gsr-hyprland-helper: workaround flatpak bug with environment variables

src/HyprlandWorkaround.cpp

@@ -1,6 +1,7 @@
 #include "../include/HyprlandWorkaround.hpp"
+#include "../include/Process.hpp"
 
-#include <iostream>
+#include <sys/wait.h>
 #include <unistd.h>
 #include <thread>
 
@@ -8,27 +9,62 @@ namespace gsr {
     static ActiveHyprlandWindow active_hyprland_window;
     static bool hyprland_listener_thread_started = false;
 
-    static void hyprland_listener_thread() {
+    static bool get_hyprland_socket_path(char *path, int path_len) {
-        const bool inside_flatpak = access("/app/manifest.json", F_OK) == 0;
+        const char* xdg_runtime_dir = getenv("XDG_RUNTIME_DIR");
+        const char* instance_sig = getenv("HYPRLAND_INSTANCE_SIGNATURE");
+        if (!xdg_runtime_dir || !instance_sig) {
+            fprintf(stderr, "Error: HyprlandWorkaround: environment variables not set\n");
+            return false;
+        }
 
+        if (snprintf(path, path_len, "%s/hypr/%s/.socket2.sock", xdg_runtime_dir, instance_sig) >= path_len) {
+            fprintf(stderr, "Error: HyprlandWorkaround: path to hyprland socket (%s/hypr/%s/.socket2.sock) is more than %d characters long\n", xdg_runtime_dir, instance_sig, path_len);
+            return false;
+        }
+
+        return true;
+    }
+
+    static void hyprland_listener_thread() {
+        char hyprland_socket_path[256];
+        char buffer[4096];
+        const std::string prefix = "Window title changed: ";
+        std::string line;
+        FILE *stdout_file = nullptr;
+
+        // Get path inside the flatpak before flatpak-spawn is called because of a bug in flatpak:
+        // https://github.com/flatpak/flatpak/issues/6486
+        // where environment variables are missing in flatpak-spawn --host
+        if(!get_hyprland_socket_path(hyprland_socket_path, sizeof(hyprland_socket_path))) {
+            fprintf(stderr, "Error: HyprlandWorkaround: failed to get hyprland socket path\n");
+            return;
+        }
+
+        const bool inside_flatpak = access("/app/manifest.json", F_OK) == 0;
         const char *hyprland_helper_bin =
             inside_flatpak ? 
             "flatpak-spawn --host -- /var/lib/flatpak/app/com.dec05eba.gpu_screen_recorder/current/active/files/bin/gsr-hyprland-helper" 
             : "gsr-hyprland-helper";
 
-        FILE* pipe = popen(hyprland_helper_bin, "r");
+        const char *args[] = { hyprland_helper_bin, hyprland_socket_path, nullptr };
-        if (!pipe) {
+        int read_fd = -1;
-            std::cerr << "Failed to start gsr-hyprland-helper process\n";
+        const pid_t process_id = exec_program(args, &read_fd, false);
+        if(process_id == -1) {
+            fprintf(stderr, "Error: HyprlandWorkaround: failed to execute gsr-hyprland-helper\n");
             return;
         }
 
-        std::cerr << "Started Hyprland helper thread\n";
+        stdout_file = fdopen(read_fd, "r");
+        if (!stdout_file) {
+            perror("Error: HyprlandWorkaround: fdopen");
+            goto done;
+            return;
+        }
+        read_fd = -1;
 
-        char buffer[4096];
+        fprintf(stderr, "Info: HyprlandWorkaround: started Hyprland helper thread\n");
-        const std::string prefix = "Window title changed: ";
 
-        std::string line;
+        while (fgets(buffer, sizeof(buffer), stdout_file) != nullptr) {
-        while (fgets(buffer, sizeof(buffer), pipe) != nullptr) {
             line = buffer;
 
             if (!line.empty() && line.back() == '\n') {
@@ -41,7 +77,21 @@ namespace gsr {
             }
         }
 
-        pclose(pipe);
+        done:
+        if(stdout_file)
+            fclose(stdout_file);
+
+        if(read_fd > 0)
+            close(read_fd);
+
+        if(process_id > 0) {
+            kill(process_id, SIGKILL);
+            int status;
+            if(waitpid(process_id, &status, 0) == -1) {
+                perror("waitpid failed");
+                /* Ignore... */
+            }
+        }
     }
 
     std::string get_current_hyprland_window_title() {

tools/gsr-hyprland-helper/main.c

@@ -1,27 +1,10 @@
 #include <unistd.h>
 #include <string.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <stdbool.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 
-static bool get_hyprland_socket_path(char *path, int path_len) {
-    const char* xdg_runtime_dir = getenv("XDG_RUNTIME_DIR");
-    const char* instance_sig = getenv("HYPRLAND_INSTANCE_SIGNATURE");
-    if (!xdg_runtime_dir || !instance_sig) {
-        fprintf(stderr, "Error: gsr-hypland-helper: environment variables not set\n");
-        return false;
-    }
-    
-    if (snprintf(path, path_len, "%s/hypr/%s/.socket2.sock", xdg_runtime_dir, instance_sig) >= path_len) {
-        fprintf(stderr, "Error: gsr-hypland-helper: path to hyprland socket (%s/hypr/%s/.socket2.sock) is more than %d characters long\n", xdg_runtime_dir, instance_sig, path_len);
-        return false;
-    }
-
-    return true;
-}
-
 static void print_window_title(const char *window_title) {
     if (window_title[0] == 0) {
         printf("Window title changed: %s\n", "Desktop");
@@ -32,7 +15,7 @@ static void print_window_title(const char *window_title) {
     fflush(stdout);
 }
 
-static int handle_ipc(void) {
+static int handle_ipc(const char *hyprland_socket_path) {
     const int sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (sock_fd == -1) {
         perror("Error: gsr-hyprland-helper: socket");
@@ -43,8 +26,9 @@ static int handle_ipc(void) {
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
 
-    if (!get_hyprland_socket_path(addr.sun_path, sizeof(addr.sun_path))) {
+    if (snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", hyprland_socket_path) >= (int)sizeof(addr.sun_path)) {
-        return 1;
+        fprintf(stderr, "Error: gsr-hypland-helper: path to hyprland socket (%s) is more than %d characters long\n", hyprland_socket_path, (int)sizeof(addr.sun_path));
+        return false;
     }
 
     if (connect(sock_fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
@@ -90,6 +74,10 @@ static int handle_ipc(void) {
 }
 
 
-int main(void) {
+int main(int argc, char **argv) {
-    return handle_ipc();
+    if(argc != 2) {
+        fprintf(stderr, "usage: gsr-hyprland-helper <hyprland-socket-path>\n");
+        return 1;
+    }
+    return handle_ipc(argv[1]);
 }