/*
* Copyright 2006-2007 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Reap any leftover children possibly holding file descriptors.
* Children are identified by the stale file descriptor or PGID / SID.
* Both can be missed but only the stale file descriptors are important for us.
* PGID / SID may be set by the children on their own.
* If we fine a candidate we kill it will all its process tree (grandchildren).
* The child process is run with `2>&1' redirection (due to forkpty(3)).
* 2007-07-10 Jan Kratochvil <jan.kratochvil@redhat.com>
*/
/* For getpgid(2). */
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <dirent.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <string.h>
#include <limits.h>
#include <fcntl.h>
#include <assert.h>
#include <pty.h>
#include <poll.h>
#define LENGTH(x) (sizeof (x) / sizeof (*(x)))
static const char *progname;
static volatile int signal_child_hit = 0;
/* We use it to race-safely emulate ppoll(2) by poll(2). */
static int pipefd[2];
static void signal_child (int signo)
{
int i;
signal_child_hit = 1;
assert (pipefd[1] != -1);
i = close (pipefd[1]);
assert (i == 0);
pipefd[1] = -1;
}
static char childptyname[LINE_MAX];
static pid_t child;
static int spawn (char **argv)
{
pid_t child_got;
int status, amaster, i;
struct sigaction act;
struct termios termios;
i = pipe (pipefd);
assert (i == 0);
/* We do not use signal(2) to be sure we have SA_RESTART set. */
memset (&act, 0, sizeof (act));
act.sa_handler = signal_child;
i = sigemptyset (&act.sa_mask);
assert (i == 0);
act.sa_flags = SA_RESTART;
i = sigaction (SIGCHLD, &act, NULL);
assert (i == 0);
/* With TERMP passed as NULL we get "\n" -> "\r\n". */
termios.c_iflag = IGNBRK | IGNPAR;
termios.c_oflag = 0;
termios.c_cflag = CS8 | CREAD | CLOCAL | HUPCL | B9600;
termios.c_lflag = IEXTEN | NOFLSH;
memset (termios.c_cc, _POSIX_VDISABLE, sizeof (termios.c_cc));
termios.c_cc[VTIME] = 0;
termios.c_cc[VMIN ] = 1;
cfmakeraw (&termios);
#ifdef FLUSHO
/* Workaround a readline deadlock bug in _get_tty_settings(). */
termios.c_lflag &= ~FLUSHO;
#endif
child = forkpty (&amaster, childptyname, &termios, NULL);
switch (child)
{
case -1:
perror ("forkpty(3)");
exit (EXIT_FAILURE);
case 0:
i = close (pipefd[0]);
assert (i == 0);
i = close (pipefd[1]);
assert (i == 0);
/* Do not replace STDIN as inferiors query its termios. */
#if 0
i = close (STDIN_FILENO);
assert (i == 0);
i = open ("/dev/null", O_RDONLY);
assert (i == STDIN_FILENO);
#endif
/* Do not setpgrp(2) in the parent process as the process-group
is shared for the whole sh(1) pipeline we could be a part
of. The process-group is set according to PID of the first
command in the pipeline.
We would rip even vi(1) in the case of:
./orphanripper sh -c 'sleep 1&' | vi -
*/
/* Do not setpgrp(2) as our pty would not be ours and we would
get `SIGSTOP' later, particularly after spawning gdb(1).
setsid(3) was already executed by forkpty(3) and it would fail if
executed again. */
if (getpid() != getpgrp ())
{
perror ("getpgrp(2)");
exit (EXIT_FAILURE);
}
execvp (argv[1], argv + 1);
perror ("execvp(2)");
exit (EXIT_FAILURE);
default:
break;
}
i = fcntl (amaster, F_SETFL, O_RDWR | O_NONBLOCK);
if (i != 0)
{
perror ("fcntl (amaster, F_SETFL, O_NONBLOCK)");
exit (EXIT_FAILURE);
}
for (;;)
{
struct pollfd pollfd[2];
char buf[LINE_MAX];
ssize_t buf_got;
pollfd[0].fd = amaster;
pollfd[0].events = POLLIN;
pollfd[1].fd = pipefd[0];
pollfd[1].events = POLLIN;
i = poll (pollfd, LENGTH (pollfd), -1);
if (i == -1 && errno == EINTR)
{
/* Weird but SA_RESTART sometimes does not work. */
continue;
}
assert (i >= 1);
/* Data available? Process it first. */
if (pollfd[0].revents & POLLIN)
{
buf_got = read (amaster, buf, sizeof buf);
if (buf_got <= 0)
{
perror ("read (amaster)");
exit (EXIT_FAILURE);
}
if (write (STDOUT_FILENO, buf, buf_got) != buf_got)
{
perror ("write(2)");
exit (EXIT_FAILURE);
}
}
if (pollfd[0].revents & POLLHUP)
break;
if ((pollfd[0].revents &= ~POLLIN) != 0)
{
fprintf (stderr, "%s: ppoll(2): revents 0x%x\n", progname,
(unsigned) pollfd[0].revents);
exit (EXIT_FAILURE);
}
/* Child exited? */
if (pollfd[1].revents & POLLHUP)
break;
assert (pollfd[1].revents == 0);
}
/* WNOHANG still could fail. */
child_got = waitpid (child, &status, 0);
if (child != child_got)
{
fprintf (stderr, "waitpid (%d) = %d: %m\n", (int) child, (int) child_got);
exit (EXIT_FAILURE);
}
if (!WIFEXITED (status))
{
fprintf (stderr, "waitpid (%d): !WIFEXITED (%d)\n", (int) child, status);
exit (EXIT_FAILURE);
}
assert (signal_child_hit != 0);
assert (pipefd[1] == -1);
i = close (pipefd[0]);
assert (i == 0);
/* Do not close the master FD as the child would have `/dev/pts/23 (deleted)'
entries which are not expected (and expecting ` (deleted)' would be
a race. */
#if 0
i = close (amaster);
if (i != 0)
{
perror ("close (forkpty ()'s amaster)");
exit (EXIT_FAILURE);
}
#endif
return WEXITSTATUS (status);
}
/* Detected commandline may look weird due to a race:
Original command:
./orphanripper sh -c 'sleep 1&' &
Correct output:
[1] 29610
./orphanripper: Killed -9 orphan PID 29612 (PGID 29611): sleep 1
Raced output (sh(1) child still did not update its argv[]):
[1] 29613
./orphanripper: Killed -9 orphan PID 29615 (PGID 29614): sh -c sleep 1&
We could delay a bit before ripping the children. */
static const char *read_cmdline (pid_t pid)
{
char cmdline_fname[32];
static char cmdline[LINE_MAX];
int fd;
ssize_t got;
char *s;
if (snprintf (cmdline_fname, sizeof cmdline_fname, "/proc/%d/cmdline",
(int) pid) < 0)
return NULL;
fd = open (cmdline_fname, O_RDONLY);
if (fd == -1)
{
/* It may have already exited - ENOENT. */
#if 0
fprintf (stderr, "%s: open (\"%s\"): %m\n", progname, cmdline_fname);
#endif
return NULL;
}
got = read (fd, cmdline, sizeof (cmdline) - 1);
if (got == -1)
fprintf (stderr, "%s: read (\"%s\"): %m\n", progname,
cmdline_fname);
if (close (fd) != 0)
fprintf (stderr, "%s: close (\"%s\"): %m\n", progname,
cmdline_fname);
if (got < 0)
return NULL;
/* Convert '\0' argument delimiters to spaces. */
for (s = cmdline; s < cmdline + got; s++)
if (!*s)
*s = ' ';
/* Trim the trailing spaces (typically single '\0'->' '). */
while (s > cmdline && isspace (s[-1]))
s--;
*s = 0;
return cmdline;
}
static int dir_scan (const char *dirname,
int (*callback) (struct dirent *dirent, const char *pathname))
{
DIR *dir;
struct dirent *dirent;
int rc = 0;
dir = opendir (dirname);
if (dir == NULL)
{
if (errno == EACCES || errno == ENOENT)
return rc;
fprintf (stderr, "%s: opendir (\"%s\"): %m\n", progname, dirname);
exit (EXIT_FAILURE);
}
while ((errno = 0, dirent = readdir (dir)))
{
char pathname[LINE_MAX];
int pathname_len;
pathname_len = snprintf (pathname, sizeof pathname, "%s/%s",
dirname, dirent->d_name);
if (pathname_len <= 0 || pathname_len >= sizeof pathname)
{
fprintf (stderr, "entry file name too long: `%s' / `%s'\n",
dirname, dirent->d_name);
continue;
}
/* RHEL-4.5 on s390x never fills in D_TYPE. */
if (dirent->d_type == DT_UNKNOWN)
{
struct stat statbuf;
int i;
/* We are not interested in the /proc/PID/fd/ links targets. */
i = lstat (pathname, &statbuf);
if (i == -1)
{
if (errno == EACCES || errno == ENOENT)
continue;
fprintf (stderr, "%s: stat (\"%s\"): %m\n", progname, pathname);
exit (EXIT_FAILURE);
}
if (S_ISDIR (statbuf.st_mode))
dirent->d_type = DT_DIR;
if (S_ISLNK (statbuf.st_mode))
dirent->d_type = DT_LNK;
/* No other D_TYPE types used in this code. */
}
rc = (*callback) (dirent, pathname);
if (rc != 0)
{
errno = 0;
break;
}
}
if (errno != 0)
{
fprintf (stderr, "%s: readdir (\"%s\"): %m\n", progname, dirname);
exit (EXIT_FAILURE);
}
if (closedir (dir) != 0)
{
fprintf (stderr, "%s: closedir (\"%s\"): %m\n", progname, dirname);
exit (EXIT_FAILURE);
}
return rc;
}
static int fd_fs_scan (pid_t pid, int (*func) (pid_t pid, const char *link))
{
char dirname[64];
if (snprintf (dirname, sizeof dirname, "/proc/%d/fd", (int) pid) < 0)
{
perror ("snprintf(3)");
exit (EXIT_FAILURE);
}
int callback (struct dirent *dirent, const char *pathname)
{
char buf[LINE_MAX];
ssize_t buf_len;
if ((dirent->d_type != DT_DIR && dirent->d_type != DT_LNK)
|| (dirent->d_type == DT_DIR && strcmp (dirent->d_name, ".") != 0
&& strcmp (dirent->d_name, "..") != 0)
|| (dirent->d_type == DT_LNK && strspn (dirent->d_name, "0123456789")
!= strlen (dirent->d_name)))
{
fprintf (stderr, "Unexpected entry \"%s\" (d_type %u)"
" on readdir (\"%s\"): %m\n",
dirent->d_name, (unsigned) dirent->d_type, dirname);
return 0;
}
if (dirent->d_type == DT_DIR)
return 0;
buf_len = readlink (pathname, buf, sizeof buf - 1);
if (buf_len <= 0 || buf_len >= sizeof buf - 1)
{
if (errno != ENOENT && errno != EACCES)
fprintf (stderr, "Error reading link \"%s\": %m\n", pathname);
return 0;
}
buf[buf_len] = 0;
return (*func) (pid, buf);
}
return dir_scan (dirname, callback);
}
static void pid_fs_scan (void (*func) (pid_t pid, void *data), void *data)
{
int callback (struct dirent *dirent, const char *pathname)
{
if (dirent->d_type != DT_DIR
|| strspn (dirent->d_name, "0123456789") != strlen (dirent->d_name))
return 0;
(*func) (atoi (dirent->d_name), data);
return 0;
}
dir_scan ("/proc", callback);
}
static int rip_check_ptyname (pid_t pid, const char *link)
{
assert (pid != getpid ());
return strcmp (link, childptyname) == 0;
}
struct pid
{
struct pid *next;
pid_t pid;
};
static struct pid *pid_list;
static int pid_found (pid_t pid)
{
struct pid *entry;
for (entry = pid_list; entry != NULL; entry = entry->next)
if (entry->pid == pid)
return 1;
return 0;
}
/* Single pass is not enough, a (multithreaded) process was seen to survive.
Repeated killing of the same process is not enough, zombies can be killed.
*/
static int cleanup_acted;
static void pid_record (pid_t pid)
{
struct pid *entry;
if (pid_found (pid))
return;
cleanup_acted = 1;
entry = malloc (sizeof (*entry));
if (entry == NULL)
{
fprintf (stderr, "%s: malloc: %m\n", progname);
exit (EXIT_FAILURE);
}
entry->pid = pid;
entry->next = pid_list;
pid_list = entry;
}
static void pid_forall (void (*func) (pid_t pid))
{
struct pid *entry;
for (entry = pid_list; entry != NULL; entry = entry->next)
(*func) (entry->pid);
}
/* Returns 0 on failure. */
static pid_t pid_get_parent (pid_t pid)
{
char fname[64];
FILE *f;
char line[LINE_MAX];
pid_t retval = 0;
if (snprintf (fname, sizeof fname, "/proc/%d/status", (int) pid) < 0)
{
perror ("snprintf(3)");
exit (EXIT_FAILURE);
}
f = fopen (fname, "r");
if (f == NULL)
{
return 0;
}
while (errno = 0, fgets (line, sizeof line, f) == line)
{
if (strncmp (line, "PPid:\t", sizeof "PPid:\t" - 1) != 0)
continue;
retval = atoi (line + sizeof "PPid:\t" - 1);
errno = 0;
break;
}
if (errno != 0)
{
fprintf (stderr, "%s: fgets (\"%s\"): %m\n", progname, fname);
exit (EXIT_FAILURE);
}
if (fclose (f) != 0)
{
fprintf (stderr, "%s: fclose (\"%s\"): %m\n", progname, fname);
exit (EXIT_FAILURE);
}
return retval;
}
static void killtree (pid_t pid);
static void killtree_pid_fs_scan (pid_t pid, void *data)
{
pid_t parent_pid = *(pid_t *) data;
/* Do not optimize it as we could miss some newly spawned processes.
Always traverse all the leaves. */
#if 0
/* Optimization. */
if (pid_found (pid))
return;
#endif
if (pid_get_parent (pid) != parent_pid)
return;
killtree (pid);
}
static void killtree (pid_t pid)
{
pid_record (pid);
pid_fs_scan (killtree_pid_fs_scan, &pid);
}
static void rip_pid_fs_scan (pid_t pid, void *data)
{
pid_t pgid;
/* Shouldn't happen. */
if (pid == getpid ())
return;
/* Check both PGID and the stale file descriptors. */
pgid = getpgid (pid);
if (pgid == child
|| fd_fs_scan (pid, rip_check_ptyname) != 0)
killtree (pid);
}
static void killproc (pid_t pid)
{
const char *cmdline;
cmdline = read_cmdline (pid);
/* Avoid printing the message for already gone processes. */
if (kill (pid, 0) != 0 && errno == ESRCH)
return;
if (cmdline == NULL)
cmdline = "<error>";
fprintf (stderr, "%s: Killed -9 orphan PID %d: %s\n", progname, (int) pid, cmdline);
if (kill (pid, SIGKILL) == 0)
cleanup_acted = 1;
else if (errno != ESRCH)
fprintf (stderr, "%s: kill (%d, SIGKILL): %m\n", progname, (int) pid);
/* RHEL-3 kernels cannot SIGKILL a `T (stopped)' process. */
kill (pid, SIGCONT);
/* Do not waitpid(2) as it cannot be our direct descendant and it gets
cleaned up by init(8). */
#if 0
pid_t pid_got;
pid_got = waitpid (pid, NULL, 0);
if (pid != pid_got)
{
fprintf (stderr, "%s: waitpid (%d) != %d: %m\n", progname,
(int) pid, (int) pid_got);
return;
}
#endif
}
static void rip (void)
{
cleanup_acted = 0;
do
{
if (cleanup_acted)
usleep (1000000 / 10);
cleanup_acted = 0;
pid_fs_scan (rip_pid_fs_scan, NULL);
pid_forall (killproc);
}
while (cleanup_acted);
}
int main (int argc, char **argv)
{
int rc;
if (argc < 2 || strcmp (argv[1], "-h") == 0
|| strcmp (argv[1], "--help") == 0)
{
fputs ("Syntax: orphanripper <execvp(3) commandline>\n", stdout);
exit (EXIT_FAILURE);
}
progname = argv[0];
rc = spawn (argv);
rip ();
return rc;
}