#include <u.h>#include <libc.h>#include <bio.h>#include <regexp.h> int	grep(Biobuf*, Reprog*, char*);char*	lower(char*); int	negate = 0;int	cflag = 0;int	hflag = 0;int	iflag = 0;int	lflag = 0;int	Lflag = 0;int	nflag = 0;int	sflag = 0; voidmain(int argc, char *argv[]){	Reprog *r;	Biobuf *b;	Biobuf bin;	int i, match; 	ARGBEGIN{	case 'c':		cflag = 1;		break;	case 'h':		hflag = 1;		break;	case 'i':		iflag = 1;		break;	case 'L':		Lflag = 1; /* fall through */	case 'l':		lflag = 1;		break;	case 'n':		nflag = 1;		break;	case 's':		sflag = 1;		break;	case 'v':		negate = 1;		break;	default:		goto Usage;	}ARGEND;	if(argc < 1)    Usage:		regerror("usage: grep [-chiLlnsv] pattern [file ...]");	r = regcomp(lower(argv[0]));	match = 0;	if(argc == 1){		hflag = 1;		Binit(&bin, 0, OREAD);		match = grep(&bin, r, "stdin");	}else for(i=1; i<argc; i++){		if(argc == 2)			hflag = 1;		b = Bopen(argv[i], OREAD);		if(b == 0)			fprint(2, "grep: can't open %s: %r\n", argv[i]);		else{			match |= grep(b, r, argv[i]);			Bclose(b);		}	}	if(match)		exits(0);	exits("no matches");} intgrep(Biobuf *b, Reprog *r, char *file){	char *buf;	int count;	long line;	char map[Bsize]; 	count = 0;	line = 0;    Loop:	while((buf=Brdline(b, '\n')) != 0){		line++;		buf[BLINELEN(b)-1] = 0;		if(iflag){			memmove(map, buf, BLINELEN(b));			lower(map);		}		if(regexec(r, iflag? map : buf, 0, 0) ^ negate){			count++;			if(lflag==0 && cflag==0 && sflag==0)				switch((nflag<<1)|hflag){				case 0:					print("%s:%s\n", file, buf);					break;				case (1<<1)|0:					print("%s:%d:%s\n", file, line, buf);					break;				case (0<<1)|1:					print("%s\n", buf);					break;				case (1<<1)|1:					print("%d:%s\n", line, buf);					break;				}		}	}	if(BLINELEN(b) > 0){	/* line too long; skip and continue */		Bseek(b, BLINELEN(b), 1);		goto Loop;	}	if(cflag && !sflag){		if(hflag)			print("%d\n", count);		else			print("%s:%d\n", file, count);	}	if(lflag){		if((count==0) == Lflag)			print("%s\n", file);	}	return count;} char*lower(char *s){	char *t; 		/* we assume the 'A'-'Z' only appear as themselves		 * in a utf encoding.		 */	if(iflag)		for (t = s; *t; t++)			*t = tolower(*t);	return s;} voidregerror(char *s){	fprint(2, "grep: %s\n", s);	exits(s);}