Use cross-platform mmap() wrapper in CompactPT.

The MmapAllocator header made use of sys/mman.h and mmap(), which are
Unix-specific.  But util has a wrapper which also works on Windows.

This also fixes the error handling: when mmap() failed, the old code would
return an invalid (but non-NULL!) pointer — leading to a crash.  The wrapper
will throw an exception with a helpful error message.

1 files changed, 4 insertions, 1 deletions

diff --git a/util/mmap.hh b/util/mmap.hh
index 9b1e120f3..37feb5bee 100644
--- a/util/mmap.hh
+++ b/util/mmap.hh
@@ -100,9 +100,12 @@ typedef enum {
 
 extern const int kFileFlags;
 
-// Wrapper around mmap to check it worked and hide some platform macros.  
+// Cross-platform, error-checking wrapper for mmap().
 void *MapOrThrow(std::size_t size, bool for_write, int flags, bool prefault, int fd, uint64_t offset = 0);
 
+// Cross-platform, error-checking wrapper for munmap().
+void UnmapOrThrow(void *start, size_t length);
+
 void MapRead(LoadMethod method, int fd, uint64_t offset, std::size_t size, scoped_memory &out);
 
 void MapAnonymous(std::size_t size, scoped_memory &to);