From c2c5ea9c60f41bcda89782228cbd8b590923cbba Mon Sep 17 00:00:00 2001
From: Connor Lane Smith <cls@lubutu.com>
Date: Thu, 31 May 2012 19:38:25 +0100
Subject: [PATCH] grep: ARGBEGIN

---
 grep.c | 67 ++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 37 insertions(+), 30 deletions(-)

diff --git a/grep.c b/grep.c
index ece4034..22fb48d 100644
--- a/grep.c
+++ b/grep.c
@@ -11,6 +11,7 @@
 enum { Match = 0, NoMatch = 1, Error = 2 };
 
 static void grep(FILE *, const char *, regex_t *);
+static void usage(void);
 
 static bool vflag = false;
 static bool many;
@@ -21,46 +22,46 @@ int
 main(int argc, char *argv[])
 {
 	char c;
-	int n, flags = REG_NOSUB;
+	int i, n, flags = REG_NOSUB;
 	regex_t preg;
 	FILE *fp;
 
-	while((c = getopt(argc, argv, "Ecilnqv")) != -1)
-		switch(c) {
-		case 'E':
-			flags |= REG_EXTENDED;
-			break;
-		case 'c':
-		case 'l':
-		case 'n':
-		case 'q':
-			mode = c;
-			break;
-		case 'i':
-			flags |= REG_ICASE;
-			break;
-		case 'v':
-			vflag = true;
-			break;
-		default:
-			exit(Error);
-		}
-	if(optind == argc)
-		enprintf(Error, "usage: %s [-Ecilnqv] pattern [files...]\n", argv[0]);
+	ARGBEGIN {
+	case 'E':
+		flags |= REG_EXTENDED;
+		break;
+	case 'c':
+	case 'l':
+	case 'n':
+	case 'q':
+		mode = c;
+		break;
+	case 'i':
+		flags |= REG_ICASE;
+		break;
+	case 'v':
+		vflag = true;
+		break;
+	default:
+		usage();
+	} ARGEND;
 
-	if((n = regcomp(&preg, argv[optind++], flags)) != 0) {
+	if(argc == 0)
+		usage(); /* no pattern */
+
+	if((n = regcomp(&preg, argv[0], flags)) != 0) {
 		char buf[BUFSIZ];
 
 		regerror(n, &preg, buf, sizeof buf);
 		enprintf(Error, "invalid pattern: %s\n", buf);
 	}
-	many = (argc > optind+1);
-	if(optind == argc)
+	many = (argc > 1);
+	if(argc == 1)
 		grep(stdin, "<stdin>", &preg);
-	else for(; optind < argc; optind++) {
-		if(!(fp = fopen(argv[optind], "r")))
-			enprintf(Error, "fopen %s:", argv[optind]);
-		grep(fp, argv[optind], &preg);
+	else for(i = 1; i < argc; i++) {
+		if(!(fp = fopen(argv[i], "r")))
+			enprintf(Error, "fopen %s:", argv[i]);
+		grep(fp, argv[i], &preg);
 		fclose(fp);
 	}
 	return match ? Match : NoMatch;
@@ -104,3 +105,9 @@ end:
 		enprintf(Error, "%s: read error:", str);
 	free(buf);
 }
+
+void
+usage(void)
+{
+	enprintf(Error, "usage: %s [-Ecilnqv] pattern [files...]\n", argv0);
+}