Add watch(1)

Makefile

@@ -13,6 +13,8 @@ LIB = \
 	util/proc.o         \
 	util/putword.o      \
 	util/recurse.o      \
+	util/strlcat.o      \
+	util/strlcpy.o      \
 	util/tty.o
 
 SRC = \
@@ -40,7 +42,8 @@ SRC = \
 	truncate.c          \
 	umount.c            \
 	unshare.c           \
-	uptime.c
+	uptime.c            \
+	watch.c
 
 OBJ = $(SRC:.c=.o) $(LIB)
 BIN = $(SRC:.c=)

util.h

@@ -14,4 +14,6 @@ void eprintf(const char *, ...);
 long estrtol(const char *, int);
 void putword(const char *);
 void recurse(const char *, void (*)(const char *));
+size_t strlcat(char *, const char *, size_t);
+size_t strlcpy(char *, const char *, size_t);
 char *ttytostr(int, int);

util/strlcat.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <string.h>
+
+size_t
+strlcat(char *dest, const char *src, size_t count)
+{
+	size_t dsize = strlen(dest);
+	size_t len = strlen(src);
+	size_t res = dsize + len;
+
+	dest += dsize;
+	count -= dsize;
+	if (len >= count)
+		len = count-1;
+	memcpy(dest, src, len);
+	dest[len] = 0;
+	return res;
+}

util/strlcpy.c

@@ -0,0 +1,15 @@
+#include <stdio.h>
+#include <string.h>
+
+size_t
+strlcpy(char *dest, const char *src, size_t size)
+{
+	size_t ret = strlen(src);
+
+	if (size) {
+		size_t len = (ret >= size) ? size - 1 : ret;
+		memcpy(dest, src, len);
+		dest[len] = '\0';
+	}
+	return ret;
+}

watch.c

@@ -0,0 +1,46 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-t] [-n interval] command\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	char cmd[BUFSIZ];
+	int i, interval = 2;
+
+	ARGBEGIN {
+	case 't':
+		break;
+	case 'n':
+		/* Only whole seconds for now */
+		interval = estrtol(EARGF(usage()), 10);
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc < 1)
+		usage();
+
+	strlcpy(cmd, argv[0], sizeof(cmd));
+	for (i = 1; i < argc; i++) {
+		strlcat(cmd, " ", sizeof(cmd));
+		strlcat(cmd, argv[i], sizeof(cmd));
+	}
+
+	for (;;) {
+		fflush(NULL);
+		system(cmd);
+		sleep(interval);
+	}
+	return 0;
+}