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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2004-2005, 2007-2012 Free Software Foundation, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General
Public License along with this library. If not, see
<http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <mailutils/daemon.h>
#include <mailutils/errno.h>
#include <mailutils/error.h>
#include <mailutils/nls.h>
static char *pidfile;
static pid_t current_pid;
/* Return 0 if DIR is writable for EUID/EGID.
Otherwise, return error code. */
static int
ewraccess (const char *dir)
{
struct stat st;
if (stat (dir, &st))
return errno;
if ((st.st_mode & S_IWOTH)
|| (st.st_gid == getegid () && (st.st_mode & S_IWGRP))
|| (st.st_uid == geteuid () && (st.st_mode & S_IWUSR)))
return 0;
else
return EACCES;
}
/* Return 0 if DIR is writable. If necessary and possible, raise to
EUID 0, in that case return prior EUID in the memory location pointed to
by PUID. */
static int
access_dir (const char *dir, uid_t *puid)
{
int ec = ewraccess (dir);
if (ec)
{
if (ec == EACCES && access (dir, W_OK) == 0)
{
uid_t uid = geteuid ();
/* See if we can become root */
if (uid && getuid () == 0 && seteuid (0) == 0)
{
*puid = uid;
return 0;
}
}
}
return ec;
}
int
mu_daemon_create_pidfile (const char *filename)
{
char *p;
int fd;
uid_t uid = 0;
int rc;
if (filename[0] != '/')
return EINVAL;
if (pidfile)
free (pidfile);
pidfile = strdup (filename);
if (!pidfile)
return ENOMEM;
/* Determine the hosting directory name */
p = strrchr (pidfile, '/');
if (pidfile == p)
{
free (pidfile);
pidfile = NULL;
/* Sorry, pidfiles in root dir are not allowed */
return EINVAL;
}
/* Check if we have write access to the directory */
*p = 0;
rc = access_dir (pidfile, &uid);
if (rc)
{
/* Nope, clean up and return */
free (pidfile);
pidfile = NULL;
return rc;
}
/* Restore directory separator */
*p = '/';
unlink (pidfile);
current_pid = getpid ();
if ((fd = open (pidfile, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0644)) != -1)
{
FILE *fp = fdopen (fd, "w");
if (!fp)
{
rc = errno;
free (pidfile);
close (fd);
}
else
{
fprintf (fp, "%lu", (unsigned long) current_pid);
fclose (fp);
atexit (mu_daemon_remove_pidfile);
}
}
else
{
rc = errno;
free (pidfile);
pidfile = NULL;
}
/* Restore previous EUID value. */
if (uid)
seteuid (uid);
return rc;
}
void
mu_daemon_remove_pidfile (void)
{
if (getpid () == current_pid)
{
int rc;
uid_t uid = 0;
/* Determine the hosting directory name */
char *p = strrchr (pidfile, '/');
if (pidfile == p)
{
/* Should not happen */
abort ();
}
/* Check if we have write access to the directory */
*p = 0;
rc = access_dir (pidfile, &uid);
*p = '/';
if (rc == 0)
{
if (unlink (pidfile) && errno != ENOENT)
rc = errno;
else
rc = 0;
}
if (rc)
mu_error (_("cannot remove pidfile %s: %s"),
pidfile, mu_strerror (rc));
free (pidfile);
pidfile = NULL;
}
}
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