
if (!needs_quotes) {
for (arg) |c| {
switch (c) {
// Known good characters that don't need to be quoted
'A'...'Z', 'a'...'z', '0'...'9', '#', '$', '*', '+', '-', '.', '/', ':', '?', '@', '\\', '_' => {},
// When in doubt, quote
else => {
needs_quotes = true;
break;
},
}
}
}
if (needs_quotes) {
try buf.append('"');
}
var backslashes: usize = 0;
for (arg) |c| {
switch (c) {
'\\' => {
backslashes += 1;
},
'"' => {
try buf.appendNTimes('\\', backslashes);
try buf.append('"');
backslashes = 0;
},
// Replace `%` with `%%cd:~,%`.
//
// cmd.exe allows extracting a substring from an environment
// variable with the syntax: `%foo:~<start_index>,<end_index>%`.
// Therefore, `%cd:~,%` will always expand to an empty string
// since both the start and end index are blank, and it is assumed
// that `%cd%` is always available since it is a built-in variable
// that corresponds to the current directory.
//
// This means that replacing `%foo%` with `%%cd:~,%foo%%cd:~,%`
// will stop `%foo%` from being expanded and *after* expansion
// we'll still be left with `%foo%` (the literal string).
'%' => {
// the trailing `%` is appended outside the switch
try buf.appendSlice("%%cd:~,");
backslashes = 0;
},
else => {
backslashes = 0;
},
}
try buf.append(c);
}
if (needs_quotes) {
try buf.appendNTimes('\\', backslashes);
try buf.append('"');
}
}
try buf.append('"');
return try unicode.wtf8ToWtf16LeAllocZ(allocator, buf.items);
}