Re: Alexandre Julliard : libwine: Ignore libraries that are of the wrong 32/ 64 class.

[Ken Thomases]

Hi Alexandre,

It seems this would fail to ignore a fat Mach-O library that doesn't  
include the right 32/64 class.  For example, a fat i386/ppc library  
when running 64-bit.

A fat library starts with the struct fat_header defined in /usr/ 
include/mach-o/fat.h, followed by a number of struct fat_arch-es.  Its  
magic is 0xcafebabe in big-endian order.

This would also fail to ignore a PowerPC-only library because the  
magic would be big-endian, but I doubt we care about that.

-Ken

On Aug 11, 2009, at 10:47 AM, Alexandre Julliard wrote:
> Module: wine
> Branch: master
> Commit: 99538272d5b4ffc852f950dd3447a7072d6316ff
> URL:    http://source.winehq.org/git/wine.git/?a=commit;h=99538272d5b4ffc852f950dd34...
>
> Author: Alexandre Julliard <julliard(a)winehq.org>
> Date:   Tue Aug 11 17:29:07 2009 +0200
>
> libwine: Ignore libraries that are of the wrong 32/64 class.
>
> ---
>
> libs/wine/loader.c |   46 +++++++++++++++++++++++++++++++++++++++++++ 
> +--
> 1 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/libs/wine/loader.c b/libs/wine/loader.c
> index d10a6e0..37c603e 100644
> --- a/libs/wine/loader.c
> +++ b/libs/wine/loader.c
> @@ -147,12 +147,54 @@ static void build_dll_path(void)
>     }
> }
>
> +/* check if the library is the correct architecture */
> +/* only returns false for a valid library of the wrong arch */
> +static int check_library_arch( int fd )
> +{
> +#ifdef __APPLE__
> +    struct  /* Mach-O header */
> +    {
> +        unsigned int magic;
> +        unsigned int cputype;
> +    } header;
> +
> +    if (read( fd, &header, sizeof(header) ) != sizeof(header))  
> return 1;
> +    if (header.magic != 0xfeedface) return 1;
> +    if (sizeof(void *) == sizeof(int)) return !(header.cputype >>  
> 24);
> +    else return (header.cputype >> 24) == 1; /* CPU_ARCH_ABI64 */
> +#else
> +    struct  /* ELF header */
> +    {
> +        unsigned char magic[4];
> +        unsigned char class;
> +        unsigned char data;
> +        unsigned char version;
> +    } header;
> +
> +    if (read( fd, &header, sizeof(header) ) != sizeof(header))  
> return 1;
> +    if (memcmp( header.magic, "\177ELF", 4 )) return 1;
> +    if (header.version != 1 /* EV_CURRENT */) return 1;
> +#ifdef WORDS_BIGENDIAN
> +    if (header.data != 2 /* ELFDATA2MSB */) return 1;
> +#else
> +    if (header.data != 1 /* ELFDATA2LSB */) return 1;
> +#endif
> +    if (sizeof(void *) == sizeof(int)) return header.class == 1; /*  
> ELFCLASS32 */
> +    else return header.class == 2; /* ELFCLASS64 */
> +#endif
> +}
> +
> /* check if a given file can be opened */
> static inline int file_exists( const char *name )
> {
> +    int ret = 0;
>     int fd = open( name, O_RDONLY );
> -    if (fd != -1) close( fd );
> -    return (fd != -1);
> +    if (fd != -1)
> +    {
> +        ret = check_library_arch( fd );
> +        close( fd );
> +    }
> +    return ret;
> }
>
> static inline char *prepend( char *buffer, const char *str, size_t  
> len )

Alexandre Julliard : libwine: Ignore libraries that are of the wrong 32/ 64 class.

[Alexandre Julliard]

Ken Thomases <ken(a)codeweavers.com> writes:
> Hi Alexandre,
>
> It seems this would fail to ignore a fat Mach-O library that doesn't
> include the right 32/64 class.  For example, a fat i386/ppc library
> when running 64-bit.
>
> A fat library starts with the struct fat_header defined in /usr/
> include/mach-o/fat.h, followed by a number of struct fat_arch-es.  Its
> magic is 0xcafebabe in big-endian order.

I doubt we are ever going to build Wine dlls as fat libraries.
> This would also fail to ignore a PowerPC-only library because the
> magic would be big-endian, but I doubt we care about that.

That's deliberate. It's only supposed to ignore valid libraries that
could be loaded if not for their wrong class. Libraries that can't be
loaded at all should trigger an error.

-- 
Alexandre Julliard
julliard(a)winehq.org