git clone + brittle ID calculation.

.drone.yml

@@ -26,7 +26,7 @@ steps:
   - alias apt-get='rm -f /var/cache/apt/archives/lock && apt-get'
   - apt-get update -q
   - apt-get install -qq build-essential cmake g++-10 clang pkg-config
-  - apt-get install -qq catch libcgicc-dev nlohmann-json3-dev
+  - apt-get install -qq catch libcgicc-dev nlohmann-json3-dev libgit2-dev
   - rm -rf build && mkdir -p build && cd build
   - cmake -G "Unix Makefiles" -DWITH_TESTS=YES ..
   - make VERBOSE=1
@@ -62,7 +62,7 @@ steps:
   - alias apt-get='rm -f /var/cache/apt/archives/lock && apt-get'
   - apt-get update -q
   - apt-get install -qq build-essential cmake clang pkg-config
-  - apt-get install -qq catch libcgicc-dev nlohmann-json-dev
+  - apt-get install -qq catch libcgicc-dev nlohmann-json-dev libgit2-dev
   - rm -rf build && mkdir -p build && cd build
   - cmake -G "Unix Makefiles" -DWITH_TESTS=YES ..
   - make VERBOSE=1

CMakeLists.txt

@@ -39,6 +39,7 @@ find_package(PkgConfig REQUIRED)
 pkg_check_modules(cgicc REQUIRED IMPORTED_TARGET cgicc)
 find_package(nlohmann_json REQUIRED CONFIG)
 find_package(Filesystem REQUIRED COMPONENTS Final Experimental)
+pkg_check_modules(libgit2 REQUIRED IMPORTED_TARGET libgit2)
 
 add_subdirectory(src)
 

README.adoc

@@ -14,6 +14,7 @@
 :uri-clang-tidy: https://clang.llvm.org/extra/clang-tidy/
 :uri-cgicc: https://www.gnu.org/software/cgicc/
 :uri-nlohmann-json: https://nlohmann.github.io/json/
+:uri-libgit2: https://libgit2.org/
 
 *{project}* turns form data into JSON and opens a pull request on
 link:https://schlomp.space/FediBlock/data[FediBlock/data].
@@ -30,6 +31,7 @@ link:https://schlomp.space/FediBlock/data[FediBlock/data].
 * link:{uri-cmake}[CMake] (at least: 3.9)
 * link:{uri-cgicc}[cgicc] (tested: 3.2)
 * link:{uri-nlohmann-json}[nlohmann-json] (tested: 3.7 / 2.1)
+* link:{uri-libgit2}[libgit2] (tested: 1.0 / 0.27)
 * Optional
   ** Tests: link:{uri-catch}[Catch] (tested: 2.5 / 1.10)
   ** DEB package: link:{uri-dpkg}[dpkg] (tested: 1.19)

src/CMakeLists.txt

@@ -15,7 +15,7 @@ target_include_directories(${PROJECT_NAME}
   PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
 
 target_link_libraries(${PROJECT_NAME}
-  PRIVATE PkgConfig::cgicc nlohmann_json std::filesystem)
+  PRIVATE PkgConfig::cgicc nlohmann_json std::filesystem PkgConfig::libgit2)
 
 install(TARGETS ${PROJECT_NAME}
   RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")

src/git.cpp

@@ -0,0 +1,89 @@
+/*  This file is part of FediBlock-backend.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "git.hpp"
+#include "files.hpp"
+
+#include <cstdint>
+#include <git2/branch.h>
+#include <git2/clone.h>
+#include <git2/errors.h>
+#include <git2/global.h>
+#include <git2/types.h>
+
+#include <stdexcept>
+#include <string>
+#include <string_view>
+
+namespace FediBlock
+{
+
+using std::runtime_error;
+using std::stoull;
+using std::string;
+using std::string_view;
+using std::uint64_t;
+
+git_repository *_repo = nullptr;
+
+void clone_repo()
+{
+    int error = git_clone(&_repo, "https://schlomp.space/FediBlock/data.git",
+                          (get_tmpdir() / "repo").c_str(), nullptr);
+    if (error < 0)
+    {
+        const git_error *e = git_error_last();
+        throw runtime_error{e->message};
+    }
+}
+
+uint64_t get_last_id()
+{
+    constexpr string_view branch_prefix{"from-web-"};
+    uint64_t id{0};
+
+    git_branch_iterator *it;
+    if (git_branch_iterator_new(&it, _repo, GIT_BRANCH_ALL) == 0)
+    {
+        git_reference *ref;
+        git_branch_t type;
+        while (git_branch_next(&ref, &type, it) == 0)
+        {
+            const char *out{nullptr};
+            git_branch_name(&out, ref);
+            if (type == GIT_BRANCH_REMOTE)
+            {
+                const string branch_name{out};
+                size_t pos{branch_name.find(branch_prefix)};
+                if (pos != string::npos)
+                {
+                    pos += branch_prefix.size();
+                    uint64_t newid{stoull(branch_name.substr(pos))};
+                    if (newid > id)
+                    {
+                        id = newid;
+                    }
+                }
+            }
+            git_reference_free(ref);
+        }
+        git_branch_iterator_free(it);
+    }
+
+    return id;
+}
+
+} // namespace FediBlock

src/git.hpp

@@ -0,0 +1,42 @@
+/*  This file is part of FediBlock-backend.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef FEDIBLOCK_BACKEND_GIT_HPP
+#define FEDIBLOCK_BACKEND_GIT_HPP
+
+#include <cstdint>
+
+namespace FediBlock
+{
+
+using std::uint64_t;
+
+// Clone the git repo.
+void clone_repo();
+
+// FIXME: This will collapse when branches are deleted, use pull request IDs?
+// Get highest branch-ID in use.
+[[nodiscard]] uint64_t get_last_id();
+
+// Make a new branch for preparing the pull request.
+void make_new_branch();
+
+// Make a new pull request.
+void make_pull_request();
+
+} // namespace FediBlock
+
+#endif // FEDIBLOCK_BACKEND_GIT_HPP

src/main.cpp

@@ -17,8 +17,11 @@
 #include "cgi.hpp"
 #include "files.hpp"
 #include "fs-compat.hpp"
+#include "git.hpp"
 #include "json.hpp"
 
+#include <git2/global.h>
+
 #include <exception>
 #include <iostream>
 
@@ -61,6 +64,11 @@ int main()
 
     print_debug(entry);
 
+    git_libgit2_init();
+
+    clone_repo();
+    cout << "Next branch ID: " << get_last_id() + 1 << "\r\n";
+
     try
     {
         remove_tmpdir();
@@ -70,5 +78,7 @@ int main()
         cerr << e.what() << '\n';
     }
 
+    git_libgit2_shutdown();
+
     return 0;
 }

tests/CMakeLists.txt

@@ -9,7 +9,7 @@ target_include_directories(${PROJECT_NAME}_testlib
   "$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/src>")
 
 target_link_libraries(${PROJECT_NAME}_testlib
-  PUBLIC PkgConfig::cgicc nlohmann_json std::filesystem)
+  PUBLIC PkgConfig::cgicc nlohmann_json std::filesystem PkgConfig::libgit2)
 
 file(GLOB sources_tests test_*.cpp)