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/*
* Copyright (c) 2020, Sahan Fernando <sahan.h.fernando@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/String.h>
#include <AK/StringBuilder.h>
#include <AK/Time.h>
#include <AK/Vector.h>
#include <LibCore/ArgsParser.h>
#include <errno.h>
#include <spawn.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
static int opt_interval = 2;
static bool flag_noheader = false;
static bool flag_beep_on_fail = false;
static volatile int exit_code = 0;
static volatile pid_t child_pid = -1;
static String build_header_string(const Vector<const char*>& command, const struct timeval& interval)
{
StringBuilder builder;
builder.appendff("Every {}", interval.tv_sec);
builder.appendff(".{}s: \x1b[1m", interval.tv_usec / 100000);
builder.join(' ', command);
builder.append("\x1b[0m");
return builder.build();
}
static struct timeval get_current_time()
{
struct timespec ts;
struct timeval tv;
clock_gettime(CLOCK_MONOTONIC_COARSE, &ts);
timespec_to_timeval(ts, tv);
return tv;
}
static int64_t usecs_from(const struct timeval& start, const struct timeval& end)
{
struct timeval diff;
timeval_sub(end, start, diff);
return 1000000 * diff.tv_sec + diff.tv_usec;
}
static void handle_signal(int signal)
{
if (child_pid > 0) {
if (kill(child_pid, signal) < 0) {
perror("kill");
}
int status;
if (waitpid(child_pid, &status, 0) < 0) {
perror("waitpid");
} else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
exit_code = 1;
}
}
exit(exit_code);
}
static int run_command(const Vector<const char*>& command)
{
if ((errno = posix_spawnp(const_cast<pid_t*>(&child_pid), command[0], nullptr, nullptr, const_cast<char**>(command.data()), environ))) {
exit_code = 1;
perror("posix_spawn");
return errno;
}
// Wait for the child to terminate, then return its exit code.
int status;
pid_t exited_pid;
do {
exited_pid = waitpid(child_pid, &status, 0);
} while (exited_pid < 0 && errno == EINTR);
VERIFY(exited_pid == child_pid);
child_pid = -1;
if (exited_pid < 0) {
perror("waitpid");
return 1;
}
if (WIFEXITED(status)) {
return WEXITSTATUS(status);
} else {
return 1;
}
}
int main(int argc, char** argv)
{
signal(SIGINT, handle_signal);
if (pledge("stdio proc exec", nullptr) < 0) {
perror("pledge");
return 1;
}
Vector<const char*> command;
Core::ArgsParser args_parser;
args_parser.set_general_help("Execute a command repeatedly, and watch its output over time.");
args_parser.add_option(opt_interval, "Amount of time between updates", "interval", 'n', "seconds");
args_parser.add_option(flag_noheader, "Turn off the header describing the command and interval", "no-title", 't');
args_parser.add_option(flag_beep_on_fail, "Beep if the command has a non-zero exit code", "beep", 'b');
args_parser.add_positional_argument(command, "Command to run", "command");
args_parser.parse(argc, argv);
struct timeval interval;
if (opt_interval <= 0) {
interval = { 0, 100000 };
} else {
interval = { opt_interval, 0 };
}
auto header = build_header_string(command, interval);
command.append(nullptr);
auto now = get_current_time();
auto next_run_time = now;
while (true) {
int usecs_to_sleep = usecs_from(now, next_run_time);
while (usecs_to_sleep > 0) {
usleep(usecs_to_sleep);
now = get_current_time();
usecs_to_sleep = usecs_from(now, next_run_time);
}
// Clear the screen, then reset the cursor position to the top left.
fprintf(stderr, "\033[H\033[2J");
// Print the header.
if (!flag_noheader) {
fprintf(stderr, "%s\n\n", header.characters());
} else {
fflush(stderr);
}
if (run_command(command) != 0) {
exit_code = 1;
if (flag_beep_on_fail) {
fprintf(stderr, "\a");
fflush(stderr);
}
}
now = get_current_time();
timeval_add(next_run_time, interval, next_run_time);
if (usecs_from(now, next_run_time) < 0) {
// The next execution is overdue, so we set next_run_time to now to prevent drift.
next_run_time = now;
}
}
}
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