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rework to allow ReadFile to complete synchronously

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This commit is contained in:
Jonathan Marler 2022-02-06 15:20:15 -07:00
parent 8f830207c4
commit 4fddb591e2
1 changed files with 36 additions and 19 deletions
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55
lib/std/child_process.zig
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@ -252,6 +252,33 @@ pub const ChildProcess = struct {
}
}
const WindowsAsyncReadResult = enum {
pending,
closed,
full,
};
fn windowsAsyncRead(
handle: windows.HANDLE,
overlapped: *windows.OVERLAPPED,
buf: *std.ArrayList(u8),
bump_amt: usize,
max_output_bytes: usize,
) !WindowsAsyncReadResult {
while (true) {
const new_capacity = std.math.min(buf.items.len + bump_amt, max_output_bytes);
try buf.ensureTotalCapacity(new_capacity);
const next_buf = buf.unusedCapacitySlice();
if (next_buf.len == 0) return .full;
const read_result = windows.kernel32.ReadFile(handle, next_buf.ptr, math.cast(u32, next_buf.len) catch maxInt(u32), null, overlapped);
if (read_result == 0) return switch (windows.kernel32.GetLastError()) {
.IO_PENDING => .pending,
.BROKEN_PIPE => .closed,
else => |err| windows.unexpectedError(err),
};
}
}
fn collectOutputWindows(child: *const ChildProcess, outs: [2]*std.ArrayList(u8), max_output_bytes: usize) !void {
const bump_amt = 512;
const handles = [_]windows.HANDLE{
@ -274,18 +301,13 @@ pub const ChildProcess = struct {
// Windows Async IO requires an initial call to ReadFile before waiting on the handle
for ([_]u1{ 0, 1 }) |i| {
const new_capacity = std.math.min(outs[i].items.len + bump_amt, max_output_bytes);
try outs[i].ensureTotalCapacity(new_capacity);
const buf = outs[i].unusedCapacitySlice();
const read_result = windows.kernel32.ReadFile(handles[i], buf.ptr, math.cast(u32, buf.len) catch maxInt(u32), null, &overlapped[i]);
std.debug.assert(read_result == 0);
switch (windows.kernel32.GetLastError()) {
.IO_PENDING => {
switch (try windowsAsyncRead(handles[i], &overlapped[i], outs[i], bump_amt, max_output_bytes)) {
.pending => {
wait_objects[wait_object_count] = handles[i];
wait_object_count += 1;
},
.BROKEN_PIPE => {}, // don't add to the wait_objects list
else => |err| return windows.unexpectedError(err),
.closed => {}, // don't add to the wait_objects list
.full => return if (i == 0) error.StdoutStreamTooLong else error.StderrStreamTooLong,
}
}
@ -319,19 +341,14 @@ pub const ChildProcess = struct {
}
outs[i].items.len += read_bytes;
const new_capacity = std.math.min(outs[i].items.len + bump_amt, max_output_bytes);
try outs[i].ensureTotalCapacity(new_capacity);
const buf = outs[i].unusedCapacitySlice();
if (buf.len == 0) return if (i == 0) error.StdoutStreamTooLong else error.StderrStreamTooLong;
const read_result = windows.kernel32.ReadFile(handles[i], buf.ptr, math.cast(u32, buf.len) catch maxInt(u32), null, &overlapped[i]);
std.debug.assert(read_result == 0);
switch (windows.kernel32.GetLastError()) {
.IO_PENDING => {
switch (try windowsAsyncRead(handles[i], &overlapped[i], outs[i], bump_amt, max_output_bytes)) {
.pending => {
wait_objects[wait_object_count] = handles[i];
wait_object_count += 1;
},
.BROKEN_PIPE => {}, // don't add to the wait_objects list
else => |err| return windows.unexpectedError(err),
.closed => {}, // don't add to the wait_objects list
.full => return if (i == 0) error.StdoutStreamTooLong else error.StderrStreamTooLong,
}
}
}