strings: Add -n len support

README

@@ -67,7 +67,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
    sort            no                           -m, -o, -d, -f, -i
 =* split           yes                          none
 =* sponge          non-posix                    none
-   strings         no                           -n, -t
+   strings         no                           -t
 =* sync            non-posix                    none
 =* tail            yes                          none
 =* tar             non-posix                    none

strings.1

@@ -7,6 +7,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl a
+.Op Fl n Ar len
 .Op Ar file ...
 .Sh DESCRIPTION
 .Nm
@@ -20,6 +21,10 @@ reads from stdin.
 .Bl -tag -width Ds
 .It Fl a
 Scan files in their entirety. This is the default.
+.It Fl n Ar len
+Only print sequences that are at least
+.Ar len
+characters.  The default is 4 characters.
 .El
 .Sh STANDARDS
 .Nm

strings.c

@@ -1,48 +1,12 @@
 /* See LICENSE file for copyright and license details. */
 #include <ctype.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "util.h"
 
-static void dostrings(FILE *fp, const char *fname);
-
 static void
-usage(void)
+strings(FILE *fp, const char *fname, int len)
-{
-	eprintf("usage: %s [-a] [file ...]\n", argv0);
-}
-
-int
-main(int argc, char *argv[])
-{
-	FILE *fp;
-	int ret = 0;
-
-	ARGBEGIN {
-	case 'a':
-		break;
-	default:
-		usage();
-	} ARGEND;
-
-	if (argc == 0) {
-		dostrings(stdin, "<stdin>");
-	} else {
-		for (; argc > 0; argc--, argv++) {
-			if (!(fp = fopen(argv[0], "r"))) {
-				weprintf("fopen %s:", argv[0]);
-				ret = 1;
-				continue;
-			}
-			dostrings(fp, argv[0]);
-			fclose(fp);
-		}
-	}
-	return ret;
-}
-
-static void
-dostrings(FILE *fp, const char *fname)
 {
 	unsigned char buf[BUFSIZ];
 	int c, i = 0;
@@ -52,7 +16,7 @@ dostrings(FILE *fp, const char *fname)
 		offset++;
 		if (isprint(c = getc(fp)))
 			buf[i++] = c;
-		if ((!isprint(c) && i >= 6) || i == sizeof(buf) - 1) {
+		if ((!isprint(c) && i >= len) || i == sizeof(buf) - 1) {
 			buf[i] = '\0';
 			printf("%8ld: %s\n", (long)offset - i - 1, buf);
 			i = 0;
@@ -61,3 +25,42 @@ dostrings(FILE *fp, const char *fname)
 	if (ferror(fp))
 		eprintf("%s: read error:", fname);
 }
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-a] [-n len] [file ...]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	FILE *fp;
+	int ret = 0;
+	int len = 4;
+
+	ARGBEGIN {
+	case 'a':
+		break;
+	case 'n':
+		len = estrtonum(EARGF(usage()), 1, INT_MAX);
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc == 0) {
+		strings(stdin, "<stdin>", len);
+	} else {
+		for (; argc > 0; argc--, argv++) {
+			if (!(fp = fopen(argv[0], "r"))) {
+				weprintf("fopen %s:", argv[0]);
+				ret = 1;
+				continue;
+			}
+			strings(fp, argv[0], len);
+			fclose(fp);
+		}
+	}
+	return ret;
+}