Add get_env and file permission utilities

CMakeLists.txt

@@ -9,7 +9,9 @@ include_directories(include)
 set(utilities_sources
   src/cmdline_parser.c
   src/concat.c
+  src/filesystem.c
   src/find.c
+  src/get_env.c
   src/split.c
   src/string_array.c)
 set_source_files_properties(
@@ -71,6 +73,33 @@ if(BUILD_TESTING)
     )
     target_link_libraries(test_concat c_utilities)
   endif()
+
+  ament_add_gtest(test_get_env test/test_get_env.cpp
+    ENV
+      EMPTY_TEST=
+      NORMAL_TEST=foo
+    APPEND_LIBRARY_DIRS "$<TARGET_FILE_DIR:${PROJECT_NAME}>"
+  )
+  if(TARGET test_get_env)
+    target_link_libraries(test_get_env ${PROJECT_NAME})
+    if(UNIX AND NOT APPLE)
+      target_link_libraries(test_get_env pthread)
+    endif()
+    if(NOT WIN32)
+      set_target_properties(test_get_env PROPERTIES COMPILE_FLAGS "-std=c++11")
+    endif()
+  endif()
+
+  ament_add_gtest(test_filesystem
+    test/test_filesystem.cpp
+  )
+  if(TARGET test_filesystem)
+    target_include_directories(test_filesystem PUBLIC
+      ${c_utilities_INCLUDE_DIRS}
+    )
+    target_link_libraries(test_filesystem c_utilities)
+  endif()
+
 endif()
 
 ament_export_dependencies(ament_cmake)

include/c_utilities/filesystem.h

@@ -0,0 +1,123 @@
+// Copyright 2017 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef C_UTILITIES__FILESYSTEM_H_
+#define C_UTILITIES__FILESYSTEM_H_
+
+#if __cplusplus
+extern "C"
+{
+#endif
+
+#include <stdbool.h>
+
+#include "c_utilities/macros.h"
+#include "c_utilities/visibility_control.h"
+
+/// Return current working directory.
+/**
+ * \param[in] buffer Allocated string to store current directory path to
+ * \param[in] max_length maximum length to be stored in buffer
+ * \return bool True if success
+ *              False if buffer is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+C_UTILITIES_WARN_UNUSED
+bool
+utilities_get_cwd(char * buffer, size_t max_length);
+
+/// Check if the provided path points to a directory.
+/**
+ * \param[in] abs_path Absolute path to check.
+ * \return bool True if directory
+ *              False if abs_path is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+bool
+utilities_is_directory(const char * abs_path);
+
+/// Check if the provided path points to a file.
+/**
+ * \param[in] abs_path Absolute path to check.
+ * \return bool True if file
+ *              False if abs_path is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+bool
+utilities_is_file(const char * abs_path);
+
+/// Check if the provided path points to an existing file/folder.
+/**
+ * \param[in] abs_path Absolute path to check.
+ * \return bool True if the path exists
+ *              False if abs_path is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+bool
+utilities_exists(const char * abs_path);
+
+/// Check if the provided path points to a file/folder readable by current user.
+/**
+ * \param[in] abs_path Absolute path to check.
+ * \return bool True if the file is readable
+ *              False if abs_path is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+bool
+utilities_is_readable(const char * abs_path);
+
+/// Check if the provided path points to a file/folder writable by current user.
+/**
+ * \param[in] abs_path Absolute path to check.
+ * \return bool True if the file is writable
+ *              False if abs_path is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+bool
+utilities_is_writable(const char * abs_path);
+
+/// Check if the provided path points to a file/folder both readable and writable by current user.
+/**
+ * \param[in] abs_path Absolute path to check.
+ * \return bool True if the file is redable and writable False otherwise
+ *              False if abs_path is NULL
+ *              False on failure
+ */
+C_UTILITIES_PUBLIC
+bool
+utilities_is_readable_and_writable(const char * abs_path);
+
+/// Concatenate path adding the right delimiter according to the platform.
+/**
+ * \param[in] left_hand_path
+ * \param[in] right_hand_path
+ * \return const char * concatenated path on success
+ *         NULL on invalid arguments
+ *         NULL on failure
+ */
+C_UTILITIES_PUBLIC
+const char *
+utilities_join_path(const char * left_hand_path, const char * right_hand_path);
+
+#if __cplusplus
+}
+#endif
+
+#endif  // C_UTILITIES__FILESYSTEM_H_

include/c_utilities/get_env.h

@@ -0,0 +1,68 @@
+// Copyright 2017 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef C_UTILITIES__GET_ENV_H_
+#define C_UTILITIES__GET_ENV_H_
+
+#if __cplusplus
+extern "C"
+{
+#endif
+
+#include "c_utilities/macros.h"
+#include "c_utilities/visibility_control.h"
+
+/// Retrieve the value of the given environment variable if it exists, or "".
+/* The c-string which is returned in the env_value output parameter is only
+ * valid until the next time this function is called, because it is a direct
+ * pointer to the static storage.
+ * The variable env_value populated by this function should never have free()
+ * called on it.
+ * If the environment variable is not set, an empty string will be returned.
+ *
+ * In both cases, environment variable set or unset, NULL is returned unless
+ * an exception has occurred, in which case the error string is returned.
+ * For example:
+ *
+ * ```c
+ * #include <stdio.h>
+ * #include <c_utilities/get_env.h>
+ * const char * env_value;
+ * const char * error_str;
+ * error_str = utilities_get_env("SOME_ENV_VAR", &env_value);
+ * if (error_str != NULL) {
+ *   fprintf(stderr, "Error getting env var: %s\n", error_str);
+ * }
+ * printf("Valued of 'SOME_ENV_VAR': %s\n", env_value);
+ * ```
+ *
+ * Environment variables will be truncated at 2048 characters on Windows.
+ *
+ * This function is not thread-safe.
+ *
+ * \param[in] env_name the name of the environment variable
+ * \param[out] env_value pointer to the value cstring, or "" if unset
+ * \return NULL on success (success can be returning an empty string)
+ *         error string on failure
+ */
+C_UTILITIES_PUBLIC
+C_UTILITIES_WARN_UNUSED
+const char *
+utilities_get_env(const char * env_name, const char ** env_value);
+
+#if __cplusplus
+}
+#endif
+
+#endif  // C_UTILITIES__GET_ENV_H_

include/c_utilities/macros.h

@@ -0,0 +1,33 @@
+// Copyright 2017 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef C_UTILITIES__MACROS_H_
+#define C_UTILITIES__MACROS_H_
+
+#if __cplusplus
+extern "C"
+{
+#endif
+
+#ifndef _WIN32
+#define C_UTILITIES_WARN_UNUSED __attribute__((warn_unused_result))
+#else
+#define C_UTILITIES_WARN_UNUSED _Check_return_
+#endif
+
+#if __cplusplus
+}
+#endif
+
+#endif  // C_UTILITIES__MACROS_H_