System-dependent interface. More...

#include "copyright.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

Functions
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	Abort ()
	Process control: abort, exit, and sleep. More...

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

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	CallOnUserAbort (VoidNoArgFunctionPtr cleanUp)
	Initialize system so that cleanUp routine is called when user hits ctl-C. More...

void	RandomInit (unsigned seed)
	Initialize the pseudo random number generator. More...

int	Random ()
	Random. More...

char *	AllocBoundedArray (int size)
	Allocate, de-allocate an array, such that de-referencing just beyond either end of the array will cause an error. More...

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

Detailed Description

System-dependent interface.

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

Function Documentation

void Abort ( )

Process control: abort, exit, and sleep.

char* AllocBoundedArray ( int size )

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 )

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 )

Initialize the pseudo random number generator.

Functions

Detailed Description

Function Documentation