1 files changed, 49 insertions, 25 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 6b24e592bb3..6ec5f78c2cf 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4746,25 +4746,39 @@ This does code conversion according to the value of
 
 This calls `write-region-annotate-functions' at the start, and
 `write-region-post-annotation-function' at the end.  */)
-  (Lisp_Object start, Lisp_Object end, Lisp_Object filename, Lisp_Object append, Lisp_Object visit, Lisp_Object lockname, Lisp_Object mustbenew)
+  (Lisp_Object start, Lisp_Object end, Lisp_Object filename, Lisp_Object append,
+   Lisp_Object visit, Lisp_Object lockname, Lisp_Object mustbenew)
+{
+  return write_region (start, end, filename, append, visit, lockname, mustbenew,
+                       -1);
+}
+
+/* Like Fwrite_region, except that if DESC is nonnegative, it is a file
+   descriptor for FILENAME, so do not open or close FILENAME.  */
+
+Lisp_Object
+write_region (Lisp_Object start, Lisp_Object end, Lisp_Object filename,
+              Lisp_Object append, Lisp_Object visit, Lisp_Object lockname,
+              Lisp_Object mustbenew, int desc)
 {
-  int desc;
   int open_flags;
   int mode;
   off_t offset IF_LINT (= 0);
+  bool open_and_close_file = desc < 0;
   bool ok;
   int save_errno = 0;
   const char *fn;
   struct stat st;
   EMACS_TIME modtime;
   ptrdiff_t count = SPECPDL_INDEX ();
-  ptrdiff_t count1;
+  ptrdiff_t count1 IF_LINT (= 0);
   Lisp_Object handler;
   Lisp_Object visit_file;
   Lisp_Object annotations;
   Lisp_Object encoded_filename;
   bool visiting = (EQ (visit, Qt) || STRINGP (visit));
   bool quietly = !NILP (visit);
+  bool file_locked = 0;
   struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;
   struct buffer *given_buffer;
   struct coding_system coding;
@@ -4832,7 +4846,6 @@ This calls `write-region-annotate-functions' at the start, and
   record_unwind_protect (build_annotations_unwind,
                          Vwrite_region_annotation_buffers);
   Vwrite_region_annotation_buffers = list1 (Fcurrent_buffer ());
-  count1 = SPECPDL_INDEX ();
 
   given_buffer = current_buffer;
 
@@ -4871,8 +4884,11 @@ This calls `write-region-annotate-functions' at the start, and
     coding.mode |= CODING_MODE_SELECTIVE_DISPLAY;
 
 #ifdef CLASH_DETECTION
-  if (!auto_saving)
-    lock_file (lockname);
+  if (open_and_close_file && !auto_saving)
+    {
+      lock_file (lockname);
+      file_locked = 1;
+    }
 #endif /* CLASH_DETECTION */
 
   encoded_filename = ENCODE_FILE (filename);
@@ -4889,19 +4905,23 @@ This calls `write-region-annotate-functions' at the start, and
   mode = auto_saving ? auto_save_mode_bits : 0666;
 #endif
 
-  desc = emacs_open (fn, open_flags, mode);
-
-  if (desc < 0)
+  if (open_and_close_file)
     {
-      int open_errno = errno;
+      desc = emacs_open (fn, open_flags, mode);
+      if (desc < 0)
+        {
+          int open_errno = errno;
 #ifdef CLASH_DETECTION
-      if (!auto_saving) unlock_file (lockname);
+          if (file_locked)
+            unlock_file (lockname);
 #endif /* CLASH_DETECTION */
-      UNGCPRO;
-      report_file_errno ("Opening output file", filename, open_errno);
-    }
+          UNGCPRO;
+          report_file_errno ("Opening output file", filename, open_errno);
+        }
 
-  record_unwind_protect_int (close_file_unwind, desc);
+      count1 = SPECPDL_INDEX ();
+      record_unwind_protect_int (close_file_unwind, desc);
+    }
 
   if (NUMBERP (append))
     {
@@ -4910,7 +4930,8 @@ This calls `write-region-annotate-functions' at the start, and
         {
           int lseek_errno = errno;
 #ifdef CLASH_DETECTION
-          if (!auto_saving) unlock_file (lockname);
+          if (file_locked)
+            unlock_file (lockname);
 #endif /* CLASH_DETECTION */
           UNGCPRO;
           report_file_errno ("Lseek error", filename, lseek_errno);
@@ -4945,9 +4966,9 @@ This calls `write-region-annotate-functions' at the start, and
 
   immediate_quit = 0;
 
-  /* fsync is not crucial for auto-save files, since they might lose
-     some work anyway.  */
-  if (!auto_saving && !write_region_inhibit_fsync)
+  /* fsync is not crucial for temporary files.  Nor for auto-save
+     files, since they might lose some work anyway.  */
+  if (open_and_close_file && !auto_saving && !write_region_inhibit_fsync)
     {
       /* Transfer data and metadata to disk, retrying if interrupted.
          fsync can report a write failure here, e.g., due to disk full
@@ -4971,12 +4992,15 @@ This calls `write-region-annotate-functions' at the start, and
         ok = 0, save_errno = errno;
     }
 
-  /* NFS can report a write failure now.  */
-  if (emacs_close (desc) < 0)
-    ok = 0, save_errno = errno;
+  if (open_and_close_file)
+    {
+      /* NFS can report a write failure now.  */
+      if (emacs_close (desc) < 0)
+        ok = 0, save_errno = errno;
 
-  /* Discard the unwind protect for close_file_unwind.  */
-  specpdl_ptr = specpdl + count1;
+      /* Discard the unwind protect for close_file_unwind.  */
+      specpdl_ptr = specpdl + count1;
+    }
 
   /* Some file systems have a bug where st_mtime is not updated
      properly after a write.  For example, CIFS might not see the
@@ -5052,7 +5076,7 @@ This calls `write-region-annotate-functions' at the start, and
   unbind_to (count, Qnil);
 
 #ifdef CLASH_DETECTION
-  if (!auto_saving)
+  if (file_locked)
     unlock_file (lockname);
 #endif /* CLASH_DETECTION */