/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
*
* Copyright (C) 2001 Ximian Inc.
*
* Authors: Michael Zucchi <notzed@ximian.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* 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
*/
/* lock helper process */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <utime.h>
#include <time.h>
#include <string.h>
#define SETEUID_SAVES (1)
/* we try and include as little as possible */
#include "camel-lock-helper.h"
#include "camel-lock.h"
#define d(x)
/* keeps track of open locks */
struct _lock_info {
struct _lock_info *next;
uid_t uid;
int id;
int depth;
time_t stamp; /* when last updated */
char path[1];
};
static int lock_id = 0;
static struct _lock_info *lock_info_list;
static uid_t lock_root_uid = -1;
static uid_t lock_real_uid = -1;
/* utility functions */
static int read_n(int fd, void *buffer, int inlen)
{
char *p = buffer;
int len, left = inlen;
do {
len = read(fd, p, left);
if (len == -1) {
if (errno != EINTR)
return -1;
} else {
left -= len;
p += len;
}
} while (left > 0 && len != 0);
return inlen - left;
}
static int write_n(int fd, void *buffer, int inlen)
{
char *p = buffer;
int len, left = inlen;
do {
len = write(fd, p, left);
if (len == -1) {
if (errno != EINTR)
return -1;
} else {
left -= len;
p += len;
}
} while (left > 0);
return inlen;
}
void
camel_exception_setv (CamelException *ex, ExceptionId id, const char *format, ...)
{
;
}
void
camel_exception_clear (CamelException *exception)
{
;
}
char *gettext (const char *msgid);
char *
gettext (const char *msgid)
{
return NULL;
}
static int lock_path(const char *path, guint32 *lockid)
{
struct _lock_info *info = NULL;
int res = CAMEL_LOCK_HELPER_STATUS_OK;
struct stat st;
d(fprintf(stderr, "locking path '%s' id = %d\n", path, lock_id));
/* check to see if we have it locked already, make the lock 'recursive' */
/* we could also error i suppose, but why bother */
info = lock_info_list;
while (info) {
if (!strcmp(info->path, path)) {
info->depth++;
return CAMEL_LOCK_HELPER_STATUS_OK;
}
info = info->next;
}
/* check we are allowed to lock it, we must own it, be able to write to it, and it has to exist */
if (stat(path, &st) == -1
|| st.st_uid != getuid()
|| !S_ISREG(st.st_mode)
|| (st.st_mode & 0400) == 0) {
return CAMEL_LOCK_HELPER_STATUS_INVALID;
}
info = malloc(sizeof(*info) + strlen(path));
if (info == NULL) {
res = CAMEL_LOCK_HELPER_STATUS_NOMEM;
goto fail;
}
/* we try the real uid first, and if that fails, try the 'root id' */
if (camel_lock_dot(path, NULL) == -1) {
#ifdef SETEUID_SAVES
if (lock_real_uid != lock_root_uid) {
if (seteuid(lock_root_uid) != -1) {
if (camel_lock_dot(path, NULL) == -1) {
seteuid(lock_real_uid);
res = CAMEL_LOCK_HELPER_STATUS_SYSTEM;
goto fail;
}
seteuid(lock_real_uid);
} else {
res = CAMEL_LOCK_HELPER_STATUS_SYSTEM;
goto fail;
}
} else {
res = CAMEL_LOCK_HELPER_STATUS_SYSTEM;
goto fail;
}
#else
res = CAMEL_LOCK_HELPER_STATUS_SYSTEM;
goto fail;
#endif
} else {
info->uid = lock_real_uid;
}
strcpy(info->path, path);
info->id = lock_id;
info->depth = 1;
info->next = lock_info_list;
info->stamp = time(0);
lock_info_list = info;
if (lockid)
*lockid = lock_id;
lock_id++;
d(fprintf(stderr, "lock ok\n"));
return res;
fail:
d(fprintf(stderr, "lock failed\n"));
if (info)
free(info);
return res;
}
static int unlock_id(guint32 lockid)
{
struct _lock_info *info, *p;
d(fprintf(stderr, "unlocking id '%d'\n", lockid));
p = (struct _lock_info *)&lock_info_list;
info = p->next;
while (info) {
if (info->id == lockid) {
d(fprintf(stderr, "found id %d path '%s'\n", lockid, info->path));
info->depth--;
if (info->depth <= 0) {
#ifdef SETEUID_SAVES
if (info->uid != lock_real_uid) {
seteuid(lock_root_uid);
camel_unlock_dot(info->path);
seteuid(lock_real_uid);
} else
#endif
camel_unlock_dot(info->path);
p->next = info->next;
free(info);
}
return CAMEL_LOCK_HELPER_STATUS_OK;
}
p = info;
info = info->next;
}
d(fprintf(stderr, "unknown id asked to be unlocked %d\n", lockid));
return CAMEL_LOCK_HELPER_STATUS_PROTOCOL;
}
static void lock_touch(const char *path)
{
char *name;
/* we could also check that we haven't had our lock stolen from us here */
name = alloca(strlen(path) + 10);
sprintf(name, "%s.lock", path);
d(fprintf(stderr, "Updating lock %s\n", name));
utime(name, NULL);
}
static void setup_process(void)
{
struct sigaction sa;
sigset_t sigset;
/* ignore sigint/sigio */
sa.sa_handler = SIG_IGN;
sigemptyset (&sa.sa_mask);
sa.sa_flags = 0;
sigemptyset(&sigset);
sigaddset(&sigset, SIGIO);
sigaddset(&sigset, SIGINT);
sigprocmask(SIG_UNBLOCK, &sigset, NULL);
sigaction (SIGIO, &sa, NULL);
sigaction (SIGINT, &sa, NULL);
/* FIXME: add more sanity checks/setup here */
#ifdef SETEUID_SAVES
/* here we change to the real user id, this is probably not particularly
portable so may need configure checks */
lock_real_uid = getuid();
lock_root_uid = geteuid();
if (lock_real_uid != lock_root_uid)
seteuid(lock_real_uid);
#endif
}
int main(int argc, char **argv)
{
struct _CamelLockHelperMsg msg;
int len;
int res;
char *path;
fd_set rset;
struct timeval tv;
struct _lock_info *info;
setup_process();
do {
/* do a poll/etc, so we can refresh the .locks as required ... */
FD_ZERO(&rset);
FD_SET(STDIN_FILENO, &rset);
/* check the minimum timeout we need to refresh the next oldest lock */
if (lock_info_list) {
time_t now = time(0);
time_t left;
time_t delay = CAMEL_DOT_LOCK_REFRESH;
info = lock_info_list;
while (info) {
left = CAMEL_DOT_LOCK_REFRESH - (now - info->stamp);
left = MAX(left, 0);
delay = MIN(left, delay);
info = info->next;
}
tv.tv_sec = delay;
tv.tv_usec = 0;
}
d(fprintf(stderr, "lock helper waiting for input\n"));
if (select(STDIN_FILENO+1, &rset, NULL, NULL, lock_info_list?&tv:NULL) == -1) {
if (errno == EINTR)
break;
continue;
}
/* did we get a timeout? scan for any locks that need updating */
if (!FD_ISSET(STDIN_FILENO, &rset)) {
time_t now = time(0);
time_t left;
d(fprintf(stderr, "Got a timeout, checking locks\n"));
info = lock_info_list;
while (info) {
left = (now - info->stamp);
if (left >= CAMEL_DOT_LOCK_REFRESH) {
lock_touch(info->path);
info->stamp = now;
}
info = info->next;
}
continue;
}
len = read_n(STDIN_FILENO, &msg, sizeof(msg));
if (len == 0)
break;
res = CAMEL_LOCK_HELPER_STATUS_PROTOCOL;
if (len == sizeof(msg) && msg.magic == CAMEL_LOCK_HELPER_MAGIC) {
switch(msg.id) {
case CAMEL_LOCK_HELPER_LOCK:
res = CAMEL_LOCK_HELPER_STATUS_NOMEM;
path = malloc(msg.data+1);
if (path != NULL) {
res = CAMEL_LOCK_HELPER_STATUS_PROTOCOL;
len = read_n(STDIN_FILENO, path, msg.data);
if (len == msg.data) {
path[len] = 0;
res = lock_path(path, &msg.data);
}
free(path);
}
break;
case CAMEL_LOCK_HELPER_UNLOCK:
res = unlock_id(msg.data);
break;
}
}
d(fprintf(stderr, "returning result %d\n", res));
msg.id = res;
msg.magic = CAMEL_LOCK_HELPER_RETURN_MAGIC;
write_n(STDOUT_FILENO, &msg, sizeof(msg));
} while (1);
d(fprintf(stderr, "parent exited, clsoing down remaining id's\n"));
while (lock_info_list)
unlock_id(lock_info_list->id);
return 0;
}
