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#define _GNU_SOURCE /* getopt_long */
#include <errno.h>
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
#define VERSION "1.0.0"
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 (WIFEXITED(status))
return;
fprintf(stderr, "Process exited with status %d, aborting.\n", status);
exit(1);
}
/* Ignore subprocesses' errors. */
void
continue_on_error(int status)
{
(void) status;
}
void
exec_child(char **argv)
{
int status;
status = execvp(argv[0], argv);
if (status < 0)
{
perror("rpt[child process]");
exit(4);
}
exit(4);
}
void
wait_child(pid_t pid, void (*handle_error_f)(int status))
{
int exit_status = 0;
waitpid(pid, &exit_status, 0);
handle_error_f(exit_status);
}
void
invoke_cmd(char **argv, void (*handle_error_f)(int status))
{
pid_t pid = fork();
if (pid < 0)
{
perror("rpt");
exit(4);
}
if (pid == 0)
exec_child(argv);
else
wait_child(pid, handle_error_f);
}
/* Invoke the executable *ARGV COUNT times, passing it the rest of ARG 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);
}
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();
return 0;
case 'V':
print_version();
return 0;
case ':':
fprintf(stderr, "COUNT value missing.\n");
print_usage(stderr);
return 1; /* invalid option */
default:
print_usage(stderr);
return 1; /* invalid option */
}
}
if (strcount)
{
char *err = NULL;
count = strtol(strcount, &err, 10);
if (err && (*err != '\0'))
{
fprintf(stderr, "Failed to read COUNT : '%s'.\n",
strcount);
return 2;
}
}
if (optind >= argc)
{
fprintf(stderr, "rpt: no command provided.\n");
return 3;
}
repeat_cmd(argv + optind, count, handle_error_f);
return 0;
}
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