Re: [PATCH v6] ld: Make archive member file extension comparisons case insensitive when cross compiling too

[Jan Beulich <jbeulich@suse.com>]

On 24.08.2022 12:47, Martin Storsjö wrote:
> On Windows, filename_cmp is case insensitive, but when cross compiling
> with libraries that may contain members with uppercase file names, we
> should keep those comparisons case insensitive when running the build
> tools on other OSes too.
> 
> Also make the check for .def consistent with the other ones, fixing
> out of bounds reads if file names are shorter than 4 characters.
> ---
> v6: Switch the check for .def extension to use strrchr, add a missed
> null pointer check at the third call site.

With that, as I've previously tried to express, ...

> --- a/ld/emultempl/pe.em
> +++ b/ld/emultempl/pe.em
> @@ -534,6 +534,28 @@ gld${EMULATION_NAME}_list_options (FILE *file)
>    fprintf (file, _("  --build-id[=STYLE]                 Generate build ID\n"));
>  }
>  
> +/* A case insensitive comparison, regardless of the host platform, used for
> +   comparing file extensions. Parameter s1 points at the extension in a file
> +   name (pointing at the starting '.'). Parameter s2 is a lower case string
> +   without the leading '.'.  */
> +static int
> +fileext_cmp (const char *s1, const char *s2)
> +{
> +  if (*s1 != '.')
> +    return 1;
> +  s1++;

... this is now properly dead code, and instead ...

> +  for (;;)
> +    {
> +      int c1 = TOLOWER (*s1++);
> +      int c2 = *s2++; /* Assumed to be lower case from the caller.  */
> +
> +      if (c1 != c2)
> +        return (c1 - c2);
> +
> +      if (c1 == '\0')
> +        return 0;
> +    }
> +}
>  
>  static void
>  set_pe_name (char *name, long val)
> @@ -1666,7 +1688,7 @@ gld${EMULATION_NAME}_after_open (void)
>  		       extension, and use that for the remainder of the
>  		       comparisons.  */
>  		    pnt = strrchr (bfd_get_filename (is3->the_bfd), '.');
> -		    if (pnt != NULL && filename_cmp (pnt, ".dll") == 0)
> +		    if (pnt != NULL && fileext_cmp (pnt, "dll") == 0)

... you'll want to pass pnt + 1 to the function here (and then similarly
below).

Jan