From 7cb1c8b5868af097c238773db20ee7c42c81c321 Mon Sep 17 00:00:00 2001
From: Jonas Maebe <jonas@freepascal.org>
Date: Fri, 4 Feb 2011 18:58:21 +0000
Subject: [PATCH]   * improvement of r16001 so that allocations even closer to
 high(ptruint)     also fail correctly rather than overflowing to 0 bytes
 (mantis #18690)

git-svn-id: trunk@16877 -
---
 .gitattributes          |  1 +
 rtl/inc/heap.inc        |  3 ++-
 tests/webtbs/tw18690.pp | 17 +++++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 tests/webtbs/tw18690.pp

diff --git a/.gitattributes b/.gitattributes
index b0453d3545..84dcaa4c76 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -10968,6 +10968,7 @@ tests/webtbs/tw1862.pp svneol=native#text/plain
 tests/webtbs/tw18620.pp svneol=native#text/pascal
 tests/webtbs/tw1863.pp svneol=native#text/plain
 tests/webtbs/tw1867.pp svneol=native#text/plain
+tests/webtbs/tw18690.pp svneol=native#text/plain
 tests/webtbs/tw1873.pp svneol=native#text/plain
 tests/webtbs/tw1883.pp svneol=native#text/plain
 tests/webtbs/tw1888.pp svneol=native#text/plain
diff --git a/rtl/inc/heap.inc b/rtl/inc/heap.inc
index 4e6b35d00f..386d021680 100644
--- a/rtl/inc/heap.inc
+++ b/rtl/inc/heap.inc
@@ -1045,7 +1045,8 @@ begin
     end
   else
     begin
-      size := (size+(sizeof(tmemchunk_var_hdr)+(blocksize-1))) and sizemask;
+      if size < high(ptruint)-((sizeof(tmemchunk_var_hdr)+(blocksize-1))) then
+        size := (size+(sizeof(tmemchunk_var_hdr)+(blocksize-1))) and sizemask;
       result := sysgetmem_var(size);
     end;
 
diff --git a/tests/webtbs/tw18690.pp b/tests/webtbs/tw18690.pp
new file mode 100644
index 0000000000..da3794aba7
--- /dev/null
+++ b/tests/webtbs/tw18690.pp
@@ -0,0 +1,17 @@
+Procedure AllocFreeGiB;
+  var
+    p: pointer;
+    RequestedSize: ptruint;
+  Begin
+    Writeln('-----------------------------');
+    RequestedSize:=high(ptruint); // n GiB - 1  
+    Writeln('RequestedSize = ',RequestedSize,' bytes');  
+    getmem(p,RequestedSize);    
+    if (p<>nil) then
+      halt(1);
+  End; 
+    
+Begin
+  ReturnNilIfGrowHeapFails:=true;
+  AllocFreeGiB;
+End.