this allows 2047-encoded atoms sepearted by only whitespace to be pasted together,
as the rfc requires.

the usage string was corrected and upas/fs will now complain about extra arguments.

i'm including the test examples from rfc-2047 as rfc2047-test

Notes:
Sat Apr 1 22:03:12 EST 2006 rsc
    thanks.  i put the test file in the distribution too.
    


Reference: /n/sources/patch/applied/upas-2047
Date: Sun Apr  2 04:55:06 CES 2006
Signed-off-by: quanstro@quanstro.net
Reviewed-by: rsc

--- /sys/src/cmd/upas/fs/fs.c	Sun Apr  2 04:50:52 2006
+++ /sys/src/cmd/upas/fs/fs.c	Sun Apr  2 04:50:31 2006
@@ -2,6 +2,7 @@
 #include <auth.h>
 #include <fcall.h>
 #include <libsec.h>
+#include <ctype.h>
 #include "dat.h"
 
 enum
@@ -139,7 +140,7 @@
 void
 usage(void)
 {
-	fprint(2, "usage: %s [-b -m mountpoint]\n", argv0);
+	fprint(2, "usage: upas/fs [-bdlnps] [-f mboxfile] [-m mountpoint]\n");
 	exits("usage");
 }
 
@@ -176,10 +177,10 @@
 		break;
 	case 'f':
 		fflag = 1;
-		mboxfile = ARGF();
+		mboxfile = EARGF(usage());
 		break;
 	case 'm':
-		mntpt = ARGF();
+		mntpt = EARGF(usage());
 		break;
 	case 'd':
 		debug = 1;
@@ -200,6 +201,8 @@
 		usage();
 	}ARGEND
 
+	if(argc)
+		usage();
 	if(pipe(p) < 0)
 		error("pipe failed");
 	mfd[0] = p[0];
@@ -1432,21 +1435,20 @@
 String*
 stringconvert(String *s, char *uneaten, int len)
 {
-	char *token;
-	char *p;
-	int i;
+	char *token, *p, *e;
 
 	s = s_reset(s);
 	p = uneaten;
-	for(i = 0; i < len; i++){
-		if(*p++ == '='){
-			token = rfc2047start(uneaten, p);
-			if(token != nil){
-				s_nappend(s, uneaten, token-uneaten);
-				if(rfc2047convert(s, token, p - token) < 0)
-					s_nappend(s, token, p - token);
-				uneaten = p;
-			}
+	for(e = p+len; p < e; ){
+		while(*p++ == '=' && (token = rfc2047start(uneaten, p))){
+			s_nappend(s, uneaten, token-uneaten);
+			if(rfc2047convert(s, token, p - token) < 0)
+				s_nappend(s, token, p - token);
+			uneaten = p;
+			for(; p<e && isspace(*p);)
+				p++;
+			if(p+2 < e && p[0] == '=' && p[1] == '?')
+				uneaten = p;	// paste
 		}
 	}
 	if(p > uneaten)