xv ignores input files specified via bash process substitution

[ahmogit]

Since ancient times (at least since 3.10 with Jumbo Patches) xv has ignored input files that are specified via bash process substitution, e.g.

$ xv <(cat somefile.jpg)

which should, ideally, behave as equivalent to

$ xv somefile.jpg

Looking at the xv.c argv handling, it appears that the /dev/fd/NN fifo symlink (which bash creates as the target filename when the process substitution is performed) is ignored simply because parseCmdLine() does a stat(2) on /dev/fd/NN and checks against filetype ISREG, which (as expected) fails for the /dev/fd/NN symlink-to-fifo. So the /dev/fd/NN filename never gets placed into namelist[], hence is completely ignored.

I attempted a quick workaround of simply changing the filetype test to accept either ISREG or ISFIFO. This does get past the initial argv processing, i.e. /dev/fd/NN gets deposited into namelist[], but alas that led to other problems further down the road when the /dev/fd/NN fifo is opened for imagetype assessment, and wasn't able to quickly come up with a simple approach to address that properly.

It may in turn out to be tricky to accomodate the /dev/fd/NN symlink-to-fifo without major surgery, but figured might as well ask. It would make a nice convenience enhancement to handle process substitution transparently.