file.c

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int fileSeek( STREAM *stream, const long position )
	{
	if( FS_FSeek( stream->pFile, position, FS_SEEK_SET ) < 0 )
		return( CRYPT_ERROR_WRITE );
	return( CRYPT_OK );
	}

/* Check whether a file is writeable */

BOOLEAN fileReadonly( const char *fileName )
	{
	FS_U8 fileAttr;

	assert( fileName != NULL );

	if( ( fileAttr = FS_GetFileAttributes( fileName ) ) == 0xFF )
		return( TRUE );

	return( ( fileAttr & FS_ATTR_READONLY ) ? TRUE : FALSE );
	}

/* File deletion functions: Wipe a file from the current position to EOF,
   and wipe and delete a file (although it's not terribly rigorous).
   Vestigia nulla retrorsum */

static void eraseFile( const STREAM *stream, long position, long length )
	{
	/* Wipe everything past the current position in the file */
	while( length > 0 )
		{
		RESOURCE_DATA msgData;
		BYTE buffer[ BUFSIZ * 2 ];
		int bytesToWrite = min( length, BUFSIZ * 2 );

		/* We need to make sure that we fill the buffer with random data for
		   each write, otherwise compressing filesystems will just compress
		   it to nothing */
		setMessageData( &msgData, buffer, bytesToWrite );
		krnlSendMessage( SYSTEM_OBJECT_HANDLE, IMESSAGE_GETATTRIBUTE_S,
						 &msgData, CRYPT_IATTRIBUTE_RANDOM_NONCE );

		if( FS_Write( stream->pFile, buffer, bytesToWrite ) < 0 )
			break;	/* An error occurred while writing, exit */
		length -= bytesToWrite;
		}

	fjchsize( stream->pFile, position );
	}

void fileClearToEOF( const STREAM *stream )
	{
	int length, position;

	assert( isReadPtr( stream, sizeof( STREAM ) ) );
	assert( stream->type == STREAM_TYPE_FILE );

	/* Wipe everything past the current position in the file */
	if( ( length = FS_GetFileSize( fileName ) ) < 0 )
		return;
	if( ( position = FS_FTell( stream->pFile ) ) < 0 )
		return;
	length -= position;
	if( length <= 0 )
		return;	/* Nothing to do, exit */
	eraseFile( stream, position, length );
	}

void fileErase( const char *fileName )
	{
	STREAM stream;
	int length, status;

	assert( fileName != NULL );

	if( ( length = FS_GetFileSize( fileName ) ) < 0 )
		return;

	/* Try and open the file so that we can erase it.  If this fails, the
	   best that we can do is a straight unlink */
	status = sFileOpen( &stream, fileName,
						FILE_READ | FILE_WRITE | FILE_EXCLUSIVE_ACCESS );
	if( cryptStatusError( status ) )
		{
		remove( fileName );
		return;
		}

	/* Determine the size of the file and erase it */
	eraseFile( &stream, 0, length );

	/* Reset the file's attributes and delete it */
	sFileClose( &stream );
	FS_SetFileAttributes( stream.pFile, FS_ATTR_ARCHIVE );
	FS_SetFileTime( stream.pFile, 0 );
	FS_Remove( fileName );
	}

/* Build the path to a file in the cryptlib directory */

void fileBuildCryptlibPath( char *path, const char *fileName,
							const BUILDPATH_OPTION_TYPE option )
	{
	/* Make sure that the open fails if we can't build the path */
	*path = '\0';

	/* Build the path to the configuration file if necessary.  We assume that
	   we're on the correct drive */
	strcpy( path, "\\cryptlib\\" );

	/* If we're being asked to create the cryptlib directory and it doesn't
	   already exist, create it now */
	if( option == BUILDPATH_CREATEPATH )
		{
		FS_DIR dirInfo;

		if( ( dirInfo = FS_OpenDir( path ) ) != NULL )
			FSCloseDir( dirInfo );
		else
			{
			/* The directory doesn't exist, try and create it */
			if( FS_MkDir( path ) < 0 )
				{
				*path = '\0';
				return;
				}
			}
		}

	/* Add the filename to the path */
	if( option == BUILDPATH_RNDSEEDFILE )
		strcat( path, "randseed.dat" );
	else
		{
		strcat( path, fileName );
		strcat( path, ".p15" );
		}
	}

/****************************************************************************
*																			*
*							uITRON File Stream Functions					*
*																			*
****************************************************************************/

/* See the comment in str_file.h for uITRON file handling */

#elif defined( __ITRON__ )

/* Open/close a file stream */

int sFileOpen( STREAM *stream, const char *fileName, const int mode )
	{
	assert( isWritePtr( stream, sizeof( STREAM ) ) );
	assert( fileName != NULL );
	assert( mode != 0 );

	/* Initialise the stream structure */
	memset( stream, 0, sizeof( STREAM ) );
	stream->type = STREAM_TYPE_FILE;
	if( ( mode & FILE_RW_MASK ) == FILE_READ )
		stream->flags = STREAM_FLAG_READONLY;

	/* If we're trying to write to the file, check whether we've got
	   permission to do so */
	if( ( mode & FILE_WRITE ) && fileReadonly( fileName ) )
		return( CRYPT_ERROR_PERMISSION );

	/* Try and open the file */
	return( CRYPT_ERROR_OPEN );
	}

int sFileClose( STREAM *stream )
	{
	assert( isWritePtr( stream, sizeof( STREAM ) ) );
	assert( stream->type == STREAM_TYPE_FILE );

	/* Close the file and clear the stream structure */
	zeroise( stream, sizeof( STREAM ) );

	return( CRYPT_OK );
	}

/* Read/write a block of data from/to a file stream */

int fileRead( STREAM *stream, void *buffer, const int length )
	{
	int bytesRead;

	return( CRYPT_ERROR_READ );
	}

int fileWrite( STREAM *stream, const void *buffer, const int length )
	{
	return( CRYPT_ERROR_WRITE );
	}

/* Commit data in a file stream to backing storage */

int fileFlush( STREAM *stream )
	{
	return( CRYPT_ERROR_WRITE );
	}

/* Change the read/write position in a file */

int fileSeek( STREAM *stream, const long position )
	{
	return( CRYPT_ERROR_WRITE );
	}

/* Check whether a file is writeable */

BOOLEAN fileReadonly( const char *fileName )
	{
	return( TRUE );
	}

/* File deletion functions: Wipe a file from the current position to EOF,
   and wipe and delete a file (although it's not terribly rigorous).
   Vestigia nulla retrorsum */

static void eraseFile( const STREAM *stream, long position, long length )
	{
	BYTE buffer[ BUFSIZ * 2 ];

	/* Wipe everything past the current position in the file */
	while( length > 0 )
		{
		RESOURCE_DATA msgData;
		int bytesToWrite = min( length, BUFSIZ * 2 );

		/* We need to make sure that we fill the buffer with random data for
		   each write, otherwise compressing filesystems will just compress
		   it to nothing */
		setMessageData( &msgData, buffer, bytesToWrite );
		krnlSendMessage( SYSTEM_OBJECT_HANDLE, IMESSAGE_GETATTRIBUTE_S,
						 &msgData, CRYPT_IATTRIBUTE_RANDOM_NONCE );
		if( fwrite( buffer, 1, bytesToWrite, stream->filePtr ) == 0 )
			break;	/* An error occurred while writing, exit */
		length -= bytesToWrite;
		}
	fflush( stream->filePtr );

	/* Truncate the file and if we're erasing the entire file, reset the
	   timestamps.  This is only possible through a file handle on some
	   systems, on others the caller has to do it via the filename */
	chsize( fileHandle, position );
	if( position <= 0 )
		{
		struct ftime fileTime;

		memset( &fileTime, 0, sizeof( struct ftime ) );
		setftime( fileHandle, &fileTime );
		}
	}

void fileClearToEOF( const STREAM *stream )
	{
	long position, length;

	assert( isReadPtr( stream, sizeof( STREAM ) ) );
	assert( stream->type == STREAM_TYPE_FILE );

	/* Wipe everything past the current position in the file */
	position = ftell( stream->filePtr );
	fseek( stream->filePtr, 0, SEEK_END );
	length = ftell( stream->filePtr ) - position;
	fseek( stream->filePtr, position, SEEK_SET );
	eraseFile( stream, position, length );
	}

void fileErase( const char *fileName )
	{
	STREAM stream;
	int fileHandle, length, status;

	assert( fileName != NULL );

	/* Try and open the file so that we can erase it.  If this fails, the
	   best that we can do is a straight unlink */
	status = sFileOpen( &stream, fileName,
						FILE_READ | FILE_WRITE | FILE_EXCLUSIVE_ACCESS );
	if( cryptStatusError( status ) )
		{
		remove( fileName );
		return;
		}

	/* Determine the size of the file and erase it */
	fileHandle = fileno( stream.filePtr );
	fseek( stream.filePtr, 0, SEEK_END );
	length = ( int ) ftell( stream.filePtr );
	fseek( stream.filePtr, 0, SEEK_SET );
	eraseFile( stream, 0, length );

	/* Truncate the file to 0 bytes if we couldn't do it in eraseFile, reset
	   the time stamps, and delete it */
	sFileClose( &stream );
	/* Under Win16 we can't really do anything without resorting to MSDOS int
	   21h calls, the best we can do is truncate the file using _lcreat() */
	hFile = _lcreat( fileName, 0 );
	if( hFile != HFILE_ERROR )
		_lclose( hFile );

	/* Finally, delete the file */
	remove( fileName );
	}

/* Build the path to a file in the cryptlib directory */

void fileBuildCryptlibPath( char *path, const char *fileName,
							const BUILDPATH_OPTION_TYPE option )
	{
	if( option == BUILDPATH_RNDSEEDFILE )
		strcpy( path, "randseed.dat" );
	else
		{
		strcpy( path, fileName );
		strcat( path, ".p15" );
		}
	}

/****************************************************************************
*																			*
*							Macintosh File Stream Functions					*
*																			*
****************************************************************************/

#elif defined( __MAC__ )

/* Convert a C to a Pascal string */

static void CStringToPString( const char *cstring, StringPtr pstring )
	{
	short len = min( strlen( cstring ), 255 );

	memmove( pstring + 1, cstring, len );
	*pstring = len;
	}

/* Open/close a file stream */

int sFileOpen( STREAM *stream, const char *fileName, const int mode )
	{
	Str255 pFileName;
	OSErr err;

	assert( isWritePtr( stream, sizeof( STREAM ) ) );
	assert( fileName != NULL );
	assert( mode != 0 );

	/* Initialise the stream structure */
	memset( stream, 0, sizeof( STREAM ) );
	stream->type = STREAM_TYPE_FILE;
	if( ( mode & FILE_RW_MASK ) == FILE_READ )
		stream->flags = STREAM_FLAG_READONLY;

	CStringToPString( fileName, pFileName );
	err = FSMakeFSSpec( 0, 0, pFileName, &stream->fsspec );
	if( err == dirNFErr || err == nsvErr )
		/* Volume or parent directory not found */
		return( CRYPT_ERROR_NOTFOUND );
	if( err != noErr && err != fnfErr )
		/* fnfErr is OK since the fsspec is still valid */
		return( CRYPT_ERROR_OPEN );

	if( mode & FILE_WRITE )
		{
		/* Try and create the file, specifying its type and creator.  The
		   wierd string-looking constants are Mac compiler-specific and
		   evaluate to 32-bit unsigned type and creator IDs */
		err = FSpCreate( &stream->fsspec, '????', 'CLib', smSystemScript );
		if( err == wPrErr || err == vLckdErr || err == afpAccessDenied )
			return( CRYPT_ERROR_PERMISSION );
		if( err != noErr && err != dupFNErr && err != afpObjectTypeErr )
			return( CRYPT_ERROR_OPEN );
		}

	err = FSpOpenDF( &stream->fsspec, mode & FILE_RW_MASK, &stream->refNum );
	if( err == nsvErr || err == dirNFErr || err == fnfErr )
		return( CRYPT_ERROR_NOTFOUND );
	if( err == opWrErr || err == permErr || err == afpAccessDenied )
		return( CRYPT_ERROR_PERMISSION );
	if( err != noErr )
		return( CRYPT_ERROR_OPEN );

	return( CRYPT_OK );
	}

int sFileClose( STREAM *stream )
	{
	assert( isWritePtr( stream, sizeof( STREAM ) ) );
	assert( stream->type == STREAM_TYPE_FILE );

	/* Close the file and clear the stream structure */
	FSClose( stream->refNum );
	zeroise( stream, sizeof( STREAM ) );

	return( CRYPT_OK );
	}

/* Read/write a block of data from/to a file stream */

int fileRead( STREAM *stream, void *buffer, const int length )