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#include <u.h>
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#include <libc.h>
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#include <thread.h>
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#include "threadimpl.h"
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#define PIPEMNT	"/mnt/temp"
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void
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procexec(Channel *pidc, char *prog, char *args[])
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{
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	int n;
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	Proc *p;
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	Thread *t;
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	_threaddebug(DBGEXEC, "procexec %s", prog);
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	/* must be only thread in proc */
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	p = _threadgetproc();
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	t = p->thread;
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	if(p->threads.head != t || p->threads.head->nextt != nil){
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		werrstr("not only thread in proc");
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	Bad:
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		if(pidc)
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			sendul(pidc, ~0);
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		return;
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	}
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	/*
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	 * We want procexec to behave like exec; if exec succeeds,
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	 * never return, and if it fails, return with errstr set.
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	 * Unfortunately, the exec happens in another proc since
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	 * we have to wait for the exec'ed process to finish.
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	 * To provide the semantics, we open a pipe with the
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	 * write end close-on-exec and hand it to the proc that
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	 * is doing the exec.  If the exec succeeds, the pipe will
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	 * close so that our read below fails.  If the exec fails,
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	 * then the proc doing the exec sends the errstr down the
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	 * pipe to us.
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	 */
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	if(bind("#|", PIPEMNT, MREPL) < 0)
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		goto Bad;
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	if((p->exec.fd[0] = open(PIPEMNT "/data", OREAD)) < 0){
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		unmount(nil, PIPEMNT);
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		goto Bad;
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	}
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	if((p->exec.fd[1] = open(PIPEMNT "/data1", OWRITE|OCEXEC)) < 0){
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		close(p->exec.fd[0]);
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		unmount(nil, PIPEMNT);
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		goto Bad;
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	}
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	unmount(nil, PIPEMNT);
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	/* exec in parallel via the scheduler */
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	assert(p->needexec==0);
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	p->exec.prog = prog;
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	p->exec.args = args;
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	p->needexec = 1;
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	_sched();
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	close(p->exec.fd[1]);
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	if((n = read(p->exec.fd[0], p->exitstr, ERRMAX-1)) > 0){	/* exec failed */
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		p->exitstr[n] = '\0';
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		errstr(p->exitstr, ERRMAX);
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		close(p->exec.fd[0]);
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		goto Bad;
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	}
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	close(p->exec.fd[0]);
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	if(pidc)
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		sendul(pidc, t->ret);
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	/* wait for exec'ed program, then exit */
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	_schedexecwait();
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}
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void
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procexecl(Channel *pidc, char *f, ...)
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{
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	procexec(pidc, f, &f+1);
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}
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