src: extended checking of mktime() return value and capability

mktime() can legitimately return -1 under glibc and FreeBSD (and
possibly others), namely for 1970-01-01T00:59:59+0100. This means the
return value alone is not good enough to determine failure status.
The Linux mktime(3) manpage gives a way out:

	[on error] leaves the tm->tm_wday member unmodified.

Since tm_wday gets normalized to [0..6], using any other value as
input allows to determine failure status.

Author: jengelh

exch/midb/mail_engine.cpp

@@ -1110,7 +1110,10 @@ static std::unique_ptr<CONDITION_TREE> me_ct_build_internal(const char *charset,
 			memset(&tmp_tm, 0, sizeof(tmp_tm));
 			if (strptime(argv[i], "%d-%b-%Y", &tmp_tm) == nullptr)
 				return {};
+			tmp_tm.tm_wday = -1;
 			ptree_node->ct_time = mktime(&tmp_tm);
+			if (ptree_node->ct_time == -1 && tmp_tm.tm_wday == -1)
+				return {};
 		} else if ('(' == argv[i][0]) {
 			len = strlen(argv[i]);
 			argv[i][len - 1] = '\0';

exch/nsp/common_util.cpp

@@ -40,8 +40,9 @@ void common_util_day_to_filetime(const char *day, FILETIME *pftime)
 
 	memset(&tmp_tm, 0, sizeof(tmp_tm));
 	strptime(day, "%Y-%m-%d", &tmp_tm);
+	tmp_tm.tm_wday = -1;
 	tmp_time = mktime(&tmp_tm);
-	if (tmp_time == -1) {
+	if (tmp_time == -1 && tmp_tm.tm_wday == -1) {
 		*pftime = {};
 		return;
 	}

lib/mapi/tnef.cpp

@@ -733,7 +733,7 @@ pack_result tnef_pull::g_attr(TNEF_ATTRIBUTE *r)
 	case ATTRIBUTE_ID_DATERECD:
 	case ATTRIBUTE_ID_ATTACHCREATEDATE:
 	case ATTRIBUTE_ID_ATTACHMODIFYDATE:
-	case ATTRIBUTE_ID_DATEMODIFY:
+	case ATTRIBUTE_ID_DATEMODIFY: {
 		r->pvalue = pext->anew<uint64_t>();
 		if (r->pvalue == nullptr)
 			return EXT_ERR_ALLOC;
@@ -750,11 +750,14 @@ pack_result tnef_pull::g_attr(TNEF_ATTRIBUTE *r)
 		tmp_tm.tm_mday = tmp_dtr.day;
 		tmp_tm.tm_mon = tmp_dtr.month - 1;
 		tmp_tm.tm_year = tmp_dtr.year - 1900;
-		tmp_tm.tm_wday = tmp_dtr.dow - 1;
+		tmp_tm.tm_wday = -1;
 		tmp_tm.tm_yday = 0;
 		tmp_tm.tm_isdst = 0;
-		*static_cast<uint64_t *>(r->pvalue) = rop_util_unix_to_nttime(mktime(&tmp_tm));
+		auto newtime = mktime(&tmp_tm);
+		*static_cast<uint64_t *>(r->pvalue) = newtime != -1 || tmp_tm.tm_wday != -1 ?
+		                                      rop_util_unix_to_nttime(newtime) : 0;
 		break;
+	}
 	case ATTRIBUTE_ID_REQUESTRES:
 	case ATTRIBUTE_ID_PRIORITY:
 		r->pvalue = pext->anew<uint16_t>();

tools/mbop_main.cpp

@@ -498,7 +498,12 @@ static int xmktime(const char *str, time_t *out)
 		fprintf(stderr, "\"%s\" not understood, error at \"%s\". Required format is \"2024-01-01T00:00:00\" [always local system time] or unixtime.\n", g_start_txt, end);
 		return -1;
 	}
+	tm.tm_wday = -1;
 	*out = mktime(&tm);
+	if (*out == -1 && tm.tm_wday == -1) {
+		fprintf(stderr, "\"%s\" not understood by mktime\n", g_start_txt);
+		return -1;
+	}
 	return 0;
 }