busybox/init/start_stop_daemon.c

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/* vi: set sw=4 ts=4: */
/*
* Mini start-stop-daemon implementation(s) for busybox
*
* Written by Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>,
* public domain.
* Adapted for busybox David Kimdon <dwhedon@gordian.com>
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <signal.h>
#include <errno.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include "busybox.h"
#include "pwd.h"
static int start = 0;
static int stop = 0;
static int fork_before_exec = 0;
static int signal_nr = 15;
static int user_id = -1;
static const char *userspec = NULL;
static const char *cmdname = NULL;
static char *execname = NULL;
static char *startas = NULL;
typedef struct pid_list {
struct pid_list *next;
int pid;
} pid_list;
static pid_list *found = NULL;
static inline void
push(int pid)
{
pid_list *p;
p = xmalloc(sizeof(*p));
p->next = found;
p->pid = pid;
found = p;
}
static void
parse_options(int argc, char * const *argv)
{
int c;
for (;;) {
c = getopt (argc, argv, "a:n:s:u:x:KSb");
if (c == EOF)
break;
switch (c) {
case 'K':
stop = 1;
break;
case 'S':
start = 1;
break;
case 'a':
startas = optarg;
break;
case 'n':
cmdname = optarg;
break;
case 's':
if (sscanf(optarg, "%d", &signal_nr) != 1)
error_msg_and_die ("-s takes a numeric argument");
break;
case 'u':
userspec = optarg;
break;
case 'x':
execname = optarg;
break;
case 'b':
fork_before_exec = 1;
break;
default:
show_usage();
}
}
if (start == stop)
error_msg_and_die ("need one of -S or -K");
if (!execname && !userspec)
error_msg_and_die ("need at least one of -x or -u");
if (!startas)
startas = execname;
if (start && !startas)
error_msg_and_die ("-S needs -x or -a");
}
static int
pid_is_exec(int pid, const char *exec)
{
char buf[PATH_MAX];
FILE *fp;
sprintf(buf, "/proc/%d/cmdline", pid);
fp = fopen(buf, "r");
if (fp && fgets (buf, sizeof (buf), fp) ) {
fclose(fp);
if (strncmp (buf, exec, strlen(exec)) == 0)
return 1;
}
return 0;
}
static int
pid_is_user(int pid, int uid)
{
struct stat sb;
char buf[32];
sprintf(buf, "/proc/%d", pid);
if (stat(buf, &sb) != 0)
return 0;
return (sb.st_uid == uid);
}
static int
pid_is_cmd(int pid, const char *name)
{
char buf[32];
FILE *f;
int c;
sprintf(buf, "/proc/%d/stat", pid);
f = fopen(buf, "r");
if (!f)
return 0;
while ((c = getc(f)) != EOF && c != '(')
;
if (c != '(') {
fclose(f);
return 0;
}
/* this hopefully handles command names containing ')' */
while ((c = getc(f)) != EOF && c == *name)
name++;
fclose(f);
return (c == ')' && *name == '\0');
}
static void
check(int pid)
{
if (execname && !pid_is_exec(pid, execname)) {
return;
}
if (userspec && !pid_is_user(pid, user_id)) {
return;
}
if (cmdname && !pid_is_cmd(pid, cmdname)) {
return;
}
push(pid);
}
static void
do_procfs(void)
{
DIR *procdir;
struct dirent *entry;
int foundany, pid;
procdir = opendir("/proc");
if (!procdir)
perror_msg_and_die ("opendir /proc");
foundany = 0;
while ((entry = readdir(procdir)) != NULL) {
if (sscanf(entry->d_name, "%d", &pid) != 1)
continue;
foundany++;
check(pid);
}
closedir(procdir);
if (!foundany)
error_msg_and_die ("nothing in /proc - not mounted?");
}
static void
do_stop(void)
{
char what[1024];
pid_list *p;
int killed = 0;
if (cmdname)
strcpy(what, cmdname);
else if (execname)
strcpy(what, execname);
else if (userspec)
sprintf(what, "process(es) owned by `%s'", userspec);
else
error_msg_and_die ("internal error, please report");
if (!found) {
printf("no %s found; none killed.\n", what);
return;
}
for (p = found; p; p = p->next) {
if (kill(p->pid, signal_nr) == 0) {
p->pid = -p->pid;
killed++;
} else {
perror_msg("warning: failed to kill %d:", p->pid);
}
}
if (killed) {
printf("stopped %s (pid", what);
for (p = found; p; p = p->next)
if(p->pid < 0)
printf(" %d", -p->pid);
printf(").\n");
}
}
int
start_stop_daemon_main(int argc, char **argv)
{
parse_options(argc, argv);
argc -= optind;
argv += optind;
if (userspec && sscanf(userspec, "%d", &user_id) != 1)
user_id = my_getpwnam(userspec);
do_procfs();
if (stop) {
do_stop();
return EXIT_SUCCESS;
}
if (found) {
printf("%s already running.\n%d\n", execname ,found->pid);
return EXIT_SUCCESS;
}
*--argv = startas;
if (fork_before_exec) {
if (daemon(0, 0) == -1)
perror_msg_and_die ("unable to fork");
}
setsid();
execv(startas, argv);
perror_msg_and_die ("unable to start %s", startas);
}