* Re: memmem() - is it correct?
@ 2014-04-09 12:14 u-igbb
0 siblings, 0 replies; 6+ messages in thread
From: u-igbb @ 2014-04-09 12:14 UTC (permalink / raw)
To: musl
On Wed, Apr 09, 2014 at 01:19:03PM +0300, Timo Teras wrote:
> > const char *haystack = "abcde";
> > return(!memmem(haystack, 4, "cde", 3));
> > returns 1 (as I would expect it to) if linked against uclibc
> > returns 0 if linked against musl
> > (on ia32)
> musl looks correct to me. "abcde" is five bytes. You test for 4 bytes
I am testing for 3 bytes "cde" inside 4 bytes "abcd", this should not
be successful.
> so it's infact searching from haystack equivalent of "abcd".
Exactly. It does _not_ contain "cde". This should return NULL
from the memmem() and hence 1 from main().
> I'd say uclibc is off-by-one, and broken.
I guess you misinterpreted the test code, there is a '!' which transforms
a returned pointer (success) to 0 exit status in main() and vice versa.
Rune
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: memmem() - is it correct?
2014-04-09 12:54 ` Timo Teras
@ 2014-04-10 1:15 ` Rich Felker
0 siblings, 0 replies; 6+ messages in thread
From: Rich Felker @ 2014-04-10 1:15 UTC (permalink / raw)
To: musl; +Cc: u-igbb
On Wed, Apr 09, 2014 at 03:54:03PM +0300, Timo Teras wrote:
> On Wed, 9 Apr 2014 15:51:16 +0300
> Timo Teras <timo.teras@iki.fi> wrote:
>
> > On Wed, 9 Apr 2014 12:49:25 +0200
> > u-igbb@aetey.se wrote:
> >
> > > On Wed, Apr 09, 2014 at 01:19:03PM +0300, Timo Teras wrote:
> > > > > const char *haystack = "abcde";
> > > > > return(!memmem(haystack, 4, "cde", 3));
> > >
> > > > > returns 1 (as I would expect it to) if linked against uclibc
> > > > > returns 0 if linked against musl
> > > > > (on ia32)
> > >
> > > I guess you misinterpreted the test code, there is a '!' which
> > > transforms a returned pointer (success) to 0 exit status in main()
> > > and vice versa.
> >
> > Right. Should have read it more carefully. Yes, looks like musl bug.
> >
> > Perhaps something like the following is in place:
>
> Wrong patch version. Should be as simple as:
>
> diff --git a/src/string/memmem.c b/src/string/memmem.c
> index 5211d75..1173020 100644
> --- a/src/string/memmem.c
> +++ b/src/string/memmem.c
> @@ -139,6 +139,7 @@ void *memmem(const void *h0, size_t k, const void
> *n0, size_t l) /* Use faster algorithms for short needles */
> h = memchr(h0, *n, k);
> if (!h || l==1) return (void *)h;
> + k -= h - (const unsigned char*)h0;
> if (l==2) return twobyte_memmem(h, k, n);
> if (l==3) return threebyte_memmem(h, k, n);
> if (l==4) return fourbyte_memmem(h, k, n);
Thanks! Committed.
Rich
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: memmem() - is it correct?
2014-04-09 12:51 ` Timo Teras
@ 2014-04-09 12:54 ` Timo Teras
2014-04-10 1:15 ` Rich Felker
0 siblings, 1 reply; 6+ messages in thread
From: Timo Teras @ 2014-04-09 12:54 UTC (permalink / raw)
To: u-igbb; +Cc: musl
On Wed, 9 Apr 2014 15:51:16 +0300
Timo Teras <timo.teras@iki.fi> wrote:
> On Wed, 9 Apr 2014 12:49:25 +0200
> u-igbb@aetey.se wrote:
>
> > On Wed, Apr 09, 2014 at 01:19:03PM +0300, Timo Teras wrote:
> > > > const char *haystack = "abcde";
> > > > return(!memmem(haystack, 4, "cde", 3));
> >
> > > > returns 1 (as I would expect it to) if linked against uclibc
> > > > returns 0 if linked against musl
> > > > (on ia32)
> >
> > I guess you misinterpreted the test code, there is a '!' which
> > transforms a returned pointer (success) to 0 exit status in main()
> > and vice versa.
>
> Right. Should have read it more carefully. Yes, looks like musl bug.
>
> Perhaps something like the following is in place:
Wrong patch version. Should be as simple as:
diff --git a/src/string/memmem.c b/src/string/memmem.c
index 5211d75..1173020 100644
--- a/src/string/memmem.c
+++ b/src/string/memmem.c
@@ -139,6 +139,7 @@ void *memmem(const void *h0, size_t k, const void
*n0, size_t l) /* Use faster algorithms for short needles */
h = memchr(h0, *n, k);
if (!h || l==1) return (void *)h;
+ k -= h - (const unsigned char*)h0;
if (l==2) return twobyte_memmem(h, k, n);
if (l==3) return threebyte_memmem(h, k, n);
if (l==4) return fourbyte_memmem(h, k, n);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: memmem() - is it correct?
[not found] ` <20140409104925.GE21662@example.net>
@ 2014-04-09 12:51 ` Timo Teras
2014-04-09 12:54 ` Timo Teras
0 siblings, 1 reply; 6+ messages in thread
From: Timo Teras @ 2014-04-09 12:51 UTC (permalink / raw)
To: u-igbb; +Cc: musl
On Wed, 9 Apr 2014 12:49:25 +0200
u-igbb@aetey.se wrote:
> On Wed, Apr 09, 2014 at 01:19:03PM +0300, Timo Teras wrote:
> > > const char *haystack = "abcde";
> > > return(!memmem(haystack, 4, "cde", 3));
>
> > > returns 1 (as I would expect it to) if linked against uclibc
> > > returns 0 if linked against musl
> > > (on ia32)
>
> I guess you misinterpreted the test code, there is a '!' which
> transforms a returned pointer (success) to 0 exit status in main()
> and vice versa.
Right. Should have read it more carefully. Yes, looks like musl bug.
Perhaps something like the following is in place:
diff --git a/src/string/memmem.c b/src/string/memmem.c
index 5211d75..0594fea 100644
--- a/src/string/memmem.c
+++ b/src/string/memmem.c
@@ -138,7 +138,9 @@ void *memmem(const void *h0, size_t k, const void
*n0, size_t l)
/* Use faster algorithms for short needles */
h = memchr(h0, *n, k);
- if (!h || l==1) return (void *)h;
+ if (!h) return 0;
+ if (l==1) return (void *)h;
+ k -= h - h0;
if (l==2) return twobyte_memmem(h, k, n);
if (l==3) return threebyte_memmem(h, k, n);
if (l==4) return fourbyte_memmem(h, k, n);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: memmem() - is it correct?
2014-04-09 10:08 u-igbb
@ 2014-04-09 10:19 ` Timo Teras
[not found] ` <20140409104925.GE21662@example.net>
0 siblings, 1 reply; 6+ messages in thread
From: Timo Teras @ 2014-04-09 10:19 UTC (permalink / raw)
To: musl; +Cc: u-igbb
On Wed, 9 Apr 2014 12:08:40 +0200
u-igbb@aetey.se wrote:
> A test case adapted from elsewhere:
> ----
> #include <string.h>
>
> main(){
> const char *haystack = "abcde";
> return(!memmem(haystack, 4, "cde", 3));
> }
> ----
>
> returns 1 (as I would expect it to) if linked against uclibc
> returns 0 if linked against musl
> (on ia32)
>
> Any comments?
musl looks correct to me. "abcde" is five bytes. You test for 4 bytes
so it's infact searching from haystack equivalent of "abcd".
I'd say uclibc is off-by-one, and broken.
- Timo
^ permalink raw reply [flat|nested] 6+ messages in thread
* memmem() - is it correct?
@ 2014-04-09 10:08 u-igbb
2014-04-09 10:19 ` Timo Teras
0 siblings, 1 reply; 6+ messages in thread
From: u-igbb @ 2014-04-09 10:08 UTC (permalink / raw)
To: musl
A test case adapted from elsewhere:
----
#include <string.h>
main(){
const char *haystack = "abcde";
return(!memmem(haystack, 4, "cde", 3));
}
----
returns 1 (as I would expect it to) if linked against uclibc
returns 0 if linked against musl
(on ia32)
Any comments?
Rune
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-04-10 1:15 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2014-04-09 12:14 memmem() - is it correct? u-igbb
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2014-04-09 10:08 u-igbb
2014-04-09 10:19 ` Timo Teras
[not found] ` <20140409104925.GE21662@example.net>
2014-04-09 12:51 ` Timo Teras
2014-04-09 12:54 ` Timo Teras
2014-04-10 1:15 ` Rich Felker
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