Implementation of system-dependent interface. More...

#include "copyright.h"
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/un.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include "interrupt.h"
#include "system.h"

Functions
int	creat (const char *name, unsigned short mode)

int	open (const char *name, int flags,...)

int	select (int numBits, void readFds, void writeFds, void exceptFds, struct timeval timeout)

int	unlink (char *name)

int	read (int filedes, char *buf, int numBytes)

int	write (int filedes, char *buf, int numBytes)

int	lseek (int filedes, int offset, int whence)

int	tell (int filedes)

int	close (int filedes)

void	srand (unsigned seed)

int	rand (void)

unsigned	sleep (unsigned)

void	abort ()

void	exit ()

int	mprotect (char *addr, int len, int prot)

int	socket (int, int, int)

int	bind (int, const void *, int)

int	recvfrom (int, void , int, int, void , int *)

int	sendto (int, const void , int, int, void , int)

bool	PollFile (int fd)
	PollFile Check open file or open socket to see if there are any characters that can be read immediately. If so, read them in, and return TRUE. More...

int	OpenForWrite (const char *name)
	OpenForWrite Open a file for writing. Create it if it doesn't exist; truncate it if it does already exist. More...

int	OpenForReadWrite (const char *name, bool crashOnError)
	OpenForReadWrite Open a file for reading or writing. More...

void	Read (int fd, char *buffer, int nBytes)
	Read Read characters from an open file. Abort if read fails.

int	ReadPartial (int fd, char *buffer, int nBytes)
	ReadPartial Read characters from an open file, returning as many as are available.

void	WriteFile (int fd, const char *buffer, int nBytes)
	WriteFile Write characters to an open file. Abort if write fails.

void	Lseek (int fd, int offset, int whence)
	Lseek Change the location within an open file. Abort on error.

int	Tell (int fd)
	Tell Report the current location within an open file.

void	Close (int fd)
	Close Close a file. Abort on error.

bool	Unlink (const char *name)
	Unlink Delete a file.

int	OpenSocket ()
	OpenSocket Open an interprocess communication (IPC) connection. For now, just open a datagram port where other Nachos (simulating workstations on a network) can send messages to this Nachos.

void	CloseSocket (int sockID)
	CloseSocket Close the IPC connection.

void	AssignNameToSocket (const char *socketName, int sockID)
	AssignNameToSocket Give a UNIX file name to the IPC port, so other instances of Nachos can locate the port.

void	DeAssignNameToSocket (const char *socketName)
	DeAssignNameToSocket Delete the UNIX file name we assigned to our IPC port, on cleanup.

bool	PollSocket (int sockID)
	PollSocket. More...

void	ReadFromSocket (int sockID, char *buffer, int packetSize)
	ReadFromSocket Read a fixed size packet off the IPC port. Abort on error.

void	SendToSocket (int sockID, const char buffer, int packetSize, const char toName)
	SendToSocket Transmit a fixed size packet to another Nachos' IPC port. Abort on error.

void	CallOnUserAbort (VoidNoArgFunctionPtr func)
	CallOnUserAbort Arrange that "func" will be called when the user aborts (e.g., by hitting ctl-C. More...

void	Delay (int seconds)
	Sleep Put the UNIX process running Nachos to sleep for x seconds, to give the user time to start up another invocation of Nachos in a different UNIX shell.

void	Abort ()
	Abort Quit and drop core. More...

void	Exit (int exitCode)
	Exit Quit without dropping core.

void	RandomInit (unsigned seed)
	RandomInit Initialize the pseudo-random number generator. We use the now obsolete "srand" and "rand" because they are more portable! More...

int	Random ()
	Random. More...

char *	AllocBoundedArray (int size)
	AllocBoundedArray. More...

void	DeallocBoundedArray (char *ptr, int size)
	DeallocBoundedArray Deallocate an array of integers, unprotecting its two boundary pages. More...

Detailed Description

Implementation of system-dependent interface.

Author: Olivier Hureau, Hugo Feydel , Julien ALaimo Nachos uses the routines defined here, rather than directly calling the UNIX library, to simplify porting between versions of UNIX, and even to other systems, such as MSDOS.

On UNIX, almost all of these routines are simple wrappers for the underlying UNIX system calls.

NOTE: all of these routines refer to operations on the underlying host machine (e.g., the DECstation, SPARC, etc.), supporting the Nachos simulation code. Nachos implements similar operations, (such as opening a file), but those are implemented in terms of hardware devices, which are simulated by calls to the underlying routines in the host workstation OS.

This file includes lots of calls to C routines. C++ requires us to wrap all C definitions with a "extern "C" block". This prevents the internal forms of the names from being changed by the C++ compiler.

Function Documentation

void Abort ( )

Abort Quit and drop core.

Process control: abort, exit, and sleep.

char* AllocBoundedArray ( int size )

AllocBoundedArray.

Allocate, de-allocate an array, such that de-referencing just beyond either end of the array will cause an error.

Returns: Return an array, with the two pages just before and after the array unmapped, to catch illegal references off the end of the array. Particularly useful for catching overflow beyond fixed-size thread execution stacks.

Note: Just return the useful part!

Parameters

size	– amount of useful space needed (in bytes)

void CallOnUserAbort ( VoidNoArgFunctionPtr func )

CallOnUserAbort Arrange that "func" will be called when the user aborts (e.g., by hitting ctl-C.

Initialize system so that cleanUp routine is called when user hits ctl-C.

void DeallocBoundedArray	(	char *	ptr,
		int	size
	)

DeallocBoundedArray Deallocate an array of integers, unprotecting its two boundary pages.

Parameters

ptr	– the array to be deallocated
size	– amount of useful space in the array (in bytes)

int OpenForReadWrite	(	const char *	name,
		bool	crashOnError
	)

OpenForReadWrite Open a file for reading or writing.

Returns: Return the file descriptor, or error if it doesn't exist.

Parameters

name	– file name

int OpenForWrite ( const char * name )

OpenForWrite Open a file for writing. Create it if it doesn't exist; truncate it if it does already exist.

Returns: Return the file descriptor.

Parameters

name	– file name

bool PollFile ( int fd )

PollFile Check open file or open socket to see if there are any characters that can be read immediately. If so, read them in, and return TRUE.

In the network case, if there are no threads for us to run, and no characters to be read, we need to give the other side a chance to get our host's CPU (otherwise, we'll go really slowly, since UNIX time-slices infrequently, and this would be like busy-waiting). So we delay for a short fixed time, before allowing ourselves to be re-scheduled (sort of like a Yield, but cast in terms of UNIX).

Parameters

fd	– the file descriptor of the file to be polled

bool PollSocket ( int sockID )

PollSocket.

Returns: Return TRUE if there are any messages waiting to arrive on the IPC port.

int Random ( )

Random.

Returns: Return a pseudo-random number.

void RandomInit ( unsigned seed )

RandomInit Initialize the pseudo-random number generator. We use the now obsolete "srand" and "rand" because they are more portable!

Initialize the pseudo random number generator.

Functions

Detailed Description

Function Documentation