open_save_file opens files relative to g_save_dir

savedir=<path> can be used to set the savedir; default is user's
documents directory.

Fixes #94

libid/save_file.cpp

@@ -1,6 +1,17 @@
 #include "save_file.h"
 
+#include "special_dirs.h"
+
+#include <filesystem>
+
+namespace fs = std::filesystem;
+
 std::FILE *open_save_file(const std::string &name, const std::string &mode)
 {
-    return std::fopen(name.c_str(), mode.c_str());
+    fs::path path{name};
+    if (path.is_relative())
+    {
+        path = fs::path{g_save_dir} / path;
+    }
+    return std::fopen(path.string().c_str(), mode.c_str());
 }

libid/special_dirs.cpp

@@ -1,3 +1,3 @@
 #include "special_dirs.h"
 
-std::string g_save_dir;
+std::string g_save_dir{get_documents_dir()};

tests/CMakeLists.txt

@@ -36,6 +36,7 @@ add_executable(test-id
     test_make_path.cpp
     test_math.cpp
     test_merge_path_names.cpp
+    test_open_save_file.cpp
     test_path_match.cpp
     test_search_path.cpp
     test_split_path.cpp

tests/images/image_compare_test.cmake

@@ -9,7 +9,7 @@ else()
     set(COMMAND_ECHO "NONE")
 endif()
 
-list(APPEND PARAMETERS "savename=${TEST_SAVE_IMAGE}")
+list(APPEND PARAMETERS "savename=${TEST_SAVE_IMAGE}" "savedir=.")
 
 if(DEBUG)
     dump_var(ID)

tests/test_open_save_file.cpp

@@ -0,0 +1,66 @@
+#include <save_file.h>
+
+#include "test_data.h"
+
+#include <special_dirs.h>
+#include <value_saver.h>
+
+#include <gtest/gtest.h>
+
+#include <filesystem>
+#include <string_view>
+
+using namespace testing;
+namespace fs = std::filesystem;
+
+TEST(TestSaveDir, initialValue)
+{
+    EXPECT_EQ(get_documents_dir(), g_save_dir);
+}
+
+TEST(TestOpenSaveFile, filename)
+{
+    constexpr std::string_view name{"tmp.txt"};
+    if (fs::exists(name))
+    {
+        fs::remove(name);
+    }
+    const auto path{fs::path{ID_TEST_DATA_DIR} / name};
+    if (exists(path))
+    {
+        fs::remove(path);
+    }
+    ValueSaver save_dir{g_save_dir, ID_TEST_DATA_DIR};
+
+    std::FILE *file{open_save_file(name.data(), "w")};
+
+    ASSERT_NE(nullptr, file);
+    std::fclose(file);
+    ASSERT_FALSE(fs::exists(name));
+    ASSERT_TRUE(fs::exists(path));
+    fs::remove(path);
+}
+
+TEST(TestOpenSaveFile, relativeDir)
+{
+    constexpr std::string_view name{"tmp.txt"};
+    if (fs::exists(name))
+    {
+        fs::remove(name);
+    }
+    const auto relative{fs::path{ID_TEST_DATA_SUBDIR_NAME} / name};
+    const auto path{fs::path{ID_TEST_DATA_DIR} / relative};
+    if (exists(path))
+    {
+        fs::remove(path);
+    }
+    ValueSaver save_dir{g_save_dir, ID_TEST_DATA_DIR};
+
+    std::FILE *file{open_save_file(relative.string(), "w")};
+
+    ASSERT_NE(nullptr, file);
+    std::fclose(file);
+    ASSERT_FALSE(fs::exists(name));
+    ASSERT_TRUE(fs::exists(path));
+    fs::remove(path);
+}