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#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <unistd.h>
#include <getopt.h>
#include <ctype.h>
#include <string.h>
#include <stdbool.h>
#include <fcntl.h>
const struct option longopts[] = {
{"chdir", no_argument, NULL, 'd'},
{"noclose", no_argument, NULL, 'n'},
{"log-stdout", required_argument, NULL, '1'},
{"log-stderr", required_argument, NULL, '2'},
{0, 0, 0, 0}
};
const char* optstring = "dn1:2:";
void q (char* fmt, ...) {
va_list args;
va_start(args, fmt);
vfprintf(stderr, fmt, args);
va_end(args);
exit(1);
}
void qusage (const char* arg0) {
q("[daemonize] Usage: %s [-d|--chdir] [-n|--noclose] [-1|--log-stdout /path/to/log] [-2|--log-stderr /path/to/log] <command>\n", arg0);
}
void qtoofewargs (const char* arg0) {
fprintf(stderr, "[daemonize] Too few arguments.\n");
qusage(arg0);
}
void qinvalidarg (const char* arg, const char* arg0) {
fprintf(stderr, "[daemonize] Unrecognized argument: %s\n", arg);
qusage(arg0);
}
char* lowerdup (const char* a) {
char* b = strdup(a);
int i;
for (i = 0; b[i] != 0; i++) {
b[i] = tolower(b[i]);
}
return b;
}
struct opts {
int nochdir;
int noclose;
FILE* stdlog;
FILE* errlog;
};
void parseargs(int argc, char** argv, struct opts* savedopts) {
if (argc < 2) qtoofewargs(argv[0]);
int c;
while ((c = getopt_long(argc, argv, optstring, longopts, NULL)) != -1) {
switch (c) {
case 'd':
savedopts->nochdir = false;
break;
case 'n':
savedopts->noclose = true;
break;
case '1':
savedopts->stdlog = fopen(optarg, "a");
if (!savedopts->stdlog) q("[daemonize] Unable to open stdout log, quitting.");
break;
case '2':
savedopts->errlog = fopen(optarg, "a");
if (!savedopts->errlog) q("[daemonize] Unable to open stderr log, quitting.");
break;
default:
// getopt will have printed an error already
qusage(argv[0]);
}
}
}
int main (int argc, char** argv) {
struct opts options = {true, false, NULL, NULL};
parseargs(argc, argv, &options);
int cmdlen = 0, buff_size = 256;
char* buffer = malloc(buff_size);
while (optind < argc) {
int arglen = strlen(argv[optind]);
while (cmdlen+arglen+1 > buff_size) {
buff_size *= 2;
}
buffer = realloc(buffer, buff_size);
if (buffer == NULL) q("[daemonize] Out of memory parsing arguments.");
strncpy(&buffer[cmdlen], argv[optind++], arglen);
cmdlen += arglen+1;
buffer[cmdlen-1] = ' ';
}
buffer[cmdlen-1] = 0;
char cmd[cmdlen];
memcpy(cmd, buffer, cmdlen);
free(buffer);
if (cmdlen < 1) qtoofewargs(argv[0]);
// Set up logs as appropriate
int logs = options.stdlog || options.errlog;
if (options.stdlog) {
dup2(fileno(options.stdlog), STDOUT_FILENO);
fclose(options.stdlog);
}
if (options.errlog) {
dup2(fileno(options.errlog), STDERR_FILENO);
fclose(options.errlog);
}
if (logs && !options.noclose) {
int devnull_out = open("/dev/null", O_WRONLY);
int devnull_in = open("/dev/null", O_RDONLY);
if (!options.errlog)
dup2(devnull_out, STDERR_FILENO);
if (!options.stdlog)
dup2(devnull_out, STDOUT_FILENO);
dup2(devnull_in, STDIN_FILENO);
close(devnull_in);
close(devnull_out);
}
daemon(options.nochdir, options.noclose | logs);
char* args[] = {"/bin/sh", "-c", cmd, NULL};
execv(args[0], args);
}
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