CMake: Make it easier for projects to consume sandboxed libraries

This change starts with Jsonnet as the canonical, ready-made sandboxed library
example. Follow-up changes should similarly migrate the OSS Internship
sandboxes.

- Add an `add_sapi_subdirectory()` which sets up source and binary directories
  correctly when consuming SAPI as sub-project
- Restructure the Jsonnet `CMakeLists.txt` and simplify header inclusions
- Update the Jsonnet README file

PiperOrigin-RevId: 425818479
Change-Id: Iba9e83201863b4ad8a91914397b310d9d4230423

cmake/SapiUtil.cmake

@@ -189,3 +189,14 @@ function(sapi_protobuf_generate)
     target_sources(${_pb_TARGET} PRIVATE ${_generated_srcs_all})
   endif()
 endfunction()
+
+# Adds a sub-directory from Sandboxed API to the build. This is a simple macro
+# that calls `add_subdirectory()` with Sandboxed API's source and binary
+# directories and `EXCLUDE_FROM_ALL`.
+# This is useful in embedding projects to be able to refer to pre-sandboxed
+# libraries easily.
+macro(add_sapi_subdirectory)
+  add_subdirectory("${SAPI_SOURCE_DIR}/${ARGV0}"
+                   "${SAPI_BINARY_DIR}/${ARGV0}"
+                   EXCLUDE_FROM_ALL)
+endmacro()

contrib/README.md

@@ -3,6 +3,12 @@
 This directory contains reusable Sandboxed API integrations with external
 libraries.
 
+## Projects Sandboxed
+
+Directory  | Project                                | Home Page                                                      | Integration
+---------- | -------------------------------------- | -------------------------------------------------------------- | -----------
+`jsonnet/` | Jsonnet - The Data Templating Language | [github.com/google/jsonnet](https://github.com/google/jsonnet) | CMake
+
 ## Projects Shipping with Sandboxed API Sandboxes
 
 Project                                 | Home Page                                                        | Integration

contrib/jsonnet/CMakeLists.txt

@@ -18,11 +18,12 @@ project(jsonnet-sapi C CXX)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED True)
 
-set(SAPI_ROOT "../.." CACHE PATH "Path to the Sandboxed API source tree")
+if(NOT TARGET sapi::sapi)
-
+  set(SAPI_ROOT "../.." CACHE PATH "Path to the Sandboxed API source tree")
-add_subdirectory("${SAPI_ROOT}"
+  add_subdirectory("${SAPI_ROOT}"
                    "${CMAKE_BINARY_DIR}/sandboxed-api-build"
                    EXCLUDE_FROM_ALL)
+endif()
 
 FetchContent_Declare(jsonnet
   GIT_REPOSITORY https://github.com/google/jsonnet.git
@@ -33,7 +34,32 @@ FetchContent_MakeAvailable(jsonnet)
 create_directory_symlink("${jsonnet_SOURCE_DIR}"
                          "${PROJECT_BINARY_DIR}/jsonnet")
 
-add_subdirectory(examples)
+configure_file("${jsonnet_SOURCE_DIR}/cmd/jsonnet.cpp"
+               "${PROJECT_BINARY_DIR}/gen_files/jsonnet.cpp" COPYONLY)
+
+add_custom_command(
+  OUTPUT "${PROJECT_BINARY_DIR}/gen_files/write_helper.cc"
+  WORKING_DIRECTORY "${PROJECT_BINARY_DIR}/gen_files"
+  COMMAND patch -o write_helper.cc
+            < "${PROJECT_SOURCE_DIR}/jsonnet.patch" > /dev/null
+)
+
+add_library(jsonnet_helper STATIC
+  "${PROJECT_BINARY_DIR}/gen_files/write_helper.cc"
+  "${jsonnet_SOURCE_DIR}/cmd/utils.cpp"
+  "${jsonnet_SOURCE_DIR}/cmd/utils.h"
+  jsonnet_helper.cc
+  jsonnet_helper.h
+)
+add_library(sapi_contrib::jsonnet_helper ALIAS jsonnet_helper)
+target_include_directories(jsonnet_helper PUBLIC
+  "${PROJECT_BINARY_DIR}"
+  "${PROJECT_BINARY_DIR}/gen_files"
+  "${SAPI_SOURCE_DIR}"
+)
+target_link_libraries(jsonnet_helper
+  libjsonnet_for_binaries
+)
 
 add_sapi_library(jsonnet_sapi
   FUNCTIONS c_free_input
@@ -53,12 +79,17 @@ add_sapi_library(jsonnet_sapi
   LIBRARY_NAME Jsonnet
   NAMESPACE ""
 )
-
+add_library(sapi_contrib::jsonnet ALIAS jsonnet_sapi)
 target_include_directories(jsonnet_sapi INTERFACE
   "${PROJECT_BINARY_DIR}"
 )
+target_link_libraries(jsonnet_sapi PUBLIC
+  sapi_contrib::jsonnet_helper
+)
 
-target_link_libraries(jsonnet_sapi PUBLIC jsonnet_helper)
+if(SAPI_ENABLE_EXAMPLES)
+  add_subdirectory(examples)
+endif()
 
 if(SAPI_ENABLE_TESTS)
   include(GoogleTest)
@@ -80,10 +111,10 @@ if(SAPI_ENABLE_TESTS)
     jsonnet_tests.cc
   )
   target_include_directories(jsonnet_tests PUBLIC
-    ${PROJECT_SOURCE_DIR}
+    "${PROJECT_SOURCE_DIR}"
   )
   target_link_libraries(jsonnet_tests
-    jsonnet_sapi
+    sapi_contrib::jsonnet
     sapi::test_main
   )
   gtest_discover_tests(jsonnet_tests)

contrib/jsonnet/README.md

@@ -3,6 +3,29 @@
 This library provides a sandboxed version of the
 [Jsonnet](https://github.com/google/jsonnet) library.
 
+## How to use from an existing Project
+
+If your project does not include Sandboxed API as a dependency yet, add the
+following lines to the main `CMakeLists.txt`:
+
+```cmake
+include(FetchContent)
+
+FetchContent_Declare(sandboxed-api
+  GIT_REPOSITORY https://github.com/google/sandboxed-api
+  GIT_TAG        main  # Or pin a specific commit/tag
+)
+FetchContent_MakeAvailable(sandboxed-api)  # CMake 3.14 or higher
+
+add_sapi_subdirectory(contrib/jsonnet)
+```
+
+The `add_sapi_subdirectory()` macro sets up the source and binary directories
+for the sandboxed jsonnet targets.
+
+Afterwards your project's code can link to `sapi_contrib::jsonnet` and use the
+corresponding header `contrib/jsonnet/jsonnet_base_sandbox.h`.
+
 ## Examples
 
 The `examples/` directory contains code to produce three command-line tools --
@@ -20,10 +43,10 @@ executable. It is based on a tool found from
 a jsonnet code formatter -- it changes poorly written jsonnet files into their
 canonical form.
 
-## Build
+### Build as part of Sandboxed API
 
-To build these examples, after cloning the whole Sandbox API project, this
+To build these examples, after cloning the whole Sandbox API project, run this
-in the `sandboxed-api/oss-internship-2020/jsonnet`:
+in the `contrib/jsonnet` directory:
 
 ```
 mkdir -p build && cd build
@@ -66,7 +89,7 @@ The formatter reads one input file and produces one output file as a result.
 Example code for this tool can also be found in `examples/jsonnet_codes`
 directory, in a file called `formatter_example.jsonnet`.
 
-## Testing
+### Running the tests
 
 A few tests prepared with a use of
 [Google Test](https://github.com/google/googletest) framework are included. To

contrib/jsonnet/examples/CMakeLists.txt

@@ -12,55 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-configure_file("${jsonnet_SOURCE_DIR}/cmd/jsonnet.cpp"
-               "${PROJECT_BINARY_DIR}/gen_files/jsonnet.cpp" COPYONLY)
-
-add_custom_command(
-  OUTPUT "${PROJECT_BINARY_DIR}/gen_files/write_helper.cc"
-  WORKING_DIRECTORY "${PROJECT_BINARY_DIR}/gen_files"
-  COMMAND patch -o write_helper.cc
-            < "${PROJECT_SOURCE_DIR}/jsonnet.patch" > /dev/null
-)
-
-list(APPEND JSONNET_SAPI_INCLUDE_DIRS
-  ${PROJECT_SOURCE_DIR}
-  ${PROJECT_BINARY_DIR}
-  ${PROJECT_BINARY_DIR}/gen_files
-)
-
-add_library(jsonnet_helper STATIC
-  ${PROJECT_SOURCE_DIR}/jsonnet_helper.cc
-  ${PROJECT_SOURCE_DIR}/jsonnet_helper.h
-  ${jsonnet_SOURCE_DIR}/cmd/utils.h
-  ${jsonnet_SOURCE_DIR}/cmd/utils.cpp
-  ${PROJECT_BINARY_DIR}/gen_files/write_helper.cc
-)
-
-target_include_directories(jsonnet_helper PUBLIC
-  ${JSONNET_SAPI_INCLUDE_DIRS}
-)
-
-target_link_libraries(jsonnet_helper
-  libjsonnet_for_binaries
-)
-
 foreach(target IN ITEMS base multiple_files yaml_stream formatter)
   add_executable(jsonnet_${target}_sandboxed
     jsonnet_${target}_example.cc
   )
-
   target_link_libraries(jsonnet_${target}_sandboxed PRIVATE
     libjsonnet
-    jsonnet_helper
+    sapi_contrib::jsonnet_helper
-    jsonnet_sapi
+    sapi_contrib::jsonnet
     sapi::file_base
     sapi::fileops
     sapi::sapi
   )
-
-  target_include_directories(jsonnet_${target}_sandboxed PUBLIC
-    ${JSONNET_SAPI_INCLUDE_DIRS}
-  )
 endforeach()
 
 add_executable(jsonnet_base_transacted
@@ -69,7 +32,7 @@ add_executable(jsonnet_base_transacted
 
 target_link_libraries(jsonnet_base_transacted PRIVATE
   libjsonnet
-  jsonnet_helper
+  sapi_contrib::jsonnet_helper
-  jsonnet_sapi
+  sapi_contrib::jsonnet
   sapi::sapi
 )

contrib/jsonnet/examples/jsonnet_base_example.cc

@@ -15,7 +15,7 @@
 #include <cstdlib>
 #include <iostream>
 
-#include "jsonnet_base_sandbox.h"  // NOLINT(build/include)
+#include "contrib/jsonnet/jsonnet_base_sandbox.h"
 #include "sandboxed_api/util/fileops.h"
 #include "sandboxed_api/util/path.h"
 

contrib/jsonnet/examples/jsonnet_base_transaction.cc

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "jsonnet_base_transaction.h"  // NOLINT(build/include)
+#include "contrib/jsonnet/jsonnet_base_transaction.h"
 
 #include "sandboxed_api/util/fileops.h"
 #include "sandboxed_api/util/path.h"

contrib/jsonnet/examples/jsonnet_formatter_example.cc

@@ -19,7 +19,6 @@
 #include <iostream>
 
 #include "jsonnet_sapi.sapi.h"  // NOLINT(build/include)
-#include "sandboxed_api/util/flag.h"
 #include "sandboxed_api/util/fileops.h"
 #include "sandboxed_api/util/path.h"
 

contrib/jsonnet/examples/jsonnet_multiple_files_example.cc

@@ -19,7 +19,6 @@
 #include <iostream>
 
 #include "jsonnet_sapi.sapi.h"  // NOLINT(build/include)
-#include "sandboxed_api/util/flag.h"
 #include "sandboxed_api/util/fileops.h"
 #include "sandboxed_api/util/path.h"
 

contrib/jsonnet/examples/jsonnet_yaml_stream_example.cc

@@ -15,7 +15,7 @@
 #include <cstdlib>
 #include <iostream>
 
-#include "jsonnet_base_sandbox.h"  // NOLINT(build/include)
+#include "contrib/jsonnet/jsonnet_base_sandbox.h"
 #include "sandboxed_api/util/fileops.h"
 #include "sandboxed_api/util/path.h"
 

contrib/jsonnet/jsonnet.patch

@@ -20,7 +20,7 @@
  #include <vector>
  
 -#include "utils.h"
-+#include "jsonnet_helper.h"  // NOLINT(build/include)
++#include "contrib/jsonnet/jsonnet_helper.h"
  
 -extern "C" {
 -#include <libjsonnet.h>

contrib/jsonnet/jsonnet_base_sandbox.h

@@ -23,7 +23,6 @@
 #include <utility>
 
 #include "jsonnet_sapi.sapi.h"  // NOLINT(build/include)
-#include "sandboxed_api/util/flag.h"
 #include "sandboxed_api/transaction.h"
 #include "sandboxed_api/vars.h"
 
@@ -33,7 +32,7 @@ class JsonnetBaseSandbox : public JsonnetSandbox {
       : in_file_(std::move(in_file)), out_file_(std::move(out_file)) {}
 
   std::unique_ptr<sandbox2::Policy> ModifyPolicy(
-      sandbox2::PolicyBuilder *) override {
+      sandbox2::PolicyBuilder*) override {
     return sandbox2::PolicyBuilder()
         .AllowStaticStartup()
         .AllowOpen()

contrib/jsonnet/jsonnet_helper.cc

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include "jsonnet_helper.h"  // NOLINT(build/include)
+#include "contrib/jsonnet/jsonnet_helper.h"
 
 #include <cstring>
 

contrib/jsonnet/jsonnet_helper.h

@@ -12,17 +12,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef CONTRIB_JSONNET_HELPER_H_
+#ifndef CONTRIB_JSONNET_JSONNET_HELPER_H_
-#define CONTRIB_JSONNET_HELPER_H_
+#define CONTRIB_JSONNET_JSONNET_HELPER_H_
 
 extern "C" {
-#include <libjsonnet.h>      // NOLINT(build/include)
+#include <libjsonnet.h>
-#include <libjsonnet_fmt.h>  // NOLINT(build/include)
+#include <libjsonnet_fmt.h>
 }
 
 #include "jsonnet/cmd/utils.h"  // NOLINT(build/include)
 
 extern "C" {
+
 struct JsonnetVm* c_jsonnet_make(void);
 
 void c_jsonnet_destroy(struct JsonnetVm* vm);
@@ -60,4 +61,4 @@ char* c_jsonnet_fmt_snippet(struct JsonnetVm* vm, const char* filename,
                             const char* snippet, int* error);
 }
 
-#endif  // CONTRIB_JSONNET_HELPER_H_
+#endif  // CONTRIB_JSONNET_JSONNET_HELPER_H_

contrib/jsonnet/jsonnet_tests.cc

@@ -20,10 +20,8 @@
 #include <streambuf>
 #include <string>
 
-#include "jsonnet_base_sandbox.h"  // NOLINT(build/include)
-#include "jsonnet_sapi.sapi.h"     // NOLINT(build/include)
 #include "gtest/gtest.h"
-#include "sandboxed_api/util/flag.h"
+#include "contrib/jsonnet/jsonnet_base_sandbox.h"
 #include "sandboxed_api/util/path.h"
 #include "sandboxed_api/util/status_matchers.h"