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To: 9front@9front.org
Subject: Re: [9front] [Bug] [PATCH] Mail cannot cope with multi-line header fields
Date: Sat, 12 Sep 2020 23:19:48 +0200
From: theinicke@bss-wf.de
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X-Bullshit: browser-aware blockchain interface markup realtime-java locator 

Sorry for the noise.
But if the solution of removing line breaks from all fields in just the info file (and not taking into account that by design some info fields never contain line breaks) is considered, please regard the following patch instead; as the former contained useless code.

--
Tobias Heinicke

diff -r 9f6e77258f69 sys/src/cmd/upas/fs/fs.c
--- a/sys/src/cmd/upas/fs/fs.c	Thu Sep 10 16:26:42 2020 -0700
+++ b/sys/src/cmd/upas/fs/fs.c	Sat Sep 12 23:09:31 2020 +0200
@@ -387,6 +387,26 @@
 	return s;
 }
 
+int
+unfold(char *s, int len, char **pp)
+{
+	int i, u;
+	char c;
+	char *p;
+
+	p = malloc(len);
+	u = 0;
+	for(i = 0; i < len; i++) {
+		c = s[i];
+		if(c != '\n') {
+			p[u++] = c;
+		}
+	}
+
+	*pp = p;
+	return u;
+}
+
 static int
 fileinfo(Mailbox *mb, Message *m, int t, char **pp)
 {
@@ -568,7 +588,7 @@
 int
 readinfo(Mailbox *mb, Message *m, char *buf, long off, int count)
 {
-	char *s, *p, *e;
+	char *s, *p, *e, *q;
 	int i, n;
 	long off0;
 
@@ -584,18 +604,24 @@
 		}
 		if((n = fileinfo(mb, m, infofields[i], &p)) < 0)
 			return -1;
+
+		/* remove line breaks in fields s.t. consumers of info
+		can rely on finding particular field on certain line */
+		n = unfold(p, n, &q);
+
 		if(off > n){
 			off -= n + 1;
 			continue;
 		}
 		if(off){
 			n -= off;
-			p += off;
+			q += off;
 			off = 0;
 		}
 		if(s + n > e)
 			n = e - s;
-		memcpy(s, p, n);
+		memcpy(s, q, n);
+		free(q);
 		s += n;
 		if(s < e)
 			*s++ = '\n';