file out: ask for confirmation to overwrite file

To avoid disrupting existing workflows, the dialog is only shown when
overwrite is disabled. If there is no UI, then it will be assumed that
the file is not overwritten.

modules/access_output/file.c

@@ -41,6 +41,7 @@
 #include <vlc_block.h>
 #include <vlc_fs.h>
 #include <vlc_strings.h>
+#include <vlc_dialog.h>
 
 #if defined( WIN32 ) || defined( __OS2__ )
 #   include <io.h>
@@ -171,9 +172,23 @@ static int Open( vlc_object_t *p_this )
         if (var_GetBool (p_access, SOUT_CFG_PREFIX"sync"))
             flags |= O_SYNC;
 #endif
+        do
+        {
             fd = vlc_open (path, flags, 0666);
+            if (fd != -1)
+                break;
             if (fd == -1)
                 msg_Err (p_access, "cannot create %s: %m", path);
+            if (overwrite || errno != EEXIST)
+                break;
+            flags &= ~O_EXCL;
+        }
+        while (dialog_Question (p_access, path,
+                                N_("The output file already exists. "
+                                "If recording continues, the file will be "
+                                "overriden and its content will be lost."),
+                                N_("Keep existing file"),
+                                N_("Overwrite"), NULL) == 2);
         free (path);
         if (fd == -1)
             return VLC_EGENERIC;