537 lines
15 KiB
C++
537 lines
15 KiB
C++
// sysdep.cc
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// Implementation of system-dependent interface. Nachos uses the
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// routines defined here, rather than directly calling the UNIX library,
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// to simplify porting between versions of UNIX, and even to
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// other systems, such as MSDOS.
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//
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// On UNIX, almost all of these routines are simple wrappers
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// for the underlying UNIX system calls.
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//
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// NOTE: all of these routines refer to operations on the underlying
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// host machine (e.g., the DECstation, SPARC, etc.), supporting the
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// Nachos simulation code. Nachos implements similar operations,
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// (such as opening a file), but those are implemented in terms
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// of hardware devices, which are simulated by calls to the underlying
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// routines in the host workstation OS.
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//
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// This file includes lots of calls to C routines. C++ requires
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// us to wrap all C definitions with a "extern "C" block".
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// This prevents the internal forms of the names from being
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// changed by the C++ compiler.
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//
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// Copyright (c) 1992-1993 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#include "copyright.h"
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extern "C" {
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#include <stdio.h>
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#include <string.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/socket.h>
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#include <sys/file.h>
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#include <sys/un.h>
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#include <sys/mman.h>
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#include <sys/time.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <errno.h>
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// UNIX routines called by procedures in this file
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#ifdef HOST_SNAKE
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// int creat(char *name, unsigned short mode);
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// int open(const char *name, int flags, ...);
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#else
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#if !defined(SOLARIS) && !defined(LINUX) && !defined(MAC_OS)
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int creat(const char *name, unsigned short mode);
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int open(const char *name, int flags, ...);
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// void signal(int sig, VoidFunctionPtr func); -- this may work now!
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#ifdef HOST_i386
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int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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struct timeval *timeout);
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#else
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int select(int numBits, void *readFds, void *writeFds, void *exceptFds,
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struct timeval *timeout);
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#endif
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#endif
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#endif
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#if !defined(SOLARIS) && !defined(LINUX) && !defined(MAC_OS)
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int unlink(char *name);
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int read(int filedes, char *buf, int numBytes);
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int write(int filedes, char *buf, int numBytes);
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int lseek(int filedes, int offset, int whence);
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int tell(int filedes);
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int close(int filedes);
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int unlink(char *name);
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// definition varies slightly from platform to platform, so don't
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// define unless gcc complains
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// extern int recvfrom(int s, void *buf, int len, int flags, void *from, int *fromlen);
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// extern int sendto(int s, void *msg, int len, int flags, void *to, int tolen);
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void srand(unsigned seed);
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int rand(void);
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unsigned sleep(unsigned);
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void abort();
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void exit();
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int mprotect(char *addr, int len, int prot);
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int socket(int, int, int);
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int bind (int, const void*, int);
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int recvfrom (int, void*, int, int, void*, int *);
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int sendto (int, const void*, int, int, void*, int);
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#endif
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}
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#include "interrupt.h"
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#include "system.h"
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//----------------------------------------------------------------------
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// PollFile
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// Check open file or open socket to see if there are any
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// characters that can be read immediately. If so, read them
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// in, and return TRUE.
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//
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// In the network case, if there are no threads for us to run,
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// and no characters to be read,
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// we need to give the other side a chance to get our host's CPU
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// (otherwise, we'll go really slowly, since UNIX time-slices
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// infrequently, and this would be like busy-waiting). So we
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// delay for a short fixed time, before allowing ourselves to be
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// re-scheduled (sort of like a Yield, but cast in terms of UNIX).
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//
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// "fd" -- the file descriptor of the file to be polled
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//----------------------------------------------------------------------
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bool
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PollFile(int fd)
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{
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#if defined(SOLARIS) || defined(LINUX) || defined(MAC_OS)
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fd_set rfd;
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int retVal;
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#else
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int rfd = (1 << fd), wfd = 0, xfd = 0, retVal;
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#endif
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struct timeval pollTime;
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// decide how long to wait if there are no characters on the file
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pollTime.tv_sec = 0;
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if (interrupt->getStatus() == IdleMode)
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pollTime.tv_usec = 20000; // delay to let other nachos run
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else
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pollTime.tv_usec = 0; // no delay
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// poll file or socket
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#if defined(SOLARIS) || defined(LINUX) || defined(MAC_OS)
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FD_ZERO(&rfd);
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FD_SET(fd, &rfd);
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retVal = select(fd + 1, &rfd, NULL, NULL, &pollTime);
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#else
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retVal = select(32, &rfd, &wfd, &xfd, &pollTime);
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#endif
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ASSERT((retVal == 0) || (retVal == 1));
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if (retVal == 0)
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return FALSE; // no char waiting to be read
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return TRUE;
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}
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//----------------------------------------------------------------------
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// OpenForWrite
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// Open a file for writing. Create it if it doesn't exist; truncate it
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// if it does already exist. Return the file descriptor.
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//
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// "name" -- file name
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//----------------------------------------------------------------------
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int
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OpenForWrite(const char *name)
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{
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int fd = open(name, O_RDWR|O_CREAT|O_TRUNC, 0666);
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ASSERT(fd >= 0);
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return fd;
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}
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//----------------------------------------------------------------------
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// OpenForReadWrite
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// Open a file for reading or writing.
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// Return the file descriptor, or error if it doesn't exist.
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//
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// "name" -- file name
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//----------------------------------------------------------------------
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int
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OpenForReadWrite(const char *name, bool crashOnError)
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{
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int fd = open(name, O_RDWR, 0);
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ASSERT(!crashOnError || fd >= 0);
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return fd;
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}
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//----------------------------------------------------------------------
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// Read
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// Read characters from an open file. Abort if read fails.
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//----------------------------------------------------------------------
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void
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Read(int fd, void *buffer, int nBytes)
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{
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int retVal = read(fd, buffer, nBytes);
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ASSERT(retVal == nBytes);
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}
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//----------------------------------------------------------------------
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// ReadPartial
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// Read characters from an open file, returning as many as are
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// available.
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//----------------------------------------------------------------------
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int
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ReadPartial(int fd, void *buffer, int nBytes)
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{
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return read(fd, buffer, nBytes);
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}
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//----------------------------------------------------------------------
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// WriteFile
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// Write characters to an open file. Abort if write fails.
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//----------------------------------------------------------------------
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void
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WriteFile(int fd, const void *buffer, int nBytes)
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{
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int retVal = write(fd, buffer, nBytes);
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ASSERT(retVal == nBytes);
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}
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//----------------------------------------------------------------------
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// Lseek
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// Change the location within an open file. Abort on error.
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//----------------------------------------------------------------------
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void
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Lseek(int fd, int offset, int whence)
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{
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int retVal = lseek(fd, offset, whence);
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ASSERT(retVal >= 0);
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}
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//----------------------------------------------------------------------
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// Tell
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// Report the current location within an open file.
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//----------------------------------------------------------------------
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int
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Tell(int fd)
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{
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#if defined(SOLARIS) || defined(LINUX) || defined(MAC_OS)
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return lseek(fd,0,SEEK_CUR); // 386BSD doesn't have the tell() system call
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#else
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return tell(fd);
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#endif
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}
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//----------------------------------------------------------------------
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// Close
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// Close a file. Abort on error.
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//----------------------------------------------------------------------
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void
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Close(int fd)
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{
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int retVal = close(fd);
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ASSERT(retVal >= 0);
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}
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//----------------------------------------------------------------------
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// Unlink
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// Delete a file.
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//----------------------------------------------------------------------
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bool
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Unlink(const char *name)
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{
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return unlink(name);
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}
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//----------------------------------------------------------------------
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// OpenSocket
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// Open an interprocess communication (IPC) connection. For now,
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// just open a datagram port where other Nachos (simulating
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// workstations on a network) can send messages to this Nachos.
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//----------------------------------------------------------------------
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int
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OpenSocket()
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{
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int sockID;
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sockID = socket(AF_UNIX, SOCK_DGRAM, 0);
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ASSERT(sockID >= 0);
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return sockID;
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}
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//----------------------------------------------------------------------
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// CloseSocket
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// Close the IPC connection.
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//----------------------------------------------------------------------
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void
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CloseSocket(int sockID)
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{
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(void) close(sockID);
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}
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//----------------------------------------------------------------------
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// InitSocketName
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// Initialize a UNIX socket address -- magical!
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//----------------------------------------------------------------------
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static void
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InitSocketName(struct sockaddr_un *uname, const char *name)
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{
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uname->sun_family = AF_UNIX;
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strcpy(uname->sun_path, name);
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}
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//----------------------------------------------------------------------
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// AssignNameToSocket
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// Give a UNIX file name to the IPC port, so other instances of Nachos
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// can locate the port.
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//----------------------------------------------------------------------
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void
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AssignNameToSocket(const char *socketName, int sockID)
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{
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struct sockaddr_un uName;
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int retVal;
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(void) unlink(socketName); // in case it's still around from last time
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InitSocketName(&uName, socketName);
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retVal = bind(sockID, (struct sockaddr *) &uName, sizeof(uName));
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ASSERT(retVal >= 0);
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DEBUG('n', "Created socket %s\n", socketName);
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}
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//----------------------------------------------------------------------
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// DeAssignNameToSocket
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// Delete the UNIX file name we assigned to our IPC port, on cleanup.
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//----------------------------------------------------------------------
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void
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DeAssignNameToSocket(const char *socketName)
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{
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(void) unlink(socketName);
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}
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//----------------------------------------------------------------------
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// PollSocket
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// Return TRUE if there are any messages waiting to arrive on the
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// IPC port.
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//----------------------------------------------------------------------
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bool
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PollSocket(int sockID)
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{
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return PollFile(sockID); // on UNIX, socket ID's are just file ID's
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}
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//----------------------------------------------------------------------
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// ReadFromSocket
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// Read a fixed size packet off the IPC port. Abort on error.
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//----------------------------------------------------------------------
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void
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ReadFromSocket(int sockID, void *buffer, int packetSize)
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{
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int retVal;
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struct sockaddr_un uName;
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// LB: Signedness problem on Solaris 5.6/SPARC, as the last
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// parameter of recvfrom is specified as a int *. In the later
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// versions, it is specified as a void *. Casting size to int instead
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// of unsigned seems to fix the problem, but it is admittingly
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// rather ad-hoc...
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#ifndef SOLARIS
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unsigned int size = sizeof(uName);
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#else
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int size = (int) sizeof(uName);
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#endif
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// End of correction.
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retVal = recvfrom(sockID, buffer, packetSize, 0,
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(struct sockaddr *) &uName, &size);
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if (retVal != packetSize) {
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perror("in recvfrom");
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}
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ASSERT(retVal == packetSize);
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}
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//----------------------------------------------------------------------
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// SendToSocket
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// Transmit a fixed size packet to another Nachos' IPC port.
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// Abort on error.
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//----------------------------------------------------------------------
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void
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SendToSocket(int sockID, const void *buffer, int packetSize, const char *toName)
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{
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struct sockaddr_un uName;
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int retVal;
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InitSocketName(&uName, toName);
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retVal = sendto(sockID, buffer, packetSize, 0,
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(sockaddr *) &uName, sizeof(uName));
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ASSERT(retVal == packetSize);
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}
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//----------------------------------------------------------------------
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// CallOnUserAbort
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// Arrange that "func" will be called when the user aborts (e.g., by
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// hitting ctl-C.
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//----------------------------------------------------------------------
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void
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CallOnUserAbort(VoidNoArgFunctionPtr func)
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{
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(void)signal(SIGINT, (void (*)(int)) func);
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}
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//----------------------------------------------------------------------
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// BlockUserAbort
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// Prevent from abortion (e.g. ctl-C)
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//----------------------------------------------------------------------
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void
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BlockUserAbort(void)
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{
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sighold(SIGINT);
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}
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//----------------------------------------------------------------------
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// UnBlockUserAbort
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// Re-allow abortion (e.g. ctl-C)
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//----------------------------------------------------------------------
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void
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UnBlockUserAbort(void)
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{
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sigrelse(SIGINT);
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}
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//----------------------------------------------------------------------
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// Sleep
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// Put the UNIX process running Nachos to sleep for x seconds,
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// to give the user time to start up another invocation of Nachos
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// in a different UNIX shell.
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//----------------------------------------------------------------------
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void
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Delay(int seconds)
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{
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(void) sleep((unsigned) seconds);
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}
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//----------------------------------------------------------------------
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// Abort
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// Quit and drop core.
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//----------------------------------------------------------------------
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void
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Abort()
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{
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#ifdef USER_PROGRAM
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if (machine)
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machine->DumpMem("abort.svg");
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#endif
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abort();
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}
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//----------------------------------------------------------------------
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// Exit
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// Quit without dropping core.
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//----------------------------------------------------------------------
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void
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Exit(int exitCode)
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{
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exit(exitCode);
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}
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//----------------------------------------------------------------------
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// RandomInit
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// Initialize the pseudo-random number generator. We use the
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// now obsolete "srand" and "rand" because they are more portable!
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//----------------------------------------------------------------------
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void
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RandomInit(unsigned seed)
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{
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srand(seed);
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}
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//----------------------------------------------------------------------
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// Random
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// Return a pseudo-random number.
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//----------------------------------------------------------------------
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int
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Random()
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{
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return rand();
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}
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//----------------------------------------------------------------------
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// AllocBoundedArray
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// Return an array, with the two pages just before
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// and after the array unmapped, to catch illegal references off
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// the end of the array. Particularly useful for catching overflow
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// beyond fixed-size thread execution stacks.
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//
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// Note: Just return the useful part!
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//
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// "size" -- amount of useful space needed (in bytes)
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//----------------------------------------------------------------------
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char *
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AllocBoundedArray(int size)
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{
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int pgSize = getpagesize();
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char *ptr = new char[pgSize * 2 + size];
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mprotect(ptr, pgSize, 0);
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mprotect(ptr + pgSize + size, pgSize, 0);
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return ptr + pgSize;
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}
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//----------------------------------------------------------------------
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// DeallocBoundedArray
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// Deallocate an array of integers, unprotecting its two boundary pages.
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//
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// "ptr" -- the array to be deallocated
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// "size" -- amount of useful space in the array (in bytes)
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//----------------------------------------------------------------------
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void
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DeallocBoundedArray(char *ptr, int size)
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{
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int pgSize = getpagesize();
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mprotect(ptr - pgSize, pgSize, PROT_READ | PROT_WRITE | PROT_EXEC);
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mprotect(ptr + size, pgSize, PROT_READ | PROT_WRITE | PROT_EXEC);
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delete [] (ptr - pgSize);
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}
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