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Subject: Re: [RFC] linux: use __fd_to_filename helper function instead of
 snprintf.
To: Florian Weimer <fweimer@redhat.com>,
 =?UTF-8?Q?=c3=89rico_Nogueira_via_Libc-alpha?= <libc-alpha@sourceware.org>
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 <87h7jsp6ma.fsf@oldenburg.str.redhat.com>
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Date: Tue, 27 Apr 2021 10:06:57 -0300
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Em 27/04/2021 03:46, Florian Weimer escreveu:
> * Érico Nogueira via Libc-alpha:
> 
>> diff --git a/sysdeps/unix/sysv/linux/fexecve.c b/sysdeps/unix/sysv/linux/fexecve.c
>> index f37c245396..218337a3b5 100644
>> --- a/sysdeps/unix/sysv/linux/fexecve.c
>> +++ b/sysdeps/unix/sysv/linux/fexecve.c
>> @@ -22,6 +22,7 @@
>>   #include <fcntl.h>
>>   #include <sys/stat.h>
>>   
>> +#include <fd_to_filename.h>
>>   #include <sysdep.h>
>>   #include <sys/syscall.h>
>>   #include <kernel-features.h>
>> @@ -50,8 +51,8 @@ fexecve (int fd, char *const argv[], char *const envp[])
>>   #ifndef __ASSUME_EXECVEAT
>>     /* We use the /proc filesystem to get the information.  If it is not
>>        mounted we fail.  */
>> -  char buf[sizeof "/proc/self/fd/" + sizeof (int) * 3];
>> -  __snprintf (buf, sizeof (buf), "/proc/self/fd/%d", fd);
>> +  struct fd_to_filename filename;
>> +  char *buf = fd_to_filename(fd, &filename);
> 
> Sorry, this patch fails to build if applied to current master:

I hadn't commited the fix from my work tree, sorry.

> 
> ../sysdeps/unix/sysv/linux/fexecve.c: In function ‘fexecve’:
> ../sysdeps/unix/sysv/linux/fexecve.c:55:15: error: implicit declaration of function ‘fd_to_filename’ [-Werror=implicit-function-declaration]
>     55 |   char *buf = fd_to_filename(fd, &filename);
>        |               ^~~~~~~~~~~~~~
> 
> Please also add a space before the opening '(', to match GNU style, and
> consider if the code becomes clearer if you avoid the buf variable.

I think it's basically as clear as, but a bit more compact, so I will 
use that instead. Thanks!

> 
> Thanks,
> Florian
>