initial commit

grep.c

@@ -0,0 +1,97 @@
+/* See LICENSE file for copyright and license details. */
+#include <regex.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void grep(FILE *, const char *, regex_t *);
+
+static bool iflag = false;
+static bool vflag = false;
+static bool many;
+static bool match = false;
+static char mode = 0;
+
+int
+main(int argc, char *argv[])
+{
+	int i, flags = 0;
+	regex_t preg;
+	FILE *fp;
+
+	for(i = 1; i < argc; i++)
+		if(!strcmp(argv[i], "-c"))
+			mode = 'c';
+		else if(!strcmp(argv[i], "-i"))
+			iflag = true;
+		else if(!strcmp(argv[i], "-l"))
+			mode = 'l';
+		else if(!strcmp(argv[i], "-n"))
+			mode = 'n';
+		else if(!strcmp(argv[i], "-q"))
+			mode = 'q';
+		else if(!strcmp(argv[i], "-v"))
+			vflag = true;
+		else
+			break;
+
+	if(i == argc) {
+		fprintf(stderr, "usage: %s [-c] [-i] [-l] [-n] [-v] pattern [files...]\n", argv[0]);
+		exit(2);
+	}
+	if(mode == 'c')
+		flags |= REG_NOSUB;
+	if(iflag)
+		flags |= REG_ICASE;
+	regcomp(&preg, argv[i++], flags);
+
+	many = (argc > i+1);
+	if(i == argc)
+		grep(stdin, "<stdin>", &preg);
+	else for(; i < argc; i++) {
+		if(!(fp = fopen(argv[i], "r"))) {
+			fprintf(stderr, "fopen %s: ", argv[i]);
+			perror(NULL);
+			exit(2);
+		}
+		grep(fp, argv[i], &preg);
+		fclose(fp);
+	}
+	return match ? 0 : 1;
+}
+
+void
+grep(FILE *fp, const char *str, regex_t *preg)
+{
+	char buf[BUFSIZ];
+	int n, c = 0;
+
+	for(n = 1; fgets(buf, sizeof buf, fp); n++) {
+		if(regexec(preg, buf, 0, NULL, 0) ^ vflag)
+			continue;
+		if(mode == 'c')
+			c++;
+		else if(mode == 'l') {
+			puts(str);
+			break;
+		}
+		else if(mode == 'q')
+			exit(0);
+		else {
+			if(many)
+				printf("%s:", str);
+			if(mode == 'n')
+				printf("%d:", n);
+			fputs(buf, stdout);
+		}
+		match = true;
+	}
+	if(mode == 'c')
+		printf("%d\n", c);
+	if(ferror(fp)) {
+		fprintf(stderr, "%s: read error: ", str);
+		perror(NULL);
+		exit(2);
+	}
+}