#include	<sys/types.h>#include	<signal.h>#include 	<pwd.h>#include	<sys/resource.h>#include	<sys/wait.h>#include	<fcntl.h> #include	"dat.h"#include	"fns.h"#include	"error.h" enum{	Debug = 0}; /* * os-specific devcmd support. * this version should be reasonably portable across Unix systems. */typedef struct Targ Targ;struct Targ{	int	fd[3];	/* fd[0] is standard input, fd[1] is standard output, fd[2] is standard error */	char**	args;	char*	dir;	int	pid;	int	wfd;	/* child writes errors that occur after the fork or on exec */	int	uid;	int	gid;}; extern int gidnobody;extern int uidnobody; static intchildproc(Targ *t){	int i, nfd; 	if(Debug)		print("devcmd: '%s'", t->args[0]); 	nfd = getdtablesize();	for(i = 0; i < nfd; i++)		if(i != t->fd[0] && i != t->fd[1] && i != t->fd[2] && i != t->wfd)			close(i); 	dup2(t->fd[0], 0);	dup2(t->fd[1], 1);	dup2(t->fd[2], 2);	close(t->fd[0]);	close(t->fd[1]);	close(t->fd[2]); 	/* should have an auth file to do host-specific authorisation? */	if(t->gid != -1){		if(setgid(t->gid) < 0 && getegid() == 0){			fprint(t->wfd, "can't set gid %d: %s", t->gid, strerror(errno));			_exit(1);		}	} 	if(t->uid != -1){		if(setuid(t->uid) < 0 && geteuid() == 0){			fprint(t->wfd, "can't set uid %d: %s", t->uid, strerror(errno));			_exit(1);		}	} 	if(t->dir != nil && chdir(t->dir) < 0){		fprint(t->wfd, "can't chdir to %s: %s", t->dir, strerror(errno));		_exit(1);	} 	signal(SIGPIPE, SIG_DFL); 	execve(t->args[0], t->args, NULL);	if(Debug)		print("execvp: %s\n",strerror(errno));	fprint(t->wfd, "exec failed: %s", strerror(errno)); 	_exit(1);} void*oscmd(char **args, int nice, char *dir, int *fd){	Targ *t;	int r, fd0[2], fd1[2], fd2[2], wfd[2], n, pid; 	t = mallocz(sizeof(*t), 1);	if(t == nil)		return nil; 	fd0[0] = fd0[1] = -1;	fd1[0] = fd1[1] = -1;	fd2[0] = fd2[1] = -1;	wfd[0] = wfd[1] = -1;	if(pipe(fd0) < 0 || pipe(fd1) < 0 || pipe(fd2) < 0 || pipe(wfd) < 0)		goto Error;	if(fcntl(wfd[1], F_SETFD, FD_CLOEXEC) < 0)	/* close on exec to give end of file on success */		goto Error; 	t->fd[0] = fd0[0];	t->fd[1] = fd1[1];	t->fd[2] = fd2[1];	t->wfd = wfd[1];	t->args = args;	t->dir = dir;	t->gid = up->env->gid;	if(t->gid == -1)		t->gid = gidnobody;	t->uid = up->env->uid;	if(t->uid == -1)		t->uid = uidnobody; 	signal(SIGCHLD, SIG_DFL);	switch(pid = fork()) {	case -1:		goto Error;	case 0:		setpgrp();		if(nice)			setpriority(PRIO_PROCESS, 0, 19);		childproc(t);		_exit(1);	default:		t->pid = pid;		if(Debug)			print("cmd pid %d\n", t->pid);		break;	} 	close(fd0[0]);	close(fd1[1]);	close(fd2[1]);	close(wfd[1]); 	n = read(wfd[0], up->genbuf, sizeof(up->genbuf)-1);	close(wfd[0]);	if(n > 0){		close(fd0[1]);		close(fd1[0]);		close(fd2[0]);		free(t);		up->genbuf[n] = 0;		if(Debug)			print("oscmd: bad exec: %q\n", up->genbuf);		error(up->genbuf);		return nil;	} 	fd[0] = fd0[1];	fd[1] = fd1[0];	fd[2] = fd2[0];	return t; Error:	r = errno;	if(Debug)		print("oscmd: %q\n",strerror(r));	close(fd0[0]);	close(fd0[1]);	close(fd1[0]);	close(fd1[1]);	close(fd2[0]);	close(fd2[1]);	close(wfd[0]);	close(wfd[1]);	error(strerror(r));	return nil;} intoscmdkill(void *a){	Targ *t = a; 	if(Debug)		print("kill: %d\n", t->pid);	return kill(-t->pid, SIGTERM);} intoscmdwait(void *a, char *buf, int n){	Targ *t = a;	int s; 	if(waitpid(t->pid, &s, 0) == -1){		if(Debug)			print("wait error: %d [in %d] %q\n", t->pid, getpid(), strerror(errno));		return -1;	}	if(WIFEXITED(s)){		if(WEXITSTATUS(s) == 0)			return snprint(buf, n, "%d 0 0 0 ''", t->pid);		return snprint(buf, n, "%d 0 0 0 'exit: %d'", t->pid, WEXITSTATUS(s));	}	if(WIFSIGNALED(s)){		if(WTERMSIG(s) == SIGTERM || WTERMSIG(s) == SIGKILL)			return snprint(buf, n, "%d 0 0 0 killed", t->pid);		return snprint(buf, n, "%d 0 0 0 'signal: %d'", t->pid, WTERMSIG(s));	}	return snprint(buf, n, "%d 0 0 0 'odd status: 0x%x'", t->pid, s);} voidoscmdfree(void *a){	free(a);}