feature/android 48b5a770f24 4/4: Fix visiting and saving writable content provider files

[Po Lu]

branch: feature/android
commit 48b5a770f247d8c027d209ce941767ab5a7d139d
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix visiting and saving writable content provider files
    
    * java/org/gnu/emacs/EmacsService.java (checkContentUri):
    Improve debug output.
    * lisp/files.el (basic-save-buffer): Check whether or not file
    itself exists before checking for the existence of the directory
    containing it.
    * src/android.c (android_open): Don't forget to set errno after
    open_content_uri fails.
---
 java/org/gnu/emacs/EmacsService.java |  2 ++
 lisp/files.el                        |  9 +++++++--
 src/android.c                        | 10 ++++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/java/org/gnu/emacs/EmacsService.java 
b/java/org/gnu/emacs/EmacsService.java
index 67de5d26f53..d9cb25f3e9c 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -752,6 +752,8 @@ public final class EmacsService extends Service
     if (writable)
       mode += "w";
 
+    Log.d (TAG, "checkContentUri: checking against mode " + mode);
+
     try
       {
        fd = resolver.openFileDescriptor (Uri.parse (name), mode);
diff --git a/lisp/files.el b/lisp/files.el
index 387a3b5dc66..35f31711065 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -5726,9 +5726,14 @@ Before and after saving the buffer, this function runs
                  (run-hook-with-args-until-success 'write-file-functions)
                  ;; If a hook returned t, file is already "written".
                  ;; Otherwise, write it the usual way now.
-                 (let ((dir (file-name-directory
+                 (let ((file (buffer-file-name))
+                        (dir (file-name-directory
                              (expand-file-name buffer-file-name))))
-                   (unless (file-exists-p dir)
+                    ;; Some systems have directories (like /content on
+                    ;; Android) in which files can exist without a
+                    ;; corresponding parent directory.
+                   (unless (or (file-exists-p file)
+                                (file-exists-p dir))
                      (if (y-or-n-p
                           (format-message
                             "Directory `%s' does not exist; create? " dir))
diff --git a/src/android.c b/src/android.c
index 1e91abffa6f..656971e154f 100644
--- a/src/android.c
+++ b/src/android.c
@@ -1715,9 +1715,19 @@ android_open (const char *filename, int oflag, int mode)
          return -1;
        }
 
+      /* If fd is -1, just assume that the file does not exist,
+        and return -1 with errno set to ENOENT.  */
+
+      if (fd == -1)
+       {
+         errno = ENOENT;
+         goto skip;
+       }
+
       if (mode & O_CLOEXEC)
        android_close_on_exec (fd);
 
+    skip:
       ANDROID_DELETE_LOCAL_REF (string);
       return fd;
     }