From c939da849d2e047534bf21813ed09e08e754522d Mon Sep 17 00:00:00 2001
From: John Ankarstrom <john@ankarstrom.se>
Date: Sat, 3 Jul 2021 15:16:27 +0200
Subject: Re-organize source code

---
 watch.c | 113 ++++++++++++++++++++++++----------------------------------------
 1 file changed, 42 insertions(+), 71 deletions(-)

diff --git a/watch.c b/watch.c
index 0cfc5c9..7e3d256 100644
--- a/watch.c
+++ b/watch.c
@@ -1,4 +1,3 @@
-#define _OPENBSD_SOURCE
 #include <err.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -10,96 +9,68 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#define LIMIT 256
-
-/* print one initial line at startup */
-int initial = 0;
+#define FD 27
+#define LIMIT 100
 
 int
-main(int argc, char *argv[]) {
-	char **filenames;
-	int fd, first_file_index, i, kq, n;
-	size_t file_count;
-	struct kevent changes[LIMIT];
-	struct kevent events[LIMIT];
-	struct rlimit rlp;
-
-	file_count = argc - 1;
-	first_file_index = 1; /* index of first file argument */
-
-	/* disable buffering even non-interactively */
-	setbuf(stdout, NULL);
-
-	if (argc < 2) goto usage; /* quit if no arguments */
+main(int argc, char *argv[argc]) {
+	char *filenames[LIMIT+FD];
+	int fd, i, kq, n;
+	struct kevent evs[LIMIT];
+	struct kevent ev[LIMIT];
+
+	/* parse arguments */
+	if (argc-1 == 0) goto usage;
 	if (argv[1][0] == '-') {
-		if (argc < 3) goto usage; /* quit if no filenames */
-
-		/* adjust indices  */
-		file_count = argc - 2;
-		first_file_index = 2;
-
-		if (strcmp(argv[1], "-i") == 0)
-			initial = 1;
-		else
-			goto usage;
+		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 (file_count > LIMIT)
+	if (argc-1 == 0) goto usage;
+	if (argc-1 > LIMIT)
 		errx(1, "more than %d files", LIMIT);
 
-	if ((kq = kqueue()) == -1) err(1, "kqueue");
+	/* disable buffering even non-interactively */
+	setbuf(stdout, NULL);
 
-	/* save filenames by file descriptor  */
-	if (getrlimit(RLIMIT_NOFILE, &rlp) == -1)
-		err(1, "getrlimit");
-	if ((filenames = reallocarray(NULL, rlp.rlim_max, sizeof(char **))) == NULL)
-		err(1, "reallocarray");
+	/* initialize kqueue */
+	if ((kq = kqueue()) == -1)
+		err(1, "kqueue");
 
-	/* add each file to change list  */
-	for (i = first_file_index; i < argc; i++) {
+	/* 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];
-
-		if (initial)
-			printf("%s\n", argv[i]);
-
-		/* specify watched events */
-		struct kevent change = {
-			.ident = fd,
-			.filter = EVFILT_VNODE,
-			.flags = EV_ADD | EV_CLEAR,
-			.fflags = NOTE_WRITE | NOTE_DELETE,
-			.data = 0,
-			.udata = 0
-		};
-
-		changes[i - first_file_index] = change;
+		EV_SET(ev+i-1, fd, EVFILT_VNODE, EV_ADD|EV_CLEAR,
+			NOTE_WRITE|NOTE_DELETE, 0, 0);
 	}
 
-#ifdef __OpenBSD__
-	if (pledge("stdio", NULL) == -1) err(1, "pledge");
-#endif
+	/* register events to watch for */
+	if (kevent(kq, ev, argc-1, NULL, 0, NULL) == -1)
+		err(1, "kevent");
 
 	for (;;) {
-		/* register changes and wait for events  */
-		if ((n = kevent(kq, changes, file_count, events, file_count, NULL)) == -1)
-			err(1, "kevent wait");
-		if (n > 0) {
-			for (i = 0; i < n; i++) {
-				if (events[i].flags & EV_ERROR)
-					errx(1, "event error: %s", strerror(events[i].data));
-				if (events[i].fflags & NOTE_WRITE)
-					printf("%s\n", filenames[events[i].ident]);
-				if (events[i].fflags & NOTE_DELETE)
-					errx(1, "%s was deleted", filenames[events[i].ident]);
+		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);
 			}
 		}
 	}
 
-	return 0; /* assume that the kernel closes the file descriptors */
-
 usage:
 	fprintf(stderr, "usage: %s [-i] file\n", argv[0]);
 	return 1;
-- 
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