imem-access: return an error when file size is unknown

include/vlc/libvlc_media.h

@@ -276,7 +276,7 @@ typedef enum libvlc_media_parse_flag_t
  *
  * \param opaque private pointer as passed to libvlc_media_new_callbacks()
  * \param datap storage space for a private data pointer [OUT]
- * \param sizep byte length of the bitstream or 0 if unknown [OUT]
+ * \param sizep byte length of the bitstream or UINT64_MAX if unknown [OUT]
  *
  * \note For convenience, *datap is initially NULL and *sizep is initially 0.
  *

modules/access/imem-access.c

@@ -22,6 +22,7 @@
 # include "config.h"
 #endif
 #include <assert.h>
+#include <stdint.h>
 
 #include <vlc_common.h>
 #include <vlc_access.h>
@@ -89,6 +90,8 @@ static int Control(access_t *access, int query, va_list args)
             break;
 
         case ACCESS_GET_SIZE:
+            if (sys->size == UINT64_MAX)
+                return VLC_EGENERIC;
             *va_arg(args, uint64_t *) = sys->size;
             break;
 
@@ -130,7 +133,7 @@ static int Open(vlc_object_t *object)
     sys->read_cb = var_InheritAddress(access, "imem-read");
     sys->seek_cb = var_InheritAddress(access, "imem-seek");
     sys->close_cb = var_InheritAddress(access, "imem-close");
-    sys->size = 0;
+    sys->size = UINT64_MAX;
 
     if (open_cb == NULL)
         open_cb = open_cb_default;