From c44052f12ff1f373ddfa5f582fbae5a33da46545 Mon Sep 17 00:00:00 2001
From: Armin Novak <armin.novak@thincast.com>
Date: Thu, 25 Sep 2025 15:35:36 +0200
Subject: [PATCH] [cmake,json] add second fallback

If both, CMake and pkg-config fail, fall back to find_path and
find_library detection
---
 cmake/JsonDetect.cmake | 89 +++++++++++++++++++++++++++++++-----------
 1 file changed, 66 insertions(+), 23 deletions(-)

diff --git a/cmake/JsonDetect.cmake b/cmake/JsonDetect.cmake
index 4bbb5e8de..d89c0de16 100644
--- a/cmake/JsonDetect.cmake
+++ b/cmake/JsonDetect.cmake
@@ -1,29 +1,55 @@
-function(detect_package name pkgconf cmake-target)
+function(detect_package name)
   set(options REQUIRED)
+  set(oneValueArgs HEADER LIBRARY PKGCONFIG CMAKE)
   cmake_parse_arguments(PARSE_ARGV 0 arg "${options}" "${oneValueArgs}" "${multiValueArgs}")
 
   find_package(${name})
   if(NOT ${name}_FOUND)
     # Fallback detection:
-    # older ubuntu releases did not ship CMake or pkg-config files
-    # for ${pkgconf}. Be optimistic and try pkg-config and as last resort
-    # try manual detection
+    # some distributions only ship pkg-config and skip CMake config files.
     find_package(PkgConfig)
     if(PKG_CONFIG_FOUND)
-      pkg_check_modules(${name} ${pkgconf})
-
-      if(${name}_FOUND)
-        # Create imported target cjson
-        add_library(${cmake-target} SHARED IMPORTED)
-        set_property(TARGET ${cmake-target} APPEND PROPERTY IMPORTED_CONFIGURATIONS NOCONFIG)
-        set_target_properties(
-          ${cmake-target}
-          PROPERTIES IMPORTED_CONFIGURATIONS NOCONFIG IMPORTED_LINK_INTERFACE_LANGUAGES_NOCONFIG "C"
-                     IMPORTED_LOCATION_NOCONFIG "${${name}_LINK_LIBRARIES}" IMPORTED_SONAME_NOCONFIG
-                                                                            "${${name}_LIBRARIES}"
-                     INTERFACE_INCLUDE_DIRECTORIES "${${name}_INCLUDE_DIRS}"
-        )
+      if(arg_PKGCONFIG)
+        set(module ${arg_PKGCONFIG})
+      else()
+        set(module ${name})
       endif()
+      pkg_check_modules(${name} ${module})
+    endif()
+
+    # No CMake nor pkg-config files available, try manual detection
+    if(NOT ${name}_FOUND)
+      find_library(
+        ${name}_LIBRARY NAMES ${arg_LIBRARY} ${arg_PKGCONFIG} ${arg_CMAKE} ${name} ${arg_CMAKE}
+        PATH_SUFFIXES ${name} ${arg_PKGCONFIG} ${arg_CMAKE}
+      )
+
+      find_path(${name}_HEADER NAMES ${arg_HEADER} ${name}.h ${arg_PKGCONFIG}.h ${arg_CMAKE}.h
+                PATH_SUFFIXES ${name} ${arg_PKGCONFIG} ${arg_CMAKE}
+      )
+
+      if(NOT ${name}_LIBRARY STREQUAL "${name}_LIBRARY-NOTFOUND" AND NOT ${name}_HEADER STREQUAL
+                                                                     "${name}_HEADER-NOTFOUND"
+      )
+        set(${name}_LINK_LIBRARIES "${${name}_LIBRARY}")
+        set(${name}_INCLUDE_DIRS "${${name}_HEADER}")
+        get_filename_component(${name}_LIB_FILE "${${name}_LIBRARY}" NAME_WE)
+        set(regex "^${CMAKE_SHARED_LIBRARY_SUFFIX}")
+        string(REGEX REPLACE ${regex} ${name}_LIBRARIES "${${name}_LIB_FILE}")
+      endif()
+    endif()
+
+    if(${name}_FOUND)
+      # Create imported target cjson
+      add_library(${arg_CMAKE} SHARED IMPORTED)
+      set_property(TARGET ${arg_CMAKE} APPEND PROPERTY IMPORTED_CONFIGURATIONS NOCONFIG)
+      set_target_properties(
+        ${arg_CMAKE}
+        PROPERTIES IMPORTED_CONFIGURATIONS NOCONFIG IMPORTED_LINK_INTERFACE_LANGUAGES_NOCONFIG "C"
+                   IMPORTED_LOCATION_NOCONFIG "${${name}_LINK_LIBRARIES}" IMPORTED_SONAME_NOCONFIG
+                                                                          "${${name}_LIBRARIES}"
+                   INTERFACE_INCLUDE_DIRECTORIES "${${name}_INCLUDE_DIRS}"
+      )
     endif()
   endif()
 
@@ -60,16 +86,33 @@ unset(cJSON_FOUND CACHE)
 unset(jansson_FOUND CACHE)
 if(NOT WITH_JSON_DISABLED)
   if(WITH_JANSSON_REQUIRED)
-    detect_package(jansson jansson jansson::jansson REQUIRED)
+    detect_package(jansson CMAKE jansson::jansson HEADER jansson.h REQUIRED)
   elseif(WITH_JSONC_REQUIRED)
-    detect_package(json-c json-c json-c::json-c REQUIRED)
+    detect_package(json-c CMAKE json-c::json-c HEADER json-c/json.h REQUIRED)
   elseif(WITH_CJSON_REQUIRED)
-    detect_package(cJSON libcjson cjson REQUIRED)
+    detect_package(
+      cJSON
+      PKGCONFIG
+      libcjson
+      CMAKE
+      cjson
+      HEADER
+      cjson/cJSON.h
+      REQUIRED
+    )
   else()
     # nothing required, so do a non fatal check for all
-    detect_package(jansson jansson jansson::jansson)
-    detect_package(json-c json-c json-c::json-c)
-    detect_package(cJSON libcjson cjson)
+    detect_package(jansson CMAKE jansson::jansson HEADER jansson.h)
+    detect_package(json-c CMAKE json-c::json-c HEADER json-c/json.h)
+    detect_package(
+      cJSON
+      PKGCONFIG
+      libcjson
+      CMAKE
+      cjson
+      HEADER
+      cjson/cJSON.h
+    )
   endif()
 
   if(NOT json-c_FOUND AND NOT cJSON_FOUND AND NOT jansson_FOUND)