Description:
------------
libgd's XBM reader calculates the maximum number of image data
bytes to read in advance. However, it doesn't take into account
the line padding, so reading of XBM files with a width that is not
a multiple of 8 is likely to fail, for instance with the following
test.xbm:

    #define test_width 10
    #define test_height 10
    static unsigned char test_bits[] = {
      0xFF, 0x03, 0x00, 0x00, 0xFF, 0x03, 0x00, 0x00, 0xFF, 0x03, 0x00, 0x00, 
      0xFF, 0x03, 0x00, 0x00, 0xFF, 0x03, 0x00, 0x00};


Test script:
---------------
<?php

$im = imagecreatefromxbm(__DIR__ . '/test.xbm');
var_dump($im);


Expected result:
----------------
resource(%d) of type (gd)

Actual result:
--------------
Warning: imagecreatefromxbm(): EOF before image was complete in %s on line %d

Warning: imagecreatefromxbm(): '%s' is not a valid XBM file in %s on line %d
bool(false)