[PATCH v2] pe/coff - add support for base64 encoded long section names

[Jan Beulich]

On 24.05.2023 07:48, Tristan Gingold via Binutils wrote:
> I have adjusted the comments to clarify.  Is it OK ?

With the earlier nit addressed (I'll repeat it below), yes. But please
allow a little bit of time for in particular Nick to raise last minute
comments, as he had looked at the earlier version of the patch. Plus ...

> Tristan.
> 
> 2023-05-22  Tristan Gingold  <tgingold@thinkpad-e15>

... I notice that in at least one case there was a similar email address
you used in a ChangeLog entry (gingold@gingold-Precision-7510), but
neither that nor the one here look like valid email addresses to me. Yet
aiui these email addresses are expected to be real ones.

> --- a/bfd/coffcode.h
> +++ b/bfd/coffcode.h
> @@ -3625,18 +3625,55 @@ coff_write_object_contents (bfd * abfd)
>   	  len = strlen (current->name);
>   	  if (len > SCNNMLEN)
>   	    {
> -	      /* The s_name field is defined to be NUL-padded but need not be
> -		 NUL-terminated.  We use a temporary buffer so that we can still
> -		 sprintf all eight chars without splatting a terminating NUL
> -		 over the first byte of the following member (s_paddr).  */
> -	      /* PR 21096: The +20 is to stop a bogus warning from gcc7 about
> -		 a possible buffer overflow.  */
> -	      char s_name_buf[SCNNMLEN + 1 + 20];
> 
>   	      /* An inherent limitation of the /nnnnnnn notation used to indicate
>   		 the offset of the long name in the string table is that we
>   		 cannot address entries beyone the ten million byte boundary.  */
> -	      if (string_size >= 10000000)
> +	      if (string_size < 10000000)
> +		{
> +		  /* The s_name field is defined to be NUL-padded but need not
> +		     be NUL-terminated.  We use a temporary buffer so that we
> +		     can still sprintf all eight chars without splatting a
> +		     terminating NUL over the first byte of the following
> +		     member (s_paddr).  */
> +		  /* PR 21096: The +20 is to stop a bogus warning from gcc7
> +		     about a possible buffer overflow.  */
> +		  char s_name_buf[SCNNMLEN + 1 + 20];
> +
> +		  /* We do not need to use snprintf here as we have already
> +		     verified that string_size is not too big, plus we have
> +		     an overlarge buffer, just in case.  */
> +		  sprintf (s_name_buf, "/%lu", (unsigned long) string_size);
> +		  /* Then strncpy takes care of any padding for us.  */
> +		  strncpy (section.s_name, s_name_buf, SCNNMLEN);
> +		}
> +	      else
> +#ifdef COFF_WITH_PE
> +		{
> +		  /* PE use a base 64 encoding for long section names whose
> +		     index is very large.  But contrary to RFC 4648, there is
> +		     no padding: 6 characters must be generated.  */
> +		  static const char base64[] =
> +		    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
> +		    "abcdefghijklmnopqrstuvwxyz"
> +		    "0123456789+/";
> +		  unsigned long off = string_size;
> +		  unsigned i;
> +
> +		  section.s_name[0] = '/';
> +		  section.s_name[1] = '/';
> +		  for (i = SCNNMLEN - 1; i >=2; i--)

Repeat of earlier nit: Please insert a blank between >= and 2.

Jan