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#include <u.h>
#include <sys/wait.h>
#include <signal.h>
#include <libc.h>
#undef rfork
int
p9rfork(int flags)
{
int pid, status;
int p[2];
int n;
char buf[128], *q;
if((flags&(RFPROC|RFFDG|RFMEM)) == (RFPROC|RFFDG)){
/* check other flags before we commit */
flags &= ~(RFPROC|RFFDG);
n = (flags & ~(RFNOTEG|RFNAMEG|RFNOWAIT));
if(n){
werrstr("unknown flags %08ux in rfork", n);
return -1;
}
if(flags&RFNOWAIT){
if(pipe(p) < 0)
return -1;
}
pid = fork();
if(pid == -1)
return -1;
if(flags&RFNOWAIT){
flags &= ~RFNOWAIT;
if(pid){
/*
* Parent - wait for child to fork wait-free child.
* Then read pid from pipe. Assume pipe buffer can absorb the write.
*/
close(p[1]);
wait4(pid, &status, 0, 0);
n = readn(p[0], buf, sizeof buf-1);
close(p[0]);
if(!WIFEXITED(status) || WEXITSTATUS(status)!=0 || n <= 0){
werrstr("pipe dance failed in rfork");
return -1;
}
buf[n] = 0;
n = strtol(buf, &q, 0);
if(*q != 0){
werrstr("%s", q);
return -1;
}
pid = n;
}else{
/*
* Child - fork a new child whose wait message can't
* get back to the parent because we're going to exit!
*/
signal(SIGCHLD, SIG_IGN);
close(p[0]);
pid = fork();
if(pid){
/* Child parent - send status over pipe and exit. */
if(pid > 0)
fprint(p[1], "%d", pid);
else
fprint(p[1], " %r");
close(p[1]);
_exit(0);
}else{
/* Child child - close pipe. */
close(p[1]);
}
}
}
if(pid != 0)
return pid;
}
if(flags&RFPROC){
werrstr("cannot use rfork for shared memory -- use ffork");
return -1;
}
if(flags&RFNAMEG){
/* XXX set $NAMESPACE to a new directory */
flags &= ~RFNAMEG;
}
if(flags&RFNOTEG){
setpgid(0, getpid());
flags &= ~RFNOTEG;
}
if(flags&RFNOWAIT){
werrstr("cannot use RFNOWAIT without RFPROC");
return -1;
}
if(flags){
werrstr("unknown flags %08ux in rfork", flags);
return -1;
}
return 0;
}
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