Introduce libmagic.

.devcontainer/Dockerfile

@@ -8,6 +8,7 @@ RUN apk update && \
     boost-build \
     build-base \
     cmake \
+    gdb \
     git \
     libstdc++ \
     libtool \

.devcontainer/devcontainer.json

@@ -4,12 +4,8 @@
 		"dockerfile": "Dockerfile"
 	},
 
-	// Features to add to the dev container. More info: https://containers.dev/features.
-	// "features": {},
-
 	// Configure tool-specific properties.
 	"customizations": {
-		// Configure properties specific to VS Code.
 		"vscode": {
 			"settings": {},
 			"extensions": [
@@ -20,13 +16,4 @@
 			]
 		}
 	}
-
-	// Use 'forwardPorts' to make a list of ports inside the container available locally.
-	// "forwardPorts": [],
-
-	// Use 'postCreateCommand' to run commands after the container is created.
-	// "postCreateCommand": "gcc -v",
-
-	// Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
-	// "remoteUser": "root"
 }

.gitignore

@@ -1,3 +1,6 @@
+
+/build
+
 # ---> C++
 # Prerequisites
 *.d

CMakeLists.txt

@@ -4,3 +4,4 @@ project(all)
 enable_testing()
 
 add_subdirectory(bmrshared)
+add_subdirectory(bmrshared-magic)

bmrshared-magic/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_subdirectory(lib)
+add_subdirectory(tst)

bmrshared-magic/include/bmrshared/magic_file_info.hpp

@@ -0,0 +1,26 @@
+// GNU Lesser General Public License v3.0
+// Copyright (c) 2025 Bart Beumer <bart@4beumer.nl>
+//
+// This program is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License v3.0 as published by
+// the Free Software Foundation.
+//
+
+#include <filesystem>
+#include <magic.h>
+
+namespace bmrshared
+{
+class magic_file_info final
+{
+  public:
+    explicit magic_file_info(const std::filesystem::path& path);
+    ~magic_file_info();
+
+    std::string get_mime(const std::filesystem::path& path) const;
+
+  private:
+    magic_t m_magic_cookie;
+};
+
+} // namespace bmrshared

bmrshared-magic/lib/CMakeLists.txt

@@ -0,0 +1,31 @@
+cmake_minimum_required(VERSION 3.20)
+
+find_package(libmagic 5.45 REQUIRED)
+
+project(bmrshared-magic)
+
+add_library(
+    ${PROJECT_NAME}
+    magic_file_info.cpp
+)
+
+set_property(
+    TARGET ${PROJECT_NAME}
+    PROPERTY CXX_STANDARD 20
+)
+
+target_include_directories(
+    ${PROJECT_NAME}
+    PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../include
+)
+
+target_link_libraries(
+    ${PROJECT_NAME}
+    PUBLIC
+    libmagic::libmagic
+)
+
+install(
+    FILES ${CONAN_LIBMAGIC_PACKAGE_FOLDER}/res/magic.mgc
+    DESTINATION bin
+)

bmrshared-magic/lib/magic_file_info.cpp

@@ -0,0 +1,59 @@
+// GNU Lesser General Public License v3.0
+// Copyright (c) 2025 Bart Beumer <bart@4beumer.nl>
+//
+// This program is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License v3.0 as published by
+// the Free Software Foundation.
+//
+#include <bmrshared/magic_file_info.hpp>
+
+namespace bmrshared
+{
+magic_file_info::magic_file_info(const std::filesystem::path& path)
+    : m_magic_cookie(nullptr)
+{
+    bool load_ok = false;
+    m_magic_cookie = magic_open(MAGIC_MIME_TYPE);
+
+    if (m_magic_cookie != nullptr && std::filesystem::is_regular_file(path))
+    {
+        load_ok = (magic_load(m_magic_cookie, path.native().c_str()) == 0);
+    }
+
+    if (m_magic_cookie && !load_ok)
+    {
+        magic_close(m_magic_cookie);
+        m_magic_cookie = nullptr;
+    }
+
+    if (!load_ok)
+    {
+        throw std::runtime_error("Could not initialize libmagic.");
+    }
+}
+
+magic_file_info::~magic_file_info()
+{
+    magic_close(m_magic_cookie);
+}
+
+std::string magic_file_info::get_mime(const std::filesystem::path& path) const
+{
+    std::string mime;
+    if (std::filesystem::is_regular_file(path))
+    {
+        const char* file_name = path.native().c_str();
+        const char* magic_full = nullptr;
+        if (file_name != nullptr)
+        {
+            magic_full = magic_file(m_magic_cookie, file_name);
+        }
+        if (magic_full != nullptr)
+        {
+            mime = magic_full;
+        }
+    }
+    return mime;
+}
+
+} // namespace bmrshared

bmrshared-magic/tst/CMakeLists.txt

@@ -0,0 +1,24 @@
+cmake_minimum_required(VERSION 3.20)
+
+find_package(GTest REQUIRED)
+include(GoogleTest)
+
+project(bmrshared-magic-test)
+add_test(NAME ${PROJECT_NAME} COMMAND ${PROJECT_NAME})
+
+add_executable(
+    ${PROJECT_NAME}
+    test_magic.cpp
+)
+
+set_property(
+    TARGET ${PROJECT_NAME}
+    PROPERTY CXX_STANDARD 20
+)
+
+target_link_libraries(
+    ${PROJECT_NAME}
+    PUBLIC
+    bmrshared-magic
+    GTest::gtest_main
+)

bmrshared-magic/tst/test_magic.cpp

@@ -0,0 +1,26 @@
+// GNU Lesser General Public License v3.0
+// Copyright (c) 2025 Bart Beumer <bart@4beumer.nl>
+//
+// This program is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License v3.0 as published by
+// the Free Software Foundation.
+//
+#include <bmrshared/magic_file_info.hpp>
+#include <gtest/gtest.h>
+
+namespace
+{
+    constexpr std::string_view magic_file_location = "/usr/local/bin/magic.mgc";
+}
+
+TEST(test_magic, no_throw_on_query)
+{
+    bmrshared::magic_file_info mfi(magic_file_location);
+    EXPECT_NO_THROW(mfi.get_mime(magic_file_location));
+}
+
+TEST(test_magic, throw_on_wrong_magic_file)
+{
+    EXPECT_THROW(bmrshared::magic_file_info mfi(""), std::exception);
+    EXPECT_THROW(bmrshared::magic_file_info mfi("/etc/hostname"), std::exception);
+}

bmrshared/tst/CMakeLists.txt

@@ -26,8 +26,3 @@ target_link_libraries(
     GTest::gmock
 
 )
-
-install(
-    TARGETS ${PROJECT_NAME}
-    RUNTIME DESTINATION bin
-)

conanfile.py

@@ -0,0 +1,20 @@
+import os
+from conan import ConanFile
+from conan.tools.files import copy
+from conan.tools.cmake import CMake, CMakeToolchain, CMakeDeps
+
+class HelloConan(ConanFile):
+    settings = "os", "compiler", "build_type", "arch"
+    requires = "boost/1.84.0", "gtest/1.14.0", "libmagic/5.45"
+    generators = "CMakeDeps"
+    build_policy = "*"
+
+    def generate(self):
+        # We need to find the folder of libmagic and supply it to cmake so that
+        # we can deploy the magic file.
+        libmagic = self.dependencies["libmagic"]
+
+        tc = CMakeToolchain(self)
+        tc.variables["CONAN_LIBMAGIC_PACKAGE_FOLDER"] = libmagic.package_folder
+        tc.generate()
+

conanfile.txt

@@ -1,7 +0,0 @@
-[requires]
-boost/1.84.0
-gtest/1.14.0
-
-[generators]
-CMakeDeps
-CMakeToolchain