lavf: Check the return value of strftime

If the buffer provided to strftime is too small, the buffer contents
are indeterminate - it does not guarantee actually null terminating
the buffer.

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 12 insertions, 9 deletions

diff --git a/libavformat/wtv.c b/libavformat/wtv.c
index fa864e840a..90984cfda0 100644
--- a/libavformat/wtv.c
+++ b/libavformat/wtv.c
@@ -429,9 +429,10 @@ static void filetime_to_iso8601(char *buf, int buf_size, int64_t value)
 {
     time_t t = (value / 10000000LL) - 11644473600LL;
     struct tm *tm = gmtime(&t);
-    if (tm)
-        strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
-    else
+    if (tm) {
+        if (!strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm))
+            buf[0] = '\0';
+    } else
         buf[0] = '\0';
 }
 
@@ -442,9 +443,10 @@ static void crazytime_to_iso8601(char *buf, int buf_size, int64_t value)
 {
     time_t t = (value / 10000000LL) - 719162LL*86400LL;
     struct tm *tm = gmtime(&t);
-    if (tm)
-        strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
-    else
+    if (tm) {
+        if (!strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm))
+            buf[0] = '\0';
+    } else
         buf[0] = '\0';
 }
 
@@ -455,9 +457,10 @@ static void oledate_to_iso8601(char *buf, int buf_size, int64_t value)
 {
     time_t t = 631112400LL + 86400*av_int2double(value);
     struct tm *tm = gmtime(&t);
-    if (tm)
-        strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm);
-    else
+    if (tm) {
+        if (!strftime(buf, buf_size, "%Y-%m-%d %H:%M:%S", tm))
+            buf[0] = '\0';
+    } else
         buf[0] = '\0';
 }