From 54caa5b2af348906607c5516a112057650d0873d Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Sun, 21 Jan 2024 14:21:27 -0600
Subject: [PATCH] Add option ENABLE_AVAHI ON/OFF/AUTO (#97)

Co-authored-by: Christian W. Zuckschwerdt <christian@zuckschwerdt.org>
---
 common/CMakeLists.txt  | 39 +++++++++++++++++++++++++--------------
 common/FindAvahi.cmake |  6 +++---
 2 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/common/CMakeLists.txt b/common/CMakeLists.txt
index 8ca6510..41dba59 100644
--- a/common/CMakeLists.txt
+++ b/common/CMakeLists.txt
@@ -62,25 +62,36 @@ endif (WIN32)
 
 #avahi for discovery over mDNS/DNS-SD daemon
 if (UNIX AND NOT APPLE)
-    list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR})
-    find_package(Avahi)
-    if (NOT AVAHI_FOUND)
-        message(WARNING
-            "Cannot find Avahi client development files:"
-            "Avahi is recommended for device discovery over mDNS."
-            "Please install libavahi-client-dev or equivalent.")
-    endif ()
-endif ()
+    set(ENABLE_AVAHI AUTO CACHE STRING "Enable support for Avahi discovery")
+    set_property(CACHE ENABLE_AVAHI PROPERTY STRINGS AUTO ON OFF)
+    if(ENABLE_AVAHI) # AUTO / ON
+        list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR})
+        find_package(Avahi)
+        if(Avahi_FOUND)
+            message(STATUS "Avahi discovery support will be compiled.")
+        elseif(ENABLE_AVAHI STREQUAL "AUTO")
+            message(WARNING
+                "Could NOT find Avahi client development files: "
+                "Avahi is recommended for device discovery over mDNS. "
+                "Consider installing libavahi-client-dev or equivalent.")
+        else()
+            message(FATAL_ERROR "Avahi client for discovery support not found.")
+        endif()
+    else()
+        message(STATUS "Avahi discovery support disabled.")
+    endif()
+endif()
 
 if (APPLE)
     target_sources(SoapySDRRemoteCommon PRIVATE SoapyMDNSEndpointApple.cpp)
-elseif (AVAHI_FOUND)
-    message(STATUS "AVAHI_INCLUDE_DIRS=${AVAHI_INCLUDE_DIRS}")
-    message(STATUS "AVAHI_LIBRARIES=${AVAHI_LIBRARIES}")
-    target_include_directories(SoapySDRRemoteCommon PRIVATE ${AVAHI_INCLUDE_DIRS})
-    target_link_libraries(SoapySDRRemoteCommon PRIVATE ${AVAHI_LIBRARIES})
+elseif (Avahi_FOUND)
+    message(STATUS "Avahi_INCLUDE_DIRS=${Avahi_INCLUDE_DIRS}")
+    message(STATUS "Avahi_LIBRARIES=${Avahi_LIBRARIES}")
+    target_include_directories(SoapySDRRemoteCommon PRIVATE ${Avahi_INCLUDE_DIRS})
+    target_link_libraries(SoapySDRRemoteCommon PRIVATE ${Avahi_LIBRARIES})
     target_sources(SoapySDRRemoteCommon PRIVATE SoapyMDNSEndpointAvahi.cpp)
 else ()
+    message(STATUS "No mDNS support configured...")
     target_sources(SoapySDRRemoteCommon PRIVATE SoapyMDNSEndpointNone.cpp)
 endif ()
 
diff --git a/common/FindAvahi.cmake b/common/FindAvahi.cmake
index bc4d5f2..f119e4e 100644
--- a/common/FindAvahi.cmake
+++ b/common/FindAvahi.cmake
@@ -3,7 +3,7 @@ find_library(AVAHI_LIBRARY-CLIENT NAMES avahi-client)
 find_path(AVAHI_INCLUDE_DIR avahi-client/publish.h)
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(Avahi DEFAULT_MSG AVAHI_LIBRARY-COMMON AVAHI_LIBRARY-CLIENT AVAHI_INCLUDE_DIR)
-if(AVAHI_FOUND)
-    set(AVAHI_LIBRARIES ${AVAHI_LIBRARY-COMMON} ${AVAHI_LIBRARY-CLIENT})
-    set(AVAHI_INCLUDE_DIRS ${AVAHI_INCLUDE_DIR})
+if(Avahi_FOUND)
+    set(Avahi_LIBRARIES ${AVAHI_LIBRARY-COMMON} ${AVAHI_LIBRARY-CLIENT})
+    set(Avahi_INCLUDE_DIRS ${AVAHI_INCLUDE_DIR})
 endif()