stream_filter/httplive.c: do not crash on seeking

After the adaptive bandwidth changes seeking could end up in a segment
that is not available. Each segment is downloaded once and after switching
to higher or lower bandwidth segments downloaded for previous bandwidths
will not be deleted or downloaded. The later is to be fixed.

modules/stream_filter/httplive.c

@@ -61,7 +61,7 @@ vlc_module_end()
 typedef struct segment_s
 {
     int         sequence;   /* unique sequence number */
-    int         length;     /* segment duration (ms) */
+    int         length;     /* segment duration (seconds) */
     uint64_t    size;       /* segment size in bytes */
 
     vlc_url_t   url;
@@ -1475,23 +1475,39 @@ static int segment_Seek(stream_t *s, uint64_t pos)
             return VLC_EGENERIC;
 
         vlc_mutex_lock(&segment->lock);
-        length += segment->size;
-        uint64_t size = segment->size -segment->data->i_buffer;
-        if (size > 0)
+        if (segment->data)
         {
-            segment->data->i_buffer += size;
-            segment->data->p_buffer -= size;
-        }
+            length += segment->size;
+            uint64_t size = segment->size -segment->data->i_buffer;
+            if (size > 0)
+            {
+                segment->data->i_buffer += size;
+                segment->data->p_buffer -= size;
+            }
+
+            if (!b_found && (pos <= length))
+            {
+                uint64_t used = length - pos;
+                segment->data->i_buffer -= used;
+                segment->data->p_buffer += used;
 
-        if (!b_found && (pos <= length))
+                count = p_sys->segment;
+                p_sys->segment = n;
+                b_found = true;
+            }
+        }
+        else
         {
-            uint64_t used = length - pos;
-            segment->data->i_buffer -= used;
-            segment->data->p_buffer += used;
+            /* FIXME: seeking is weird when seeking in segments
+               that have not been downloaded yet */
+            length += segment->length * hls->bandwidth;
 
-            count = p_sys->segment;
-            p_sys->segment = n;
-            b_found = true;
+            if (!b_found && (pos <= length))
+            {
+                count = p_sys->segment;
+                p_sys->segment = n;
+                b_found = true;
+            }
         }
         vlc_mutex_unlock(&segment->lock);
     }