From 46345060aa9414aad838acad2af11176fa094891 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Thu, 22 Jul 2021 11:26:23 +0200
Subject: Rename to when

This is to resolve the name conflict with another program called
watch, which is for watching command output.
---
 when.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 when.c

(limited to 'when.c')

diff --git a/when.c b/when.c
new file mode 100644
index 0000000..12cfbee
--- /dev/null
+++ b/when.c
@@ -0,0 +1,75 @@
+#include <err.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/event.h>
+#include <unistd.h>
+
+#define FD 27
+#define MAXFILES 100
+#define MAXFD 127 /* FD + MAXFILES */
+
+int
+main(int argc, char *argv[argc])
+{
+	char *filenames[MAXFD];
+	int fd, i, kq, n;
+	struct kevent evs[MAXFILES];
+	struct kevent ev[MAXFILES];
+
+	/* parse arguments */
+	if (argc-1 == 0) goto usage;
+	if (argv[1][0] == '-') {
+		if (argv[1][1] == 'i')
+			for (i = 2; i < argc; i++)
+				printf("%s\n", argv[i]);
+		else if (argv[1][1] == '-') ;
+		else goto usage;
+		argv++; argc--;
+	}
+	if (argc-1 == 0) goto usage;
+	if (argc-1 > MAXFILES)
+		errx(1, "more than %d files", MAXFILES);
+
+	/* disable buffering even non-interactively */
+	setbuf(stdout, NULL);
+
+	/* initialize kqueue */
+	if ((kq = kqueue()) == -1)
+		err(1, "kqueue");
+
+	/* process each file */
+	for (i = 1; i < argc; i++) {
+		if ((fd = open(argv[i], O_RDONLY)) == -1)
+			err(1, "%s", argv[i]);
+
+		filenames[fd] = argv[i];
+		EV_SET(ev+i-1, fd, EVFILT_VNODE, EV_ADD|EV_CLEAR,
+			NOTE_WRITE|NOTE_DELETE, 0, 0);
+	}
+
+	/* register events to watch for */
+	if (kevent(kq, ev, argc-1, NULL, 0, NULL) == -1)
+		err(1, "kevent");
+
+	for (;;) {
+		if ((n = kevent(kq, NULL, 0, evs, argc-1, NULL)) == -1)
+			err(1, "kevent");
+		for (i = 0; i < n; i++) {
+			if (evs[i].fflags & NOTE_WRITE)
+				printf("%s\n", filenames[evs[i].ident]);
+			if (evs[i].flags & EV_ERROR)
+				fprintf(stderr, "event error: %s\n",
+					strerror(evs[i].data));
+			if (evs[i].fflags & NOTE_DELETE) {
+				fprintf(stderr, "%s deleted\n",
+					filenames[evs[i].ident]);
+				close(evs[i].ident);
+			}
+		}
+	}
+
+usage:
+	fprintf(stderr, "usage: %s [-i] file\n", argv[0]);
+	return 1;
+}
-- 
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