runtime, cgo: cgo call to setgid hangs on GNU/Linux #3871
Description
This program hangs on GNU/Linux.
package main
/*
#include <sys/types.h>
#include <unistd.h>
*/
import "C"
import "fmt"
func main() {
i, errno := C.setgid(1)
fmt.Println(i, errno)
}
The problem is that when a threaded program calls setgid, the pthreads library sends a
SIGSETXID signal to each thread, and waits for the thread to acknowledge it. The Go
runtime overrides the default signal handler with a Go-specific one. Since the
os/signal package is not imported, the Go-specific signal handler simply ignores
SIGSETXID. This means that the acknowledgement is never sent, and the program hangs.