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#define _GNU_SOURCE /* for getopt_long */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <getopt.h>
#include <syslog.h>
#include <debian-installer.h>
#ifdef __GNUC__
# define ATTRIBUTE_UNUSED __attribute__((__unused__))
#else
# define ATTRIBUTE_UNUSED
#endif
/* See below for why this empty handler exists. */
static void sigchld_handler(int signum ATTRIBUTE_UNUSED)
{
}
static int close_orig_stdout(pid_t pid ATTRIBUTE_UNUSED, void *user_data)
{
int orig_stdout = *(int *) user_data;
close(orig_stdout);
return 0;
}
static int restore_orig_stdout(pid_t pid ATTRIBUTE_UNUSED, void *user_data)
{
int orig_stdout = *(int *) user_data;
if (dup2(orig_stdout, 1) == -1)
return 1;
close(orig_stdout);
return 0;
}
static int logger(const char *buf, size_t len ATTRIBUTE_UNUSED, void *user_data)
{
static int log_open = 0;
if (!log_open) {
const char *ident = (const char *) user_data;
if (!ident)
ident = "log-output";
openlog(ident, 0, LOG_USER);
log_open = 1;
}
syslog(LOG_NOTICE, "%s", buf);
return 0;
}
static void usage(FILE *output)
{
fprintf(output, "Usage: log-output -t TAG [--pass-stdout] PROGRAM [ARGUMENTS]\n");
}
int main(int argc, char **argv)
{
char *tag = NULL;
static int pass_stdout = 0;
static struct option long_options[] = {
{ "help", no_argument, NULL, 'h' },
{ "pass-stdout", no_argument, &pass_stdout, 1 },
{ NULL, 0, NULL, 0 }
};
di_io_handler *stdout_handler = NULL, *stderr_handler = NULL;
di_process_handler *parent_prepare_handler = NULL;
di_process_handler *child_prepare_handler = NULL;
void *prepare_user_data = NULL;
int orig_stdout = -1;
int status;
for (;;) {
int c = getopt_long(argc, argv, "+t:", long_options, NULL);
if (c == -1)
break;
switch (c) {
case 0: /* long option */
break;
case 'h':
usage(stdout);
break;
case 't':
tag = strdup(optarg);
break;
default:
usage(stderr);
exit(1);
}
}
if (!argv[optind])
return 0;
if (pass_stdout) {
/* di_exec is a bit odd, and won't always notice that the
* subsidiary process has gone away if a stdout_handler
* isn't installed. We install a no-op SIGCHLD handler to
* make sure that its poll() gets EINTR and gives up.
*
* Technically, this is exploiting a bug in di_exec, and a
* better solution would be nice ...
*/
struct sigaction sa;
sa.sa_handler = &sigchld_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_NOCLDSTOP;
sigaction(SIGCHLD, &sa, NULL);
orig_stdout = dup(1);
parent_prepare_handler = &close_orig_stdout;
child_prepare_handler = &restore_orig_stdout;
prepare_user_data = &orig_stdout;
} else
stdout_handler = &logger;
stderr_handler = &logger;
status = di_exec_path_full(argv[optind], (const char **) &argv[optind],
stdout_handler, stderr_handler, tag,
parent_prepare_handler, prepare_user_data,
child_prepare_handler, prepare_user_data);
return di_exec_mangle_status(status);
}
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