• Andrew Clayton's avatar
    src/md5: Replace the MD5 implementation with the FSF LGPL one · 3dbbdfb5
    Andrew Clayton authored
    With GCC 4.8.3 on x86_64 Fedora 20 we get the following warnings from
    src/md5.c
    
        src/md5.c: In function 'md5_finish_ctx':
        src/md5.c:102:3: warning: dereferencing type-punned pointer will
         break strict-aliasing rules [-Wstrict-aliasing]
        *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] <<
         3);
        ^
        src/md5.c:103:3: warning: dereferencing type-punned pointer will
         break strict-aliasing rules [-Wstrict-aliasing]
        *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP
         ((ctx->total[1] << 3) |
        ^
    
    Rather than trying to fix this, Jean-Baptiste Kempf suggested it would
    be better to replace this old implementation with something newer such
    as the one used in VLC. So, this is what this does.
    
    We take src/misc/md5.c as src/md5.c and include/vlc_md5.h as src/md5.h
    
    md5.c had little changed in it, just some #include changes, I also had
    to remove the restrict keyword from the AddMD5() function definition as
    this is a C99 thing. This shouldn't really make much difference in this
    usage.
    
    md5.h had the VLC_API macro usage removed and I removed the psz_md5_hash
    function as it's not used.
    
    Finally DVDDiscID() in src/dvd_reader.c was changed to make use of this
    new implementation. I tested this with the following program
    
        /*
         * gcc -O2 -Wall -o dvddiscid dvddiscid.c -ldvdread
         */
    
        #include <stdio.h>
    
        #include <dvdread/dvd_reader.h>
    
        int main(void)
        {
            int i;
            dvd_reader_t *dvd;
            unsigned char id[16];
    
            dvd = DVDOpen("/dev/sr0");
            DVDDiscID(dvd, id);
            DVDClose(dvd);
    
            for (i = 0; i < 16; i++)
                 printf("%.2x", id[i]);
            printf("\n");
    
            return 0;
        }
    
    and get the same MD5 before and after this change.
    
        $ ./dvddiscid
        a02f30eb3e76e624b766ec0248757901
    
        $ LD_LIBRARY_PATH=/opt/libdvdread/lib ./dvddiscid
        a02f30eb3e76e624b766ec0248757901
    Signed-off-by: default avatarAndrew Clayton <andrew@digital-domain.net>
    Signed-off-by: Jean-Baptiste Kempf's avatarJean-Baptiste Kempf <jb@videolan.org>
    Tested-by: default avatarSteve Dibb <beandog@gentoo.org>
    3dbbdfb5