* scanf %x bug
@ 2012-03-13 13:51 Szabolcs Nagy
2012-03-13 15:05 ` Rich Felker
2012-03-13 16:24 ` Rich Felker
0 siblings, 2 replies; 4+ messages in thread
From: Szabolcs Nagy @ 2012-03-13 13:51 UTC (permalink / raw)
To: musl
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: scanf %x bug
2012-03-13 13:51 scanf %x bug Szabolcs Nagy
@ 2012-03-13 15:05 ` Rich Felker
2012-03-13 16:24 ` Rich Felker
1 sibling, 0 replies; 4+ messages in thread
From: Rich Felker @ 2012-03-13 15:05 UTC (permalink / raw)
To: musl
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
Bleh, musl's scanf is really bad but I don't feel like rewriting it...
Maybe I'll see if I can do that at the same time I replace the strtod
code (which scanf will need to use). In the mean time I'll see if
there's a fix for this specific issue. Have you found the corner case
that triggers it?
Rich
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: scanf %x bug
2012-03-13 13:51 scanf %x bug Szabolcs Nagy
2012-03-13 15:05 ` Rich Felker
@ 2012-03-13 16:24 ` Rich Felker
2012-03-13 16:32 ` Szabolcs Nagy
1 sibling, 1 reply; 4+ messages in thread
From: Rich Felker @ 2012-03-13 16:24 UTC (permalink / raw)
To: musl
[-- Attachment #1: Type: text/plain, Size: 532 bytes --]
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
[-- Attachment #2: scanf_fix.diff --]
[-- Type: text/plain, Size: 1051 bytes --]
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) {
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: scanf %x bug
2012-03-13 16:24 ` Rich Felker
@ 2012-03-13 16:32 ` Szabolcs Nagy
0 siblings, 0 replies; 4+ messages in thread
From: Szabolcs Nagy @ 2012-03-13 16:32 UTC (permalink / raw)
To: musl
* Rich Felker <dalias@aerifal.cx> [2012-03-13 12:24:27 -0400]:
> 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.
>
looks ok
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-03-13 16:32 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2012-03-13 13:51 scanf %x bug Szabolcs Nagy
2012-03-13 15:05 ` Rich Felker
2012-03-13 16:24 ` Rich Felker
2012-03-13 16:32 ` Szabolcs Nagy
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