Refactor config handling and related stuff

config.cpp

@@ -1,27 +1,77 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <sys/stat.h>
 #include <string>
-#include <fstream>
+#include <memory>
+#include <system_error>
 
 #include "config.h"
 
-std::string get_config_path() {
+static FILE* fopen_or_raise(const char* path, const char* mode, bool ignore_enoent) {
+    FILE* file = fopen(path, mode);
+    if (file || (ignore_enoent && errno == ENOENT)) {
+        return file;
+    }
+    throw std::system_error(errno, std::generic_category(), "fopen()");
+}
+
+static void fclose_and_log(FILE* file) {
+    if (!fclose(file)) {
+        return;
+    }
+    // TODO log() when logging exists
+}
+
+static bool write(const std::string& ptr, FILE* file) {
+    return fwrite(ptr.data(), sizeof(char), ptr.size(), file) == ptr.size() * sizeof(char);
+}
+static bool write(const char* ptr, FILE* file) {
+    return fwrite(ptr, 1, strlen(ptr), file) == strlen(ptr);
+}
+
+
+std::string get_config_folder() {
     const char* path;
 
     path = getenv("XDG_CONFIG_HOME");
     if (path) {
-        return std::string(path) + "/logmeow/config";
+        return std::string(path) + "/logmeow";
     }
     path = getenv("HOME");
     if (path) {
-        return std::string(path) + "/.config/logmeow/config";
+        return std::string(path) + "/.config/logmeow";
     }
 
     throw std::runtime_error("cannot find suitable config folder, please set XDG_CONFIG_HOME or HOME");
 }
 
-Config parse_config(FILE* file) {
+std::string get_config_file_path() {
+    return get_config_folder() + "/config";
+}
+
+// tries to create a directory with an empty string if it's just "/" but who cares
+void create_config_folders_if_necessary() {
+    std::string path = get_config_folder();
+    size_t pos = 0;
+
+    while (pos != std::string::npos) {
+        pos = path.find('/', pos);
+        if (pos != std::string::npos) {
+            pos++;
+        }
+        if (!mkdir(path.substr(0, pos).c_str(), 0600)) {
+            continue;
+        }
+        if (errno == EEXIST) {
+            continue;
+        }
+        throw std::system_error(errno, std::generic_category(), "mkdir()");
+    }
+}
+
+
+static inline Config load_config(FILE* file) {
     size_t line_capacity_size = 128 * sizeof(char);
     char* line = static_cast<char*>(malloc(line_capacity_size));
     if (line == nullptr) {
@@ -37,7 +87,7 @@ Config parse_config(FILE* file) {
             if (errsv == ENOMEM) {
                 throw std::bad_alloc();
             } else if (errsv != 0) {
-                throw std::system_error(errsv, std::generic_category(), "getline()");
+                throw std::system_error(errsv, std::generic_category(), "reading config line");
             } else {
                 break;
             }
@@ -50,8 +100,8 @@ Config parse_config(FILE* file) {
         }
 
         if (strncmp(line, "logcat_command=", 15 * sizeof(char)) == 0) {
-            config.logcat_command = &line[16];
+            config.logcat_command = &line[15];
-        } else {
+        } else if (line[0] != '\0') {
             std::invalid_argument e = std::invalid_argument(std::string("unknown config line: ") + line);
             free(line);
             throw e;
@@ -61,11 +111,44 @@ Config parse_config(FILE* file) {
     return config;
 }
 
-void write_config(std::ofstream& file, const Config& config) {
+Config load_config() {
-    file << "# This is an auto-generated file, comments made will be lost\n"
+    std::string config_file_path = get_config_file_path();
-         << "# This is a poor man's config file \"format\", there are only three legal lines:\n"
+    std::unique_ptr<FILE, decltype(&fclose_and_log)> config_file(fopen_or_raise(config_file_path.c_str(), "r", true), fclose_and_log);
-         << "#     # a comment, only available at the start of a line\n"
+
-         << "#     (an empty line, no whitespace)\n"
+    if (!config_file) {
-         << "#     key=value pairs, no spaces around the delimiter, and no unknown keys\n\n"
+        return Config();
-         << "logcat_command=" << config.logcat_command;
+    }
+
+    return load_config(config_file.get());
+}
+
+
+static inline void write_config(FILE* file, const Config& config) {
+    if (!write("# This is an auto-generated file, modifications will be lost\n"
+               "# This is a poor man's config file \"format\", there are only three legal lines:\n"
+               "#     # a comment, only available at the start of a line\n"
+               "#     (an empty line, no whitespace)\n"
+               "#     key=value pairs, no spaces around the delimiter, and no unknown keys\n\n", file)) {
+        throw std::runtime_error("failed to write info comment");
+    }
+    if (!write("logcat_command=", file)) {
+        throw std::runtime_error("failed to write logcat command key");
+    }
+    if (!write(config.logcat_command, file)) {
+        throw std::runtime_error("failed to write logcat command value");
+    }
+}
+
+void write_config(const Config& config) {
+    std::string config_file_path = get_config_file_path();
+    std::string tmp_config_file_path = config_file_path + ".tmp";
+
+    std::unique_ptr<FILE, decltype(&fclose_and_log)> config_file(fopen_or_raise(tmp_config_file_path.c_str(), "w", false), fclose_and_log);
+    write_config(config_file.get(), config);
+    config_file.reset();
+
+    if (!rename(tmp_config_file_path.c_str(), config_file_path.c_str())) {
+        return;
+    }
+    throw std::system_error(errno, std::generic_category(), "rename()");
 }

config.h

@@ -1,12 +1,12 @@
 #pragma once
 
 #include <string>
-#include <fstream>
 
 struct Config {
     std::string logcat_command;
 };
 
-std::string get_config_path();
+std::string get_config_folder();
-Config parse_config(FILE* file);
+void create_config_folders_if_necessary();
-void write_config(std::ofstream& file, const Config& config);
+Config load_config();
+void write_config(const Config& config);

event_loop.cpp

@@ -3,66 +3,76 @@
 
 #include "config.h"
 
-static inline void settings_window(Config& inactive_config, bool* show_settings_window) {
+static inline void write_config_and_update_structures(const Config& config) {
+    try {
+        write_config(config);
+    } catch (const std::exception& e) {
+        // TODO log() when logging exists
+        throw;
+    }
+}
+
+static inline void settings_window(Config& config, float* config_write_timer, bool* show_settings_window) {
     if (!ImGui::Begin("Settings", show_settings_window)) {
         ImGui::End();
         return;
     }
-    ImGui::Text("Modifying logcat command will take effect after closing this window and will restart logcat");
+    // TODO actually have process control
-    ImGui::InputTextWithHint("Logcat command", "adb logcat -Dv 'threadtime UTC epoch usec'", &inactive_config.logcat_command);
+    ImGui::Text("Logcat command is only modifiable when logcat is stopped");
+    if (ImGui::InputTextWithHint("Logcat command", "adb logcat -Dv 'threadtime UTC epoch usec'", &config.logcat_command)) {
+        *config_write_timer = *config_write_timer > 0.0f ? *config_write_timer : 5.0f;
+    }
     ImGui::End();
 }
 
-static inline void main_window(Config& active_config, Config& inactive_config, bool* show_demo_window,
+static inline void main_window(Config& active_config, bool* show_demo_window,
-        bool* show_settings_window, bool* save_settings_when_settings_window_closed, bool* exit_requested_rev) {
+        bool* show_settings_window, bool* exit_requested_rev) {
     if (!ImGui::Begin("LogMeow", exit_requested_rev)) {
         ImGui::End();
         return;
     }
     ImGui::Checkbox("Show Dear ImGui Demo Window", show_demo_window);
     if (ImGui::Button("Settings")) {
-        if (!*show_settings_window) {
-            inactive_config = active_config;
-        }
         *show_settings_window = true;
-        *save_settings_when_settings_window_closed = true;
     }
     ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
     ImGui::End();
 }
 
 static inline void exit_modal_if_necessary(bool* run_event_loop) {
-    if (ImGui::BeginPopupModal("Exit?", nullptr, ImGuiWindowFlags_NoResize)) {
+    if (!ImGui::BeginPopupModal("Exit?", nullptr, ImGuiWindowFlags_NoResize)) {
-        ImGui::Text("Are you sure you want to exit?");
+        return;
-
-        if (ImGui::Button("Yes", ImVec2(120, 0))) {
-            *run_event_loop = false;
-        }
-        ImGui::SameLine();
-        if (ImGui::Button("No", ImVec2(120, 0))) {
-            ImGui::CloseCurrentPopup();
-        }
-        ImGui::SetItemDefaultFocus();
-        ImGui::EndPopup();
     }
+    ImGui::Text("Are you sure you want to exit?");
+
+    if (ImGui::Button("Yes", ImVec2(120, 0))) {
+        *run_event_loop = false;
+    }
+    ImGui::SameLine();
+    if (ImGui::Button("No", ImVec2(120, 0))) {
+        ImGui::CloseCurrentPopup();
+    }
+    ImGui::SetItemDefaultFocus();
+    ImGui::EndPopup();
 }
 
-void event_loop(Config& active_config, bool* run_event_loop) {
+void event_loop(Config& config, float* config_write_timer, bool* run_event_loop) {
     static bool show_demo_window = false;
     static bool show_settings_window = false;
-    static bool save_settings_when_settings_window_closed = false;
     static bool exit_requested_rev = true;
-    static Config inactive_config;
 
     if (show_demo_window) {
         ImGui::ShowDemoWindow(&show_demo_window);
     }
 
     if (show_settings_window) {
-        settings_window(inactive_config, &show_settings_window);
+        settings_window(config, config_write_timer, &show_settings_window);
-    } else if (save_settings_when_settings_window_closed) {
+    }
-        active_config = inactive_config;
+    if (*config_write_timer > 0.0f) {
-        save_settings_when_settings_window_closed = false;
+        *config_write_timer -= ImGui::GetIO().DeltaTime;
+        if (*config_write_timer <= 0.0f) {
+            write_config_and_update_structures(config);
+        }
     }
 
     if (!exit_requested_rev) {
@@ -70,5 +80,5 @@ void event_loop(Config& active_config, bool* run_event_loop) {
         exit_requested_rev = true;
     }
     exit_modal_if_necessary(run_event_loop);
-    main_window(active_config, inactive_config, &show_demo_window, &show_settings_window, &save_settings_when_settings_window_closed, &exit_requested_rev);
+    main_window(config, &show_demo_window, &show_settings_window, &exit_requested_rev);
 }

event_loop.h

@@ -2,4 +2,4 @@
 
 #include "config.h"
 
-void event_loop(Config& config, bool* run_event_loop);
+void event_loop(Config& config, float* config_write_timer, bool* run_event_loop);

main.cpp

@@ -17,23 +17,18 @@
 int main(int, char**)
 {
     Config config;
-    FILE* config_file = nullptr;
     try {
-        config_file = fopen(get_config_path().c_str(), "r");
+        config = load_config();
-        if (config_file) {
-            config = parse_config(config_file);
-        } else if (errno != ENOENT) {
-            perror("Failed to open config file");
-            return 1;
-        }
     } catch (const std::exception& e) {
-        fprintf(stderr, "Failed to parse config: %s\n", e.what());
+        fprintf(stderr, "Failed to load config: %s\n", e.what());
         return 1;
     }
-    if (config_file) {
+
-        if (fclose(config_file)) {
+    try {
-            perror("Failed to close config file");
+        create_config_folders_if_necessary();
-        }
+    } catch (const std::exception& e) {
+        fprintf(stderr, "Failed to create config folder: %s\n", e.what());
+        return 1;
     }
 
     // Setup SDL
@@ -82,7 +77,10 @@ int main(int, char**)
     // Setup Dear ImGui context
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
-    ImGuiIO& io = ImGui::GetIO(); (void)io;
+    ImGuiIO& io = ImGui::GetIO();
+    // needs to be a variable to keep the c-style string around
+    std::string ini_file_path = get_config_folder() + "/imgui.ini";
+    io.IniFilename = ini_file_path.c_str();
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
 
@@ -112,8 +110,9 @@ int main(int, char**)
 
     // Main loop
     bool run_event_loop = true;
-    while (run_event_loop)
+    float config_write_timer = 0.0f;
-    {
+
+    while (run_event_loop) {
         // Poll and handle events (inputs, window resize, etc.)
         // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
@@ -134,7 +133,7 @@ int main(int, char**)
         ImGui_ImplSDL2_NewFrame();
         ImGui::NewFrame();
 
-        event_loop(config, &run_event_loop);
+        event_loop(config, &config_write_timer, &run_event_loop);
 
         // Rendering
         ImGui::Render();
@@ -154,5 +153,14 @@ int main(int, char**)
     SDL_DestroyWindow(window);
     SDL_Quit();
 
+    if (config_write_timer > 0.0f) {
+        try {
+            write_config(config);
+        } catch (const std::exception& e) {
+            fprintf(stderr, "Failed to write config: %s\n", e.what());
+            return 1;
+        }
+    }
+
     return 0;
 }