/*
zone.c - zone memory allocation from DarkPlaces
Copyright (C) 1996-1997 Id Software, Inc.
Copyright (C) 2000-2007 DarkPlaces contributors
Copyright (C) 2007 Uncle Mike
Copyright (C) 2015-2023 Xash3D FWGS contributors

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
*/

#include "common.h"

#define MEMHEADER_SENTINEL1	0xDEADF00DU
#define MEMHEADER_SENTINEL2	0xDFU

#ifdef XASH_CUSTOM_SWAP
#include "platform/swap/swap.h"
#define Q_malloc SWAP_Malloc
#define Q_free SWAP_Free
#else
#define Q_malloc malloc
#define Q_free free
#endif

typedef struct memheader_s
{
	struct memheader_s	*next;		// next and previous memheaders in chain belonging to pool
	struct memheader_s	*prev;
	struct mempool_s	*pool;		// pool this memheader belongs to
	size_t		size;		// size of the memory after the header (excluding header and sentinel2)
	const char	*filename;	// file name and line where Mem_Alloc was called
	int		fileline;
#if !XASH_64BIT
	uint32_t		pad0; // doesn't have value, only to make Mem_Alloc return aligned addresses on ILP32
#endif
	uint32_t		sentinel1;	// should always be MEMHEADER_SENTINEL1

	// immediately followed by data, which is followed by a MEMHEADER_SENTINEL2 byte
} memheader_t;

typedef struct mempool_s
{
	uint32_t		sentinel1;	// should always be MEMHEADER_SENTINEL1
	struct memheader_s	*chain;		// chain of individual memory allocations
	size_t		totalsize;	// total memory allocated in this pool (inside memheaders)
	size_t		realsize;		// total memory allocated in this pool (actual malloc total)
	size_t		lastchecksize;	// updated each time the pool is displayed by memlist
	struct mempool_s	*next;		// linked into global mempool list
	const char	*filename;	// file name and line where Mem_AllocPool was called
	int		fileline;
#if XASH_64BIT
	poolhandle_t idx;
#endif
	char		name[64];		// name of the pool
	uint32_t		sentinel2;	// should always be MEMHEADER_SENTINEL1
} mempool_t;

static mempool_t *poolchain = NULL; // critical stuff

#if XASH_64BIT
// a1ba: due to mempool being passed with the model through reused 32-bit field
// which makes engine incompatible with 64-bit pointers I changed mempool type
// from pointer to 32-bit handle, thankfully mempool structure is private
// But! Mempools are handled through linked list so we can't index them safely
static poolhandle_t lastidx = 0;

static mempool_t *Mem_FindPool( poolhandle_t poolptr )
{
	mempool_t *pool;

	for( pool = poolchain; pool; pool = pool->next )
	{
		if( pool->idx == poolptr )
			return pool;
	}

	Sys_Error( "%s: not allocated or double freed pool %d", __FUNCTION__, poolptr );

	return NULL;
}
#else
static mempool_t *Mem_FindPool( poolhandle_t poolptr )
{
	return (mempool_t *)poolptr;
}
#endif

void *_Mem_Alloc( poolhandle_t poolptr, size_t size, qboolean clear, const char *filename, int fileline )
{
	memheader_t *mem;
	mempool_t   *pool;

	if( size <= 0 ) return NULL;
	if( !poolptr ) Sys_Error( "Mem_Alloc: pool == NULL (alloc at %s:%i)\n", filename, fileline );

	pool = Mem_FindPool( poolptr );

	pool->totalsize += size;

	// big allocations are not clumped
	pool->realsize += sizeof( memheader_t ) + size + sizeof( size_t );
	mem = (memheader_t *)Q_malloc( sizeof( memheader_t ) + size + sizeof( size_t ));
	if( mem == NULL ) Sys_Error( "Mem_Alloc: out of memory (alloc at %s:%i)\n", filename, fileline );

	mem->filename = filename;
	mem->fileline = fileline;
	mem->size = size;
	mem->pool = pool;
	mem->sentinel1 = MEMHEADER_SENTINEL1;
	// we have to use only a single byte for this sentinel, because it may not be aligned
	// and some platforms can't use unaligned accesses
	*((byte *)mem + sizeof( memheader_t ) + mem->size ) = MEMHEADER_SENTINEL2;
	// append to head of list
	mem->next = pool->chain;
	mem->prev = NULL;
	pool->chain = mem;
	if( mem->next ) mem->next->prev = mem;
	if( clear )
		memset((void *)((byte *)mem + sizeof( memheader_t )), 0, mem->size );

	return (void *)((byte *)mem + sizeof( memheader_t ));
}

static const char *Mem_CheckFilename( const char *filename )
{
	static const char	*dummy = "<corrupted>\0";
	const char	*out = filename;
	int		i;

	if( !COM_CheckString( out ))
		return dummy;

	for( i = 0; i < MAX_OSPATH; i++, out++ )
	{
		if( *out == '\0' )
			return filename; // valid name
	}

	return dummy;
}

static void Mem_FreeBlock( memheader_t *mem, const char *filename, int fileline )
{
	mempool_t		*pool;

	if( mem->sentinel1 != MEMHEADER_SENTINEL1 )
	{
		mem->filename = Mem_CheckFilename( mem->filename ); // make sure what we don't crash var_args
		Sys_Error( "Mem_Free: trashed header sentinel 1 (alloc at %s:%i, free at %s:%i)\n", mem->filename, mem->fileline, filename, fileline );
	}

	if( *((byte *)mem + sizeof( memheader_t ) + mem->size ) != MEMHEADER_SENTINEL2 )
	{
		mem->filename = Mem_CheckFilename( mem->filename ); // make sure what we don't crash var_args
		Sys_Error( "Mem_Free: trashed header sentinel 2 (alloc at %s:%i, free at %s:%i)\n", mem->filename, mem->fileline, filename, fileline );
	}

	pool = mem->pool;
	// unlink memheader from doubly linked list
	if(( mem->prev ? mem->prev->next != mem : pool->chain != mem ) || ( mem->next && mem->next->prev != mem ))
		Sys_Error( "Mem_Free: not allocated or double freed (free at %s:%i)\n", filename, fileline );

	if( mem->prev ) mem->prev->next = mem->next;
	else pool->chain = mem->next;

	if( mem->next )
		mem->next->prev = mem->prev;

	// memheader has been unlinked, do the actual free now
	pool->totalsize -= mem->size;

	pool->realsize -= sizeof( memheader_t ) + mem->size + sizeof( size_t );
	Q_free( mem );
}

void _Mem_Free( void *data, const char *filename, int fileline )
{
	if( data == NULL ) Sys_Error( "Mem_Free: data == NULL (called at %s:%i)\n", filename, fileline );
	Mem_FreeBlock((memheader_t *)((byte *)data - sizeof( memheader_t )), filename, fileline );
}

void *_Mem_Realloc( poolhandle_t poolptr, void *memptr, size_t size, qboolean clear, const char *filename, int fileline )
{
	memheader_t	*memhdr = NULL;
	char		*nb;

	if( size <= 0 ) return memptr; // no need to reallocate

	if( memptr )
	{
		memhdr = (memheader_t *)((byte *)memptr - sizeof( memheader_t ));
		if( size == memhdr->size ) return memptr;
	}

	nb = _Mem_Alloc( poolptr, size, clear, filename, fileline );

	if( memptr ) // first allocate?
	{
		size_t newsize = memhdr->size < size ? memhdr->size : size; // upper data can be trucnated!
		memcpy( nb, memptr, newsize );
		_Mem_Free( memptr, filename, fileline ); // free unused old block
	}

	return (void *)nb;
}

poolhandle_t _Mem_AllocPool( const char *name, const char *filename, int fileline )
{
	mempool_t *pool;

	pool = (mempool_t *)Q_malloc( sizeof( mempool_t ));
	if( pool == NULL )
	{
		Sys_Error( "Mem_AllocPool: out of memory (allocpool at %s:%i)\n", filename, fileline );
		return 0;
	}
	memset( pool, 0, sizeof( mempool_t ));

	// fill header
	pool->sentinel1 = MEMHEADER_SENTINEL1;
	pool->sentinel2 = MEMHEADER_SENTINEL1;
	pool->filename = filename;
	pool->fileline = fileline;
	pool->chain = NULL;
	pool->totalsize = 0;
	pool->realsize = sizeof( mempool_t );
	Q_strncpy( pool->name, name, sizeof( pool->name ));
	pool->next = poolchain;
	poolchain = pool;
	
#if XASH_64BIT
	pool->idx = ++lastidx;
	return pool->idx;
#else
	return (poolhandle_t)pool;
#endif
}

void _Mem_FreePool( poolhandle_t *poolptr, const char *filename, int fileline )
{
	mempool_t	*pool;
	mempool_t	**chainaddress;

	if( *poolptr && ( pool = Mem_FindPool( *poolptr )))
	{
		// unlink pool from chain
		for( chainaddress = &poolchain; *chainaddress && *chainaddress != pool; chainaddress = &((*chainaddress)->next));
		if( *chainaddress != pool ) Sys_Error( "Mem_FreePool: pool already free (freepool at %s:%i)\n", filename, fileline );
		if( pool->sentinel1 != MEMHEADER_SENTINEL1 ) Sys_Error( "Mem_FreePool: trashed pool sentinel 1 (allocpool at %s:%i, freepool at %s:%i)\n", pool->filename, pool->fileline, filename, fileline );
		if( pool->sentinel2 != MEMHEADER_SENTINEL1 ) Sys_Error( "Mem_FreePool: trashed pool sentinel 2 (allocpool at %s:%i, freepool at %s:%i)\n", pool->filename, pool->fileline, filename, fileline );
		*chainaddress = pool->next;

		// free memory owned by the pool
		while( pool->chain ) Mem_FreeBlock( pool->chain, filename, fileline );
		// free the pool itself
		memset( pool, 0xBF, sizeof( mempool_t ));
		Q_free( pool );
		*poolptr = 0;
	}
}

void _Mem_EmptyPool( poolhandle_t poolptr, const char *filename, int fileline )
{
	mempool_t *pool = Mem_FindPool( poolptr );
	if( !poolptr ) Sys_Error( "Mem_EmptyPool: pool == NULL (emptypool at %s:%i)\n", filename, fileline );

	if( pool->sentinel1 != MEMHEADER_SENTINEL1 ) Sys_Error( "Mem_EmptyPool: trashed pool sentinel 1 (allocpool at %s:%i, emptypool at %s:%i)\n", pool->filename, pool->fileline, filename, fileline );
	if( pool->sentinel2 != MEMHEADER_SENTINEL1 ) Sys_Error( "Mem_EmptyPool: trashed pool sentinel 2 (allocpool at %s:%i, emptypool at %s:%i)\n", pool->filename, pool->fileline, filename, fileline );

	// free memory owned by the pool
	while( pool->chain ) Mem_FreeBlock( pool->chain, filename, fileline );
}

static qboolean Mem_CheckAlloc( mempool_t *pool, void *data )
{
	memheader_t *header, *target;

	if( pool )
	{
		// search only one pool
		target = (memheader_t *)((byte *)data - sizeof( memheader_t ));
		for( header = pool->chain; header; header = header->next )
			if( header == target ) return true;
	}
	else
	{
		// search all pools
		for( pool = poolchain; pool; pool = pool->next )
			if( Mem_CheckAlloc( pool, data ))
				return true;
	}
	return false;
}

/*
========================
Check pointer for memory
========================
*/
qboolean Mem_IsAllocatedExt( poolhandle_t poolptr, void *data )
{
	mempool_t	*pool = NULL;
	if( poolptr ) pool = Mem_FindPool( poolptr );

	return Mem_CheckAlloc( pool, data );
}

static void Mem_CheckHeaderSentinels( void *data, const char *filename, int fileline )
{
	memheader_t	*mem;

	if( data == NULL )
		Sys_Error( "Mem_CheckSentinels: data == NULL (sentinel check at %s:%i)\n", filename, fileline );

	mem = (memheader_t *)((byte *) data - sizeof(memheader_t));

	if( mem->sentinel1 != MEMHEADER_SENTINEL1 )
	{
		mem->filename = Mem_CheckFilename( mem->filename ); // make sure what we don't crash var_args
		Sys_Error( "Mem_CheckSentinels: trashed header sentinel 1 (block allocated at %s:%i, sentinel check at %s:%i)\n", mem->filename, mem->fileline, filename, fileline );
	}

	if( *((byte *)mem + sizeof(memheader_t) + mem->size) != MEMHEADER_SENTINEL2 )
	{
		mem->filename = Mem_CheckFilename( mem->filename ); // make sure what we don't crash var_args
		Sys_Error( "Mem_CheckSentinels: trashed header sentinel 2 (block allocated at %s:%i, sentinel check at %s:%i)\n", mem->filename, mem->fileline, filename, fileline );
	}
}

void _Mem_Check( const char *filename, int fileline )
{
	memheader_t *mem;
	mempool_t   *pool;

	for( pool = poolchain; pool; pool = pool->next )
	{
		if( pool->sentinel1 != MEMHEADER_SENTINEL1 )
			Sys_Error( "Mem_CheckSentinelsGlobal: trashed pool sentinel 1 (allocpool at %s:%i, sentinel check at %s:%i)\n", pool->filename, pool->fileline, filename, fileline );
		if( pool->sentinel2 != MEMHEADER_SENTINEL1 )
			Sys_Error( "Mem_CheckSentinelsGlobal: trashed pool sentinel 2 (allocpool at %s:%i, sentinel check at %s:%i)\n", pool->filename, pool->fileline, filename, fileline );
	}

	for( pool = poolchain; pool; pool = pool->next )
		for( mem = pool->chain; mem; mem = mem->next )
			Mem_CheckHeaderSentinels((void *)((byte *) mem + sizeof(memheader_t)), filename, fileline );
}

void Mem_PrintStats( void )
{
	size_t    count = 0, size = 0, realsize = 0;
	mempool_t *pool;

	Mem_Check();
	for( pool = poolchain; pool; pool = pool->next )
	{
		count++;
		size += pool->totalsize;
		realsize += pool->realsize;
	}

	Con_Printf( "^3%lu^7 memory pools, totalling: ^1%s\n", count, Q_memprint( size ));
	Con_Printf( "total allocated size: ^1%s\n", Q_memprint( realsize ));
}

void Mem_PrintList( size_t minallocationsize )
{
	mempool_t		*pool;
	memheader_t	*mem;

	Mem_Check();

	Con_Printf( "memory pool list:\n""  ^3size                          name\n");
	for( pool = poolchain; pool; pool = pool->next )
	{
		long	changed_size = (long)pool->totalsize - (long)pool->lastchecksize;

		// poolnames can contain color symbols, make sure what color is reset
		if( changed_size != 0 )
		{
			char	sign = (changed_size < 0) ? '-' : '+';

			Con_Printf( "%10s (%10s actual) %s (^7%c%s change)\n", Q_memprint( pool->totalsize ), Q_memprint( pool->realsize ),
			pool->name, sign, Q_memprint( abs( changed_size )));
		}
		else
		{
			Con_Printf( "%5s (%5s actual) %s\n", Q_memprint( pool->totalsize ), Q_memprint( pool->realsize ), pool->name );
		}

		pool->lastchecksize = pool->totalsize;
		for( mem = pool->chain; mem; mem = mem->next )
			if( mem->size >= minallocationsize )
				Con_Printf( "%10s allocated at %s:%i\n", Q_memprint( mem->size ), mem->filename, mem->fileline );
	}
}

/*
========================
Memory_Init
========================
*/
void Memory_Init( void )
{
	poolchain = NULL; // init mem chain
}
