From 8313646e4f770b90e62eab238e5a0a0c4425262e Mon Sep 17 00:00:00 2001
From: Tristan Gingold <tgingold@free.fr>
Date: Mon, 13 Nov 2017 06:08:55 +0100
Subject: files_map.adb: check for too large file.

Improve output of #456
---
 src/files_map.adb | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

(limited to 'src/files_map.adb')

diff --git a/src/files_map.adb b/src/files_map.adb
index 7d7676c81..b7cc795a1 100644
--- a/src/files_map.adb
+++ b/src/files_map.adb
@@ -797,10 +797,12 @@ package body Files_Map is
       use GNAT.OS_Lib;
       Fd : File_Descriptor;
 
-      Res: Source_File_Entry;
+      Res : Source_File_Entry;
 
-      Length: Source_Ptr;
-      Buffer: File_Buffer_Acc;
+      Raw_Length : Long_Integer;
+      Length : Source_Ptr;
+
+      Buffer : File_Buffer_Acc;
    begin
       --  If the file is already loaded, nothing to do!
       Res := Find_Source_File (Directory, Name);
@@ -822,9 +824,20 @@ package body Files_Map is
          end if;
       end;
 
+      Raw_Length := File_Length (Fd);
+
+      --  Check for too large files.  Use 'Pos (ie universal integer) to avoid
+      --  errors in conversions.
+      if Long_Integer'Pos (Raw_Length) > Source_Ptr'Pos (Source_Ptr'Last)
+        or else Long_Integer'Pos (Raw_Length) > Integer'Pos (Integer'Last)
+      then
+         Close (Fd);
+         return No_Source_File_Entry;
+      end if;
+
       Res := Create_Source_File_Entry (Directory, Name);
 
-      Length := Source_Ptr (File_Length (Fd));
+      Length := Source_Ptr (Raw_Length);
 
       Buffer :=
         new File_Buffer (Source_Ptr_Org .. Source_Ptr_Org + Length + 1);
-- 
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