feat: Add C bindings

.gitignore

@@ -46,6 +46,4 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
-allure-*
-
-!build_android.sh
+allure-*

CMakeLists.txt

@@ -25,6 +25,9 @@ include_directories(${PROJECT_ROOT_DIR}/src)
 option(BUILD_PYTHON_BINDINGS "Build Python bindings using pybind11" OFF)
 message(STATUS "BUILD_PYTHON_BINDINGS:${BUILD_PYTHON_BINDINGS}")
 
+option(BUILD_C_BINDINGS "Build C bindings (libzvec_c) for Rust/FFI consumers" OFF)
+message(STATUS "BUILD_C_BINDINGS:${BUILD_C_BINDINGS}")
+
 option(BUILD_TOOLS "Build tools" ON)
 message(STATUS "BUILD_TOOLS:${BUILD_TOOLS}")
 

src/CMakeLists.txt

@@ -8,6 +8,6 @@ git_version(ZVEC_VERSION ${CMAKE_CURRENT_SOURCE_DIR})
 cc_directory(ailego)
 cc_directory(core)
 cc_directory(db)
-if(BUILD_PYTHON_BINDINGS)
+if(BUILD_PYTHON_BINDINGS OR BUILD_C_BINDINGS)
     cc_directory(binding)
 endif()

src/ailego/io/file.cc

@@ -39,6 +39,50 @@ static inline int OpenSafely(const char *path, int flags) {
   return fd;
 }
 
+static inline bool SetCloseOnExec(int fd) {
+  int current_flags = fcntl(fd, F_GETFD);
+  while (current_flags == -1 && errno == EINTR) {
+    current_flags = fcntl(fd, F_GETFD);
+  }
+  if (current_flags == -1) {
+    return false;
+  }
+  if ((current_flags & FD_CLOEXEC) != 0) {
+    return true;
+  }
+
+  int ret = fcntl(fd, F_SETFD, current_flags | FD_CLOEXEC);
+  while (ret == -1 && errno == EINTR) {
+    ret = fcntl(fd, F_SETFD, current_flags | FD_CLOEXEC);
+  }
+  return ret == 0;
+}
+
+static inline int OpenWithCloseOnExec(const char *path, int flags) {
+#ifdef O_CLOEXEC
+  int cloexec_fd = OpenSafely(path, flags | O_CLOEXEC);
+  if (cloexec_fd != -1) {
+    return cloexec_fd;
+  }
+  if (errno != EINVAL) {
+    return -1;
+  }
+#endif
+
+  int fd = OpenSafely(path, flags);
+  if (fd == -1) {
+    return -1;
+  }
+  if (!SetCloseOnExec(fd)) {
+    int ret = close(fd);
+    while (ret == -1 && errno == EINTR) {
+      ret = close(fd);
+    }
+    return -1;
+  }
+  return fd;
+}
+
 static inline void CloseSafely(int fd) {
   int ret = close(fd);
   while (ret == -1 && errno == EINTR) {
@@ -144,7 +188,7 @@ bool File::create(const char *path, size_t len, bool direct) {
   (void)direct;
 #endif
 
-  int fd = OpenSafely(path, flags);
+  int fd = OpenWithCloseOnExec(path, flags);
   ailego_false_if_lt_zero(fd);
 
 #ifdef F_NOCACHE
@@ -178,7 +222,7 @@ bool File::open(const char *path, bool rdonly, bool direct) {
   (void)direct;
 #endif
 
-  int fd = OpenSafely(path, flags);
+  int fd = OpenWithCloseOnExec(path, flags);
   ailego_false_if_lt_zero(fd);
 
 #ifdef F_NOCACHE
@@ -724,4 +768,4 @@ void File::MemoryWarmup(void *addr, size_t len) {
 }
 
 }  // namespace ailego
-}  // namespace zvec
+}  // namespace zvec

src/binding/CMakeLists.txt

@@ -5,4 +5,10 @@ include(${PROJECT_ROOT_DIR}/cmake/option.cmake)
 git_version(ZVEC_VERSION ${CMAKE_CURRENT_SOURCE_DIR})
 
 # Add repository
-cc_directory(python)
+if(BUILD_PYTHON_BINDINGS)
+    cc_directory(python)
+endif()
+
+if(BUILD_C_BINDINGS)
+    cc_directory(c)
+endif()

src/binding/c/CMakeLists.txt

@@ -0,0 +1,70 @@
+include(${PROJECT_ROOT_DIR}/cmake/bazel.cmake)
+include(${PROJECT_ROOT_DIR}/cmake/option.cmake)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# ── nlohmann/json (header-only) ──────────────────────────────────────────────
+include(FetchContent)
+FetchContent_Declare(
+    nlohmann_json
+    GIT_REPOSITORY https://github.com/nlohmann/json.git
+    GIT_TAG        v3.11.3
+    GIT_SHALLOW    TRUE
+)
+set(JSON_BuildTests   OFF CACHE BOOL "" FORCE)
+set(JSON_Install      OFF CACHE BOOL "" FORCE)
+set(JSON_MultipleHeaders OFF CACHE BOOL "" FORCE)
+FetchContent_MakeAvailable(nlohmann_json)
+
+# ── Build zvec_c as a shared library ─────────────────────────────────────────
+add_library(zvec_c SHARED zvec_c.cc)
+
+target_include_directories(zvec_c
+    PRIVATE
+        ${PROJECT_ROOT_DIR}/src
+        ${PROJECT_ROOT_DIR}/src/include
+)
+
+target_link_libraries(zvec_c PRIVATE nlohmann_json::nlohmann_json)
+
+# Replicate the same whole-archive / force_load strategy used by the Python
+# binding so every algorithm implementation is included in the shared lib.
+if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    target_link_libraries(zvec_c PRIVATE
+        -Wl,--whole-archive
+        $<TARGET_FILE:core_knn_flat_static>
+        $<TARGET_FILE:core_knn_flat_sparse_static>
+        $<TARGET_FILE:core_knn_hnsw_static>
+        $<TARGET_FILE:core_knn_hnsw_sparse_static>
+        $<TARGET_FILE:core_knn_ivf_static>
+        $<TARGET_FILE:core_knn_cluster_static>
+        $<TARGET_FILE:core_mix_reducer_static>
+        $<TARGET_FILE:core_metric_static>
+        $<TARGET_FILE:core_utility_static>
+        $<TARGET_FILE:core_quantizer_static>
+        -Wl,--no-whole-archive
+        zvec_db
+    )
+elseif (APPLE)
+    target_link_libraries(zvec_c PRIVATE
+        -Wl,-force_load,$<TARGET_FILE:core_knn_flat_static>
+        -Wl,-force_load,$<TARGET_FILE:core_knn_flat_sparse_static>
+        -Wl,-force_load,$<TARGET_FILE:core_knn_hnsw_static>
+        -Wl,-force_load,$<TARGET_FILE:core_knn_hnsw_sparse_static>
+        -Wl,-force_load,$<TARGET_FILE:core_knn_ivf_static>
+        -Wl,-force_load,$<TARGET_FILE:core_knn_cluster_static>
+        -Wl,-force_load,$<TARGET_FILE:core_mix_reducer_static>
+        -Wl,-force_load,$<TARGET_FILE:core_metric_static>
+        -Wl,-force_load,$<TARGET_FILE:core_utility_static>
+        -Wl,-force_load,$<TARGET_FILE:core_quantizer_static>
+        zvec_db
+    )
+endif()
+
+# Install so that Rust's build.rs (cmake crate) can find it under $OUT_DIR/lib
+install(TARGETS zvec_c
+    LIBRARY DESTINATION lib
+    RUNTIME DESTINATION lib   # Windows DLL goes here too
+)
+install(FILES zvec_c.h DESTINATION include)