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samba-mirror/ctdb/server/ctdb_lock_helper.c

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/*
ctdb lock helper
Copyright (C) Amitay Isaacs 2013
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "replace.h"
#include "system/filesys.h"
#include "system/network.h"
#include "system/wait.h"
#include <talloc.h>
#include <tevent.h>
#include <tdb.h>
#include "lib/util/sys_rw.h"
#include "lib/util/tevent_unix.h"
#include "protocol/protocol.h"
#include "common/system.h"
static bool realtime = true;
struct lock_state {
struct tdb_context *tdb;
TDB_DATA key;
};
static void set_priority(void)
{
const char *ptr;
ptr = getenv("CTDB_NOSETSCHED");
if (ptr != NULL) {
realtime = false;
}
if (! realtime) {
return;
}
realtime = set_scheduler();
if (! realtime) {
fprintf(stderr,
"locking: Unable to set real-time scheduler priority\n");
}
}
static void reset_priority(void)
{
if (realtime) {
reset_scheduler();
}
}
static void send_result(int fd, char result)
{
sys_write(fd, &result, 1);
if (result == 1) {
exit(1);
}
}
static void usage(const char *progname)
{
fprintf(stderr, "\n");
fprintf(stderr, "Usage: %s <ctdbd-pid> <output-fd> RECORD <db-path> <db-flags> <db-key>\n", progname);
fprintf(stderr, " %s <ctdbd-pid> <output-fd> DB <db-path> <db-flags>\n", progname);
}
static uint8_t *hex_decode_talloc(TALLOC_CTX *mem_ctx,
const char *hex_in, size_t *len)
{
int i, num;
uint8_t *buffer;
*len = strlen(hex_in) / 2;
buffer = talloc_array(mem_ctx, unsigned char, *len);
for (i=0; i<*len; i++) {
sscanf(&hex_in[i*2], "%02X", &num);
buffer[i] = (uint8_t)num;
}
return buffer;
}
static int lock_record(const char *dbpath, const char *dbflags,
const char *dbkey, struct lock_state *state)
{
int tdb_flags;
/* No error checking since CTDB always passes sane values */
tdb_flags = strtol(dbflags, NULL, 0);
/* Convert hex key to key */
if (strcmp(dbkey, "NULL") == 0) {
state->key.dptr = NULL;
state->key.dsize = 0;
} else {
state->key.dptr = hex_decode_talloc(NULL, dbkey,
&state->key.dsize);
}
state->tdb = tdb_open(dbpath, 0, tdb_flags, O_RDWR, 0600);
if (state->tdb == NULL) {
fprintf(stderr, "locking: Error opening database %s\n", dbpath);
return 1;
}
set_priority();
if (tdb_chainlock(state->tdb, state->key) < 0) {
fprintf(stderr, "locking: Error getting record lock (%s)\n",
tdb_errorstr(state->tdb));
return 1;
}
reset_priority();
return 0;
}
static int lock_db(const char *dbpath, const char *dbflags,
struct lock_state *state)
{
int tdb_flags;
/* No error checking since CTDB always passes sane values */
tdb_flags = strtol(dbflags, NULL, 0);
state->tdb = tdb_open(dbpath, 0, tdb_flags, O_RDWR, 0600);
if (state->tdb == NULL) {
fprintf(stderr, "locking: Error opening database %s\n", dbpath);
return 1;
}
set_priority();
if (tdb_lockall(state->tdb) < 0) {
fprintf(stderr, "locking: Error getting db lock (%s)\n",
tdb_errorstr(state->tdb));
return 1;
}
reset_priority();
return 0;
}
struct wait_for_parent_state {
struct tevent_context *ev;
pid_t ppid;
};
static void wait_for_parent_check(struct tevent_req *subreq);
static struct tevent_req *wait_for_parent_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
pid_t ppid)
{
struct tevent_req *req, *subreq;
struct wait_for_parent_state *state;
req = tevent_req_create(mem_ctx, &state, struct wait_for_parent_state);
if (req == NULL) {
return NULL;
}
state->ev = ev;
state->ppid = ppid;
if (ppid == 1) {
tevent_req_done(req);
return tevent_req_post(req, ev);
}
subreq = tevent_wakeup_send(state, ev,
tevent_timeval_current_ofs(5,0));
if (tevent_req_nomem(subreq, req)) {
return tevent_req_post(req, ev);
}
tevent_req_set_callback(subreq, wait_for_parent_check, req);
return req;
}
static void wait_for_parent_check(struct tevent_req *subreq)
{
struct tevent_req *req = tevent_req_callback_data(
subreq, struct tevent_req);
struct wait_for_parent_state *state = tevent_req_data(
req, struct wait_for_parent_state);
bool status;
status = tevent_wakeup_recv(subreq);
TALLOC_FREE(subreq);
if (! status) {
/* Ignore error */
fprintf(stderr, "locking: tevent_wakeup_recv() failed\n");
}
if (kill(state->ppid, 0) == -1 && errno == ESRCH) {
tevent_req_done(req);
return;
}
subreq = tevent_wakeup_send(state, state->ev,
tevent_timeval_current_ofs(5,0));
if (tevent_req_nomem(subreq, req)) {
return;
}
tevent_req_set_callback(subreq, wait_for_parent_check, req);
}
static bool wait_for_parent_recv(struct tevent_req *req)
{
if (tevent_req_is_unix_error(req, NULL)) {
return false;
}
return true;
}
static void cleanup(struct lock_state *state)
{
if (state->tdb != NULL) {
if (state->key.dsize == 0) {
tdb_unlockall(state->tdb);
} else {
tdb_chainunlock(state->tdb, state->key);
}
tdb_close(state->tdb);
}
}
static void signal_handler(struct tevent_context *ev,
struct tevent_signal *se,
int signum, int count, void *siginfo,
void *private_data)
{
struct lock_state *state = (struct lock_state *)private_data;
cleanup(state);
exit(0);
}
int main(int argc, char *argv[])
{
struct tevent_context *ev;
struct tevent_signal *se;
struct tevent_req *req;
struct lock_state state = { 0 };
int write_fd;
char result = 0;
int ppid;
const char *lock_type;
bool status;
reset_scheduler();
if (argc < 4) {
usage(argv[0]);
exit(1);
}
ppid = atoi(argv[1]);
write_fd = atoi(argv[2]);
lock_type = argv[3];
ev = tevent_context_init(NULL);
if (ev == NULL) {
fprintf(stderr, "locking: tevent_context_init() failed\n");
exit(1);
}
se = tevent_add_signal(ev, ev, SIGTERM, 0,
signal_handler, &state);
if (se == NULL) {
fprintf(stderr, "locking: tevent_add_signal() failed\n");
talloc_free(ev);
exit(1);
}
if (strcmp(lock_type, "RECORD") == 0) {
if (argc != 7) {
fprintf(stderr,
"locking: Invalid number of arguments (%d)\n",
argc);
usage(argv[0]);
exit(1);
}
result = lock_record(argv[4], argv[5], argv[6], &state);
} else if (strcmp(lock_type, "DB") == 0) {
if (argc != 6) {
fprintf(stderr,
"locking: Invalid number of arguments (%d)\n",
argc);
usage(argv[0]);
exit(1);
}
result = lock_db(argv[4], argv[5], &state);
} else {
fprintf(stderr, "locking: Invalid lock-type '%s'\n", lock_type);
usage(argv[0]);
exit(1);
}
send_result(write_fd, result);
req = wait_for_parent_send(ev, ev, ppid);
if (req == NULL) {
fprintf(stderr, "locking: wait_for_parent_send() failed\n");
cleanup(&state);
exit(1);
}
tevent_req_poll(req, ev);
status = wait_for_parent_recv(req);
if (! status) {
fprintf(stderr, "locking: wait_for_parent_recv() failed\n");
}
talloc_free(ev);
cleanup(&state);
return 0;
}