* linux-user: keep the name-ending parenthesis in /proc/self/stat
@ 2020-03-30 19:07 Brice Goglin
2020-03-30 22:05 ` Philippe Mathieu-Daudé
0 siblings, 1 reply; 11+ messages in thread
From: Brice Goglin @ 2020-03-30 19:07 UTC (permalink / raw)
To: qemu-devel
[-- Attachment #1: Type: text/plain, Size: 1478 bytes --]
When the program name is very long, qemu-user may truncate it in
/proc/self/stat. However the truncation must keep the ending ") "
to conform to the proc manpage which says:
(2) comm %s
The filename of the executable, in parentheses. This
is visible whether or not the executable is swapped
out.
To reproduce:
$ ln -s /bin/cat <filenamewithmorethan128chars>
$ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
Before the patch, you get:
1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
After the patch:
1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
This fixes an issue with hwloc failing to parse /proc/self/stat
when Ludovic Courtes was testing it in guix over qemu-aarch64.
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5af55fca78..a1126dcf5b 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7305,7 +7305,10 @@ static int open_self_stat(void *cpu_env, int fd)
snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
} else if (i == 1) {
/* app name */
- snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ len = snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ if (len >= sizeof(buf))
+ /* bring back the ending ") " that was truncated */
+ strcpy(buf+sizeof(buf)-3, ") ");
} else if (i == 27) {
/* stack bottom */
val = start_stack;
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^ permalink raw reply related [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-03-30 19:07 linux-user: keep the name-ending parenthesis in /proc/self/stat Brice Goglin
@ 2020-03-30 22:05 ` Philippe Mathieu-Daudé
2020-03-30 22:29 ` Brice Goglin
0 siblings, 1 reply; 11+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-03-30 22:05 UTC (permalink / raw)
To: Brice Goglin, qemu-devel, Laurent Vivier
On 3/30/20 9:07 PM, Brice Goglin wrote:
> When the program name is very long, qemu-user may truncate it in
> /proc/self/stat. However the truncation must keep the ending ") "
> to conform to the proc manpage which says:
> (2) comm %s
> The filename of the executable, in parentheses. This
> is visible whether or not the executable is swapped
> out.
>
> To reproduce:
> $ ln -s /bin/cat <filenamewithmorethan128chars>
> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>
> Before the patch, you get:
> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
> After the patch:
> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>
> This fixes an issue with hwloc failing to parse /proc/self/stat
> when Ludovic Courtes was testing it in guix over qemu-aarch64.
>
> Signed-off-by: Brice Goglin<Brice.Goglin@inria.fr>
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 5af55fca78..a1126dcf5b 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -7305,7 +7305,10 @@ static int open_self_stat(void *cpu_env, int fd)
> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
> } else if (i == 1) {
> /* app name */
> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
> + len = snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
> + if (len >= sizeof(buf))
> + /* bring back the ending ") " that was truncated */
> + strcpy(buf+sizeof(buf)-3, ") ");
Maybe we can avoid the sprintf() call:
-- >8 --
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
} else if (i == 1) {
/* app name */
- snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ char *ptr = buf;
+
+ *ptr++ = '(';
+ ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
+ strcpy(ptr, ") ");
} else if (i == 27) {
/* stack bottom */
val = start_stack;
---
> } else if (i == 27) {
> /* stack bottom */
> val = start_stack;
>
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-03-30 22:05 ` Philippe Mathieu-Daudé
@ 2020-03-30 22:29 ` Brice Goglin
2020-04-08 6:40 ` Brice Goglin
0 siblings, 1 reply; 11+ messages in thread
From: Brice Goglin @ 2020-03-30 22:29 UTC (permalink / raw)
To: Philippe Mathieu-Daudé, qemu-devel, Laurent Vivier
Le 31/03/2020 à 00:05, Philippe Mathieu-Daudé a écrit :
> On 3/30/20 9:07 PM, Brice Goglin wrote:
>> When the program name is very long, qemu-user may truncate it in
>> /proc/self/stat. However the truncation must keep the ending ") "
>> to conform to the proc manpage which says:
>> (2) comm %s
>> The filename of the executable, in parentheses. This
>> is visible whether or not the executable is swapped
>> out.
>>
>> To reproduce:
>> $ ln -s /bin/cat <filenamewithmorethan128chars>
>> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>>
>> Before the patch, you get:
>> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
>> After the patch:
>> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>>
>> This fixes an issue with hwloc failing to parse /proc/self/stat
>> when Ludovic Courtes was testing it in guix over qemu-aarch64.
>>
>> Signed-off-by: Brice Goglin<Brice.Goglin@inria.fr>
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> index 5af55fca78..a1126dcf5b 100644
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -7305,7 +7305,10 @@ static int open_self_stat(void *cpu_env, int fd)
>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>> } else if (i == 1) {
>> /* app name */
>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>> + len = snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>> + if (len >= sizeof(buf))
>> + /* bring back the ending ") " that was truncated */
>> + strcpy(buf+sizeof(buf)-3, ") ");
>
> Maybe we can avoid the sprintf() call:
>
> -- >8 --
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
> } else if (i == 1) {
> /* app name */
> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
> + char *ptr = buf;
> +
> + *ptr++ = '(';
> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
> + strcpy(ptr, ") ");
> } else if (i == 27) {
> /* stack bottom */
> val = start_stack;
>
This works too.
Brice
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-03-30 22:29 ` Brice Goglin
@ 2020-04-08 6:40 ` Brice Goglin
2020-04-08 8:09 ` Laurent Vivier
0 siblings, 1 reply; 11+ messages in thread
From: Brice Goglin @ 2020-04-08 6:40 UTC (permalink / raw)
To: Philippe Mathieu-Daudé, qemu-devel, Laurent Vivier
Le 31/03/2020 à 00:29, Brice Goglin a écrit :
> Le 31/03/2020 à 00:05, Philippe Mathieu-Daudé a écrit :
>> On 3/30/20 9:07 PM, Brice Goglin wrote:
>>> When the program name is very long, qemu-user may truncate it in
>>> /proc/self/stat. However the truncation must keep the ending ") "
>>> to conform to the proc manpage which says:
>>> (2) comm %s
>>> The filename of the executable, in parentheses. This
>>> is visible whether or not the executable is swapped
>>> out.
>>>
>>> To reproduce:
>>> $ ln -s /bin/cat <filenamewithmorethan128chars>
>>> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>>>
>>> Before the patch, you get:
>>> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
>>> After the patch:
>>> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>>>
>>> This fixes an issue with hwloc failing to parse /proc/self/stat
>>> when Ludovic Courtes was testing it in guix over qemu-aarch64.
>>>
>>> Signed-off-by: Brice Goglin<Brice.Goglin@inria.fr>
>>>
>>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>>> index 5af55fca78..a1126dcf5b 100644
>>> --- a/linux-user/syscall.c
>>> +++ b/linux-user/syscall.c
>>> @@ -7305,7 +7305,10 @@ static int open_self_stat(void *cpu_env, int fd)
>>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>>> } else if (i == 1) {
>>> /* app name */
>>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>>> + len = snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>>> + if (len >= sizeof(buf))
>>> + /* bring back the ending ") " that was truncated */
>>> + strcpy(buf+sizeof(buf)-3, ") ");
>> Maybe we can avoid the sprintf() call:
>>
>> -- >8 --
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>> } else if (i == 1) {
>> /* app name */
>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>> + char *ptr = buf;
>> +
>> + *ptr++ = '(';
>> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
>> + strcpy(ptr, ") ");
>> } else if (i == 27) {
>> /* stack bottom */
>> val = start_stack;
>>
> This works too.
Hello
Is anybody going to fix this anyhow for the next release?
Thank you
Brice
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-04-08 6:40 ` Brice Goglin
@ 2020-04-08 8:09 ` Laurent Vivier
0 siblings, 0 replies; 11+ messages in thread
From: Laurent Vivier @ 2020-04-08 8:09 UTC (permalink / raw)
To: Brice Goglin, Philippe Mathieu-Daudé, qemu-devel
Le 08/04/2020 à 08:40, Brice Goglin a écrit :
> Le 31/03/2020 à 00:29, Brice Goglin a écrit :
>> Le 31/03/2020 à 00:05, Philippe Mathieu-Daudé a écrit :
>>> On 3/30/20 9:07 PM, Brice Goglin wrote:
>>>> When the program name is very long, qemu-user may truncate it in
>>>> /proc/self/stat. However the truncation must keep the ending ") "
>>>> to conform to the proc manpage which says:
>>>> (2) comm %s
>>>> The filename of the executable, in parentheses. This
>>>> is visible whether or not the executable is swapped
>>>> out.
>>>>
>>>> To reproduce:
>>>> $ ln -s /bin/cat <filenamewithmorethan128chars>
>>>> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>>>>
>>>> Before the patch, you get:
>>>> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
>>>> After the patch:
>>>> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>>>>
>>>> This fixes an issue with hwloc failing to parse /proc/self/stat
>>>> when Ludovic Courtes was testing it in guix over qemu-aarch64.
>>>>
>>>> Signed-off-by: Brice Goglin<Brice.Goglin@inria.fr>
>>>>
>>>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>>>> index 5af55fca78..a1126dcf5b 100644
>>>> --- a/linux-user/syscall.c
>>>> +++ b/linux-user/syscall.c
>>>> @@ -7305,7 +7305,10 @@ static int open_self_stat(void *cpu_env, int fd)
>>>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>>>> } else if (i == 1) {
>>>> /* app name */
>>>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>>>> + len = snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>>>> + if (len >= sizeof(buf))
>>>> + /* bring back the ending ") " that was truncated */
>>>> + strcpy(buf+sizeof(buf)-3, ") ");
>>> Maybe we can avoid the sprintf() call:
>>>
>>> -- >8 --
>>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>>> --- a/linux-user/syscall.c
>>> +++ b/linux-user/syscall.c
>>> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
>>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>>> } else if (i == 1) {
>>> /* app name */
>>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>>> + char *ptr = buf;
>>> +
>>> + *ptr++ = '(';
>>> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
>>> + strcpy(ptr, ") ");
>>> } else if (i == 27) {
>>> /* stack bottom */
>>> val = start_stack;
>>>
>> This works too.
>
>
> Hello
>
> Is anybody going to fix this anyhow for the next release?
Hi,
we are expecting you fix the patch according to Philippe's comment and
re-send it or explain why you don't want.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 11+ messages in thread
* linux-user: keep the name-ending parenthesis in /proc/self/stat
@ 2020-04-08 8:24 Brice Goglin
2020-04-08 15:48 ` Laurent Vivier
2020-04-09 15:27 ` Alex Bennée
0 siblings, 2 replies; 11+ messages in thread
From: Brice Goglin @ 2020-04-08 8:24 UTC (permalink / raw)
To: qemu-devel; +Cc: Philippe Mathieu-Daudé
[-- Attachment #1: Type: text/plain, Size: 1513 bytes --]
When the program name is very long, qemu-user may truncate it in
/proc/self/stat. However the truncation must keep the ending ") "
to conform to the proc manpage which says:
(2) comm %s
The filename of the executable, in parentheses. This
is visible whether or not the executable is swapped
out.
To reproduce:
$ ln -s /bin/cat <filenamewithmorethan128chars>
$ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
Before the patch, you get:
1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
After the patch:
1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
This fixes an issue with hwloc failing to parse /proc/self/stat
when Ludovic Courtes was testing it in Guix over qemu-aarch64.
Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
} else if (i == 1) {
/* app name */
- snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+ char *ptr = buf;
+
+ *ptr++ = '(';
+ ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
+ strcpy(ptr, ") ");
} else if (i == 27) {
/* stack bottom */
val = start_stack;
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^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-04-08 8:24 Brice Goglin
@ 2020-04-08 15:48 ` Laurent Vivier
2020-04-08 15:56 ` Brice Goglin
2020-04-09 15:27 ` Alex Bennée
1 sibling, 1 reply; 11+ messages in thread
From: Laurent Vivier @ 2020-04-08 15:48 UTC (permalink / raw)
To: Brice Goglin, qemu-devel; +Cc: Philippe Mathieu-Daudé
Le 08/04/2020 à 10:24, Brice Goglin a écrit :
> When the program name is very long, qemu-user may truncate it in
> /proc/self/stat. However the truncation must keep the ending ") "
> to conform to the proc manpage which says:
> (2) comm %s
> The filename of the executable, in parentheses. This
> is visible whether or not the executable is swapped
> out.
>
> To reproduce:
> $ ln -s /bin/cat <filenamewithmorethan128chars>
> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>
> Before the patch, you get:
> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
> After the patch:
> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>
> This fixes an issue with hwloc failing to parse /proc/self/stat
> when Ludovic Courtes was testing it in Guix over qemu-aarch64.
>
> Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
You can't add "Signed-off-by" of someone else, in this case you could
add "Suggested-by:".
The subject of your patch should include "[PATCH]" (and the version of
the patch, "[PATCH v2]").
https://wiki.qemu.org/Contribute/SubmitAPatch
> Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
> } else if (i == 1) {
> /* app name */
> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
> + char *ptr = buf;
> +
> + *ptr++ = '(';
> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
To have space for the NUL character I think it should be "sizeof(buf) - 4".
> + strcpy(ptr, ") ");
> } else if (i == 27) {
> /* stack bottom */
> val = start_stack;
>
Thanks,
Laurent
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-04-08 15:48 ` Laurent Vivier
@ 2020-04-08 15:56 ` Brice Goglin
0 siblings, 0 replies; 11+ messages in thread
From: Brice Goglin @ 2020-04-08 15:56 UTC (permalink / raw)
To: Laurent Vivier, qemu-devel; +Cc: Philippe Mathieu-Daudé
Please apply my first patch if you believe Philippe's patch is wrong. I
can't spend more time debugging this trivial issue unfortunately.
Brice
Le 08/04/2020 à 17:48, Laurent Vivier a écrit :
> Le 08/04/2020 à 10:24, Brice Goglin a écrit :
>> When the program name is very long, qemu-user may truncate it in
>> /proc/self/stat. However the truncation must keep the ending ") "
>> to conform to the proc manpage which says:
>> (2) comm %s
>> The filename of the executable, in parentheses. This
>> is visible whether or not the executable is swapped
>> out.
>>
>> To reproduce:
>> $ ln -s /bin/cat <filenamewithmorethan128chars>
>> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>>
>> Before the patch, you get:
>> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
>> After the patch:
>> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>>
>> This fixes an issue with hwloc failing to parse /proc/self/stat
>> when Ludovic Courtes was testing it in Guix over qemu-aarch64.
>>
>> Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
> You can't add "Signed-off-by" of someone else, in this case you could
> add "Suggested-by:".
>
> The subject of your patch should include "[PATCH]" (and the version of
> the patch, "[PATCH v2]").
>
> https://wiki.qemu.org/Contribute/SubmitAPatch
>
>> Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>> } else if (i == 1) {
>> /* app name */
>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>> + char *ptr = buf;
>> +
>> + *ptr++ = '(';
>> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
> To have space for the NUL character I think it should be "sizeof(buf) - 4".
>
>> + strcpy(ptr, ") ");
>> } else if (i == 27) {
>> /* stack bottom */
>> val = start_stack;
>>
> Thanks,
> Laurent
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-04-08 8:24 Brice Goglin
2020-04-08 15:48 ` Laurent Vivier
@ 2020-04-09 15:27 ` Alex Bennée
2020-04-09 15:34 ` Brice Goglin
1 sibling, 1 reply; 11+ messages in thread
From: Alex Bennée @ 2020-04-09 15:27 UTC (permalink / raw)
To: Brice Goglin; +Cc: Philippe Mathieu-Daudé, qemu-devel
Brice Goglin <Brice.Goglin@inria.fr> writes:
> When the program name is very long, qemu-user may truncate it in
> /proc/self/stat. However the truncation must keep the ending ") "
> to conform to the proc manpage which says:
> (2) comm %s
> The filename of the executable, in parentheses. This
> is visible whether or not the executable is swapped
> out.
>
> To reproduce:
> $ ln -s /bin/cat <filenamewithmorethan128chars>
> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>
> Before the patch, you get:
> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
> After the patch:
> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>
> This fixes an issue with hwloc failing to parse /proc/self/stat
> when Ludovic Courtes was testing it in Guix over qemu-aarch64.
>
> Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
> } else if (i == 1) {
> /* app name */
> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
> + char *ptr = buf;
> +
> + *ptr++ = '(';
> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
> + strcpy(ptr, ") ");
why not just use a format string:
snprintf(buf, sizeof(buf), "(%.125s) ", ts->bprm->argv[0]);
although to be honest when ever I see a bunch of sizeof(buf) code for
strings I tend to re-write it to use the glib GString functions.
> } else if (i == 27) {
> /* stack bottom */
> val = start_stack;
--
Alex Bennée
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-04-09 15:27 ` Alex Bennée
@ 2020-04-09 15:34 ` Brice Goglin
2020-04-09 19:59 ` Alex Bennée
0 siblings, 1 reply; 11+ messages in thread
From: Brice Goglin @ 2020-04-09 15:34 UTC (permalink / raw)
To: Alex Bennée; +Cc: Philippe Mathieu-Daudé, qemu-devel
Le 09/04/2020 à 17:27, Alex Bennée a écrit :
> Brice Goglin <Brice.Goglin@inria.fr> writes:
>
>> When the program name is very long, qemu-user may truncate it in
>> /proc/self/stat. However the truncation must keep the ending ") "
>> to conform to the proc manpage which says:
>> (2) comm %s
>> The filename of the executable, in parentheses. This
>> is visible whether or not the executable is swapped
>> out.
>>
>> To reproduce:
>> $ ln -s /bin/cat <filenamewithmorethan128chars>
>> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>>
>> Before the patch, you get:
>> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
>> After the patch:
>> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>>
>> This fixes an issue with hwloc failing to parse /proc/self/stat
>> when Ludovic Courtes was testing it in Guix over qemu-aarch64.
>>
>> Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
>> Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>> } else if (i == 1) {
>> /* app name */
>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>> + char *ptr = buf;
>> +
>> + *ptr++ = '(';
>> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
>> + strcpy(ptr, ") ");
> why not just use a format string:
>
> snprintf(buf, sizeof(buf), "(%.125s) ", ts->bprm->argv[0]);
>
Go ahead and apply what you want (maybe 124 instead of 125 because of
the ending \0).
My commit message above explains how to test things very quickly.
I don't use qemu-user or Guix myself, and I can't spend time
debugging/testing this further.
Thank you
Brice
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: linux-user: keep the name-ending parenthesis in /proc/self/stat
2020-04-09 15:34 ` Brice Goglin
@ 2020-04-09 19:59 ` Alex Bennée
0 siblings, 0 replies; 11+ messages in thread
From: Alex Bennée @ 2020-04-09 19:59 UTC (permalink / raw)
To: Brice Goglin; +Cc: Philippe Mathieu-Daudé, qemu-devel
Brice Goglin <Brice.Goglin@inria.fr> writes:
> Le 09/04/2020 à 17:27, Alex Bennée a écrit :
>> Brice Goglin <Brice.Goglin@inria.fr> writes:
>>
>>> When the program name is very long, qemu-user may truncate it in
>>> /proc/self/stat. However the truncation must keep the ending ") "
>>> to conform to the proc manpage which says:
>>> (2) comm %s
>>> The filename of the executable, in parentheses. This
>>> is visible whether or not the executable is swapped
>>> out.
Huh testing on my box here it seems to truncate a lot earlier than that:
20:54:41 [alex@zen:~/l/q/b/all] sanitiser/fixes-for-5.1|●1✚1…(+1/-1) +
./cat_with9_12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890___4567890 /proc/self/stat
23132 (cat_with9_12345) R 15690 23132 15676 34827 23132 4194304 87 0 0 0 0 0 0 0 20 0 1 0 133272440 6172672 188 18446744073709551615 94698916007936 94698916032905 140729243846896 0 0 0 0 0 0 0 0 0 17 2 0 0 0 0 0 94698916052048 94698916053600 94698933542912 140729243849857 140729243850006 140729243850006 140729243852659 0
20:55:21 [alex@zen:~/l/q/b/all] sanitiser/fixes-for-5.1|●1✚1…(+1/-1) 126 +
./x86_64-linux-user/qemu-x86_64 ./cat_with9_12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890___4567890 /proc/s
elf/stat
23519 (./cat_with9_12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890___40 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 274903122400 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>>>
>>> To reproduce:
>>> $ ln -s /bin/cat <filenamewithmorethan128chars>
>>> $ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat
>>>
>>> Before the patch, you get:
>>> 1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
>>> After the patch:
>>> 1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...
>>>
>>> This fixes an issue with hwloc failing to parse /proc/self/stat
>>> when Ludovic Courtes was testing it in Guix over qemu-aarch64.
>>>
>>> Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
>>> Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
>>>
>>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>>> --- a/linux-user/syscall.c
>>> +++ b/linux-user/syscall.c
>>> @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
>>> snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
>>> } else if (i == 1) {
>>> /* app name */
>>> - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
>>> + char *ptr = buf;
>>> +
>>> + *ptr++ = '(';
>>> + ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
>>> + strcpy(ptr, ") ");
>> why not just use a format string:
>>
>> snprintf(buf, sizeof(buf), "(%.125s) ", ts->bprm->argv[0]);
>>
>
> Go ahead and apply what you want (maybe 124 instead of 125 because of
> the ending \0).
>
> My commit message above explains how to test things very quickly.
>
> I don't use qemu-user or Guix myself, and I can't spend time
> debugging/testing this further.
>
> Thank you
>
> Brice
--
Alex Bennée
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2020-04-09 19:59 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz follow: Atom feed
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2020-03-30 19:07 linux-user: keep the name-ending parenthesis in /proc/self/stat Brice Goglin
2020-03-30 22:05 ` Philippe Mathieu-Daudé
2020-03-30 22:29 ` Brice Goglin
2020-04-08 6:40 ` Brice Goglin
2020-04-08 8:09 ` Laurent Vivier
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2020-04-08 8:24 Brice Goglin
2020-04-08 15:48 ` Laurent Vivier
2020-04-08 15:56 ` Brice Goglin
2020-04-09 15:27 ` Alex Bennée
2020-04-09 15:34 ` Brice Goglin
2020-04-09 19:59 ` Alex Bennée
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