* configure.ac: Check whether sys/sysinfo.h provides

Linux 'sysinfo' function and 'struct sysinfo' type.
* src/alloc.c (Fmemory_info): New function.
* lisp/files.el (warn-maybe-out-of-memory): New function.
(find-file-noselect): Use it.

2 files changed, 23 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d14a3a8584b..ffb1eee945e 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2014-07-10  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        * files.el (warn-maybe-out-of-memory): New function.
+        (find-file-noselect): Use it.
+
 2014-07-09  Sam Steingold  <sds@gnu.org>
 
         * progmodes/cperl-mode.el (cperl-block-p): Treat the perl keyword
diff --git a/lisp/files.el b/lisp/files.el
index 27d3ec7464e..63bdf636b63 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1796,6 +1796,22 @@ OP-TYPE specifies the file operation being performed (for message to user)."
                                     (file-size-human-readable size) op-type))))
     (error "Aborted")))
 
+(defun warn-maybe-out-of-memory (size)
+  "Warn if an attempt to open file of SIZE bytes may run out of memory."
+  (let ((meminfo (memory-info)))
+    (when (consp meminfo)
+      (let ((total-free-memory (+ (nth 1 meminfo) (nth 3 meminfo))))
+        (when (and (not (zerop size))
+                   (> (/ size 1024) total-free-memory))
+          (warn
+           "You are trying to open file which size (%s)
+exceeds an amount of available free memory (%s).  If that
+fails, try to open it with `find-file-literally' (but note
+that some characters may be displayed incorrectly)."
+           (file-size-human-readable size)
+           (file-size-human-readable
+            (* (float total-free-memory) 1024))))))))
+
 (defun find-file-noselect (filename &optional nowarn rawfile wildcards)
   "Read file FILENAME into a buffer and return the buffer.
 If a buffer exists visiting FILENAME, return that one, but
@@ -1848,7 +1864,8 @@ the various files."
                   (setq buf other))))
         ;; Check to see if the file looks uncommonly large.
         (when (not (or buf nowarn))
-          (abort-if-file-too-large (nth 7 attributes) "open" filename))
+          (abort-if-file-too-large (nth 7 attributes) "open" filename)
+          (warn-maybe-out-of-memory (nth 7 attributes)))
         (if buf
             ;; We are using an existing buffer.
             (let (nonexistent)