Add unit test for mg_parse_date_string

    PUBLISHED_FROM=aec7d5e6c6598fbc5141c40c9638cc96d288c8dc

mongoose.c

@@ -101,6 +101,10 @@ MG_INTERNAL size_t mg_handle_chunked(struct mg_connection *nc,
                                      struct http_message *hm, char *buf,
                                      size_t blen);
 
+#ifndef MG_DISABLE_FILESYSTEM
+MG_INTERNAL time_t mg_parse_date_string(const char *datetime);
+#endif
+
 /* Forward declarations for testing. */
 extern void *(*test_malloc)(size_t);
 extern void *(*test_calloc)(size_t, size_t);
@@ -5914,7 +5918,7 @@ static void handle_cgi(struct mg_connection *nc, const char *prog,
 }
 #endif
 
-static int get_month_index(const char *s) {
+static int mg_get_month_index(const char *s) {
   static const char *month_names[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
                                       "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
   size_t i;
@@ -5925,12 +5929,12 @@ static int get_month_index(const char *s) {
   return -1;
 }
 
-static int num_leap_years(int year) {
+static int mg_num_leap_years(int year) {
   return year / 4 - year / 100 + year / 400;
 }
 
 /* Parse UTC date-time string, and return the corresponding time_t value. */
-static time_t parse_date_string(const char *datetime) {
+MG_INTERNAL time_t mg_parse_date_string(const char *datetime) {
   static const unsigned short days_before_month[] = {
       0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
   char month_str[32];
@@ -5945,8 +5949,8 @@ static time_t parse_date_string(const char *datetime) {
                &hour, &minute, &second) == 6) ||
        (sscanf(datetime, "%d-%3s-%d %d:%d:%d", &day, month_str, &year, &hour,
                &minute, &second) == 6)) &&
-      year > 1970 && (month = get_month_index(month_str)) != -1) {
-    leap_days = num_leap_years(year) - num_leap_years(1970);
+      year > 1970 && (month = mg_get_month_index(month_str)) != -1) {
+    leap_days = mg_num_leap_years(year) - mg_num_leap_years(1970);
     year -= 1970;
     days = year * 365 + days_before_month[month] + (day - 1) + leap_days;
     result = days * 24 * 3600 + hour * 3600 + minute * 60 + second;
@@ -5961,7 +5965,7 @@ static int mg_is_not_modified(struct http_message *hm, cs_stat_t *st) {
   struct mg_str *inm = mg_get_http_header(hm, "If-None-Match");
   construct_etag(etag, sizeof(etag), st);
   return (inm != NULL && !mg_vcasecmp(inm, etag)) ||
-         (ims != NULL && st->st_mtime <= parse_date_string(ims->p));
+         (ims != NULL && st->st_mtime <= mg_parse_date_string(ims->p));
 }
 
 static void mg_send_digest_auth_request(struct mg_connection *c,