1 files changed, 37 insertions, 0 deletions

diff --git a/lisp/files.el b/lisp/files.el
index 3706ad54edf..89ff4da76a6 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -861,6 +861,43 @@ it means chase no more than that many links and then stop."
         (setq count (1+ count))))
     newname))
 
+(defun make-temp-file (prefix &optional dir-flag suffix)
+  "Create a temporary file.
+The returned file name (created by appending some random characters at the end
+of PREFIX, and expanding against `temporary-file-directory' if necessary),
+is guaranteed to point to a newly created empty file.
+You can then use `write-region' to write new data into the file.
+
+If DIR-FLAG is non-nil, create a new empty directory instead of a file.
+
+If SUFFIX is non-nil, add that at the end of the file name."
+  (let ((umask (default-file-modes))
+        file)
+    (unwind-protect
+        (progn
+          ;; Create temp files with strict access rights.  It's easy to
+          ;; loosen them later, whereas it's impossible to close the
+          ;; time-window of loose permissions otherwise.
+          (set-default-file-modes ?\700)
+          (while (condition-case ()
+                     (progn
+                       (setq file
+                             (make-temp-name
+                              (expand-file-name prefix temporary-file-directory)))
+                       (if suffix
+                           (setq file (concat file suffix)))
+                       (if dir-flag
+                           (make-directory file)
+                         (write-region "" nil file nil 'silent nil 'excl))
+                       nil)
+                   (file-already-exists t))
+            ;; the file was somehow created by someone else between
+            ;; `make-temp-name' and `write-region', let's try again.
+            nil)
+          file)
+      ;; Reset the umask.
+      (set-default-file-modes umask))))
+
 (defun recode-file-name (file coding new-coding &optional ok-if-already-exists)
   "Change the encoding of FILE's name from CODING to NEW-CODING.
 The value is a new name of FILE.