From 7dbf5d4ce5795ec4d7638efff2d06f7a3fc8fc80 Mon Sep 17 00:00:00 2001
From: Richard Kistruck <rhsk@ravenbrook.com>
Date: Thu, 1 May 2008 15:22:01 +0100
Subject: [PATCH] Mps br/vmarenagrow:

mps_arena_vm_growth should give MPS_RES_PARAM is desired < minimum

Copied from Perforce
 Change: 164898
 ServerID: perforce.ravenbrook.com
---
 mps/code/amcss.c   | 8 +++++++-
 mps/code/arenavm.c | 6 ++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/mps/code/amcss.c b/mps/code/amcss.c
index f0c24868b32..4de5f143dc1 100644
--- a/mps/code/amcss.c
+++ b/mps/code/amcss.c
@@ -295,8 +295,14 @@ int main(int argc, char **argv)
   randomize(argc, argv);
 
   /* /4 => too-small arena, to test arena growth */
-  die(mps_arena_create(&arena, mps_arena_class_vm(), testArenaSIZE/4),
+  die(mps_arena_create(&arena, mps_arena_class_vm(), testArenaSIZE/2),
       "arena_create");
+  {
+    mps_res_t res;
+    /* May not desire an increment smaller than the minimum! */
+    res = mps_arena_vm_growth(arena, 16 * 0x1000, 17 * 0x1000);
+    cdie(res == MPS_RES_PARAM, "mps_arena_vm_growth should give MPS_RES_PARAM");
+  }
   die(mps_arena_vm_growth(arena, 16 * 0x1000, 0),
       "arena_vm_growth");
   
diff --git a/mps/code/arenavm.c b/mps/code/arenavm.c
index 3c90ad9863b..67e34d1bb2a 100644
--- a/mps/code/arenavm.c
+++ b/mps/code/arenavm.c
@@ -1718,6 +1718,12 @@ mps_res_t mps_arena_vm_growth(mps_arena_t mps_arena,
   vmArena = Arena2VMArena(arena);
   AVERT(VMArena, vmArena);
   
+  if(desired < minimum) {
+    /* May not desire an increment smaller than the minimum! */
+    ArenaLeave(arena);
+    return MPS_RES_PARAM;
+  }
+  
   vmArena->extendBy = desired;
   vmArena->extendMin = minimum;