path: root/main.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#include <errno.h>
#include <sys/wait.h>
#include <X11/extensions/scrnsaver.h>
#include <getopt.h>
#include <string.h>
#include <assert.h>
#include <limits.h>

#include "sleep_utils.h"
#include "time_utils.h"
#include "tty_utils.h"

#ifndef VERSION
#define VERSION 'unkown'
#endif

int verbose = 0;
int quiet = 0;
int debug = 0;
int xscreensaver_is_available;
Display *x_display;
XScreenSaverInfo *xscreensaver_info;
const long unsigned IDLE_TIME_NOT_AVAILABLE_VALUE = ULONG_MAX;

volatile sig_atomic_t interruption_received = 0;
int command_paused = 0;
pid_t pid;

void handle_kill_error(char *signal_name, pid_t pid) {
    const char *reason;
    if (errno == EPERM) {
        reason = "Operation not permitted";
    } else if (errno == EINVAL) {
        reason = "Invalid signal number";
    } else if (errno == ESRCH) {
        reason = "No such process";
    }

    printf("Failed to send %s signal to PID %i: %s\n", signal_name, pid, reason);
}
void send_signal_to_pid(pid_t pid, int signal, char *signal_name) {
    if (debug) {
        printf("Sending %s to %i\n",signal_name, pid);
    }
    int kill_result = kill(pid, signal);
    if (kill_result == -1) {
        handle_kill_error(signal_name, pid);
        exit(1);
    } else {
        if (debug) fprintf(stderr, "kill function sending %s returned %i\n",signal_name, kill_result);
    }
}

void pause_command(pid_t pid) {
    if (!quiet) {
        printf("User activity is detected, pausing PID %i\n", pid);
    }
    send_signal_to_pid(pid, SIGTSTP, "SIGTSTP");
}

void resume_command(pid_t pid) {
    if (!quiet) {
        printf("Resuming PID %i\n", pid);
    }
    send_signal_to_pid(pid, SIGCONT, "SIGCONT");
}

void print_usage(char *binary_name) {
    printf("Usage: %s [--timeout|-t timeout_value_in_seconds] [--verbose|-v] [--debug] [--quiet|-q] [--version|-V] shell_command_to_run [shell_command_arguments]\n",
           binary_name);
}
void print_version() {
    printf("runwhenidle %s\n", VERSION);
}

pid_t run_shell_command(const char *shell_command_to_run, pid_t pid) {
    if (verbose) {
        printf("Starting \"%s\"\n", shell_command_to_run);
    }
    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);
    }
    if (!quiet) {
        printf("Started \"%s\" with PID %i\n", shell_command_to_run, pid);
    }
    return pid;
}

void exit_if_pid_has_finished(pid_t pid) {
    int status;
    if (debug) fprintf(stderr, "Checking if PID %i has finished\n", pid);
    if (waitpid(pid, &status, WNOHANG + WUNTRACED) == pid && WIFEXITED(status)) {
        int exit_code = WEXITSTATUS(status);
        if (verbose) {
            fprintf(stderr, "PID %i has finished with exit code %u\n", pid, exit_code);
        }
        exit(exit_code);
    }
}

char *read_remaining_arguments_as_char(int argc,
                                       char *const *argv) {
    if (optind == argc) { //there is one argument remaining
        char *last_and_only_argument = strdup(argv[optind]);
        return last_and_only_argument;
    }

    size_t memory_to_be_allocated_for_remaining_arguments_string = 0;
    for (int i = optind; i < argc; i++) {
        memory_to_be_allocated_for_remaining_arguments_string +=
                strlen(argv[i]) + 1; // +1 for space separator or null terminator
    }

    char *remaining_arguments_string = NULL; // Variable to store the remaining_arguments_string

    // Allocate memory for the remaining_arguments_string
    remaining_arguments_string = malloc(memory_to_be_allocated_for_remaining_arguments_string);
    if (remaining_arguments_string == NULL) {
        //not using fprintf_error here intentionally
        fprintf(stderr, "Failed to allocate memory while parsing command to be ran.\n");
        exit(1);
    }

    size_t current_length_of_all_arguments = 0;
    for (int i = optind; i < argc; i++) {
        size_t current_argument_length = strlen(argv[i]);
        memcpy(remaining_arguments_string + current_length_of_all_arguments, argv[i], current_argument_length);
        current_length_of_all_arguments += current_argument_length;
        remaining_arguments_string[current_length_of_all_arguments++] = ' '; // Add space separator
    }
    assert(current_length_of_all_arguments == memory_to_be_allocated_for_remaining_arguments_string);
    remaining_arguments_string[current_length_of_all_arguments - 1] = '\0'; // Replace the last space separator with a null terminator

    return remaining_arguments_string;
}
long unsigned query_user_idle_time()
{
    if (xscreensaver_is_available) {
        XScreenSaverQueryInfo(x_display, DefaultRootWindow(x_display), xscreensaver_info);
        return xscreensaver_info->idle;
    }

    return IDLE_TIME_NOT_AVAILABLE_VALUE;
}
int wait_for_pid_to_exit_synchronously(int pid) {
    // Wait for the child process to complete
    int status;
    waitpid(pid, &status, 0);
    int exit_code = WEXITSTATUS(status);
    if (verbose) {
        fprintf(stderr, "PID %i has finished with exit code %u\n", pid, exit_code);
    }

    return exit_code;
}
int handle_interruption() {
    if (command_paused) {
        if (verbose) {
            fprintf(stderr,
                    "Since command was previously paused, we will try to resume it now to be able to handle the interruption before exiting\n"
            );
        }
        resume_command(pid);
    }
    return wait_for_pid_to_exit_synchronously(pid);
}
void sigint_handler(int signum) {
    if (!quiet) {
        printf("Received SIGINT, sending SIGINT to the command and waiting for it to finish.\n");
    }
    send_signal_to_pid(pid, signum, "SIGINT");
    interruption_received = 1;
}
void sigterm_handler(int signum) {
    if (!quiet) {
        printf("Received SIGTERM, sending SIGTERM to the command and waiting for it to finish.\n");
    }
    send_signal_to_pid(pid, signum, "SIGTERM");
    interruption_received = 1;
}
int main(int argc, char *argv[]) {
    long unsigned user_idle_timeout_ms = 300000;

    // Define command line options
    struct option long_options[] = {
            {"timeout", required_argument, NULL, 't'},
            {"verbose", no_argument,       NULL, 'v'},
            {"debug", no_argument,         NULL, 'd'},
            {"quiet",   no_argument,       NULL, 'q'},
            {"help",    no_argument,       NULL, 'h'},
            {"version",    no_argument,    NULL, 'V'},
            {NULL, 0,                      NULL, 0}
    };

    // Parse command line options
    int option;
    while ((option = getopt_long(argc, argv, "+hvqt:V", long_options, NULL)) != -1) {
        switch (option) {
            case 't': {
                const long TIMEOUT_MAX_SUPPORTED_VALUE = 100000000; //~3 years
                const long TIMEOUT_MIN_SUPPORTED_VALUE = 1;
                long timeout_arg_value = strtol(optarg, NULL, 10);
                if (timeout_arg_value < TIMEOUT_MIN_SUPPORTED_VALUE ||
                    timeout_arg_value > TIMEOUT_MAX_SUPPORTED_VALUE || errno != 0) {
                    fprintf_error("Invalid timeout value: \"%s\". Range supported: %ld-%ld", optarg,
                                  TIMEOUT_MIN_SUPPORTED_VALUE, TIMEOUT_MAX_SUPPORTED_VALUE);
                    print_usage(argv[0]);
                    return 1;
                }
                user_idle_timeout_ms = timeout_arg_value * 1000;
                break;
            }
            case 'V':
                print_version();
                return 0