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From: telephil9@gmail.com
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Message-ID: <7BC56C4EE66212C553EFF6B020551A32@gmail.com>
Date: Thu, 7 May 2020 09:49:01 +0200
To: 9front@9front.org
Cc: telephil9@gmail.com
Subject: [PATCH] fix APE sscanf [ specifier
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X-Bullshit: virtual service API-scale descriptor 

Hi,

APE sscanf return value is wrong when using a [ specifier and there is no match.
The following code highlights the issue (full example: http://okturing.com/src/8478/body)
	char s[2];
	sscanf("H", " %1[Zz] ", s); // SHOULD NOT RETURN 1

This patch fixes the issue:
---

diff -r 8006152d13d2 sys/src/ape/lib/ap/stdio/vfscanf.c
--- a/sys/src/ape/lib/ap/stdio/vfscanf.c	Tue Apr 28 20:51:19 2020 -0700
+++ b/sys/src/ape/lib/ap/stdio/vfscanf.c	Thu May 07 09:44:39 2020 +0200
@@ -396,13 +396,14 @@
 			if(nn==0) return 0;
 			else goto Done;
 		}
-		if(!match(c, pat))
-			break;
+		if(!match(c, pat)){
+			nungetc(c, f);
+			return 0;
+		}
 		if(store)
 			*s++=c;
 		nn++;
 	}
-	nungetc(c, f);
 Done:
 	if(store) *s='\0';
 	return 1;

---

Regards,
Philippe