Diffutils patch regarding special files

[Jason Todd]

Hi,

I have put together the attached simple patch for diff.c of the Diffutils 
package (specifically version 2.8.1).  This patch suppresses the messages 
(and failure exit status) when non-regular files are encountered during 
recursive comparisons, if the "-Q" or "--ignore_special" command line 
arguments are given.  Examples of the suppressed messages are:

File original/dev/char1-3 is a character special file while file 
test1/dev/char1-3 is a character special file
File original/misc/a-fifo is a fifo while file test1/misc/a-fifo is a fifo
File original/misc/a-socket is a socket while file test1/misc/a-socket is 
a fifo

Instead, the patch looks a little further, and if the files are of the 
same type and are not device files, it considers them a match.  In the 
case of device files, if they are of the same type (block or character) 
and refer to the same device (via stat.st_rdev), then it considers them a 
match.

When comparing two complete filesystems, or large portions of them (which 
I do a lot), these messages tend to get in the way.  Broken symlinks, 
which are common in almost every distribution, are still reported, but 
those messages I am willing to filter outside of diff.

I can submit a larger patch that includes the relevant changes to the 
documentation supplied with Diffutils, if you would like.  Further, I can 
update and re-package everything as diffutils-2.8.2 if you would like (but 
I don't want to intrude too much).  Just let me know.

Thanks,
Jason Todd

diff-ignore_special.patch
Description: Text document