[PATCH 1/2 V3] gas/as.c: print input and output filenames when error

[Robert Yang]

Hi Nick,

Thank you very much.

// Robert

On 08/14/2018 07:27 PM, Nick Clifton wrote:
> Hi Robert,
> 
>    Thanks.  I have applied your V3 patches (both 1/2 and 2/2) along
>    with a small change to add some more comments which I hope will
>    make the code more readable.
> 
> Cheers
>    Nick
> 
> gas/ChangeLog
> 2018-08-14  Robert Yang  <liezhi.yang@windriver.com>
> 
> 	* as.c (main): Improve check for input file matching output file.
> 
> diff --git a/gas/as.c b/gas/as.c
> index b2a908a2f7..3105d068c4 100644
> --- a/gas/as.c
> +++ b/gas/as.c
> @@ -1259,14 +1259,27 @@ main (int argc, char ** argv)
>   	{
>   	  struct stat sib;
>   
> -	  if (stat (argv[i], &sib) == 0)
> +	  /* Check that the input file and output file are different.  */
> +	  if (stat (argv[i], &sib) == 0
> +	      && sib.st_ino == sob.st_ino
> +	      /* POSIX emulating systems may support stat() but if the
> +		 underlying file system does not support a file serial number
> +		 of some kind then they will return 0 for the inode.  So
> +		 two files with an inode of 0 may not actually be the same.
> +		 On real POSIX systems no ordinary file will ever have an
> +		 inode of 0.  */
> +	      && sib.st_ino != 0
> +	      /* Different files may have the same inode number if they
> +		 reside on different devices, so check the st_dev field as
> +		 well.  */
> +	      && sib.st_dev == sob.st_dev)
>   	    {
> -	      if (sib.st_ino == sob.st_ino && sib.st_ino != 0)
> -		{
> -		  /* Don't let as_fatal remove the output file!  */
> -		  out_file_name = NULL;
> -		  as_fatal (_("The input and output files must be distinct"));
> -		}
> +	      const char *saved_out_file_name = out_file_name;
> +
> +	      /* Don't let as_fatal remove the output file!  */
> +	      out_file_name = NULL;
> +	      as_fatal (_("The input '%s' and output '%s' files are the same"),
> +			argv[i], saved_out_file_name);
>   	    }
>   	}
>       }
>