Start/stop recording if not running/already running

src/Process.cpp

@@ -0,0 +1,93 @@
+#include "../include/Process.hpp"
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <limits.h>
+#include <fcntl.h>
+
+namespace gsr {
+    bool exec_program_daemonized(const char **args) {
+        /* 1 argument */
+        if(args[0] == nullptr)
+            return -1;
+
+        pid_t pid = vfork();
+        if(pid == -1) {
+            perror("Failed to vfork");
+            return false;
+        } else if(pid == 0) { /* child */
+            setsid();
+            signal(SIGHUP, SIG_IGN);
+
+            // Daemonize child to make the parent the init process which will reap the zombie child
+            pid_t second_child = vfork();
+            if(second_child == 0) { // child
+                execvp(args[0], (char* const*)args);
+                perror("execvp");
+                _exit(127);
+            } else if(second_child != -1) {
+                _exit(0);
+            }
+        } else { /* parent */
+            waitpid(pid, nullptr, 0);
+        }
+        return true;
+    }
+
+    static const char *pid_file = "/tmp/gpu-screen-recorder";
+
+    static bool is_process_running_program(pid_t pid, const char *program_name) {
+        char filepath[256];
+        snprintf(filepath, sizeof(filepath), "/proc/%ld/exe", (long)pid);
+
+        char resolved_path[PATH_MAX];
+        const ssize_t resolved_path_len = readlink(filepath, resolved_path, sizeof(resolved_path) - 1);
+        if(resolved_path_len == -1)
+            return false;
+        
+        resolved_path[resolved_path_len] = '\0';
+
+        const int program_name_len = strlen(program_name);
+        return resolved_path_len >= program_name_len && memcmp(resolved_path + resolved_path_len - program_name_len, program_name, program_name_len) == 0;
+    }
+
+    bool is_gpu_screen_recorder_running(int &gsr_pid, GsrMode &mode) {
+        gsr_pid = -1;
+        mode = GsrMode::Unknown;
+
+        char buffer[256];
+        int fd = open(pid_file, O_RDONLY);
+        if(fd == -1)
+            return false;
+
+        ssize_t bytes_read = read(fd, buffer, sizeof(buffer) - 1);
+        if(bytes_read < 0) {
+            perror("failed to read gpu-screen-recorder pid file");
+            close(fd);
+            return true;
+        }
+        buffer[bytes_read] = '\0';
+        close(fd);
+
+        long pid = 0;
+        if(sscanf(buffer, "%ld %120s", &pid, buffer) == 2) {
+            gsr_pid = pid;
+            if(is_process_running_program(pid, "gpu-screen-recorder")) {
+                if(strcmp(buffer, "replay") == 0)
+                    mode = GsrMode::Replay;
+                else if(strcmp(buffer, "record") == 0)
+                    mode = GsrMode::Record;
+                else if(strcmp(buffer, "stream") == 0)
+                    mode = GsrMode::Stream;
+                else
+                    mode = GsrMode::Unknown;
+                return true;
+            }
+        } else {
+            fprintf(stderr, "Warning: gpu-screen-recorder pid file is in incorrect format, it's possible that its corrupt. Ignoring...\n");
+        }
+        return false;
+    }
+}