From c7a9ad2ffc2066ec571bd08ed40f0e5b49a05d65 Mon Sep 17 00:00:00 2001
From: Konstantin Pereiaslov <perk11@perk11.info>
Date: Sun, 14 May 2023 19:01:33 -0500
Subject: [PATCH] First version

---
 .idea/.gitignore |   8 ++++
 Makefile         |   8 ++++
 main.c           | 122 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 138 insertions(+)
 create mode 100644 .idea/.gitignore
 create mode 100644 Makefile
 create mode 100644 main.c

diff --git a/.idea/.gitignore b/.idea/.gitignore
new file mode 100644
index 0000000..13566b8
--- /dev/null
+++ b/.idea/.gitignore
@@ -0,0 +1,8 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..9173eb4
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,8 @@
+TARGET_EXEC := runwhenidle
+LDLIBS=-lXss -lX11
+CFLAGS=-O2
+CC=gcc
+release:
+	$(CC) -o $(TARGET_EXEC) $(CFLAGS) $(LDFLAGS) $(LDLIBS) main.c
+clean:
+	rm -f runwhenidle
\ No newline at end of file
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..6883ad6
--- /dev/null
+++ b/main.c
@@ -0,0 +1,122 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <X11/extensions/scrnsaver.h>
+#include <getopt.h>
+
+
+// Function to pause the command
+void pause_command(pid_t pid) {
+    printf("Pausing command...\n");
+    if (kill(pid, SIGTSTP) == -1) {
+        printf("Pause didn't complete: command has already finished.\n");
+        exit(1);
+    }
+}
+
+// Function to resume the command
+void resume_command(pid_t pid) {
+    printf("Resuming command...\n");
+    if (kill(pid, SIGCONT) == -1) {
+        printf("Resume didn't complete: command has already finished.\n");
+        exit(1);
+    }
+}
+
+int main(int argc, char *argv[]) {
+    const char *shell_command_to_run = NULL;
+    pid_t pid;
+    int userIdleTimeoutMs = 300000;
+
+    // Define command line options
+    struct option long_options[] = {
+        {"timeout", required_argument, NULL, 't'},
+        {NULL, 0, NULL, 0}
+    };
+
+    // Parse command line options
+    int option;
+    while ((option = getopt_long(argc, argv, "t:", long_options, NULL)) != -1) {
+        switch (option) {
+            case 't':
+                userIdleTimeoutMs = atoi(optarg);
+                break;
+            default:
+                printf("Usage: %s [--timeout timeout] shell_command_to_run\n", argv[0]);
+                return 1;
+        }
+    }
+    if (optind >= argc) {
+        printf("Usage: %s [--timeout timeout] shell_command_to_run\n", argv[0]);
+        return 1;
+    }
+
+    shell_command_to_run = argv[optind];
+
+    // Fork a child process to run the command
+    pid = fork();
+    if (pid < 0) {
+        perror("fork");
+        exit(1);
+    } else if (pid == 0) {
+        // Child process
+        execl("/bin/sh", "sh", "-c", shell_command_to_run, (char *) NULL);
+        perror("execl");
+        exit(1);
+    }
+
+    // Flag to track the command status
+    int command_paused = 0;
+
+    Display *dpy = XOpenDisplay(NULL);
+    if (!dpy) {
+        printf("Couldn't open an X11 display\n");
+        return (1);
+    }
+    XScreenSaverInfo *info = XScreenSaverAllocInfo();
+
+    int pollingInterval = 1;
+    int sleepTimeSeconds = pollingInterval;
+    // Monitor user activity
+    while (1) {
+        sleep(sleepTimeSeconds);
+        XScreenSaverQueryInfo(dpy, DefaultRootWindow(dpy), info);
+
+        if (info->idle > userIdleTimeoutMs) {
+            // User is inactive
+            if (command_paused) {
+                sleepTimeSeconds = pollingInterval; //reset to default value
+                fprintf(stderr,"Idle time: %lums\n", info->idle);
+
+                resume_command(pid);
+                command_paused = 0;
+            }
+        } else {
+            // User is active
+            if (!command_paused) {
+                fprintf(stderr, "Idle time: %lums\n", info->idle);
+                pause_command(pid);
+                command_paused = 1;
+            }
+            //TODO: this doesn't account for the time it took to pause the command
+            sleepTimeSeconds = ((userIdleTimeoutMs - info->idle) / 1000) - 1;
+            if (sleepTimeSeconds < 1) {
+                sleepTimeSeconds = 1;
+            }
+            fprintf(stderr, "User is active, we will check again in %u seconds\n", sleepTimeSeconds);
+        }
+
+        // Check if the command has finished
+        int status;
+        if (waitpid(pid, &status, WNOHANG) == pid && WIFEXITED(status)) {
+            fprintf(stderr, "Command has finished\n");
+            break;
+        }
+
+
+    }
+
+    return 0;
+}