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+// -*- mode: cpp; mode: fold -*-
+// SPDX-License-Identifier: GPL-2.0+
+// Description								/*{{{*/
+/* ######################################################################
+   
+   MMap Class - Provides 'real' mmap or a faked mmap using read().
+
+   The purpose of this code is to provide a generic way for clients to
+   access the mmap function. In environments that do not support mmap
+   from file fd's this function will use read and normal allocated 
+   memory.
+   
+   Writing to a public mmap will always fully commit all changes when the
+   class is deleted. Ie it will rewrite the file, unless it is readonly
+
+   The DynamicMMap class is used to help the on-disk data structure 
+   generators. It provides a large allocated workspace and members
+   to allocate space from the workspace in an efficient fashion.
+   
+   This file had this historic note, but now includes further changes
+   under the GPL-2.0+:
+
+   This source is placed in the Public Domain, do with it what you will
+   It was originally written by Jason Gunthorpe.
+
+   ##################################################################### */
+									/*}}}*/
+#ifndef PKGLIB_MMAP_H
+#define PKGLIB_MMAP_H
+
+#include <string>
+#include <limits>
+
+#include <sys/mman.h>
+
+
+class FileFd;
+
+/* This should be a 32 bit type, larger types use too much ram and smaller
+   types are too small. Where ever possible 'unsigned long' should be used
+   instead of this internal type */
+typedef unsigned int map_ptrloc;
+
+class MMap
+{
+   protected:
+   
+   unsigned long Flags;
+   unsigned long long iSize;
+   void *Base;
+
+   // In case mmap can not be used, we keep a dup of the file
+   // descriptor that should have been mmaped so that we can write to
+   // the file in Sync().
+   FileFd *SyncToFd;
+
+   bool Map(FileFd &Fd);
+   bool Close(bool DoSync = true);
+   
+   public:
+
+   enum OpenFlags {NoImmMap = (1<<0),Public = (1<<1),ReadOnly = (1<<2),
+                   UnMapped = (1<<3), Moveable = (1<<4), Fallback = (1 << 5)};
+      
+   // Simple accessors
+   inline operator void *() {return Base;};
+   inline void *Data() {return Base;}; 
+   inline unsigned long long Size() {return iSize;};
+   inline void AddSize(unsigned long long const size) {iSize += size;};
+   inline bool validData() const { return Base != MAP_FAILED && Base != 0; };
+   
+   // File manipulators
+   bool Sync();
+   bool Sync(unsigned long Start,unsigned long Stop);
+   
+   MMap(FileFd &F,unsigned long Flags);
+   explicit MMap(unsigned long Flags);
+   virtual ~MMap();
+};
+
+class DynamicMMap : public MMap
+{
+   public:
+   
+   // This is the allocation pool structure
+   struct Pool
+   {
+      unsigned long ItemSize;
+      unsigned long Start;
+      unsigned long Count;
+   };
+   
+   protected:
+   
+   FileFd *Fd;
+   unsigned long WorkSpace;
+   unsigned long const GrowFactor;
+   unsigned long const Limit;
+   Pool *Pools;
+   unsigned int PoolCount;
+
+   bool Grow();
+   
+   public:
+
+   // Allocation
+   unsigned long RawAllocate(unsigned long long Size,unsigned long Aln = 0);
+   unsigned long Allocate(unsigned long ItemSize);
+   unsigned long WriteString(const char *String,unsigned long Len = std::numeric_limits<unsigned long>::max());
+   inline unsigned long WriteString(const std::string &S) {return WriteString(S.c_str(),S.length());};
+   void UsePools(Pool &P,unsigned int Count) {Pools = &P; PoolCount = Count;};
+   
+   DynamicMMap(FileFd &F,unsigned long Flags,unsigned long const &WorkSpace = 2*1024*1024,
+	       unsigned long const &Grow = 1024*1024, unsigned long const &Limit = 0);
+   DynamicMMap(unsigned long Flags,unsigned long const &WorkSpace = 2*1024*1024,
+	       unsigned long const &Grow = 1024*1024, unsigned long const &Limit = 0);
+   virtual ~DynamicMMap();
+};
+
+#endif