From b3ac0a2ceb89fc26ed272e8b338e4858382ac285 Mon Sep 17 00:00:00 2001
From: Danny Greenstein <danny.gr@gmail.com>
Date: Tue, 19 Sep 2023 20:13:14 -0700
Subject: [PATCH] Print build-time warnings for LGPL gotchas (#3958)

Print helpful reminder to check licenses when using libheif or
ffmpeg statically linked.

Fixes #3916

Signed-off-by: grdanny <danny.gr@gmail.com>
---
 src/ffmpeg.imageio/CMakeLists.txt | 22 ++++++++++++++++++++++
 src/heif.imageio/CMakeLists.txt   | 22 ++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/src/ffmpeg.imageio/CMakeLists.txt b/src/ffmpeg.imageio/CMakeLists.txt
index 59fe404c30..a34402cf2e 100644
--- a/src/ffmpeg.imageio/CMakeLists.txt
+++ b/src/ffmpeg.imageio/CMakeLists.txt
@@ -3,6 +3,28 @@
 # https://github.com/OpenImageIO/oiio
 
 if (FFmpeg_FOUND)
+    if (LINKSTATIC)
+        set (_static_suffixes .lib .a)
+        set (_static_libraries_found 0)
+
+        foreach (_ffmpeg_library IN LISTS FFMPEG_LIBRARIES)
+            get_filename_component (_ext ${_ffmpeg_library} LAST_EXT)
+            list (FIND _static_suffixes ${_ext} _index)
+            if (${_index} GREATER -1)
+                MATH (EXPR _static_libraries_found "${_static_libraries_found}+1")
+            endif()
+        endforeach()
+
+        if (${_static_libraries_found} GREATER 0)
+            message (STATUS "${ColorYellow}")
+            message (STATUS "You are linking OpenImageIO against a static version of FFmpeg, which may have")
+            message (STATUS "LGPL and possibly GPL licensed components (depending on exactly how your copy")
+            message (STATUS "of FFmpeg was built). If you intend to redistribute this build of OpenImageIO,")
+            message (STATUS "we recommend that you review the FFmpeg build flags and licensing terms.")        
+            message ("${ColorReset}")
+        endif()
+    endif()
+
     add_oiio_plugin (ffmpeginput.cpp
                      INCLUDE_DIRS ${FFMPEG_INCLUDES}
                      LINK_LIBRARIES ${FFMPEG_LIBRARIES}
diff --git a/src/heif.imageio/CMakeLists.txt b/src/heif.imageio/CMakeLists.txt
index 12ad634002..86a099539e 100644
--- a/src/heif.imageio/CMakeLists.txt
+++ b/src/heif.imageio/CMakeLists.txt
@@ -3,6 +3,28 @@
 # https://github.com/OpenImageIO/oiio
 
 if (Libheif_FOUND)
+    if (LINKSTATIC)
+        set (_static_suffixes .lib .a)    
+        set (_static_libraries_found 0)
+
+        foreach (_libeheif_library IN LISTS LIBHEIF_LIBRARIES)
+            get_filename_component (_ext ${_libeheif_library} LAST_EXT)
+            list (FIND _static_suffixes ${_ext} _index)
+            if (${_index} GREATER -1)
+                MATH (EXPR _static_libraries_found "${static_libraries_found}+1")
+            endif()
+        endforeach()
+
+        if (${_static_libraries_found} GREATER 0)
+            message (STATUS "${ColorYellow}")
+            message (STATUS "You are linking OpenImageIO against a static version of libheif, which is LGPL")
+            message (STATUS "licensed. If you intend to redistribute this build of OpenImageIO, we recommend")
+            message (STATUS "that you review the libheif license terms, or you may wish to switch to using a")
+            message (STATUS "dynamically-linked libheif.")
+            message ("${ColorReset}")
+        endif()
+    endif()
+
     add_oiio_plugin (heifinput.cpp heifoutput.cpp
                      INCLUDE_DIRS ${LIBHEIF_INCLUDES}
                      LINK_LIBRARIES ${LIBHEIF_LIBRARIES}