From 0f352f4e2593289ded5597ed231e8a66d7d99f62 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20E=C3=9Fer?= <se@FreeBSD.org>
Date: Fri, 30 Oct 2020 10:44:46 +0000
Subject: [PATCH] Re-implement comment parsing missing in the internal
 pre-processor

The internal pre-processor ignored lines that did not parse a calendar
entries, but did not support multi-line comments in the way the external
cpp did.

The calendar files distributed with the base system (now in a port) do
use comments, though.

Implement comment processing for single-line (//) and multi-line comments
(/* */) with same semantics as in a standard C pre-processor.

All tests pass with this version, but there are no tests that specifically
verify comment processing.

Reported by:	jhs@berklix.com (Julian H. Stacey)
MFC after:	3 days
---
 usr.bin/calendar/io.c | 62 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 51 insertions(+), 11 deletions(-)

diff --git a/usr.bin/calendar/io.c b/usr.bin/calendar/io.c
index f0abd363db35..286cf5026ac9 100644
--- a/usr.bin/calendar/io.c
+++ b/usr.bin/calendar/io.c
@@ -278,6 +278,8 @@ cal_parse(FILE *in, FILE *out)
 	char *pp, p;
 	struct tm tm;
 	int flags;
+	char *c, *cc;
+	bool incomment = false;
 
 	/* Unused */
 	tm.tm_sec = 0;
@@ -289,8 +291,55 @@ cal_parse(FILE *in, FILE *out)
 		return (1);
 
 	while ((linelen = getline(&line, &linecap, in)) > 0) {
-		if (*line == '#') {
-			switch (token(line+1, out, &skip)) {
+		buf = line;
+		if (buf[linelen - 1] == '\n')
+			buf[--linelen] = '\0';
+
+		if (incomment) {
+			c = strstr(buf, "*/");
+			if (c) {
+				c += 2;
+				linelen -= c - buf;
+				buf = c;
+				incomment = false;
+			} else {
+				continue;
+			}
+		}
+		if (!incomment) {
+			do {
+				c = strstr(buf, "//");
+				cc = strstr(buf, "/*");
+				if (c != NULL && (cc == NULL || c - cc < 0)) {
+					*c = '\0';
+					linelen = c - buf;
+					break;
+				} else if (cc != NULL) {
+					c = strstr(cc + 2, "*/");
+					if (c != NULL) {
+						c += 2;
+						memmove(cc, c, c - buf + linelen);
+						linelen -= c - cc;
+					} else {
+						*cc = '\0';
+						linelen = cc - buf;
+						incomment = true;
+						break;
+					}
+				}
+			} while (c != NULL || cc != NULL);
+		}
+
+		for (l = linelen;
+		     l > 0 && isspace((unsigned char)buf[l - 1]);
+		     l--)
+			;
+		buf[l] = '\0';
+		if (buf[0] == '\0')
+			continue;
+
+		if (buf == line && *buf == '#') {
+			switch (token(buf+1, out, &skip)) {
 			case T_ERR:
 				free(line);
 				return (1);
@@ -306,15 +355,6 @@ cal_parse(FILE *in, FILE *out)
 		if (skip != 0)
 			continue;
 
-		buf = line;
-		for (l = linelen;
-		     l > 0 && isspace((unsigned char)buf[l - 1]);
-		     l--)
-			;
-		buf[l] = '\0';
-		if (buf[0] == '\0')
-			continue;
-
 		/*
 		 * Setting LANG in user's calendar was an old workaround
 		 * for 'calendar -a' being run with C locale to properly