diff --git a/lib/std/Build/Step/Run.zig b/lib/std/Build/Step/Run.zig index 37db10916f..a9d4808bc0 100644 --- a/lib/std/Build/Step/Run.zig +++ b/lib/std/Build/Step/Run.zig @@ -1354,6 +1354,9 @@ fn spawnChildAndCollect( _ = child.kill() catch {}; } + // We need to report `error.InvalidExe` *now* if applicable. + try child.waitForSpawn(); + var timer = try std.time.Timer.start(); const result = if (run.stdio == .zig_test) diff --git a/lib/std/process/Child.zig b/lib/std/process/Child.zig index 72277c2e62..fa824e0aec 100644 --- a/lib/std/process/Child.zig +++ b/lib/std/process/Child.zig @@ -73,7 +73,7 @@ cwd: ?[]const u8, /// 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 [2]posix.fd_t, +err_pipe: if (native_os == .windows) void else ?posix.fd_t, expand_arg0: Arg0Expand, @@ -211,7 +211,7 @@ pub fn init(argv: []const []const u8, allocator: mem.Allocator) ChildProcess { .argv = argv, .id = undefined, .thread_handle = undefined, - .err_pipe = null, + .err_pipe = if (native_os == .windows) {} else null, .term = null, .env_map = null, .cwd = null, @@ -293,17 +293,49 @@ pub fn killPosix(self: *ChildProcess) !Term { error.ProcessNotFound => return error.AlreadyTerminated, else => return err, }; - self.waitUnwrapped(); + 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 { - const term = if (native_os == .windows) try self.waitWindows() else self.waitPosix(); + 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 term; + return self.term.?; } pub const RunResult = struct { @@ -405,26 +437,6 @@ pub fn run(args: struct { }; } -fn waitWindows(self: *ChildProcess) WaitError!Term { - if (self.term) |term| { - self.cleanupStreams(); - return term; - } - - try self.waitUnwrappedWindows(); - return self.term.?; -} - -fn waitPosix(self: *ChildProcess) SpawnError!Term { - if (self.term) |term| { - self.cleanupStreams(); - return term; - } - - self.waitUnwrapped(); - return self.term.?; -} - fn waitUnwrappedWindows(self: *ChildProcess) WaitError!void { const result = windows.WaitForSingleObjectEx(self.id, windows.INFINITE, false); @@ -447,7 +459,7 @@ fn waitUnwrappedWindows(self: *ChildProcess) WaitError!void { return result; } -fn waitUnwrapped(self: *ChildProcess) void { +fn waitUnwrappedPosix(self: *ChildProcess) void { const res: posix.WaitPidResult = res: { if (self.request_resource_usage_statistics) { switch (native_os) { @@ -469,7 +481,7 @@ fn waitUnwrapped(self: *ChildProcess) void { } fn handleWaitResult(self: *ChildProcess, status: u32) void { - self.term = self.cleanupAfterWait(status); + self.term = statusToTerm(status); } fn cleanupStreams(self: *ChildProcess) void { @@ -487,46 +499,6 @@ fn cleanupStreams(self: *ChildProcess) void { } } -fn cleanupAfterWait(self: *ChildProcess, status: u32) !Term { - if (self.err_pipe) |err_pipe| { - defer destroyPipe(err_pipe); - - if (native_os == .linux) { - var fd = [1]posix.pollfd{posix.pollfd{ - .fd = err_pipe[0], - .events = posix.POLL.IN, - .revents = undefined, - }}; - - // Check if the eventfd buffer stores a non-zero value by polling - // it, that's the error code returned by the child process. - _ = posix.poll(&fd, 0) catch unreachable; - - // According to eventfd(2) the descriptor is readable if the counter - // has a value greater than 0 - if ((fd[0].revents & posix.POLL.IN) != 0) { - const err_int = try readIntFd(err_pipe[0]); - return @as(SpawnError, @errorCast(@errorFromInt(err_int))); - } - } else { - // Write maxInt(ErrInt) to the write end of the err_pipe. This is after - // waitpid, so this write is guaranteed to be after the child - // pid potentially wrote an error. This way we can do a blocking - // read on the error pipe and either get maxInt(ErrInt) (no error) or - // an error code. - try writeIntFd(err_pipe[1], maxInt(ErrInt)); - const err_int = try readIntFd(err_pipe[0]); - // Here we potentially return the fork child's error from the parent - // pid. - if (err_int != maxInt(ErrInt)) { - return @as(SpawnError, @errorCast(@errorFromInt(err_int))); - } - } - } - - return statusToTerm(status); -} - fn statusToTerm(status: u32) Term { return if (posix.W.IFEXITED(status)) Term{ .Exited = posix.W.EXITSTATUS(status) } @@ -636,18 +608,9 @@ fn spawnPosix(self: *ChildProcess) SpawnError!void { } }; - // This pipe is used to communicate errors between the time of fork - // and execve from the child process to the parent process. - const err_pipe = blk: { - if (native_os == .linux) { - const fd = try posix.eventfd(0, linux.EFD.CLOEXEC); - // There's no distinction between the readable and the writeable - // end with eventfd - break :blk [2]posix.fd_t{ fd, fd }; - } else { - break :blk try posix.pipe2(.{ .CLOEXEC = true }); - } - }; + // 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(); @@ -687,6 +650,11 @@ fn spawnPosix(self: *ChildProcess) SpawnError!void { } // 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] }; @@ -705,7 +673,6 @@ fn spawnPosix(self: *ChildProcess) SpawnError!void { } self.id = pid; - self.err_pipe = err_pipe; self.term = null; if (self.stdin_behavior == .Pipe) {