marshal.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

			fatal("input error");
		if(n == 0)
			break;
		m = enc64(obuf, sizeof(obuf), buf, n);
		if(Bwrite(out, obuf, m) < 0)
			fatal("output error");
	}
	lastchar = '\n';
}

// pass message to sendmail, make sure body starts with a newline
void
copy(Biobuf *in, Biobuf *out)
{
	char buf[4*1024];
	int n;

	for(;;){
		n = Bread(in, buf, sizeof(buf));
		if(n < 0)
			fatal("input error");
		if(n == 0)
			break;
		if(Bwrite(out, buf, n) < 0)
			fatal("output error");
	}
}

void
attachment(Attach *a, Biobuf *out)
{
	Biobuf *f;
	char *p;

	// if it's already mime encoded, just copy
	if(strcmp(a->type, "mime") == 0){
		f = Bopen(a->path, OREAD);
		if(f == nil){
			/* hack: give marshal time to stdin, before we kill it (for dead.letter) */
			sleep(500);
			postnote(PNPROC, pid, "interrupt");
			sysfatal("opening %s: %r", a->path);
		}
		copy(f, out);
		Bterm(f);
	}
	
	// if it's not already mime encoded ...
	if(strcmp(a->type, "text/plain") != 0)
		Bprint(out, "Content-Type: %s\n", a->type);

	if(a->ainline){
		Bprint(out, "Content-Disposition: inline\n");
	} else {
		p = strrchr(a->path, '/');
		if(p == nil)
			p = a->path;
		else
			p++;
		Bprint(out, "Content-Disposition: attachment; filename=%Z\n", p);
	}

	f = Bopen(a->path, OREAD);
	if(f == nil){
		/* hack: give marshal time to stdin, before we kill it (for dead.letter) */
		sleep(500);
		postnote(PNPROC, pid, "interrupt");
		sysfatal("opening %s: %r", a->path);
	}

	/* dump our local 'From ' line when passing along mail messages */
	if(strcmp(a->type, "message/rfc822") == 0){
		p = Brdline(f, '\n');
		if(strncmp(p, "From ", 5) != 0)
			Bseek(f, 0, 0);
	}
	if(a->ctype->display){
		body(f, out, strcmp(a->type, "text/plain") == 0);
	} else {
		Bprint(out, "Content-Transfer-Encoding: base64\n");
		body64(f, out);
	}
	Bterm(f);
}

char *ascwday[] =
{
	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};

char *ascmon[] =
{
	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

int
printdate(Biobuf *b)
{
	Tm *tm;
	int tz;

	tm = localtime(time(0));
	tz = (tm->tzoff/3600)*100 + ((tm->tzoff/60)%60);

	return Bprint(b, "Date: %s, %d %s %d %2.2d:%2.2d:%2.2d %s%.4d\n",
		ascwday[tm->wday], tm->mday, ascmon[tm->mon], 1900+tm->year,
		tm->hour, tm->min, tm->sec, tz>=0?"+":"", tz);
}

int
printfrom(Biobuf *b)
{
	return Bprint(b, "From: %s\n", user);
}

int
printto(Biobuf *b, Addr *a)
{
	int i;

	if(Bprint(b, "To: %s", a->v) < 0)
		return -1;
	i = 0;
	for(a = a->next; a != nil; a = a->next)
		if(Bprint(b, "%s%s", ((i++ & 7) == 7)?",\n\t":", ", a->v) < 0)
			return -1;
	if(Bprint(b, "\n") < 0)
		return -1;
	return 0;
}

int
printcc(Biobuf *b, Addr *a)
{
	int i;

	if(a == nil)
		return 0;
	if(Bprint(b, "CC: %s", a->v) < 0)
		return -1;
	i = 0;
	for(a = a->next; a != nil; a = a->next)
		if(Bprint(b, "%s%s", ((i++ & 7) == 7)?",\n\t":", ", a->v) < 0)
			return -1;
	if(Bprint(b, "\n") < 0)
		return -1;
	return 0;
}

int
printsubject(Biobuf *b, char *subject)
{
	return Bprint(b, "Subject: %U\n", subject);
}

int
printinreplyto(Biobuf *out, char *dir)
{
	String *s = s_copy(dir);
	char buf[256];
	int fd;
	int n;

	s_append(s, "/messageid");
	fd = open(s_to_c(s), OREAD);
	s_free(s);
	if(fd < 0)
		return 0;
	n = read(fd, buf, sizeof(buf)-1);
	close(fd);
	if(n <= 0)
		return 0;
	buf[n] = 0;
	return Bprint(out, "In-Reply-To: %s\n", buf);
}

Attach*
mkattach(char *file, char *type, int ainline)
{
	Ctype *c;
	Attach *a;
	char ftype[64];
	char *p;
	int n, pfd[2];

	if(file == nil)
		return nil;
	if(access(file, 4) == -1){
		fprint(2, "%s: %s can't read file\n", argv0, file);
		return nil;
	}
	a = emalloc(sizeof(*a));
	a->path = file;
	a->next = nil;
	a->type = type;
	a->ainline = ainline;
	a->ctype = nil;
	if(type != nil){
		for(c = ctype; ; c++)
			if(strncmp(type, c->type, strlen(c->type)) == 0){
				a->ctype = c;
				break;
			}
		return a;
	}

	// pick a type depending on extension
	p = strchr(file, '.');
	if(p != nil)
		p++;

	// check the builtin extensions
	if(p != nil){
		for(c = ctype; c->ext != nil; c++)
			if(strcmp(p, c->ext) == 0){
				a->type = c->type;
				a->ctype = c;
				return a;
			}
	}

	// try the mime types file
	if(p != nil){
		if(mimetypes == nil)
			readmimetypes();
		for(c = mimetypes; c != nil && c->ext != nil; c++)
			if(strcmp(p, c->ext) == 0){
				a->type = c->type;
				a->ctype = c;
				return a;
			}
	}

	// run file to figure out the type
	a->type = "application/octet-stream";		// safest default
	if(pipe(pfd) < 0)
		return a;
	switch(fork()){
	case -1:
		break;
	case 0:
		close(pfd[1]);
		close(0);
		dup(pfd[0], 0);
		close(1);
		dup(pfd[0], 1);
		execl("/bin/file", "file", "-m", file, nil);
		exits(0);
	default:
		close(pfd[0]);
		n = read(pfd[1], ftype, sizeof(ftype));
		if(n > 0){
			ftype[n-1] = 0;
			a->type = estrdup(ftype);
		}
		close(pfd[1]);
		waitpid();
		break;
	}

	for(c = ctype; ; c++)
		if(strncmp(a->type, c->type, strlen(c->type)) == 0){
			a->ctype = c;
			break;
		}

	return a;
}

char*
mkboundary(void)
{
	char buf[32];
	int i;

	srand((time(0)<<16)|getpid());
	strcpy(buf, "upas-");
	for(i = 5; i < sizeof(buf)-1; i++)
		buf[i] = 'a' + nrand(26);
	buf[i] = 0;
	return estrdup(buf);
}

// copy types to two fd's
static void
tee(int in, int out1, int out2)
{
	char buf[8*1024];
	int n;

	for(;;){
		n = read(in, buf, sizeof(buf));
		if(n <= 0)
			break;
		if(write(out1, buf, n) < 0)
			break;
		if(write(out2, buf, n) < 0)
			break;
	}
}

// print the unix from line
int
printunixfrom(int fd)
{
	Tm *tm;
	int tz;

	tm = localtime(time(0));
	tz = (tm->tzoff/3600)*100 + ((tm->tzoff/60)%60);

	return fprint(fd, "From %s %s %s %d %2.2d:%2.2d:%2.2d %s%.4d %d\n",
		user,
		ascwday[tm->wday], ascmon[tm->mon], tm->mday,
		tm->hour, tm->min, tm->sec, tz>=0?"+":"", tz, 1900+tm->year);
}

char *specialfile[] =
{
	"pipeto",
	"pipefrom",
	"L.mbox",
	"forward",
	"names"
};

// return 1 if this is a special file
static int
special(String *s)
{
	char *p;
	int i;

	p = strrchr(s_to_c(s), '/');
	if(p == nil)
		p = s_to_c(s);
	else
		p++;
	for(i = 0; i < nelem(specialfile); i++)
		if(strcmp(p, specialfile[i]) == 0)
			return 1;
	return 0;
}

// open the folder using the recipients account name
static int
openfolder(char *rcvr)
{
	char *p;
	int c;
	String *file;
	Dir *d;
	int fd;
	int scarey;

	file = s_new();
	mboxpath("f", user, file, 0);

	// if $mail/f exists, store there, otherwise in $mail
	d = dirstat(s_to_c(file));
	if(d == nil || d->qid.type != QTDIR){
		scarey = 1;
		file->ptr -= 1;
	} else {
		s_putc(file, '/');
		scarey = 0;
	}
	free(d);

	p = strrchr(rcvr, '!');
	if(p != nil)
		rcvr = p+1;

	while(*rcvr && *rcvr != '@'){
		c = *rcvr++;
		if(c == '/')
			c = '_';
		s_putc(file, c);
	}
	s_terminate(file);

	if(scarey && special(file)){
		fprint(2, "%s: won't overwrite %s\n", argv0, s_to_c(file));
		s_free(file);
		return -1;
	}

	fd = open(s_to_c(file), OWRITE);
	if(fd < 0)
		fd = create(s_to_c(file), OWRITE, 0660);

	s_free(file);
	return fd;
}

// start up sendmail and return an fd to talk to it with
int
sendmail(Addr *to, Addr *cc, int *pid, char *rcvr)
{
	char **av, **v;
	int ac, fd;
	int pfd[2];
	String *cmd;
	Addr *a;

	fd = -1;
	if(rcvr != nil)
		fd = openfolder(rcvr);

	ac = 0;
	for(a = to; a != nil; a = a->next)
		ac++;
	for(a = cc; a != nil; a = a->next)
		ac++;
	v = av = emalloc(sizeof(char*)*(ac+20));
	ac = 0;
	v[ac++] = "sendmail";
	if(xflag)
		v[ac++] = "-x";
	if(rflag)
		v[ac++] = "-r";
	if(lbflag)
		v[ac++] = "-#";
	if(dflag)
		v[ac++] = "-d";
	for(a = to; a != nil; a = a->next)
		v[ac++] = a->v;
	for(a = cc; a != nil; a = a->next)
		v[ac++] = a->v;
	v[ac] = 0;

	if(pipe(pfd) < 0)
		fatal("%r");
	switch(*pid = rfork(RFFDG|RFREND|RFPROC|RFENVG)){
	case -1:
		fatal("%r");
		break;
	case 0:
		if(holding)
			close(holding);
		close(pfd[1]);
		dup(pfd[0], 0);
		close(pfd[0]);

		if(rcvr != nil){
			if(pipe(pfd) < 0)
				fatal("%r");
			switch(fork()){
			case -1:
				fatal("%r");
				break;
			case 0:
				close(pfd[0]);
				seek(fd, 0, 2);
				printunixfrom(fd);
				tee(0, pfd[1], fd);
				write(fd, "\n", 1);
				exits(0);
			default:
				close(fd);
				close(pfd[1]);
				dup(pfd[0], 0);
				break;
			}
		}

		if(replymsg != nil)
			putenv("replymsg", replymsg);

		cmd = mboxpath("pipefrom", login, s_new(), 0);
		exec(s_to_c(cmd), av);
		exec("/bin/myupassend", av);
		exec("/bin/upas/send", av);
		fatal("execing: %r");
		break;
	default:
		if(rcvr != nil)
			close(fd);
		close(pfd[0]);
		break;
	}
	return pfd[1];
}

// start up pgp process and return an fd to talk to it with.
// its standard output will be the original fd, which goes to sendmail.
int
pgpfilter(int *pid, int fd, int pgpflag)
{
	char **av, **v;
	int ac;
	int pfd[2];

	v = av = emalloc(sizeof(char*)*8);
	ac = 0;
	v[ac++] = "pgp";
	v[ac++] = "-fat";		/* operate as a filter, generate text */
	if(pgpflag & PGPsign)
		v[ac++] = "-s";
	if(pgpflag & PGPencrypt)
		v[ac++] = "-e";
	v[ac] = 0;

	if(pipe(pfd) < 0)
		fatal("%r");
	switch(*pid = fork()){
	case -1:
		fatal("%r");
		break;
	case 0:
		close(pfd[1]);
		dup(pfd[0], 0);
		close(pfd[0]);
		dup(fd, 1);
		close(fd);

		/* add newline to avoid confusing pgp output with 822 headers */
		write(1, "\n", 1);
		exec("/bin/pgp", av);
		fatal("execing: %r");
		break;
	default:
		close(pfd[0]);
		break;
	}
	close(fd);
	return pfd[1];
}

// wait for sendmail and pgp to exit; exit here if either failed
char*
waitforsubprocs(void)
{
	Waitmsg *w;
	char *err;

	err = nil;
	while((w = wait()) != nil){
		if(w->pid == pid || w->pid == pgppid){
			if(w->msg[0] != 0)
				err = estrdup(w->msg);
		}
		free(w);
	}
	if(err)
		exits(err);
	return nil;
}

int
cistrncmp(char *a, char *b, int n)
{
	while(n-- > 0){
		if(tolower(*a++) != tolower(*b++))
			return -1;
	}
	return 0;
}

int
cistrcmp(char *a, char *b)
{
	for(;;){
		if(tolower(*a) != tolower(*b++))
			return -1;
		if(*a++ == 0)
			break;
	}
	return 0;
}

static uchar t64d[256];
static char t64e[64];

static void
init64(void)
{
	int c, i;

	memset(t64d, 255, 256);
	memset(t64e, '=', 64);
	i = 0;
	for(c = 'A'; c <= 'Z'; c++){
		t64e[i] = c;
		t64d[c] = i++;
	}
	for(c = 'a'; c <= 'z'; c++){
		t64e[i] = c;
		t64d[c] = i++;
	}
	for(c = '0'; c <= '9'; c++){
		t64e[i] = c;
		t64d[c] = i++;
	}
	t64e[i] = '+';
	t64d['+'] = i++;
	t64e[i] = '/';
	t64d['/'] = i;
}

int
enc64(char *out, int lim, uchar *in, int n)
{
	int i;
	ulong b24;
	char *start = out;
	char *e = out + lim;

	if(t64e[0] == 0)
		init64();
	for(i = 0; i < n/3; i++){
		b24 = (*in++)<<16;
		b24 |= (*in++)<<8;
		b24 |= *in++;
		if(out + 5 >= e)
			goto exhausted;
		*out++ = t64e[(b24>>18)];
		*out++ = t64e[(b24>>12)&0x3f];
		*out++ = t64e[(b24>>6)&0x3f];
		*out++ = t64e[(b24)&0x3f];
		if((i%18) == 17)
			*out++ = '\n';
	}

	switch(n%3){
	case 2:
		b24 = (*in++)<<16;
		b24 |= (*in)<<8;
		if(out + 4 >= e)
			goto exhausted;
		*out++ = t64e[(b24>>18)];
		*out++ = t64e[(b24>>12)&0x3f];
		*out++ = t64e[(b24>>6)&0x3f];
		break;
	case 1:
		b24 = (*in)<<16;