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#define _GNU_SOURCE /* getopt_long */
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#define VERSION "1.1.3"
/* Size of the buffer used to clone stdin. */
#define BUFSIZE 8000
/* Exit status */
#define EXIT_SUCCESS 0
#define EXIT_INVALID_ARG 1
#define EXIT_INVALID_COUNT 2
#define EXIT_NO_COMMAND 3
#define EXIT_OTHER 4
/* Clone of stdin. Used to perform lseek(2) calls between each child
process. */
FILE *stdin_clone = NULL;
/* File descriptor associated to the clone of stdin. */
int clone_fd;
void
print_usage(FILE *output)
{
fprintf(output, "Usage:\n");
fprintf(output, "rpt [-n | --count COUNT] [-f | --force] COMMAND\n");
fprintf(output, "rpt [-h | --help]\n");
fprintf(output, "rpt [-V | --version]\n");
}
void
print_help()
{
puts("Repeat : repeat a shell command");
puts("");
print_usage(stdout);
}
void
print_version()
{
puts(VERSION);
}
/* Exit whenever a subprocess fails. */
void
exit_on_error(int status)
{
if (!status)
return;
fprintf(stderr, "rpt: child process exited with status %d, aborting\n",
status);
if (stdin_clone)
fclose(stdin_clone);
exit(status);
}
/* Ignore subprocesses' errors. */
void
continue_on_error(int status)
{
(void) status;
}
void
exec_child(char **argv)
{
int status;
if (stdin_clone)
{
status = lseek(clone_fd, 0, L_SET);
if (status < 0)
{
perror("lseek");
exit(EXIT_OTHER);
}
}
status = dup2(clone_fd, STDIN_FILENO);
if (status < 0)
{
perror("dup2");
exit(EXIT_OTHER);
}
status = execvp(argv[0], argv);
if (status < 0)
{
perror("execvp");
exit(EXIT_OTHER);
}
exit(EXIT_OTHER);
}
void
wait_child(void (*handle_error_f)(int status))
{
int wstatus;
wait(&wstatus);
handle_error_f(WEXITSTATUS(wstatus));
}
void
invoke_cmd(char **argv, void (*handle_error_f)(int status))
{
pid_t pid = fork();
if (pid < 0)
{
perror("fork");
exit(EXIT_OTHER);
}
if (pid == 0)
exec_child(argv);
else
wait_child(handle_error_f);
}
/* Invoke the executable *ARGV COUNT times, passing it the rest of ARGV as
arguments. Call HANDLE_ERROR_F between each process. */
void
repeat_cmd(char **argv, long count, void (*handle_error_f)(int status))
{
for(long i = 0; i < count; ++i)
invoke_cmd(argv, handle_error_f);
}
void
copy_stdin()
{
ssize_t nbytes;
char buf[BUFSIZE];
stdin_clone = tmpfile(); /* closed at the end of the main */
if (!stdin_clone)
{
perror("tmpfile");
exit(EXIT_OTHER);
}
clone_fd = fileno(stdin_clone);
while ((nbytes = read(STDIN_FILENO, buf, BUFSIZE)) > 0)
{
if (write(clone_fd, buf, nbytes) < 0)
break;
}
if (errno)
{
fclose(stdin_clone);
perror("read/write");
exit(EXIT_OTHER);
}
}
int
main(int argc, char* argv[])
{
struct option const opts[] = {
{"count", required_argument, NULL, 'n'},
{"force", no_argument, NULL, 'f'},
{"version", no_argument, NULL, 'V'},
{"help", no_argument, NULL, 'h'},
{NULL, 0, NULL, 0}
};
opterr = 0; /* dismiss getopt error message */
int opt;
char *strcount = NULL;
long count = 1;
void (*handle_error_f)(int status) = exit_on_error;
while ((opt = getopt_long(argc, argv, "+:n:fVh", opts, NULL)) >= 0)
{
switch(opt)
{
case 'n':
strcount = optarg;
break;
case 'f':
handle_error_f = continue_on_error;
break;
case 'h':
print_help();
exit(EXIT_SUCCESS);
case 'V':
print_version();
exit(EXIT_SUCCESS);
case ':':
fprintf(stderr, "rpt: COUNT value missing\n");
print_usage(stderr);
exit(EXIT_INVALID_ARG);
default:
print_usage(stderr);
exit(EXIT_INVALID_ARG);
}
}
if (strcount)
{
char *err = NULL;
count = strtol(strcount, &err, 10);
if (err && (*err != '\0'))
{
fprintf(stderr, "rpt: failed to convert COUNT : '%s'\n",
strcount);
exit(EXIT_INVALID_COUNT);
}
}
if (optind >= argc)
{
fprintf(stderr, "rpt: no command provided\n");
return 3;
}
struct pollfd pollfd = {.fd=STDIN_FILENO, .events=POLLIN, .revents=0};
if (poll(&pollfd, 1, 0) < 0)
{
perror("poll");
exit(EXIT_OTHER);
}
if (pollfd.revents & POLLIN)
copy_stdin();
repeat_cmd(argv + optind, count, handle_error_f);
if (stdin_clone)
fclose(stdin_clone);
return EXIT_SUCCESS;
}
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