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109 lines
2.1 KiB
109 lines
2.1 KiB
5 years ago
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/*
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sbrk.c - swap memory allocation
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Copyright (C) 2019 mittorn
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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#define _GNU_SOURCE
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#include <dlfcn.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <signal.h>
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#define _GNU_SOURCE
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#include <dlfcn.h>
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#include "platform/swap/swap.h"
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#include "string.h"
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#ifndef XASH_DEFAULT_SWAP_PATH
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#define XASH_DEFAULT_SWAP_PATH "/tmp/xash3d-swap"
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#endif
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#define PAGE_SIZE 4096
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static struct sbrk_state_s
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{
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void *top;
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int fd;
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size_t size;
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size_t prealloc;
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pid_t pid;
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} s;
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static void SWAP_Initialize(void)
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{
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char *path;
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char *prealloc = getenv("SWAP_SIZE");
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int fd;
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if( s.top )
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return;
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path = getenv("SWAP_PATH");
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if( !path )
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path = XASH_DEFAULT_SWAP_PATH;
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fd = open( path, O_CREAT|O_RDWR, 0600 );
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if( prealloc ) s.prealloc = atoi(prealloc);
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else s.prealloc = 128*1024*1024;
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s.prealloc &= ~(PAGE_SIZE - 1);
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s.fd = fd;
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ftruncate( fd, s.prealloc );
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s.top = mmap( 0, s.prealloc, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0 );
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// space will be freed on exit
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//unlink(path);
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}
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void *SWAP_Sbrk(size_t size)
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{
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char buf[64];
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SWAP_Initialize();
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if( size == 0 )
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return s.top;
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else if( size > 0 )
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{
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void *res;
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//write(1, buf, snprintf(buf, 32, "allocating %d\n", size) );
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res = s.top;
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s.size += size;
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s.top = res + size;
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if( s.size + size > s.prealloc )
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return (void*)-1;
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memset( res, 0, size );
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return res;
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}
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else
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{
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void *res = s.top;
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if( -size > s.size )
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res = (void*)-1;
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else
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{
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s.top += size;
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s.size += size;
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//write(1, buf, snprintf(buf, 32, "freed %d\n", -size) );
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}
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return res;
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}
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}
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