SF bug # 585792, Invalid mmap crashes Python interpreter

Raise ValueError if user passes a size to mmap which is larger
than the file.

2 files changed, 16 insertions, 0 deletions

diff --git a/Lib/test/output/test_mmap b/Lib/test/output/test_mmap
index 4adf702..1706ad5 100644
--- a/Lib/test/output/test_mmap
+++ b/Lib/test/output/test_mmap
@@ -24,6 +24,7 @@ test_mmap
   Ensuring that readonly mmap can't be write() to.
   Ensuring that readonly mmap can't be write_byte() to.
   Ensuring that readonly mmap can't be resized.
+  Opening mmap with size too big
   Opening mmap with access=ACCESS_WRITE
   Modifying write-through memory map.
   Opening mmap with access=ACCESS_COPY
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
index 11edbaf..dd1fb3f 100644
--- a/Lib/test/test_mmap.py
+++ b/Lib/test/test_mmap.py
@@ -189,6 +189,21 @@ def test_both():
         verify(open(TESTFN, "rb").read() == 'a'*mapsize,
                "Readonly memory map data file was modified")
 
+        print "  Opening mmap with size too big"
+        import sys
+        f = open(TESTFN, "r+b")
+        try:
+            m = mmap.mmap(f.fileno(), mapsize+1)
+        except ValueError:
+            # we do not expect a ValueError on Windows
+            if sys.platform.startswith('win'):
+                verify(0, "Opening mmap with size+1 should work on Windows.")
+            pass
+        else:
+            # we expect a ValueError on Unix, but not on Windows
+            if not sys.platform.startswith('win'):
+                verify(0, "Opening mmap with size+1 should raise ValueError.")
+
         print "  Opening mmap with access=ACCESS_WRITE"
         f = open(TESTFN, "r+b")
         m = mmap.mmap(f.fileno(), mapsize, access=mmap.ACCESS_WRITE)