##       Software from the book "Inferno Programming with Limbo"#       published by John Wiley & Sons, January 2003.##       p. Stanley-Marbell <pip@gemusehaken.org>#implement SHA; include "sys.m";include "draw.m";include "keyring.m"; sys : Sys;keyring : Keyring; stdin, stderr	: ref Sys->FD; SHA : module{	init : fn(nil : ref Draw->Context, args : list of string);}; init (nil : ref Draw->Context, args : list of string){	sys = load Sys Sys->PATH;	keyring = load Keyring Keyring->PATH; 	stdin = sys->fildes(0);	stderr = sys->fildes(2); 	args = tl args;	if (args == nil)	{		sha(nil);	}	else while (args != nil)	{		sha(hd args); 		args = tl args;	}} sha(filename : string){	cksum	 	: string;	n		: int;	nbytes		: big;	fd		: ref Sys->FD;	digeststate 	: ref Keyring->DigestState;  	if (filename == nil)	{		fd = stdin;		filename = "stdin";	}	else	{		fd = sys->open(filename, Sys->OREAD);	} 	if (fd == nil)	{		sys->fprint(stderr, "SHA : Could not open input stream : %r\n");		exit;	} 	buf := array [Sys->ATOMICIO] of byte;	while ((n = sys->read(fd, buf, len buf)) > 0)	{		digeststate = keyring->sha(buf[:n], n, nil, digeststate);		nbytes += big n;	}	if (n < 0)	{		sys->fprint(stderr, "SHA : Could not read input stream : %r\n");		exit;	} 	digest := array[Keyring->SHAdlen] of byte;	keyring->sha(buf[:n], n, digest, digeststate); 	cksum += sys->sprint("SHA (%s) = ", filename);	for (i := 0; i < Keyring->SHAdlen; i++)	{		cksum += sys->sprint("%2.2ux", int digest[i]);	} 	sys->print("%s\n", cksum);}