#include <u.h>#include <libc.h> int chatty = 0;char *mppath; static voidusage(void){	fprint(2, "mp-writer [-D] [-e] [-n num-times] [-s testsize] <mpipe-data-path>\n");	exits("usage");} char *prepdata(int size){	char *buf = malloc(size);	int count; 	for(count=0; count < size; count++)		buf[count] = '0'+(count % 10); 	buf[size-1] = 0;	return buf;} /* pkthdr format:	type: char {p, <, >}	size: data size {for payload}	which: which slot, 0 for don't care	path: for streaming*/	intstreamout(int fd, ulong which, char *path){	int n; 	char hdr[255];	ulong tag = ~0;	char pkttype='>'; 	/* header byte is at offset ~0 */	n = snprint(hdr, 31, "%c\n%lud\n%lud\n%s\n", pkttype, (ulong)0, which, path);	n = pwrite(fd, hdr, n+1, tag);		return n;} intstreamin(int fd, ulong which, char *path){	int n; 	char hdr[255];	ulong tag = ~0;	char pkttype='<'; 	/* header byte is at offset ~0 */	n = snprint(hdr, 31, "%c\n%lud\n%lud\n%s\n", pkttype, (ulong)0, which, path);	n = pwrite(fd, hdr, n+1, tag);		return n;} intpipewrite(int fd, char *data, ulong size, ulong which){		int n; 	char hdr[255];	ulong tag = ~0;	char pkttype='p'; 	/* header byte is at offset ~0 */	n = snprint(hdr, 31, "%c\n%lud\n%lud\n\n", pkttype, size, which);	n = pwrite(fd, hdr, n+1, tag);	if(n <= 0)		return n; 	return write(fd, data, size);} voidmain(int argc, char *argv[]){	int times=5;	int size=1024;	int which=1;	int count;	int n;	int fd;	char *d = nil;	char *sin = nil;	char *sout = nil; 	ARGBEGIN{	case 'D':		chatty++;		break;	case 'n':		times = atoi(ARGF());		break;	case 'e':		/* add an enumerator to front of buffer */		which = atoi(ARGF());		break;	case 's':		size = atoi(ARGF());		break;	case 'i':		sin = ARGF();		break;	case 'o':		sout = ARGF();		break;	default:		usage();	}ARGEND 	if(argc != 1)		usage(); 	if(argc)		mppath = argv[0]; 	if(chatty)		fprint(2, "initializing\n"); 	fd = open(mppath, OWRITE);	if(fd < 0) {		fprint(2, "couldn't open file (%s): %r\n", mppath);		exits("open pipe");	} 	if(sin) {		streamin(fd, which, sin);		goto out;	}	if(sout) {		streamout(fd, which, sout);		goto out;	}		d = prepdata(size); 	for(count = 0; count < times; count++) {		if(chatty)			fprint(2, "writing %d time\n", count);		n = pipewrite(fd, d, size, count);		if(n != size) {			fprint(2, "pipe write failed: %d: %r\n", n);			exits("pipe failed");		}		}out:	if(chatty)		fprint(2, "closing and exiting\n"); 	free(d);	close(fd);	exits("done");}