More checks for localtime() and gmtime() returning NULL.

And some comments in the case where we're converting the result of
time() - if your machine's idea of time predates January 1, 1970,
00:00:00 UTC, it'll crash on Windows, but that's not a case where a
*file* can cause the problem due either to a bad file time stamp or bad
time stamps in the file.

Change-Id: I837a438e4b875dd8c4f3ec2137df7a16ee4e9498
Reviewed-on: https://code.wireshark.org/review/18369
Reviewed-by: Guy Harris <guy@alum.mit.edu>

3 files changed, 52 insertions, 19 deletions

diff --git a/wiretap/commview.c b/wiretap/commview.c
index f44dbe5578..e6dbd8101f 100644
--- a/wiretap/commview.c
+++ b/wiretap/commview.c
@@ -422,13 +422,26 @@ static gboolean commview_dump(wtap_dumper *wdh,
 	cv_hdr.version = 0;
 
 	tm = localtime(&phdr->ts.secs);
-	cv_hdr.year = tm->tm_year + 1900;
-	cv_hdr.month = tm->tm_mon + 1;
-	cv_hdr.day = tm->tm_mday;
-	cv_hdr.hours = tm->tm_hour;
-	cv_hdr.minutes = tm->tm_min;
-	cv_hdr.seconds = tm->tm_sec;
-	cv_hdr.usecs = GUINT32_TO_LE(phdr->ts.nsecs / 1000);
+	if (tm != NULL) {
+		cv_hdr.year = tm->tm_year + 1900;
+		cv_hdr.month = tm->tm_mon + 1;
+		cv_hdr.day = tm->tm_mday;
+		cv_hdr.hours = tm->tm_hour;
+		cv_hdr.minutes = tm->tm_min;
+		cv_hdr.seconds = tm->tm_sec;
+		cv_hdr.usecs = GUINT32_TO_LE(phdr->ts.nsecs / 1000);
+	} else {
+		/*
+		 * Second before the Epoch.
+		 */
+		cv_hdr.year = 1969;
+		cv_hdr.month = 12;
+		cv_hdr.day = 31;
+		cv_hdr.hours = 23;
+		cv_hdr.minutes = 59;
+		cv_hdr.seconds = 59;
+		cv_hdr.usecs = 0;
+	}
 
 	switch(phdr->pkt_encap) {
 
diff --git a/wiretap/logcat_text.c b/wiretap/logcat_text.c
index 551358170f..2f7e5bc294 100644
--- a/wiretap/logcat_text.c
+++ b/wiretap/logcat_text.c
@@ -104,6 +104,7 @@ static gchar *logcat_log(const struct dumper_t *dumper, guint32 seconds,
 {
     gchar  time_buffer[15];
     time_t datetime;
+    struct tm *tm;
 
     datetime = (time_t) seconds;
 
@@ -123,20 +124,38 @@ static gchar *logcat_log(const struct dumper_t *dumper, guint32 seconds,
             return g_strdup_printf("%c(%5i:%5i) %s\n",
                     priority, pid, tid, log);
         case WTAP_ENCAP_LOGCAT_TIME:
-            strftime(time_buffer, sizeof(time_buffer), "%m-%d %H:%M:%S",
-                    gmtime(&datetime));
-            return g_strdup_printf("%s.%03i %c/%-8s(%5i): %s\n",
-                    time_buffer, milliseconds, priority, tag, pid, log);
+            tm = gmtime(&datetime);
+            if (tm != NULL) {
+                strftime(time_buffer, sizeof(time_buffer), "%m-%d %H:%M:%S",
+                        tm);
+                return g_strdup_printf("%s.%03i %c/%-8s(%5i): %s\n",
+                        time_buffer, milliseconds, priority, tag, pid, log);
+            } else {
+                return g_strdup_printf("Not representable %c/%-8s(%5i): %s\n",
+                        priority, tag, pid, log);
+            }
         case WTAP_ENCAP_LOGCAT_THREADTIME:
-            strftime(time_buffer, sizeof(time_buffer), "%m-%d %H:%M:%S",
-                    gmtime(&datetime));
-            return g_strdup_printf("%s.%03i %5i %5i %c %-8s: %s\n",
-                    time_buffer, milliseconds, pid, tid, priority, tag, log);
+            tm = gmtime(&datetime);
+            if (tm != NULL) {
+                strftime(time_buffer, sizeof(time_buffer), "%m-%d %H:%M:%S",
+                        tm);
+                return g_strdup_printf("%s.%03i %5i %5i %c %-8s: %s\n",
+                        time_buffer, milliseconds, pid, tid, priority, tag, log);
+            } else {
+                return g_strdup_printf("Not representable %5i %5i %c %-8s: %s\n",
+                        pid, tid, priority, tag, log);
+            }
         case WTAP_ENCAP_LOGCAT_LONG:
-            strftime(time_buffer, sizeof(time_buffer), "%m-%d %H:%M:%S",
-                    gmtime(&datetime));
-            return g_strdup_printf("[ %s.%03i %5i:%5i %c/%-8s ]\n%s\n\n",
-                    time_buffer, milliseconds, pid, tid, priority, tag, log);
+            tm = gmtime(&datetime);
+            if (tm != NULL) {
+                strftime(time_buffer, sizeof(time_buffer), "%m-%d %H:%M:%S",
+                        tm);
+                return g_strdup_printf("[ %s.%03i %5i:%5i %c/%-8s ]\n%s\n\n",
+                        time_buffer, milliseconds, pid, tid, priority, tag, log);
+            } else {
+                return g_strdup_printf("[ Not representable %5i:%5i %c/%-8s ]\n%s\n\n",
+                        pid, tid, priority, tag, log);
+            }
         default:
             return NULL;
     }
diff --git a/wiretap/network_instruments.c b/wiretap/network_instruments.c
index 19ff6fbba8..fb335f445c 100644
--- a/wiretap/network_instruments.c
+++ b/wiretap/network_instruments.c
@@ -614,6 +614,7 @@ gboolean network_instruments_dump_open(wtap_dumper *wdh, int *err)
     /* create the file comment TLV */
     {
         time(&system_time);
+        /* We trusst the OS not to return a time before the Epoch */
         current_time = localtime(&system_time);
         memset(&comment, 0x00, sizeof(comment));
         g_snprintf(comment, 64, "This capture was saved from Wireshark on %s", asctime(current_time));