/* sbrk.c - swap memory allocation Copyright (C) 2019 mittorn 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. */ #define _GNU_SOURCE #include <dlfcn.h> #include <sys/mman.h> #include <unistd.h> #include <sys/types.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <signal.h> #define _GNU_SOURCE #include <dlfcn.h> #include "platform/swap/swap.h" #include "string.h" #ifndef XASH_DEFAULT_SWAP_PATH #define XASH_DEFAULT_SWAP_PATH "/tmp/xash3d-swap" #endif #define PAGE_SIZE 4096 static struct sbrk_state_s { void *top; int fd; size_t size; size_t prealloc; pid_t pid; } s; static void SWAP_Initialize(void) { char *path; char *prealloc = getenv("SWAP_SIZE"); int fd; if( s.top ) return; path = getenv("SWAP_PATH"); if( !path ) path = XASH_DEFAULT_SWAP_PATH; fd = open( path, O_CREAT|O_RDWR, 0600 ); if( prealloc ) s.prealloc = atoi(prealloc); else s.prealloc = 128*1024*1024; s.prealloc &= ~(PAGE_SIZE - 1); s.fd = fd; ftruncate( fd, s.prealloc ); s.top = mmap( 0, s.prealloc, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0 ); // space will be freed on exit //unlink(path); } void *SWAP_Sbrk(size_t size) { char buf[64]; SWAP_Initialize(); if( size == 0 ) return s.top; else if( size > 0 ) { void *res; //write(1, buf, snprintf(buf, 32, "allocating %d\n", size) ); res = s.top; s.size += size; s.top = res + size; if( s.size + size > s.prealloc ) return (void*)-1; memset( res, 0, size ); return res; } else { void *res = s.top; if( -size > s.size ) res = (void*)-1; else { s.top += size; s.size += size; //write(1, buf, snprintf(buf, 32, "freed %d\n", -size) ); } return res; } }