From: Rich Felker <dalias@aerifal.cx>
To: musl@lists.openwall.com
Subject: Re: scanf %x bug
Date: Tue, 13 Mar 2012 12:24:27 -0400 [thread overview]
Message-ID: <20120313162427.GT184@brightrain.aerifal.cx> (raw)
In-Reply-To: <20120313135118.GD5728@port70.net>
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On Tue, Mar 13, 2012 at 02:51:18PM +0100, Szabolcs Nagy wrote:
> i found a scanf bug:
>
> #include <stdio.h>
> int main(){
> int n, a=7;
> n = sscanf("0", "%x", &a);
> printf("%d %d\n", n, a);
> return 0;
> }
>
> prints 0 7
> instead of 1 0
Please tell me what you think of this patch. Note that m is the
"match" flag (m!=0 means "the sequence scanned so far is valid").
I wanted to just switch to the new __intparse code, but I feel like
it's appropriate to fix this bug first with a less invasive patch.
Rich
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diff --git a/src/stdio/__scanf.c b/src/stdio/__scanf.c
index 062327d..7c82cca 100644
--- a/src/stdio/__scanf.c
+++ b/src/stdio/__scanf.c
@@ -319,34 +319,29 @@ int __scanf(rctx_t *r, const wchar_t *fmt, va_list ap)
unread(r);
break;
}
+ m = 1;
if (((c=read(r))|0x20) != 'x') {
- if (t == 'i') {
- t = 'o';
- /* lone 0 is valid octal */
- if ((unsigned)(c-'0') >= 8) {
- m = 1;
- goto int_finish;
- }
- }
+ if (t == 'i') t = 'o';
unread(r);
break;
}
t = 'x';
+ m = 0;
}
}
switch (t) {
case 'd':
case 'u':
- for (m=0; isdigit(c=read(r)); m=1)
+ for (; isdigit(c=read(r)); m=1)
i = 10*i + c-'0';
goto int_finish;
case 'o':
- for (m=0; (unsigned)(c=read(r))-'0' < 8; m=1)
+ for (; (unsigned)(c=read(r))-'0' < 8; m=1)
i = (i<<3) + c-'0';
goto int_finish;
case 'x':
- for (m=0; ; m=1) {
+ for (; ; m=1) {
if (isdigit(c=read(r))) {
i = (i<<4) + c-'0';
} else if ((unsigned)(c|0x20)-'a' < 6) {
next prev parent reply other threads:[~2012-03-13 16:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 13:51 Szabolcs Nagy
2012-03-13 15:05 ` Rich Felker
2012-03-13 16:24 ` Rich Felker [this message]
2012-03-13 16:32 ` Szabolcs Nagy
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