Implement rcutils_mkdir. (#166)

* Implement rcutils_mkdir.

Needed for the spdlog logging backend.

Signed-off-by: Chris Lalancette <clalancette@openrobotics.org>

* Add in tests for rcutils_mkdir.

Signed-off-by: Chris Lalancette <clalancette@openrobotics.org>

* Fix small nit for documentation.

Signed-off-by: Chris Lalancette <clalancette@openrobotics.org>

* Add in a warning that the thread isn't thread-safe.

Signed-off-by: Chris Lalancette <clalancette@openrobotics.org>

CMakeLists.txt

@@ -271,6 +271,7 @@ if(BUILD_TESTING)
   if(TARGET test_filesystem)
     ament_target_dependencies(test_filesystem "osrf_testing_tools_cpp")
     target_link_libraries(test_filesystem ${PROJECT_NAME})
+    target_compile_definitions(test_filesystem PRIVATE BUILD_DIR="${CMAKE_CURRENT_BINARY_DIR}")
   endif()
 
   rcutils_custom_add_gtest(test_strdup

include/rcutils/filesystem.h

@@ -144,6 +144,29 @@ rcutils_to_native_path(
   const char * path,
   rcutils_allocator_t allocator);
 
+/// Create the specified directory.
+/**
+ * This function creates an absolutely-specified directory.
+ * If any of the intermediate directories do not exist, this function will
+ * return False.
+ * If the abs_path already exists, and is a directory, this function will
+ * return True.
+ *
+ * This function is not thread-safe due to mkdir races as described in the
+ * openat(2) documentation.
+ *
+ * \param[in] abs_path
+ * \param[in] allocator
+ * \return bool True if making the directory was successful, False otherwise
+ *              False if path is NULL
+ *              False if path is empty
+ *              False if path is not absolute
+ *              False if any intermediate directories don't exist
+ */
+RCUTILS_PUBLIC
+bool
+rcutils_mkdir(const char * abs_path);
+
 #ifdef __cplusplus
 }
 #endif

src/filesystem.c

@@ -18,6 +18,7 @@ extern "C"
 #endif
 #include "rcutils/filesystem.h"
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -177,6 +178,38 @@ rcutils_to_native_path(
   return rcutils_repl_str(path, "/", RCUTILS_PATH_DELIMITER, &allocator);
 }
 
+bool
+rcutils_mkdir(const char * abs_path)
+{
+  if (NULL == abs_path) {
+    return false;
+  }
+
+  if (abs_path[0] == '\0') {
+    return false;
+  }
+
+  bool success = false;
+#ifdef _WIN32
+  // TODO(clalancette): Check to ensure that the path is absolute on Windows.
+  // In theory we can use PathRelativeA to do this, but I was unable to make
+  // it work.  Needs further investigation.
+
+  int ret = _mkdir(abs_path);
+#else
+  if (abs_path[0] != '/') {
+    return false;
+  }
+
+  int ret = mkdir(abs_path, 0775);
+#endif
+  if (ret == 0 || (errno == EEXIST && rcutils_is_directory(abs_path))) {
+    success = true;
+  }
+
+  return success;
+}
+
 #ifdef __cplusplus
 }
 #endif

test/test_filesystem.cpp

@@ -236,3 +236,47 @@ TEST_F(TestFilesystemFixture, is_readable_and_writable) {
     EXPECT_FALSE(rcutils_is_readable_and_writable(path));
   }
 }
+
+TEST_F(TestFilesystemFixture, mkdir) {
+  {
+    // Make a new directory
+    char * path =
+      rcutils_join_path(BUILD_DIR, "mkdir_test_dir", g_allocator);
+    ASSERT_FALSE(nullptr == path);
+    OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT({
+      g_allocator.deallocate(path, g_allocator.state);
+    });
+    ASSERT_TRUE(rcutils_mkdir(path));
+  }
+  {
+    // Purposely do it again, to make sure mkdir handles the case where the
+    // directory already exists
+    char * path =
+      rcutils_join_path(BUILD_DIR, "mkdir_test_dir", g_allocator);
+    ASSERT_FALSE(nullptr == path);
+    OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT({
+      g_allocator.deallocate(path, g_allocator.state);
+    });
+    ASSERT_TRUE(rcutils_mkdir(path));
+  }
+  {
+    ASSERT_FALSE(rcutils_mkdir(nullptr));
+  }
+  {
+    ASSERT_FALSE(rcutils_mkdir("foo/bar"));
+  }
+  {
+    // Make sure it throws an error when the intermediate path doesn't exist
+    char * path =
+      rcutils_join_path(BUILD_DIR, "mkdir_test_dir2", g_allocator);
+    ASSERT_FALSE(nullptr == path);
+    char * path2 =
+      rcutils_join_path(path, "mkdir_test_dir3", g_allocator);
+    OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT({
+      g_allocator.deallocate(path2, g_allocator.state);
+      g_allocator.deallocate(path, g_allocator.state);
+    });
+    ASSERT_FALSE(nullptr == path2);
+    ASSERT_FALSE(rcutils_mkdir(path2));
+  }
+}