Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Mickaël Salaün 

On 28/11/2015 23:07, Richard Weinberger wrote:
> Am 28.11.2015 um 22:32 schrieb Mickaël Salaün:
>> Open the memory mapped file with the O_TMPFILE flag when available.
>>
>> Signed-off-by: Mickaël Salaün 
>> ---
>>  arch/um/os-Linux/mem.c | 12 
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
>> index 798aeb4..fe52e2d 100644
>> --- a/arch/um/os-Linux/mem.c
>> +++ b/arch/um/os-Linux/mem.c
>> @@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
>>  }
>>  }
>>  
>> +#ifdef O_TMPFILE
>> +fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
>> +/*
>> + * If the running system does not support O_TMPFILE flag then retry
>> + * without it.
>> + */
>> +if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
> 
> Why are you handling EISDIR?

I follow the man page for open [1], I think it was a workaround needed for some 
kernel versions just after the O_TMPFILE was added but before the support for 
EOPNOTSUPP.
We may need to add the EACCES too for some version of glibc [2, 3]?

1. http://man7.org/linux/man-pages/man2/openat.2.html#BUGS
2. Commit 69a91c237ab0ebe4e9fdeaf6d0090c85275594ec and 
https://sourceware.org/bugzilla/show_bug.cgi?id=17523
3. https://bugs.gentoo.org/529044

> 
>> +errno != EOPNOTSUPP))
>> +return fd;
>> +errno = 0;
> 
> Why are you resetting errno?

It's to ignore/reset the error code from open, but it may not be needed because 
of the next call to malloc?

 Mickaël



signature.asc
Description: OpenPGP digital signature

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Mickaël Salaün 

 +  errno != EOPNOTSUPP))
 +  return fd;
 +  errno = 0;
>>>
>>> Why are you resetting errno?
>>
>> It's to ignore/reset the error code from open, but it may not be needed 
>> because of the next call to malloc?
> 
> But then you'd have to reset errno after every syscall. :-)

OK, I will remove it then :)

 Mickaël



signature.asc
Description: OpenPGP digital signature

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Richard Weinberger 
Am 28.11.2015 um 23:56 schrieb Mickaël Salaün:
> 
> On 28/11/2015 23:07, Richard Weinberger wrote:
>> Am 28.11.2015 um 22:32 schrieb Mickaël Salaün:
>>> Open the memory mapped file with the O_TMPFILE flag when available.
>>>
>>> Signed-off-by: Mickaël Salaün 
>>> ---
>>>  arch/um/os-Linux/mem.c | 12 
>>>  1 file changed, 12 insertions(+)
>>>
>>> diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
>>> index 798aeb4..fe52e2d 100644
>>> --- a/arch/um/os-Linux/mem.c
>>> +++ b/arch/um/os-Linux/mem.c
>>> @@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
>>> }
>>> }
>>>  
>>> +#ifdef O_TMPFILE
>>> +   fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
>>> +   /*
>>> +* If the running system does not support O_TMPFILE flag then retry
>>> +* without it.
>>> +*/
>>> +   if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
>>
>> Why are you handling EISDIR?
> 
> I follow the man page for open [1], I think it was a workaround needed for 
> some kernel versions just after the O_TMPFILE was added but before the 
> support for EOPNOTSUPP.
> We may need to add the EACCES too for some version of glibc [2, 3]?

Makes sense! :)

> 1. http://man7.org/linux/man-pages/man2/openat.2.html#BUGS
> 2. Commit 69a91c237ab0ebe4e9fdeaf6d0090c85275594ec and 
> https://sourceware.org/bugzilla/show_bug.cgi?id=17523
> 3. https://bugs.gentoo.org/529044
> 
>>
>>> +   errno != EOPNOTSUPP))
>>> +   return fd;
>>> +   errno = 0;
>>
>> Why are you resetting errno?
> 
> It's to ignore/reset the error code from open, but it may not be needed 
> because of the next call to malloc?

But then you'd have to reset errno after every syscall. :-)

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Mickaël Salaün 
Open the memory mapped file with the O_TMPFILE flag when available.

Signed-off-by: Mickaël Salaün 
---
 arch/um/os-Linux/mem.c | 12 
 1 file changed, 12 insertions(+)

diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 798aeb4..fe52e2d 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
}
}
 
+#ifdef O_TMPFILE
+   fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+   /*
+* If the running system does not support O_TMPFILE flag then retry
+* without it.
+*/
+   if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
+   errno != EOPNOTSUPP))
+   return fd;
+   errno = 0;
+#endif
+
tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
-- 
2.6.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Richard Weinberger 
Am 28.11.2015 um 22:32 schrieb Mickaël Salaün:
> Open the memory mapped file with the O_TMPFILE flag when available.
> 
> Signed-off-by: Mickaël Salaün 
> ---
>  arch/um/os-Linux/mem.c | 12 
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
> index 798aeb4..fe52e2d 100644
> --- a/arch/um/os-Linux/mem.c
> +++ b/arch/um/os-Linux/mem.c
> @@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
>   }
>   }
>  
> +#ifdef O_TMPFILE
> + fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
> + /*
> +  * If the running system does not support O_TMPFILE flag then retry
> +  * without it.
> +  */
> + if (fd != -1 || (errno != EINVAL && errno != EISDIR &&

Why are you handling EISDIR?

> + errno != EOPNOTSUPP))
> + return fd;
> + errno = 0;

Why are you resetting errno?

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Mickaël Salaün 
Open the memory mapped file with the O_TMPFILE flag when available.

Signed-off-by: Mickaël Salaün 
---
 arch/um/os-Linux/mem.c | 12 
 1 file changed, 12 insertions(+)

diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 798aeb4..fe52e2d 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
}
}
 
+#ifdef O_TMPFILE
+   fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+   /*
+* If the running system does not support O_TMPFILE flag then retry
+* without it.
+*/
+   if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
+   errno != EOPNOTSUPP))
+   return fd;
+   errno = 0;
+#endif
+
tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
-- 
2.6.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Richard Weinberger 
Am 28.11.2015 um 23:56 schrieb Mickaël Salaün:
> 
> On 28/11/2015 23:07, Richard Weinberger wrote:
>> Am 28.11.2015 um 22:32 schrieb Mickaël Salaün:
>>> Open the memory mapped file with the O_TMPFILE flag when available.
>>>
>>> Signed-off-by: Mickaël Salaün 
>>> ---
>>>  arch/um/os-Linux/mem.c | 12 
>>>  1 file changed, 12 insertions(+)
>>>
>>> diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
>>> index 798aeb4..fe52e2d 100644
>>> --- a/arch/um/os-Linux/mem.c
>>> +++ b/arch/um/os-Linux/mem.c
>>> @@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
>>> }
>>> }
>>>  
>>> +#ifdef O_TMPFILE
>>> +   fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
>>> +   /*
>>> +* If the running system does not support O_TMPFILE flag then retry
>>> +* without it.
>>> +*/
>>> +   if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
>>
>> Why are you handling EISDIR?
> 
> I follow the man page for open [1], I think it was a workaround needed for 
> some kernel versions just after the O_TMPFILE was added but before the 
> support for EOPNOTSUPP.
> We may need to add the EACCES too for some version of glibc [2, 3]?

Makes sense! :)

> 1. http://man7.org/linux/man-pages/man2/openat.2.html#BUGS
> 2. Commit 69a91c237ab0ebe4e9fdeaf6d0090c85275594ec and 
> https://sourceware.org/bugzilla/show_bug.cgi?id=17523
> 3. https://bugs.gentoo.org/529044
> 
>>
>>> +   errno != EOPNOTSUPP))
>>> +   return fd;
>>> +   errno = 0;
>>
>> Why are you resetting errno?
> 
> It's to ignore/reset the error code from open, but it may not be needed 
> because of the next call to malloc?

But then you'd have to reset errno after every syscall. :-)

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Richard Weinberger 
Am 28.11.2015 um 22:32 schrieb Mickaël Salaün:
> Open the memory mapped file with the O_TMPFILE flag when available.
> 
> Signed-off-by: Mickaël Salaün 
> ---
>  arch/um/os-Linux/mem.c | 12 
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
> index 798aeb4..fe52e2d 100644
> --- a/arch/um/os-Linux/mem.c
> +++ b/arch/um/os-Linux/mem.c
> @@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
>   }
>   }
>  
> +#ifdef O_TMPFILE
> + fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
> + /*
> +  * If the running system does not support O_TMPFILE flag then retry
> +  * without it.
> +  */
> + if (fd != -1 || (errno != EINVAL && errno != EISDIR &&

Why are you handling EISDIR?

> + errno != EOPNOTSUPP))
> + return fd;
> + errno = 0;

Why are you resetting errno?

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Mickaël Salaün 

 +  errno != EOPNOTSUPP))
 +  return fd;
 +  errno = 0;
>>>
>>> Why are you resetting errno?
>>
>> It's to ignore/reset the error code from open, but it may not be needed 
>> because of the next call to malloc?
> 
> But then you'd have to reset errno after every syscall. :-)

OK, I will remove it then :)

 Mickaël



signature.asc
Description: OpenPGP digital signature

Re: [PATCH 2/2] um: Use race-free temporary file creation

2015-11-28 Thread Mickaël Salaün 

On 28/11/2015 23:07, Richard Weinberger wrote:
> Am 28.11.2015 um 22:32 schrieb Mickaël Salaün:
>> Open the memory mapped file with the O_TMPFILE flag when available.
>>
>> Signed-off-by: Mickaël Salaün 
>> ---
>>  arch/um/os-Linux/mem.c | 12 
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
>> index 798aeb4..fe52e2d 100644
>> --- a/arch/um/os-Linux/mem.c
>> +++ b/arch/um/os-Linux/mem.c
>> @@ -106,6 +106,18 @@ static int __init make_tempfile(const char *template)
>>  }
>>  }
>>  
>> +#ifdef O_TMPFILE
>> +fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
>> +/*
>> + * If the running system does not support O_TMPFILE flag then retry
>> + * without it.
>> + */
>> +if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
> 
> Why are you handling EISDIR?

I follow the man page for open [1], I think it was a workaround needed for some 
kernel versions just after the O_TMPFILE was added but before the support for 
EOPNOTSUPP.
We may need to add the EACCES too for some version of glibc [2, 3]?

1. http://man7.org/linux/man-pages/man2/openat.2.html#BUGS
2. Commit 69a91c237ab0ebe4e9fdeaf6d0090c85275594ec and 
https://sourceware.org/bugzilla/show_bug.cgi?id=17523
3. https://bugs.gentoo.org/529044

> 
>> +errno != EOPNOTSUPP))
>> +return fd;
>> +errno = 0;
> 
> Why are you resetting errno?

It's to ignore/reset the error code from open, but it may not be needed because 
of the next call to malloc?

 Mickaël



signature.asc
Description: OpenPGP digital signature