* [PATCH] kconfig: Fix checking return value of 'fwrite'
@ 2011-10-06 11:14 Reinhard Tartler
2011-10-07 2:34 ` Cong Wang
2011-10-07 3:29 ` Arnaud Lacombe
0 siblings, 2 replies; 10+ messages in thread
From: Reinhard Tartler @ 2011-10-06 11:14 UTC (permalink / raw)
To: linux-kbuild; +Cc: Jean Sacren, Michal Marek, linux-kernel, vamos-dev
fwrite indicates '1' written member if a zero-length string is written.
---
scripts/kconfig/lkc.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
index b633bdb..727d265 100644
--- a/scripts/kconfig/lkc.h
+++ b/scripts/kconfig/lkc.h
@@ -90,7 +90,7 @@ struct conf_printer {
/* confdata.c and expr.c */
static inline void xfwrite(const void *str, size_t len, size_t count, FILE *out)
{
- if (fwrite(str, len, count, out) < count)
+ if (len > 0 && fwrite(str, len, count, out) < count)
fprintf(stderr, "\nError in writing or end of file.\n");
}
--
1.7.0.4
--
Reinhard Tartler Department of Computer Science IV
Martensstr 1, 91058 Erlangen Germany, University of Erlangen-Nuremberg
http://www4.informatik.uni-erlangen.de/~tartler
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-10-06 11:14 [PATCH] kconfig: Fix checking return value of 'fwrite' Reinhard Tartler
@ 2011-10-07 2:34 ` Cong Wang
2011-10-07 3:29 ` Arnaud Lacombe
1 sibling, 0 replies; 10+ messages in thread
From: Cong Wang @ 2011-10-07 2:34 UTC (permalink / raw)
To: Reinhard Tartler
Cc: linux-kbuild, Jean Sacren, Michal Marek, linux-kernel, vamos-dev
于 2011年10月06日 19:14, Reinhard Tartler 写道:
> fwrite indicates '1' written member if a zero-length string is written.
For completeness, xfwrite() is called like this,
xfwrite(str, strlen(str), 1, data);
so if strlen() returns 0, xfwrite() will print out the error message,
which is wrong, no error in this case.
Acked-by: WANG Cong <amwang@redhat.com>
Thanks!
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-10-06 11:14 [PATCH] kconfig: Fix checking return value of 'fwrite' Reinhard Tartler
2011-10-07 2:34 ` Cong Wang
@ 2011-10-07 3:29 ` Arnaud Lacombe
2011-11-20 13:24 ` Michal Marek
1 sibling, 1 reply; 10+ messages in thread
From: Arnaud Lacombe @ 2011-10-07 3:29 UTC (permalink / raw)
To: Reinhard Tartler
Cc: linux-kbuild, Jean Sacren, Michal Marek, linux-kernel, vamos-dev
Hi,
2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
> fwrite indicates '1' written member if a zero-length string is written.
you forgot the "Signed-off-by: " part :)
- Arnaud
> ---
> scripts/kconfig/lkc.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
> index b633bdb..727d265 100644
> --- a/scripts/kconfig/lkc.h
> +++ b/scripts/kconfig/lkc.h
> @@ -90,7 +90,7 @@ struct conf_printer {
> /* confdata.c and expr.c */
> static inline void xfwrite(const void *str, size_t len, size_t count, FILE *out)
> {
> - if (fwrite(str, len, count, out) < count)
> + if (len > 0 && fwrite(str, len, count, out) < count)
> fprintf(stderr, "\nError in writing or end of file.\n");
> }
>
> --
> 1.7.0.4
>
> --
> Reinhard Tartler Department of Computer Science IV
> Martensstr 1, 91058 Erlangen Germany, University of Erlangen-Nuremberg
> http://www4.informatik.uni-erlangen.de/~tartler
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-10-07 3:29 ` Arnaud Lacombe
@ 2011-11-20 13:24 ` Michal Marek
2011-11-20 15:53 ` Reinhard Tartler
2011-11-23 5:53 ` Jean Sacren
0 siblings, 2 replies; 10+ messages in thread
From: Michal Marek @ 2011-11-20 13:24 UTC (permalink / raw)
To: Reinhard Tartler
Cc: Arnaud Lacombe, linux-kbuild, Jean Sacren, linux-kernel, vamos-dev
On 7.10.2011 05:29, Arnaud Lacombe wrote:
> Hi,
>
> 2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
>> fwrite indicates '1' written member if a zero-length string is written.
> you forgot the "Signed-off-by: " part :)
Reinhard, can I assume
Signed-off-by: Reinhard Tartler
<Reinhard.Tartler@informatik.uni-erlangen.de>
? The patch is otherwise correct.
Michal
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-11-20 13:24 ` Michal Marek
@ 2011-11-20 15:53 ` Reinhard Tartler
2011-11-23 5:53 ` Jean Sacren
1 sibling, 0 replies; 10+ messages in thread
From: Reinhard Tartler @ 2011-11-20 15:53 UTC (permalink / raw)
To: Michal Marek
Cc: Arnaud Lacombe, linux-kbuild, Jean Sacren, linux-kernel, vamos-dev
On So, Nov 20, 2011 at 14:24:35 (CET), Michal Marek wrote:
> On 7.10.2011 05:29, Arnaud Lacombe wrote:
>> Hi,
>>
>> 2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
>>> fwrite indicates '1' written member if a zero-length string is written.
>> you forgot the "Signed-off-by: " part :)
>
> Reinhard, can I assume
>
> Signed-off-by: Reinhard Tartler
> <Reinhard.Tartler@informatik.uni-erlangen.de>
>
> ? The patch is otherwise correct.
I merely forgot to add that part. I fully agree with the (legal)
implications.
Cheers,
Reinhard,
--
Reinhard Tartler Department of Computer Science IV
Martensstr 1, 91058 Erlangen Germany, University of Erlangen-Nuremberg
http://www4.informatik.uni-erlangen.de/~tartler
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-11-20 13:24 ` Michal Marek
2011-11-20 15:53 ` Reinhard Tartler
@ 2011-11-23 5:53 ` Jean Sacren
2011-11-23 6:30 ` Reinhard Tartler
1 sibling, 1 reply; 10+ messages in thread
From: Jean Sacren @ 2011-11-23 5:53 UTC (permalink / raw)
To: Michal Marek
Cc: Reinhard Tartler, Arnaud Lacombe, linux-kbuild, linux-kernel,
vamos-dev, amwang, sakiwit
From: Michal Marek <mmarek@suse.cz>
Date: Sun, 20 Nov 2011 14:24:35 +0100
>
> On 7.10.2011 05:29, Arnaud Lacombe wrote:
> > Hi,
> >
> > 2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
> >> fwrite indicates '1' written member if a zero-length string is written.
> > you forgot the "Signed-off-by: " part :)
>
> Reinhard, can I assume
>
> Signed-off-by: Reinhard Tartler
> <Reinhard.Tartler@informatik.uni-erlangen.de>
>
> ? The patch is otherwise correct.
I have two reasons to oppose this patch.
1. If 'len' value is zero, there is an issue already and it should be
taken care of _before_ calling fwrite().
2. xfwrite() doesn't fix anything except for the compiler warning. It
assumes this world is perfect and it's definitely not a place to take
care of the zero-length string.
--
Jean Sacren
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-11-23 5:53 ` Jean Sacren
@ 2011-11-23 6:30 ` Reinhard Tartler
2011-11-23 18:05 ` Arnaud Lacombe
0 siblings, 1 reply; 10+ messages in thread
From: Reinhard Tartler @ 2011-11-23 6:30 UTC (permalink / raw)
To: Jean Sacren
Cc: Michal Marek, Arnaud Lacombe, linux-kbuild, linux-kernel,
vamos-dev, amwang
On Mi, Nov 23, 2011 at 06:53:51 (CET), Jean Sacren wrote:
> From: Michal Marek <mmarek@suse.cz>
> Date: Sun, 20 Nov 2011 14:24:35 +0100
>>
>> On 7.10.2011 05:29, Arnaud Lacombe wrote:
>> > Hi,
>> >
>> > 2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
>> >> fwrite indicates '1' written member if a zero-length string is written.
>> > you forgot the "Signed-off-by: " part :)
>>
>> Reinhard, can I assume
>>
>> Signed-off-by: Reinhard Tartler
>> <Reinhard.Tartler@informatik.uni-erlangen.de>
>>
>> ? The patch is otherwise correct.
>
> I have two reasons to oppose this patch.
>
> 1. If 'len' value is zero, there is an issue already and it should be
> taken care of _before_ calling fwrite().
So you're saying the function assumes a non-empty string? Why? It is a
simple "writing-helper" and this seems a perfectly valid corner case to
me. Can you perhaps elaborate why you consider this corner case invalid
and require (possibly out-of-tree) callers to check this for themselves?
> 2. xfwrite() doesn't fix anything except for the compiler warning. It
> assumes this world is perfect and it's definitely not a place to take
> care of the zero-length string.
It seems to me that you rather oppose to the introduction of xfwrite()
than to the patch here at hand. Is that correct?
Cheers,
Reinhard
--
Reinhard Tartler Department of Computer Science IV
Martensstr 1, 91058 Erlangen Germany, University of Erlangen-Nuremberg
http://www4.informatik.uni-erlangen.de/~tartler
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH] kconfig: Fix checking return value of 'fwrite'
2011-11-23 6:30 ` Reinhard Tartler
@ 2011-11-23 18:05 ` Arnaud Lacombe
2011-11-25 23:42 ` [PATCH] kbuild: Fix compiler warning with assertion when calling 'fwrite' Jean Sacren
0 siblings, 1 reply; 10+ messages in thread
From: Arnaud Lacombe @ 2011-11-23 18:05 UTC (permalink / raw)
To: Reinhard Tartler
Cc: Jean Sacren, Michal Marek, linux-kbuild, linux-kernel, vamos-dev, amwang
Hi,
2011/11/23 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
> On Mi, Nov 23, 2011 at 06:53:51 (CET), Jean Sacren wrote:
>
>> From: Michal Marek <mmarek@suse.cz>
>> Date: Sun, 20 Nov 2011 14:24:35 +0100
>>>
>>> On 7.10.2011 05:29, Arnaud Lacombe wrote:
>>> > Hi,
>>> >
>>> > 2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
>>> >> fwrite indicates '1' written member if a zero-length string is written.
>>> > you forgot the "Signed-off-by: " part :)
>>>
>>> Reinhard, can I assume
>>>
>>> Signed-off-by: Reinhard Tartler
>>> <Reinhard.Tartler@informatik.uni-erlangen.de>
>>>
>>> ? The patch is otherwise correct.
>>
>> I have two reasons to oppose this patch.
>>
>> 1. If 'len' value is zero, there is an issue already and it should be
>> taken care of _before_ calling fwrite().
>
> So you're saying the function assumes a non-empty string? Why?
AFAIK, fwrite(3) is currently used:
1) in comment printers. Empty comment are not allowed.
2) in a callback passed to expr_print(), where the string printed is
non-empty[0]
2) in the lexer, auto-generated, and unused
So Jean's point is valid, but for this comment to be pedantic, I would
not weakly test for `len > 0', but enforce assumptions above with an
assertion, by both converting the existing direct call to xfwrite()
and add `assert(len > 0)' before calling fwrite(3).
- Arnaud
[0]: symbol's name is either NULL or a non-empty string.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH] kbuild: Fix compiler warning with assertion when calling 'fwrite'
2011-11-23 18:05 ` Arnaud Lacombe
@ 2011-11-25 23:42 ` Jean Sacren
2012-01-14 23:19 ` Michal Marek
0 siblings, 1 reply; 10+ messages in thread
From: Jean Sacren @ 2011-11-25 23:42 UTC (permalink / raw)
To: Arnaud Lacombe
Cc: Reinhard Tartler, Michal Marek, linux-kbuild, linux-kernel,
amwang, sakiwit
From: Arnaud Lacombe <lacombar@gmail.com>
Date: Wed, 23 Nov 2011 13:05:53 -0500
>
> Hi,
>
> 2011/11/23 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
> > On Mi, Nov 23, 2011 at 06:53:51 (CET), Jean Sacren wrote:
> >
> >> From: Michal Marek <mmarek@suse.cz>
> >> Date: Sun, 20 Nov 2011 14:24:35 +0100
> >>>
> >>> On 7.10.2011 05:29, Arnaud Lacombe wrote:
> >>> > Hi,
> >>> >
> >>> > 2011/10/6 Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>:
> >>> >> fwrite indicates '1' written member if a zero-length string is written.
> >>> > you forgot the "Signed-off-by: " part :)
> >>>
> >>> Reinhard, can I assume
> >>>
> >>> Signed-off-by: Reinhard Tartler
> >>> <Reinhard.Tartler@informatik.uni-erlangen.de>
> >>>
> >>> ? The patch is otherwise correct.
> >>
> >> I have two reasons to oppose this patch.
> >>
> >> 1. If 'len' value is zero, there is an issue already and it should be
> >> taken care of _before_ calling fwrite().
> >
> > So you're saying the function assumes a non-empty string? Why?
> AFAIK, fwrite(3) is currently used:
> 1) in comment printers. Empty comment are not allowed.
> 2) in a callback passed to expr_print(), where the string printed is
> non-empty[0]
> 2) in the lexer, auto-generated, and unused
>
> So Jean's point is valid, but for this comment to be pedantic, I would
> not weakly test for `len > 0', but enforce assumptions above with an
> assertion, by both converting the existing direct call to xfwrite()
> and add `assert(len > 0)' before calling fwrite(3).
I prepared a patch to take care of this corner case. Review is
appreciated. Thanks.
--
Jean Sacren
-->8
[PATCH] kbuild: Fix compiler warning with assertion when calling 'fwrite'
Reinhard Tartler discovered a corner case of calling xfwrite() where the
length of the string is zero.
Arnaud Lacombe suggested to use assertion for the corner case, as
fwrite(3) is currently used:
1) in comment printers. Empty comment are not allowed.
2) in a callback passed to expr_print(), where the string printed is
either NULL OR non-empty.
3) in the lexer, auto-generated, and unused.
I feel using assertion is a good solution:
1) It cleanly takes care of the above-mentioned corner case.
2) It can be easily disabled by defining NDEBUG.
3) It asserts xfwrite() is simply a wrapper for fwrite().
Reported-by: Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
---
scripts/kconfig/expr.h | 1 +
scripts/kconfig/lkc.h | 6 ++++--
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 80fce57..d4ecce8 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -10,6 +10,7 @@
extern "C" {
#endif
+#include <assert.h>
#include <stdio.h>
#ifndef __cplusplus
#include <stdbool.h>
diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
index b633bdb..c18f2bd 100644
--- a/scripts/kconfig/lkc.h
+++ b/scripts/kconfig/lkc.h
@@ -90,8 +90,10 @@ struct conf_printer {
/* confdata.c and expr.c */
static inline void xfwrite(const void *str, size_t len, size_t count, FILE *out)
{
- if (fwrite(str, len, count, out) < count)
- fprintf(stderr, "\nError in writing or end of file.\n");
+ assert(len != 0);
+
+ if (fwrite(str, len, count, out) != count)
+ fprintf(stderr, "Error in writing or end of file.\n");
}
/* menu.c */
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH] kbuild: Fix compiler warning with assertion when calling 'fwrite'
2011-11-25 23:42 ` [PATCH] kbuild: Fix compiler warning with assertion when calling 'fwrite' Jean Sacren
@ 2012-01-14 23:19 ` Michal Marek
0 siblings, 0 replies; 10+ messages in thread
From: Michal Marek @ 2012-01-14 23:19 UTC (permalink / raw)
To: Jean Sacren
Cc: Arnaud Lacombe, Reinhard Tartler, linux-kbuild, linux-kernel, amwang
On Fri, Nov 25, 2011 at 04:42:53PM -0700, Jean Sacren wrote:
> Reinhard Tartler discovered a corner case of calling xfwrite() where the
> length of the string is zero.
>
> Arnaud Lacombe suggested to use assertion for the corner case, as
> fwrite(3) is currently used:
>
> 1) in comment printers. Empty comment are not allowed.
> 2) in a callback passed to expr_print(), where the string printed is
> either NULL OR non-empty.
> 3) in the lexer, auto-generated, and unused.
>
> I feel using assertion is a good solution:
>
> 1) It cleanly takes care of the above-mentioned corner case.
> 2) It can be easily disabled by defining NDEBUG.
> 3) It asserts xfwrite() is simply a wrapper for fwrite().
>
> Reported-by: Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>
> Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
> Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Applied to kbuild.git#kconfig.
Michal
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2012-01-14 23:19 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-10-06 11:14 [PATCH] kconfig: Fix checking return value of 'fwrite' Reinhard Tartler
2011-10-07 2:34 ` Cong Wang
2011-10-07 3:29 ` Arnaud Lacombe
2011-11-20 13:24 ` Michal Marek
2011-11-20 15:53 ` Reinhard Tartler
2011-11-23 5:53 ` Jean Sacren
2011-11-23 6:30 ` Reinhard Tartler
2011-11-23 18:05 ` Arnaud Lacombe
2011-11-25 23:42 ` [PATCH] kbuild: Fix compiler warning with assertion when calling 'fwrite' Jean Sacren
2012-01-14 23:19 ` Michal Marek
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