CI: expand functionality of build.sh

Make it easier to "just do the nightly build" in a Docker
setting by passing the name of the workflow to the script.

CONTRIBUTING.md

@@ -154,10 +154,15 @@ dependencies for the image (in this example, for openSUSE and Qt6).
 - `./ci/deps-opensuse-qt6.sh`
 
 Then run CMake (add any CMake options you like at the end) and ninja.
-There is a script `ci/build.sh` that does this, too (without options).
 - `cmake -S /src -B /build -G Ninja`
 - `ninja -C /build`
 
+There is a script `ci/build.sh` that does the CMake an ninja steps.
+- If you set `CMAKE_ARGS` in the environment those extra CMake options are used.
+- If you add an argument to the script command which names a workflow
+  (e.g. "nightly-opensuse-qt6") then `CMAKE_ARGS` are extracted from that
+  workflow and used for the build.
+
 ### Running in Docker
 
 To run Calamares inside the container, or e.g. `loadmodule` to test

ci/build.sh

@@ -5,6 +5,36 @@
 # - BUILDDIR    (e.g. /build)
 # - CMAKE_ARGS  (e.g. "-DWITH_QT6=ON -DCMAKE_BUILD_TYPE=Debug")
 #
+# If SRCDIR is not set, it is assumed to be the directory above
+# wherever this script is being run from (this script is in ci/).
+#
+# If BUILDDIR is not set, and /build exists (e.g. in the recommended
+# Docker setup) then /build is used.
+#
+# If CMAKE_ARGS is not set, but the script is given an argument
+# that exists as a workflow (e.g. "nightly-opensuse-qt6" or
+# "nightly-debian.yml") and yq is installed, then the CMAKE_ARGS
+# are extracted from that workflow file.
+#
+# Summary, pick one:
+# - set environment variables, run "build.sh"
+# - set no variables, run "build.sh <workflow-name>"
+
+if test -z "$SRCDIR" ; then
+	_d=$(dirname "$0" )
+	_d=$(dirname "$_d" )
+	test -f "$_d/CMakeLists.txt" && SRCDIR="$_d"
+fi
+if test -z "$BUILDDIR" ; then
+	test -d "/build" && BUILDDIR=/build
+fi
+if test -z "$CMAKE_ARGS" -a -n "$1" ; then
+	test -x "$(which yq)" || { echo "! No yq command for finding CMAKE_ARGS for workflow $1" ; exit 1 ; }
+	_d="$SRCDIR/.github/workflows/$1"
+	test -f "$_d" || _d="$SRCDIR/.github/workflows/$1.yml"
+	test -f "$_d" || { echo "! No workflow $1" ; exit 1 ; }
+	CMAKE_ARGS=$(yq ".env.CMAKE_ARGS" "$_d")
+fi
 
 # Sanity check
 test -n "$BUILDDIR" || { echo "! \$BUILDDIR not set" ; exit 1 ; }