• Micolas Pitre's avatar
    fix >4GiB source delta assertion failure · 506049c7
    Micolas Pitre authored
    When people try insane things such as delta-compressing 4GiB files, they
    get this assertion:
    
    diff-delta.c:285: create_delta_index: Assertion `packed_entry - (struct index_entry *)mem == entries' failed.
    
    This happens because:
    
    1) the 'entries' variable is an unsigned int
    
    2) it is assigned with entries = (bufsize - 1) / RABIN_WINDOW
       (that itself is not a problem unless bufsize > 4G * RABIN_WINDOW)
    
    3) the buffer is indexed from top to bottom starting at
       "data = buffer + entries * RABIN_WINDOW" and the multiplication
       here does indeed overflows, making the resulting top of the buffer
       much lower than expected.
    
    This makes the number of actually produced index entries smaller than
    what was computed initially, hence the assertion.
    
    Furthermore, the current delta encoding format cannot represent offsets
    into a reference buffer with more than 32 bits anyway.  So let's just
    limit the number of entries to what the delta format can encode.
    Reported-by: default avatarIlari Liusvaara <ilari.liusvaara@elisanet.fi>
    Signed-off-by: Micolas Pitre's avatarNicolas Pitre <nico@fluxnic.net>
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    506049c7
diff-delta.c 15.5 KB