From: Ori Bernstein <ori@eigenstate.org>
Date: Sat, 9 May 2020 22:10:39 +0000 (-0700)
Subject: fix '%[]' specifiers and '%n' (thanks phil9)
X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=bfc8cdfff5aba1da7ddef1c2ef7e1167f8dd2e8d;p=plan9front.git

fix '%[]' specifiers and '%n' (thanks phil9)

When a match() fails, we need to unget the character we
tried to match against, rather than leaving it consumed.

Also, we can't break out of a conversion before we reach
the end of a format string, because things like the '%n'
conversion do not consume anything, and should still be
handled.
---

diff --git a/sys/src/ape/lib/ap/stdio/vfscanf.c b/sys/src/ape/lib/ap/stdio/vfscanf.c
index c44bd7576..95c14b7b2 100644
--- a/sys/src/ape/lib/ap/stdio/vfscanf.c
+++ b/sys/src/ape/lib/ap/stdio/vfscanf.c
@@ -72,7 +72,6 @@ int vfscanf(FILE *f, const char *s, va_list args)
 			do
 				c=ngetc(f);
 			while(isspace(c));
-			if(c==EOF) return ncvt?ncvt:EOF;
 			nungetc(c, f);
 			break;
 		}
@@ -396,13 +395,14 @@ icvt_sq(FILE *f, va_list *args, int store, int width, int)
 			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;
diff --git a/sys/src/libstdio/vfscanf.c b/sys/src/libstdio/vfscanf.c
index d17dcf2c4..d811b7803 100644
--- a/sys/src/libstdio/vfscanf.c
+++ b/sys/src/libstdio/vfscanf.c
@@ -68,7 +68,6 @@ int vfscanf(FILE *f, const char *s, va_list args){
 			do
 				c=ngetc(f);
 			while(isspace(c));
-			if(c==EOF) return ncvt?ncvt:EOF;
 			nungetc(c, f);
 			break;
 		}
@@ -353,11 +352,13 @@ static int icvt_sq(FILE *f, va_list *args, int store, int width, int type){
 			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;