/*	execcmd - proc file system execution wrapper wrapper 	Copyright (C) 2010, IBM Corporation,  		Eric Van Hensbergen (bergevan@us.ibm.com) 	Description:		This provides a small wrapper the file system can use		to boot strap the application while maintaining expected		clone semantics. 	TODO:		* fork namespace after mounting mpipes		* support for ns configuration prior to exec */ #include <u.h>#include <libc.h>#include <fcall.h>#include <thread.h>#include <9p.h> char Estdios[] = "execcmd: couldn't open stdios";char Ebadctl[] = "execcmd: bad ctl command";char Ebadexec[] = "execcmd: bad exec command"; /* using parsecmd for later expansion */enum{	Cexec,}; Cmdtab ctltab[]={	Cexec,	"exec", 0,};	 voidmain(int argc, char **argv){	int stdinfd = -1;	int stdoutfd = -1;	int stderrfd = -1;	int ctlfd;	int ret;	char ctlbuf[255];	Cmdbuf *cb;	Cmdtab *cmd;	char *srvctl;	char fname[255];	int pid = getpid(); 	assert(argc == 2);	srvctl = argv[1]; 	/* open our files */	ctlfd = open(srvctl, ORDWR|OCEXEC);	assert(ctlfd>= 0);	remove(srvctl); 	ret = read(ctlfd, ctlbuf, 255);	if(ret <= 0) {		goto error;	} 	/* need to open our bit */	snprint(fname, 255, "/proc/%d/stdin", pid);	fprint(2, "just a test you see - [%s]\n", fname);	stdinfd = open(fname, OREAD);	if(stdinfd < 0)		fprint(2, "opening stdin failed: %r\n");	snprint(fname, 255, "/proc/%d/stdout", pid);	stdoutfd = open(fname, OWRITE);	if(stdoutfd < 0)		fprint(2, "opening stdout failed: %r\n");	snprint(fname, 255, "/proc/%d/stderr", pid);	stderrfd = open(fname, OWRITE);	if(stderrfd < 0)		fprint(2, "opening stderr failed: %r\n"); 	if((stdinfd < 0)||(stdoutfd < 0)||(stderrfd < 0)) {		write(ctlfd, Estdios, strlen(Estdios));		exits("stdios");	} 	ret = write(ctlfd, "1", 1);	/* report partial sucess */	if(ret < 0)		exits("ctlfdack"); 	while((ret = read(ctlfd, ctlbuf, 255)) > 0) {		cb = parsecmd(ctlbuf, ret);		cmd = lookupcmd(cb, ctltab, nelem(ctltab));		if(cmd == nil) {			write(ctlfd, Ebadctl, strlen(Ebadctl));			continue;		} 		switch(cmd->index){		case Cexec:			if(cb->nf < 2) {				write(ctlfd, Ebadexec, strlen(Ebadexec));				continue;			} 			dup(stdinfd, 0);			dup(stdoutfd, 1);			dup(stderrfd, 2); 			/* go baby go */			exec(cb->f[1], &cb->f[1]); 			/* something happened report it */			ret = snprint(ctlbuf, 255, "execcmd: exec: %r");			write(ctlfd, ctlbuf, ret);			goto error;			break;		/* room for more commands later */		}			} error:	close(ctlfd);	close(stdinfd);	close(stdoutfd);	close(stderrfd);	exits("ctl abort");}