Ekdohibs
/
zig
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #3922 from LemonBoy/eventfd-err 

More eventfd stuff
master
Andrew Kelley 2019-12-16 10:45:09 -05:00 committed by GitHub
parent 2c7a2aefbf 9d9b0720f5
commit 650acc5e3d
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 44 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
lib/std/child_process.zig
View File

@ -280,22 +280,38 @@ pub const ChildProcess = struct {
}
fn cleanupAfterWait(self: *ChildProcess, status: u32) !Term {
defer {
os.close(self.err_pipe[0]);
os.close(self.err_pipe[1]);
}
defer destroyPipe(self.err_pipe);
// 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(self.err_pipe[1], maxInt(ErrInt));
const err_int = try readIntFd(self.err_pipe[0]);
// Here we potentially return the fork child's error
// from the parent pid.
if (err_int != maxInt(ErrInt)) {
return @errSetCast(SpawnError, @intToError(err_int));
if (builtin.os == .linux) {
var fd = [1]std.os.pollfd{std.os.pollfd{
.fd = self.err_pipe[0],
.events = std.os.POLLIN,
.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.
_ = std.os.poll(&fd, 0) catch unreachable;
// According to eventfd(2) the descriptro is readable if the counter
// has a value greater than 0
if ((fd[0].revents & std.os.POLLIN) != 0) {
const err_int = try readIntFd(self.err_pipe[0]);
return @errSetCast(SpawnError, @intToError(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(self.err_pipe[1], maxInt(ErrInt));
const err_int = try readIntFd(self.err_pipe[0]);
// Here we potentially return the fork child's error from the parent
// pid.
if (err_int != maxInt(ErrInt)) {
return @errSetCast(SpawnError, @intToError(err_int));
}
}
return statusToTerm(status);
@ -359,7 +375,16 @@ pub const ChildProcess = struct {
// 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 = try os.pipe();
const err_pipe = blk: {
if (builtin.os == .linux) {
const fd = try os.eventfd(0, 0);
// There's no distinction between the readable and the writeable
// end with eventfd
break :blk [2]os.fd_t{ fd, fd };
} else {
break :blk try os.pipe();
}
};
errdefer destroyPipe(err_pipe);
const pid_result = try os.fork();
@ -773,7 +798,7 @@ fn windowsMakePipeOut(rd: *?windows.HANDLE, wr: *?windows.HANDLE, sattr: *const
fn destroyPipe(pipe: [2]os.fd_t) void {
os.close(pipe[0]);
os.close(pipe[1]);
if (pipe[0] != pipe[1]) os.close(pipe[1]);
}
// Child of fork calls this to report an error to the fork parent.
@ -787,12 +812,12 @@ const ErrInt = @IntType(false, @sizeOf(anyerror) * 8);
fn writeIntFd(fd: i32, value: ErrInt) !void {
const stream = &File.openHandle(fd).outStream().stream;
stream.writeIntNative(ErrInt, value) catch return error.SystemResources;
stream.writeIntNative(u64, @intCast(u64, value)) catch return error.SystemResources;
}
fn readIntFd(fd: i32) !ErrInt {
const stream = &File.openHandle(fd).inStream().stream;
return stream.readIntNative(ErrInt) catch return error.SystemResources;
return @intCast(ErrInt, stream.readIntNative(u64) catch return error.SystemResources);
}
/// Caller must free result.