fortify/internal/fmsg/defer.go
Ophestra Umiker ae1a102882
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fmsg: support temporarily withholding output
Trying to print to a shared stdout is a terrible idea. This change makes it possible to withhold output for the lifetime of the sandbox.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>
2024-10-26 23:09:32 +09:00

71 lines
944 B
Go

package fmsg
import (
"os"
"sync"
"sync/atomic"
)
var (
wstate atomic.Bool
withhold = make(chan struct{}, 1)
msgbuf = make(chan dOp, 64) // these ops are tiny so a large buffer is allocated for withholding output
dequeueOnce sync.Once
queueSync sync.WaitGroup
)
func dequeue() {
go func() {
for {
select {
case op := <-msgbuf:
op.Do()
queueSync.Done()
case <-withhold:
<-withhold
}
}
}()
}
type dOp interface{ Do() }
func Exit(code int) {
queueSync.Wait()
os.Exit(code)
}
func Withhold() {
if wstate.CompareAndSwap(false, true) {
withhold <- struct{}{}
}
}
func Resume() {
if wstate.CompareAndSwap(true, false) {
withhold <- struct{}{}
}
}
type dPrint []any
func (v dPrint) Do() {
std.Print(v...)
}
type dPrintf struct {
format string
v []any
}
func (d *dPrintf) Do() {
std.Printf(d.format, d.v...)
}
type dPrintln []any
func (v dPrintln) Do() {
std.Println(v...)
}