prepare 2.7.0 release

.circleci/config.yml

@@ -152,12 +152,20 @@ jobs:
           command: |
             apt-get update -y
             apt-get install -y \
+              gpg \
+              wget \
               libcurl4-openssl-dev \
               libpcre3-dev \
               libhiredis-dev \
               build-essential \
-              cmake \
               git
+      - run:
+          name: Obtain recent 32-bit cmake from Kitware # Ubuntu repositories only contain cmake 3.10; we require >= 3.11.
+          command: |
+            wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | tee /usr/share/keyrings/kitware-archive-keyring.gpg >/dev/null
+            echo 'deb [signed-by=/usr/share/keyrings/kitware-archive-keyring.gpg] https://apt.kitware.com/ubuntu/ bionic main' | tee /etc/apt/sources.list.d/kitware.list >/dev/null
+            apt-get update -y
+            apt-get install -y cmake
       - run:
           name: Build
           command: |

.ldrelease/config.yml

@@ -7,7 +7,7 @@ repo:
 jobs:
   - circleCI:
       linux:
-        image: ldcircleci/ld-c-sdk-ubuntu:2  # defined in sdks-ci-docker project
+        image: ldcircleci/ld-c-sdk-ubuntu:3  # defined in sdks-ci-docker project
     env:
       LD_LIBRARY_FILE_PREFIX: linux-gcc-64bit
   - circleCI:

CMakeFiles/README.md

@@ -0,0 +1,96 @@
+## 3rd Party Dependency Strategy
+
+Dependency management for the `c-server-sdk` is complicated by a few factors:
+- The codebase for the SDK is written in C89 style
+- Many libraries that could be of use are written in C99
+- Libraries may use a variety of build systems, be hosted in a variety of places, using a variety of protocols.
+
+Therefore, a flexible approach is necessary. 
+
+## History
+
+The `third-party` directory was previously host to a collection of single-purpose C libraries, with patches
+applied directly to source.
+
+Additional system-level packages were found using cmake's `find_package()`, while other libraries were pulled in via 
+cmake's `FetchContent`.
+
+As of the commit that introduced this README, the dependencies living in `third-party` have been removed 
+in favor of `FetchContent`. The historical patches made directly to source have been extracted into diffs that can be applied
+on top of the downloaded sources. 
+
+
+## Strategy 1: find_package()
+
+See: `FindXXX.cmake`
+
+
+The `CURL` and `PCRE` packages are found on the host system via cmake Find Modules.
+
+`FindCURL` is [distributed with cmake](https://cmake.org/cmake/help/latest/manual/cmake-modules.7.html),
+whereas `FindPCRE` is distributed with this SDK.
+
+## Strategy 2: FetchContent
+
+See: `XXX.cmake`
+
+The SDK utilizes a collection of focused 3rd party C libraries. Some of these need to be patched
+to be useful for the SDK.
+
+These libraries are downloaded via cmake's `FetchContent` capability, which was introduced
+in cmake 3.11. 
+
+The `FetchContent_MakeAvailable` was introduced in cmake 3.14. This command is convenient for use with
+projects supporting cmake, as it exposes those projects' targets, 
+significantly reducing `CMakeLists.txt` boilerplate. 
+
+Most of the libraries used by the SDK do not support cmake, so the `XXX.cmake` files
+in this repo need to setup the targets manually. If the upstream repos provided such targets, it would be 
+possible to remove that boilerplate in favor of `FetchContent_MakeAvailable`.
+
+Therefore, cmake 3.11 is sufficient for the time being. 
+
+For reference:
+- Ubuntu 18.04 ships with cmake 3.10
+- Ubuntu 20.04 ships with cmake 3.16
+
+Recent cmake versions can be obtained directly from [Kitware](https://cmake.org/download/).
+
+## Updating dependencies
+
+To upgrade one of the dependencies here, update the `GIT_TAG` hash. 
+
+Note: use a hash, not a tag - tags are not immutable.
+
+Problem: cmake errors when changing the `GIT_TAG`.
+
+Solution: remove build directory and rerun cmake. Because the `UPDATE_COMMAND` is set to `""`, cmake
+won't be able to update the dependency when you modify the tag, and instead it should be fetched again. See below.
+
+## Patching dependencies 
+
+The libraries are patched using diffs found in the `patches` directory.
+
+These patches were extracted from the vendored version of these libraries by comparison with the upstream
+upstream repos.
+
+If the upstream repo changes due to an update of `GIT_TAG`, the patch may need to be regenerated.
+
+The `PATCH_COMMAND` step in `FetchContent_Declare` will fail if applied more than once to the downloaded sources
+(since the patch has already been applied.)
+This command was intended by cmake authors to be used for patching artifacts, rather than git repos, so
+this usage is inherently fragile. 
+
+To suppress the errors that would otherwise be caused by applying the patches multiple times
+whenever cmake reruns, the `UPDATE_COMMAND` is set to `""` - meaning disabled. This in turn should disable 
+the patch step from running again after its initial run.
+
+A better solution would be to maintain dedicated forks of each repository, such that `FetchContent` can obtain
+the source directly without patching.
+
+There are various bugs/race-conditions in the interaction of `FetchContent` and `ExternalProject` (implementation of `FetchContent`)
+which may cause spurious failures in CI. It remains to be seen how much of a problem this will be, and it may be solved
+by upgrading the cmake version on all hosts.
+
+
+

CMakeFiles/hexify.cmake

@@ -0,0 +1,17 @@
+FetchContent_Declare(hexify
+    GIT_REPOSITORY https://github.com/pepaslabs/hexify.c
+    GIT_TAG "f823bd619f73584a75829cc1e44a532f5e09336e"
+    CONFIGURE_COMMAND ""
+    UPDATE_COMMAND "" # patching will fail if applied more than once; disable updates.
+    PATCH_COMMAND git apply "${PROJECT_SOURCE_DIR}/patches/hexify.patch"
+)
+
+FetchContent_GetProperties(hexify)
+if(NOT hexify_POPULATED)
+    FetchContent_Populate(hexify)
+endif()
+
+add_library(hexify STATIC ${hexify_SOURCE_DIR}/hexify.c)
+target_include_directories(hexify PUBLIC ${hexify_SOURCE_DIR})
+
+

contract-tests/lib/external/httplib/CMakeLists.txt.in → CMakeFiles/httplib.cmake

@@ -1,18 +1,11 @@
-cmake_minimum_required(VERSION 3.10)
-
-project(httplib-download NONE)
-
 set(HTTPLIB_USE_OPENSSL_IF_AVAILABLE OFF)
 set(HTTPLIB_COMPILE ON)
 
-include(ExternalProject)
-ExternalProject_Add(httplib
+FetchContent_Declare(httplib
         GIT_REPOSITORY    https://github.com/yhirose/cpp-httplib.git
         GIT_TAG           v0.10.2
         SOURCE_DIR        "${CMAKE_BINARY_DIR}/httplib-src"
         BINARY_DIR        "${CMAKE_BINARY_DIR}/httplib-build"
-        CONFIGURE_COMMAND ""
-        BUILD_COMMAND     ""
-        INSTALL_COMMAND   ""
-        TEST_COMMAND      ""
-        )
+)
+
+FetchContent_MakeAvailable(httplib)

contract-tests/lib/external/json/CMakeLists.txt → CMakeFiles/json.cmake

@@ -8,8 +8,4 @@ FetchContent_Declare(json
   URL https://github.com/nlohmann/json/releases/download/v3.10.5/json.tar.xz
 )
 
-FetchContent_GetProperties(json)
-if(NOT json_POPULATED)
-  FetchContent_Populate(json)
-  add_subdirectory(${json_SOURCE_DIR} ${json_BINARY_DIR} EXCLUDE_FROM_ALL)
-endif()
+FetchContent_MakeAvailable(json)

CMakeFiles/semver.cmake

@@ -0,0 +1,17 @@
+FetchContent_Declare(semver
+    GIT_REPOSITORY https://github.com/h2non/semver.c
+    GIT_TAG "bd1db234a68f305ed10268bd023df1ad672061d7"
+    CONFIGURE_COMMAND ""
+    UPDATE_COMMAND "" # patching will fail if applied more than once; disable updates.
+    PATCH_COMMAND git apply "${PROJECT_SOURCE_DIR}/patches/semver.patch"
+)
+
+FetchContent_GetProperties(semver)
+if(NOT semver_POPULATED)
+    FetchContent_Populate(semver)
+endif()
+
+add_library(semver STATIC ${semver_SOURCE_DIR}/semver.c)
+target_include_directories(semver PUBLIC ${semver_SOURCE_DIR})
+
+

CMakeFiles/sha1.cmake

@@ -0,0 +1,13 @@
+FetchContent_Declare(sha1
+    GIT_REPOSITORY https://github.com/clibs/sha1
+    GIT_TAG "fa1d96ec293d2968791603548125e3274bd6b472"
+    CONFIGURE_COMMAND ""
+)
+
+FetchContent_GetProperties(sha1)
+if(NOT sha1_POPULATED)
+    FetchContent_Populate(sha1)
+endif()
+
+add_library(sha1 STATIC ${sha1_SOURCE_DIR}/sha1.c)
+target_include_directories(sha1 PUBLIC ${sha1_SOURCE_DIR})

CMakeFiles/timestamp.cmake

@@ -0,0 +1,20 @@
+FetchContent_Declare(timestamp
+    GIT_REPOSITORY https://github.com/chansen/c-timestamp
+    GIT_TAG "b205c407ae6680d23d74359ac00444b80989792f"
+    CONFIGURE_COMMAND ""
+    UPDATE_COMMAND "" # patching will fail if applied more than once; disable updates.
+    PATCH_COMMAND git apply "${PROJECT_SOURCE_DIR}/patches/timestamp.patch"
+)
+
+FetchContent_GetProperties(timestamp)
+if(NOT timestamp_POPULATED)
+    FetchContent_Populate(timestamp)
+endif()
+
+add_library(timestamp STATIC
+    ${timestamp_SOURCE_DIR}/timestamp_compare.c
+    ${timestamp_SOURCE_DIR}/timestamp_parse.c
+)
+target_include_directories(timestamp PUBLIC ${timestamp_SOURCE_DIR})
+
+

CMakeFiles/uthash.cmake

@@ -0,0 +1,15 @@
+FetchContent_Declare(uthash
+    URL https://github.com/troydhanson/uthash/archive/v2.3.0.tar.gz
+    URL_HASH SHA256=e10382ab75518bad8319eb922ad04f907cb20cccb451a3aa980c9d005e661acc
+    CONFIGURE_COMMAND ""
+)
+
+FetchContent_GetProperties(uthash)
+if(NOT uthash_POPULATED)
+    FetchContent_Populate(uthash)
+endif()
+
+add_library(uthash INTERFACE)
+target_include_directories(uthash INTERFACE ${uthash_SOURCE_DIR}/src)
+
+

CMakeLists.txt

@@ -1,9 +1,21 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.11)
 
 project(ldserverapi)
 
+
+include(FetchContent)
+
+include(CMakeFiles/uthash.cmake)
+include(CMakeFiles/hexify.cmake)
+include(CMakeFiles/semver.cmake)
+include(CMakeFiles/sha1.cmake)
+include(CMakeFiles/timestamp.cmake)
+
+
 include(CTest)
 
+
+
 if(BUILD_TESTING)
     set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
     configure_file(external/googletest/CMakeLists.txt.in
@@ -35,6 +47,7 @@ if (COVERAGE)
     setup_target_for_coverage_gcovr_html(NAME coverage)
 endif (COVERAGE)
 
+
 find_package(CURL REQUIRED)
 find_package(PCRE REQUIRED)
 
@@ -44,7 +57,6 @@ endif()
 
 set(LD_INCLUDE_PATHS
     "src"
-    "third-party/include"
     "c-sdk-common/include"
     "c-sdk-common/src"
     ${CURL_INCLUDE_DIR}
@@ -73,7 +85,16 @@ set(LD_LIBRARIES ${LD_LIBRARIES} ${CURL_LIBRARIES} ${PCRE_LIBRARIES})
 
 add_library(ldserverapi ${SOURCES})
 
-target_link_libraries(ldserverapi PRIVATE ${LD_LIBRARIES})
+
+target_link_libraries(ldserverapi
+    PRIVATE
+        uthash
+        hexify
+        semver
+        sha1
+        timestamp
+        ${LD_LIBRARIES}
+)
 
 target_include_directories(ldserverapi
     PUBLIC  "include"
@@ -141,12 +162,17 @@ if(BUILD_TESTING)
 
     add_library(test-utils STATIC ${TEST_UTILS_SRC})
 
-    target_link_libraries(test-utils ldserverapi)
+    target_link_libraries(test-utils PRIVATE ldserverapi )
 
     target_include_directories(test-utils
-        PUBLIC ${LD_INCLUDE_PATHS}
+        PUBLIC
                "test-utils/include"
                "c-sdk-common/test-utils/include"
+                $<TARGET_PROPERTY:ldserverapi,INCLUDE_DIRECTORIES> # Some of the internal headers of ldserverapi
+                # include 3rd party dependencies, which are not part of the public interface of the SDK. Therefore
+                # any test code that imports these internal headers, for testing purposes, will need access to those
+                # 3rd party includes. The INCLUDE_DIRECTORIES property of target ldserverapi includes both the public
+                # and private headers, so propagate them here.
     )
 
     target_compile_definitions(test-utils

README.md

@@ -20,6 +20,41 @@ This version of the LaunchDarkly SDK is compatible with POSIX environments (Linu
 
 Download a release archive from the [GitHub Releases](https://github.com/launchdarkly/c-server-sdk/releases) for use in your project. Refer to the [SDK documentation](https://docs.launchdarkly.com/sdk/server-side/c-c--#getting-started) for complete instructions on getting started with using the SDK.
 
+## CMake Compatability
+
+Currently, the minimum required version of CMake necessary to build the SDK is 3.11. 
+
+At configuration time, CMake will download various 3rd party dependencies of the SDK from remote locations.
+
+Other dependencies must be present on the build host:
+- `CURL` (`FindPackage(CURL)`)
+- `PCRE` (`FindPackage(PCRE)`)
+
+The project uses C++ for unit testing. 
+To exclude the unit tests from the build, disable via CMake option:
+```
+-DBUILD_TESTING=OFF
+```
+To enable the Redis store integration, enable via CMake option:
+```
+-DREDIS_STORE=ON
+```
+
+The SDK may be included in another project via `add_subdirectory`. 
+For example, 
+```
+add_subdirectory(c-server-sdk)
+add_executable(main main.c)
+target_link_libraries(main ldserverapi)
+```
+
+It is also possible to install the SDK to a desired location, for example:
+```
+mkdir build && cd build
+cmake .. -DCMAKE_INSTALL_PREFIX=/path/to/desired/install/location
+cmake --build . --target install
+```
+
 ## Learn more
 
 Read our [documentation](https://docs.launchdarkly.com) for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the [complete reference guide for this SDK](https://docs.launchdarkly.com/docs/c-server-sdk-reference).