Fix truncation for the Android internal storage provider

* java/org/gnu/emacs/EmacsSafThread.java (openDocument1): If
truncate is specified while resorting to `w', try truncating the
file by hand.

1 files changed, 7 insertions, 2 deletions

diff --git a/java/org/gnu/emacs/EmacsSafThread.java b/java/org/gnu/emacs/EmacsSafThread.java
index 9f5d7f3d0cf..421e82c5759 100644
--- a/java/org/gnu/emacs/EmacsSafThread.java
+++ b/java/org/gnu/emacs/EmacsSafThread.java
@@ -1598,7 +1598,7 @@ public final class EmacsSafThread extends HandlerThread
           /* Set mode to w when WRITE && !READ, disregarding TRUNCATE.
              In contradiction with the ContentResolver documentation,
              document providers seem to truncate files whenever w is
-             specified, at least superficially.  */
+             specified, at least superficially.  (But see below.)  */
           mode = "w";
       }
     else
@@ -1607,7 +1607,6 @@ public final class EmacsSafThread extends HandlerThread
     fileDescriptor
       = resolver.openFileDescriptor (documentUri, mode,
                                      signal);
-    Log.d (TAG, "openDocument1: " + mode + " " + fileDescriptor);
 
     /* If a writable on-disk file descriptor is requested and TRUNCATE
        is set, then probe the file descriptor to detect if it is
@@ -1644,6 +1643,12 @@ public final class EmacsSafThread extends HandlerThread
         if (fileDescriptor != null)
           EmacsNative.ftruncate (fileDescriptor.getFd ());
       }
+    else if (!read && write && truncate && fileDescriptor != null)
+      /* Moreover, document providers that return actual seekable
+         files characteristically neglect to truncate the file
+         returned when the access mode is merely w, so attempt to
+         truncate it by hand.  */
+      EmacsNative.ftruncate (fileDescriptor.getFd ());
 
     /* Every time a document is opened, remove it from the file status
        cache.  */