Add a way for users to provide local directories for external libraries

Allow the users to provide their own directories for all the external libraries that are downloaded as part of the build process, by overriding name_SOURCE_DIR and name_BINARY_DIR.

PiperOrigin-RevId: 246938364

CMakeLists.txt

@@ -88,8 +88,7 @@ set(FLATBUFFERS_BUILD_TESTS OFF CACHE BOOL "")
 
 # Add flatbuffers as a subdirectory, and set the directory variables for it,
 # so that the sub Firebase projects can depend upon it if necessary.
-add_external_subdirectory(flatbuffers)
-populate_external_source_vars(flatbuffers)
+add_external_library(flatbuffers)
 
 # Some of the external libraries are not used for mobile.
 if (NOT ANDROID AND NOT IOS)
@@ -98,18 +97,15 @@ if (NOT ANDROID AND NOT IOS)
   if (WIN32)
     set(CMAKE_USE_WINSSL ON CACHE BOOL "")
   endif()
-  add_external_subdirectory(curl)
-  populate_external_source_vars(curl)
+  add_external_library(curl)
 
-  add_external_subdirectory(libuv)
-  populate_external_source_vars(libuv)
+  add_external_library(libuv)
 
   find_package(OpenSSL)
 
-  add_external_subdirectory(zlib)
-  populate_external_source_vars(zlib)
+  add_external_library(zlib)
 
-  populate_external_source_vars(uWebSockets)
+  add_external_library(uWebSockets)
   # uWebSockets does not come with a CMakeLists file, so define the target.
   # Note that since it depends on OpenSSL, only do so if that was found.
   if (OPENSSL_FOUND)
@@ -118,18 +114,18 @@ if (NOT ANDROID AND NOT IOS)
     else()
       # Epoll is only used on Linux, otherwise LibUV is used.
       set(uWebSockets_extra_src
-          ${uWebSockets_SOURCE_DIR}/src/Epoll.cpp)
+          ${UWEBSOCKETS_SOURCE_DIR}/src/Epoll.cpp)
     endif()
     add_library(libuWS STATIC
         ${uWebSockets_extra_src}
-        ${uWebSockets_SOURCE_DIR}/src/Extensions.cpp
-        ${uWebSockets_SOURCE_DIR}/src/Group.cpp
-        ${uWebSockets_SOURCE_DIR}/src/HTTPSocket.cpp
-        ${uWebSockets_SOURCE_DIR}/src/Hub.cpp
-        ${uWebSockets_SOURCE_DIR}/src/Networking.cpp
-        ${uWebSockets_SOURCE_DIR}/src/Node.cpp
-        ${uWebSockets_SOURCE_DIR}/src/Socket.cpp
-        ${uWebSockets_SOURCE_DIR}/src/WebSocket.cpp)
+        ${UWEBSOCKETS_SOURCE_DIR}/src/Extensions.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/Group.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/HTTPSocket.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/Hub.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/Networking.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/Node.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/Socket.cpp
+        ${UWEBSOCKETS_SOURCE_DIR}/src/WebSocket.cpp)
     if(MSVC)
       set(websockets_additional_defines
         -DWIN32_LEAN_AND_MEAN # Ensure that windows doesn't include winsock.h by
@@ -149,10 +145,10 @@ if (NOT ANDROID AND NOT IOS)
     )
     target_include_directories(libuWS
       PUBLIC
-        ${libuv_SOURCE_DIR}/include
-        ${uWebSockets_SOURCE_DIR}
-        ${zlib_SOURCE_DIR}
-        ${zlib_BINARY_DIR}
+        ${LIBUV_SOURCE_DIR}/include
+        ${UWEBSOCKETS_SOURCE_DIR}
+        ${ZLIB_SOURCE_DIR}
+        ${ZLIB_BINARY_DIR}
       PRIVATE
         ${OPENSSL_INCLUDE_DIR}
     )
@@ -167,19 +163,18 @@ if (NOT ANDROID AND NOT IOS)
   find_package(Protobuf)
   if (PROTOBUF_FOUND)
     # NanoPB requires Protobuf to be present, so only add it if it was found.
-    add_external_subdirectory(nanopb)
-    populate_external_source_vars(nanopb)
+    add_external_library(nanopb)
     # NanoPB has a FindNanopb which defines the function to generate files, so
     # add it to the module path, and use that.
-    list(INSERT CMAKE_MODULE_PATH 0 ${nanopb_SOURCE_DIR}/extra)
+    list(INSERT CMAKE_MODULE_PATH 0 ${NANOPB_SOURCE_DIR}/extra)
     find_package(Nanopb)
   endif()
 endif()
 
 if(ANDROID OR IOS)
   # Mobile platforms build flatc externally so that it works on the platform
   # performing the build.
-  set(firebase_external_flatc_build_dir "${flatbuffers_BINARY_DIR}-flatc")
+  set(firebase_external_flatc_build_dir "${FLATBUFFERS_BINARY_DIR}-flatc")
   set(firebase_external_flatc "${firebase_external_flatc_build_dir}/flatc")
 
   if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
@@ -224,7 +219,7 @@ if(ANDROID OR IOS)
   add_custom_command(
     OUTPUT ${firebase_external_flatc}
     COMMAND cd ${firebase_external_flatc_build_dir} ${COMMAND_CONCAT}
-            ${ENV_COMMAND} cmake ${flatbuffers_SOURCE_DIR} ${COMMAND_CONCAT}
+            ${ENV_COMMAND} cmake ${FLATBUFFERS_SOURCE_DIR} ${COMMAND_CONCAT}
             ${ENV_COMMAND} cmake --build . --target flatc
     COMMENT "Building flatc (the FlatBuffer schema compiler)")
 

README.md

@@ -119,6 +119,34 @@ cmake -G “Visual Studio 15 2017” ..
 More information on generators can be found at
 <https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html>.
 
+By default, when building the SDK, the CMake process will download any third
+party dependencies that are needed for the build. This logic is in
+[cmake/external_rules.cmake](/cmake/external_rules.cmake), and the accompanying
+[cmake/external/CMakeLists.txt](/cmake/external/CMakeLists.txt). If you would
+like to provide your own directory for these dependencies, you can override
+`[[dependency_name]]_SOURCE_DIR` and `[[dependency_name]]_BINARY_DIR`. If the
+binary directory is not provided, it defaults to the given source directory,
+appended with `-build`.
+
+For example, to provide a custom flatbuffer directory you could run:
+
+``` bash
+cmake -DFLATBUFFERS_SOURCE_DIR=/tmp/flatbuffers ..
+```
+
+And the binary directory would automatically be set to `/tmp/flatbuffers-build`.
+
+Currently, the third party libraries that can be provided this way are:
+
+| Library |
+| ------- |
+| CURL |
+| FLATBUFFERS |
+| LIBUV |
+| NANOPB |
+| UWEBSOCKETS |
+| ZLIB |
+
 #### Building with CMake for iOS
 The Firebase C++ SDK comes with a CMake config file to build the library for
 iOS platforms, [cmake/ios.cmake](/cmake/ios.cmake).  In order to build with it,

app/CMakeLists.txt

@@ -248,7 +248,7 @@ target_include_directories(firebase_app
     ${FIREBASE_GEN_FILE_DIR}
   PRIVATE
     ${FIREBASE_CPP_SDK_ROOT_DIR}
-    ${flatbuffers_SOURCE_DIR}/include
+    ${FLATBUFFERS_SOURCE_DIR}/include
 )
 target_compile_definitions(firebase_app
   PRIVATE

app/rest/CMakeLists.txt

@@ -42,11 +42,11 @@ add_library(firebase_rest_lib STATIC
 target_include_directories(firebase_rest_lib
   PUBLIC
     ${FIREBASE_CPP_SDK_ROOT_DIR}
-    ${flatbuffers_SOURCE_DIR}/include
-    ${zlib_SOURCE_DIR}/..
-    ${zlib_BINARY_DIR}
+    ${FLATBUFFERS_SOURCE_DIR}/include
+    ${ZLIB_SOURCE_DIR}/..
+    ${ZLIB_BINARY_DIR}
   PRIVATE
-    ${curl_SOURCE_DIR}/include
+    ${CURL_SOURCE_DIR}/include
 )
 
 if(MSVC)

auth/CMakeLists.txt

@@ -167,7 +167,7 @@ if(ANDROID OR IOS)
   set(additional_target_definitions)
 else()
   set(additional_include_DIR
-      ${flatbuffers_SOURCE_DIR}/include
+      ${FLATBUFFERS_SOURCE_DIR}/include
       ${LIBSECRET_INCLUDE_DIRS})
   set(additional_link_LIB
       firebase_rest_lib

cmake/external/curl.cmake

@@ -14,12 +14,10 @@
 
 include(ExternalProject)
 
-if(TARGET curl)
+if(TARGET curl OR NOT DOWNLOAD_CURL)
   return()
 endif()
 
-# TODO(b/117950963): Use a system- or user-supplied curl if available
-
 ExternalProject_Add(
   curl
 
@@ -32,4 +30,4 @@ ExternalProject_Add(
   BUILD_COMMAND ""
   INSTALL_COMMAND ""
   TEST_COMMAND ""
-)
+)

cmake/external/flatbuffers.cmake

@@ -14,7 +14,7 @@
 
 include(ExternalProject)
 
-if(TARGET flatbuffers)
+if(TARGET flatbuffers OR NOT DOWNLOAD_FLATBUFFERS)
   return()
 endif()
 

cmake/external/libuv.cmake

@@ -14,12 +14,10 @@
 
 include(ExternalProject)
 
-if(TARGET libuv)
+if(TARGET libuv OR NOT DOWNLOAD_LIBUV)
   return()
 endif()
 
-# TODO(b/117950963): Use a system- or user-supplied libuv if available
-
 ExternalProject_Add(
   libuv
 
@@ -32,4 +30,4 @@ ExternalProject_Add(
   BUILD_COMMAND ""
   INSTALL_COMMAND ""
   TEST_COMMAND ""
-)
+)

cmake/external/nanopb.cmake

@@ -14,7 +14,7 @@
 
 include(ExternalProject)
 
-if(TARGET nanopb)
+if(TARGET nanopb OR NOT DOWNLOAD_NANOPB)
   return()
 endif()
 
@@ -31,4 +31,4 @@ ExternalProject_Add(
   BUILD_COMMAND ""
   INSTALL_COMMAND ""
   TEST_COMMAND ""
-)
+)

cmake/external/uWebSockets.cmake

@@ -14,12 +14,10 @@
 
 include(ExternalProject)
 
-if(TARGET uWebSockets)
+if(TARGET uWebSockets OR NOT DOWNLOAD_UWEBSOCKETS)
   return()
 endif()
 
-# TODO(b/117950963): Use a system- or user-supplied openssl if available
-
 ExternalProject_Add(
   uWebSockets
 
@@ -32,4 +30,4 @@ ExternalProject_Add(
   BUILD_COMMAND ""
   INSTALL_COMMAND ""
   TEST_COMMAND ""
-)
+)

cmake/external/zlib.cmake

@@ -14,12 +14,10 @@
 
 include(ExternalProject)
 
-if(TARGET zlib)
+if(TARGET zlib OR NOT DOWNLOAD_ZLIB)
   return()
 endif()
 
-# TODO(b/117950963): Use a system- or user-supplied zlib if available
-
 ExternalProject_Add(
   zlib
 
@@ -34,4 +32,4 @@ ExternalProject_Add(
   BUILD_COMMAND ""
   INSTALL_COMMAND ""
   TEST_COMMAND ""
-)
+)

cmake/external_rules.cmake

@@ -36,13 +36,35 @@ function(download_external_sources)
   else()
     set(external_platform DESKTOP)
   endif()
-
+
+  # Set variables to indicate if local versions of third party libraries should
+  # be used instead of downloading them.
+  function(check_use_local_directory NAME)
+    if (EXISTS ${${NAME}_SOURCE_DIR})
+      set(DOWNLOAD_${NAME} OFF PARENT_SCOPE)
+    else()
+      set(DOWNLOAD_${NAME} ON PARENT_SCOPE)
+    endif()
+  endfunction()
+  check_use_local_directory(CURL)
+  check_use_local_directory(FLATBUFFERS)
+  check_use_local_directory(LIBUV)
+  check_use_local_directory(NANOPB)
+  check_use_local_directory(UWEBSOCKETS)
+  check_use_local_directory(ZLIB)
+
   execute_process(
     COMMAND
       ${ENV_COMMAND} cmake
       -DCMAKE_INSTALL_PREFIX=${FIREBASE_INSTALL_DIR}
       -DFIREBASE_DOWNLOAD_DIR=${FIREBASE_DOWNLOAD_DIR}
       -DFIREBASE_EXTERNAL_PLATFORM=${external_platform}
+      -DDOWNLOAD_CURL=${DOWNLOAD_CURL}
+      -DDOWNLOAD_FLATBUFFERS=${DOWNLOAD_FLATBUFFERS}
+      -DDOWNLOAD_LIBUV=${DOWNLOAD_LIBUV}
+      -DDOWNLOAD_NANOPB=${DOWNLOAD_NANOPB}
+      -DDOWNLOAD_UWEBSOCKETS=${DOWNLOAD_UWEBSOCKETS}
+      -DDOWNLOAD_ZLIB=${DOWNLOAD_ZLIB}
       ${PROJECT_SOURCE_DIR}/cmake/external
     OUTPUT_FILE ${PROJECT_BINARY_DIR}/external/output_cmake_config.txt
     WORKING_DIRECTORY ${PROJECT_BINARY_DIR}/external
@@ -60,20 +82,24 @@ function(download_external_sources)
   )
 endfunction()
 
-# Populates directory variables for the given name, to the location that name
-# would be in after a call to download_external_sources.
-function(populate_external_source_vars NAME)
-  set(${NAME}_SOURCE_DIR "${FIREBASE_BINARY_DIR}/external/src/${NAME}"
-      PARENT_SCOPE)
-  set(${NAME}_BINARY_DIR "${FIREBASE_BINARY_DIR}/external/src/${NAME}-build"
-      PARENT_SCOPE)
-endfunction()
+# Populates directory variables for the given name to the location that name
+# would be in after a call to download_external_sources, if the variable is
+# not already a valid directory.
+# Adds the source directory as a subdirectory if a CMakeLists file is found.
+function(add_external_library NAME)
+  string(TOUPPER ${NAME} UPPER_NAME)
+  if (NOT EXISTS ${${UPPER_NAME}_SOURCE_DIR})
+    set(${UPPER_NAME}_SOURCE_DIR "${FIREBASE_BINARY_DIR}/external/src/${NAME}")
+    set(${UPPER_NAME}_SOURCE_DIR "${${UPPER_NAME}_SOURCE_DIR}" PARENT_SCOPE)
+  endif()
 
-# Adds the given library's location as a subdirectory that the caller uses.
-function(add_external_subdirectory NAME)
-  add_subdirectory(
-    ${FIREBASE_BINARY_DIR}/external/src/${NAME}
-    ${FIREBASE_BINARY_DIR}/external/src/${NAME}-build
-    EXCLUDE_FROM_ALL
-  )
-endfunction()
+  if (NOT EXISTS ${${UPPER_NAME}_BINARY_DIR})
+    set(${UPPER_NAME}_BINARY_DIR "${${UPPER_NAME}_SOURCE_DIR}-build")
+    set(${UPPER_NAME}_BINARY_DIR "${${UPPER_NAME}_BINARY_DIR}" PARENT_SCOPE)
+  endif()
+
+  if (EXISTS "${${UPPER_NAME}_SOURCE_DIR}/CMakeLists.txt")
+    add_subdirectory(${${UPPER_NAME}_SOURCE_DIR} ${${UPPER_NAME}_BINARY_DIR}
+                     EXCLUDE_FROM_ALL)
+  endif()
+endfunction()

database/CMakeLists.txt

@@ -134,9 +134,9 @@ if(ANDROID OR IOS)
   set(additional_DEFINES)
 else()
   set(additional_include_DIR
-      ${flatbuffers_SOURCE_DIR}/include
+      ${FLATBUFFERS_SOURCE_DIR}/include
       ${OPENSSL_INCLUDE_DIR}
-      ${uWebSockets_SOURCE_DIR}/..)
+      ${UWEBSOCKETS_SOURCE_DIR}/..)
 
   set(additional_link_LIB
       flatbuffers

messaging/CMakeLists.txt

@@ -97,7 +97,7 @@ target_include_directories(firebase_messaging
 if(ANDROID)
   target_include_directories(firebase_messaging
     PRIVATE
-      ${flatbuffers_SOURCE_DIR}/include
+      ${FLATBUFFERS_SOURCE_DIR}/include
   )
 endif()
 target_compile_definitions(firebase_messaging

remote_config/CMakeLists.txt

@@ -76,7 +76,7 @@ if(ANDROID OR IOS OR use_stub)
   set(additional_link_LIB)
 else()
   set(additional_include_DIR
-      ${flatbuffers_SOURCE_DIR}/include
+      ${FLATBUFFERS_SOURCE_DIR}/include
       ${NANOPB_INCLUDE_DIRS}
       ${PROJECT_BINARY_DIR}/..)
   set(additional_link_LIB