0001-auto-generated-pppds-do-not-set-rgb-default-on-mono-printers.patch

From 9799398713b941557642d0b2bdbef360837ece0c Mon Sep 17 00:00:00 2001
From: Till Kamppeter <till.kamppeter@gmail.com>
Date: Wed, 15 Feb 2023 22:29:38 +0100
Subject: [PATCH] In auto-generated PPDs do not set RGB default on mono
 printers

When a PPD for a driverless printer is generated by the
_ppdCreateFromIPP2() function and the get-printer-attributes IPP
response gives "print-color-mode-default=auto" the PPD's default
setting for "ColorModel" is always "RGB", even on monochrome printers,
which makes printing fail on most devices.

Now we ignore the "print-color-mode-default" if set to "auto" and
proceed as if no default was given, finding the default by selecting
the most desirable of the existing "ColorModel" choices.

Discovered via

https://github.com/OpenPrinting/cups/issues/614

The bug was originally reported against ipp-usb as the reporter's
printer was connected via IPP-over-USB, but actually the PPD
generators are at fault, and here not only the one in CUPS but also
the one in cups-filters 1.x and libppd 2.x.
---
 cupsfilters/ppdgenerator.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/cupsfilters/ppdgenerator.c b/cupsfilters/ppdgenerator.c
index 32f94c625..0d4dd7097 100644
--- a/cupsfilters/ppdgenerator.c
+++ b/cupsfilters/ppdgenerator.c
@@ -2801,7 +2801,8 @@ ppdCreateFromIPP2(char         *buffer,          /* I - Filename buffer */
       have_bi_level = 0,
       have_mono = 0;
 
-    if ((keyword = ippGetString(defattr, 0, NULL)) != NULL)
+    if ((keyword = ippGetString(defattr, 0, NULL)) != NULL &&
+	strcmp(keyword, "auto"))
     {
       if (!strcmp(keyword, "bi-level"))
         default_color = "FastGray";