1 files changed, 163 insertions, 0 deletions
diff --git a/crontab.c b/crontab.c
new file mode 100644
index 0000000..4532b09
--- /dev/null
+++ b/crontab.c
@@ -0,0 +1,163 @@
+/*
+ * UNG's Not GNU
+ *
+ * Copyright (c) 2011-2017, Jakob Kaivo <jkk@ung.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#define _XOPEN_SOURCE 700
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <pwd.h>
+#include <unistd.h>
+
+#define CRONTAB_PATH "/var/cron/"
+
+static char *getcrontabname(void)
+{
+	static char path[PATH_MAX] = CRONTAB_PATH;
+	struct passwd *pwd = getpwuid(getuid());
+	if (pwd == NULL) {
+		fprintf(stderr, "crontab: Couldn't determine username\n");
+		exit(1);
+	}
+	strcat(path, pwd->pw_name);
+	return path;
+}
+
+static int readcrontab(const char *file)
+{
+	if (file && !strcmp(file, getcrontabname())) {
+		/* daemonize */
+		return 0;
+	}
+
+	FILE *in = file ? fopen(file, "r") : stdin;
+	if (in == NULL) {
+		fprintf(stderr, "crontab: Couldn't open %s: %s\n", file, strerror(errno));
+		return 1;
+	}
+	FILE *out = fopen(getcrontabname(), "w");
+	if (out == NULL) {
+		fprintf(stderr, "crontab: Couldn't open entry to save: %s\n", strerror(errno));
+		return 1;
+	}
+
+	while (!feof(in)) {
+		/* read input */
+		/* verify formatting */
+		/* write output */
+	}
+
+	fclose(in);
+	fclose(out);
+
+	/* advanced: daeemonize and run the thing */
+	
+	return 0;
+}
+
+static int listcrontab(void)
+{
+	FILE *f = fopen(getcrontabname(), "r");
+	if (f == NULL) {
+		fprintf(stderr, "crontab: Couldn't open entry: %s\n", strerror(errno));
+		return 1;
+	}
+
+	int c;
+	while ((c = fgetc(f)) != EOF) {
+		putchar(c);
+	}
+
+	fclose(f);
+
+	return 0;
+}
+
+static int removecrontab(void)
+{
+	if (remove(getcrontabname()) != 0) {
+		fprintf(stderr, "Couldn't remove entry: %s\n", strerror(errno));
+		return 1;
+	}
+
+	return 0;
+}
+
+static int editcrontab(void)
+{
+	char *editor = getenv("EDITOR");
+	if (editor == NULL) {
+		editor = "vi";
+	}
+
+	execlp(editor, editor, getcrontabname(), 0);
+
+	fprintf(stderr, "crontab: Couldn't edit entry: %s\n", strerror(errno));
+
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	enum { READ, EDIT, LIST, REMOVE } mode = READ;
+	int c;
+	while ((c = getopt(argc, argv, "elr")) != -1) {
+		switch (c) {
+		case 'e':	/** edit the current user's crontab entry **/
+			mode = EDIT;
+			break;
+
+		case 'l':	/** list the current user's crontab entry **/
+			mode = LIST;
+			break;
+
+		case 'r':	/** remove the current user's crontab entry **/
+			mode = REMOVE;
+			break;
+
+		default:
+			return 1;
+		}
+	}
+
+	if (mode != READ && optind != argc) {
+		fprintf(stderr, "crontab: Option takes no additional arguments\n");
+		return 1;
+	}
+
+	if (mode == LIST) {
+		return listcrontab();
+	}
+
+	if (mode == REMOVE) {
+		return removecrontab();
+	}
+
+	if (mode == EDIT) {
+		return editcrontab();
+	}
+	
+	if (optind < argc - 1) {
+		fprintf(stderr, "crontab: At most one file may be specified\n");
+		return 1;
+	}
+
+	return readcrontab(argv[optind]);
+}