config

commit 0f047b44b0972948e5111e239de384ee997fc729
parent e2b13aab75d18436a6e06e4ae2ee78ef41e8ae21
Author: Jacob R. Edwards <jacob@jacobedwards.org>
Date:   Sun,  8 Oct 2023 08:47:39 -0700

Add timedec program

timedec is a simple program to convert an ASCII representation of
time to the seconds elapsed since the UNIX epoch. It's purpose is
to provide a standard interface to specifying time in other programs.

Diffstat:
M
local/src/src/singles/Makefile
 | 
1
+
A
local/src/src/singles/timedec.c
 | 
100
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 101 insertions(+), 0 deletions(-)
diff --git a/local/src/src/singles/Makefile b/local/src/src/singles/Makefile
@@ -1,5 +1,6 @@
 names =\
 	datediff\
+	timedec\
 	numsep\
 	urldecode\
 	urlencode\
diff --git a/local/src/src/singles/timedec.c b/local/src/src/singles/timedec.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2023 Jacob R. Edwards <jacob@jacobedwards.org>
+ *
+ * Permission to use, copy, modify, and 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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+char *
+die(char *msg)
+{
+	perror(msg);
+	exit(1);
+}
+
+char *
+xstrptime(char *buf, char *fmt, struct tm *tm)
+{
+	char *ep;
+	struct tm ref;
+
+	memcpy(&ref, tm, sizeof(ref));
+	if ((ep = strptime(buf, fmt, tm)))
+		return ep;
+	memcpy(tm, &ref, sizeof(ref));
+	return NULL;
+}
+
+char *
+strptimes(char *buf, char **fmts, struct tm *tm)
+{
+	char *ep;
+
+	for (; *fmts; ++fmts)
+		if ((ep = xstrptime(buf, *fmts, tm)))
+			return ep;
+	return NULL;
+}
+
+time_t
+decodedatetime(char *s)
+{
+	char *ep;
+	struct tm *tm;
+	time_t t;
+
+	t = time(NULL);
+	tm = localtime(&t);
+	tm->tm_hour = 0;
+	tm->tm_min = 0;
+	tm->tm_sec = 0;
+
+	ep = xstrptime(s, "%F", tm);
+	if (ep) {
+		if (ep[0] == '\0')
+			return mktime(tm);
+		else if (ep[0] != ' ')
+			return 0;
+		s = ep + 1;
+	}
+
+	ep = strptimes(s, (char *[]){ "%T", "%R", NULL }, tm);
+	if (!ep || (ep && ep[0]))
+		return 0;
+	return mktime(tm);
+}
+
+/*
+ * This program takes a time given in the strftime(3) format '%F'
+ * or '[%F ]%H:%M[:%S]' and outputs the time elapsed since Jan 1,
+ * 1970 00:00 in seconds.
+ *
+ * It is meant as to be a standard interface to specifying time.
+ */
+int
+main(int argc, char *argv[])
+{
+	char *ts;
+	time_t t;
+
+	if (!argv[1])
+		die("usage: timedec time");
+	t = decodedatetime(argv[1]);
+	if (t == 0)
+		die("invalid time (must be of the form '%F' or '[%F ]%H:%M[:%S]')");
+	return printf("%d\n", t) < 0;
+}