ctdb/server/ctdb_lock_helper.c

   1 /*
   2    ctdb lock helper
   3
   4    Copyright (C) Amitay Isaacs  2013
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "replace.h"
  21 #include "system/filesys.h"
  22 #include "system/network.h"
  23 #include "system/wait.h"
  24
  25 #include <talloc.h>
  26 #include <tevent.h>
  27 #include <tdb.h>
  28
  29 #include "lib/util/sys_rw.h"
  30 #include "lib/util/tevent_unix.h"
  31
  32 #include "protocol/protocol.h"
  33
  34 #include "common/system.h"
  35
  36 static bool realtime = true;
  37
  38 struct lock_state {
  39         struct tdb_context *tdb;
  40         TDB_DATA key;
  41 };
  42
  43 static void set_priority(void)
  44 {
  45         const char *ptr;
  46
  47         ptr = getenv("CTDB_NOSETSCHED");
  48         if (ptr != NULL) {
  49                 realtime = false;
  50         }
  51
  52         if (! realtime) {
  53                 return;
  54         }
  55
  56         realtime = set_scheduler();
  57         if (! realtime) {
  58                 fprintf(stderr,
  59                         "locking: Unable to set real-time scheduler priority\n");
  60         }
  61 }
  62
  63 static void reset_priority(void)
  64 {
  65         if (realtime) {
  66                 reset_scheduler();
  67         }
  68 }
  69
  70 static void send_result(int fd, char result)
  71 {
  72         sys_write(fd, &result, 1);
  73         if (result == 1) {
  74                 exit(1);
  75         }
  76 }
  77
  78
  79 static void usage(const char *progname)
  80 {
  81         fprintf(stderr, "\n");
  82         fprintf(stderr, "Usage: %s <ctdbd-pid> <output-fd> RECORD <db-path> <db-flags> <db-key>\n", progname);
  83         fprintf(stderr, "       %s <ctdbd-pid> <output-fd> DB <db-path> <db-flags>\n", progname);
  84 }
  85
  86 static uint8_t *hex_decode_talloc(TALLOC_CTX *mem_ctx,
  87                                   const char *hex_in, size_t *len)
  88 {
  89         int i, num;
  90         uint8_t *buffer;
  91
  92         *len = strlen(hex_in) / 2;
  93         buffer = talloc_array(mem_ctx, unsigned char, *len);
  94
  95         for (i=0; i<*len; i++) {
  96                 sscanf(&hex_in[i*2], "%02X", &num);
  97                 buffer[i] = (uint8_t)num;
  98         }
  99
 100         return buffer;
 101 }
 102
 103 static int lock_record(const char *dbpath, const char *dbflags,
 104                        const char *dbkey, struct lock_state *state)
 105 {
 106         int tdb_flags;
 107
 108         /* No error checking since CTDB always passes sane values */
 109         tdb_flags = strtol(dbflags, NULL, 0);
 110
 111         /* Convert hex key to key */
 112         if (strcmp(dbkey, "NULL") == 0) {
 113                 state->key.dptr = NULL;
 114                 state->key.dsize = 0;
 115         } else {
 116                 state->key.dptr = hex_decode_talloc(NULL, dbkey,
 117                                                     &state->key.dsize);
 118         }
 119
 120         state->tdb = tdb_open(dbpath, 0, tdb_flags, O_RDWR, 0600);
 121         if (state->tdb == NULL) {
 122                 fprintf(stderr, "locking: Error opening database %s\n", dbpath);
 123                 return 1;
 124         }
 125
 126         set_priority();
 127
 128         if (tdb_chainlock(state->tdb, state->key) < 0) {
 129                 fprintf(stderr, "locking: Error getting record lock (%s)\n",
 130                         tdb_errorstr(state->tdb));
 131                 return 1;
 132         }
 133
 134         reset_priority();
 135
 136         return 0;
 137
 138 }
 139
 140 static int lock_db(const char *dbpath, const char *dbflags,
 141                    struct lock_state *state)
 142 {
 143         int tdb_flags;
 144
 145         /* No error checking since CTDB always passes sane values */
 146         tdb_flags = strtol(dbflags, NULL, 0);
 147
 148         state->tdb = tdb_open(dbpath, 0, tdb_flags, O_RDWR, 0600);
 149         if (state->tdb == NULL) {
 150                 fprintf(stderr, "locking: Error opening database %s\n", dbpath);
 151                 return 1;
 152         }
 153
 154         set_priority();
 155
 156         if (tdb_lockall(state->tdb) < 0) {
 157                 fprintf(stderr, "locking: Error getting db lock (%s)\n",
 158                         tdb_errorstr(state->tdb));
 159                 return 1;
 160         }
 161
 162         reset_priority();
 163
 164         return 0;
 165 }
 166
 167 struct wait_for_parent_state {
 168         struct tevent_context *ev;
 169         pid_t ppid;
 170 };
 171
 172 static void wait_for_parent_check(struct tevent_req *subreq);
 173
 174 static struct tevent_req *wait_for_parent_send(TALLOC_CTX *mem_ctx,
 175                                                struct tevent_context *ev,
 176                                                pid_t ppid)
 177 {
 178         struct tevent_req *req, *subreq;
 179         struct wait_for_parent_state *state;
 180
 181         req = tevent_req_create(mem_ctx, &state, struct wait_for_parent_state);
 182         if (req == NULL) {
 183                 return NULL;
 184         }
 185
 186         state->ev = ev;
 187         state->ppid = ppid;
 188
 189         if (ppid == 1) {
 190                 tevent_req_done(req);
 191                 return tevent_req_post(req, ev);
 192         }
 193
 194         subreq = tevent_wakeup_send(state, ev,
 195                                     tevent_timeval_current_ofs(5,0));
 196         if (tevent_req_nomem(subreq, req)) {
 197                 return tevent_req_post(req, ev);
 198         }
 199         tevent_req_set_callback(subreq, wait_for_parent_check, req);
 200
 201         return req;
 202 }
 203
 204 static void wait_for_parent_check(struct tevent_req *subreq)
 205 {
 206         struct tevent_req *req = tevent_req_callback_data(
 207                 subreq, struct tevent_req);
 208         struct wait_for_parent_state *state = tevent_req_data(
 209                 req, struct wait_for_parent_state);
 210         bool status;
 211
 212         status = tevent_wakeup_recv(subreq);
 213         TALLOC_FREE(subreq);
 214         if (! status) {
 215                 /* Ignore error */
 216                 fprintf(stderr, "locking: tevent_wakeup_recv() failed\n");
 217         }
 218
 219         if (kill(state->ppid, 0) == -1 && errno == ESRCH) {
 220                 tevent_req_done(req);
 221                 return;
 222         }
 223
 224         subreq = tevent_wakeup_send(state, state->ev,
 225                                     tevent_timeval_current_ofs(5,0));
 226         if (tevent_req_nomem(subreq, req)) {
 227                 return;
 228         }
 229         tevent_req_set_callback(subreq, wait_for_parent_check, req);
 230 }
 231
 232 static bool wait_for_parent_recv(struct tevent_req *req)
 233 {
 234         if (tevent_req_is_unix_error(req, NULL)) {
 235                 return false;
 236         }
 237
 238         return true;
 239 }
 240
 241 static void cleanup(struct lock_state *state)
 242 {
 243         if (state->tdb != NULL) {
 244                 if (state->key.dsize == 0) {
 245                         tdb_unlockall(state->tdb);
 246                 } else {
 247                         tdb_chainunlock(state->tdb, state->key);
 248                 }
 249                 tdb_close(state->tdb);
 250         }
 251 }
 252
 253 static void signal_handler(struct tevent_context *ev,
 254                            struct tevent_signal *se,
 255                            int signum, int count, void *siginfo,
 256                            void *private_data)
 257 {
 258         struct lock_state *state = (struct lock_state *)private_data;
 259
 260         cleanup(state);
 261         exit(0);
 262 }
 263
 264 int main(int argc, char *argv[])
 265 {
 266         struct tevent_context *ev;
 267         struct tevent_signal *se;
 268         struct tevent_req *req;
 269         struct lock_state state = { 0 };
 270         int write_fd;
 271         char result = 0;
 272         int ppid;
 273         const char *lock_type;
 274         bool status;
 275
 276         reset_scheduler();
 277
 278         if (argc < 4) {
 279                 usage(argv[0]);
 280                 exit(1);
 281         }
 282
 283         ppid = atoi(argv[1]);
 284         write_fd = atoi(argv[2]);
 285         lock_type = argv[3];
 286
 287         ev = tevent_context_init(NULL);
 288         if (ev == NULL) {
 289                 fprintf(stderr, "locking: tevent_context_init() failed\n");
 290                 exit(1);
 291         }
 292
 293         se = tevent_add_signal(ev, ev, SIGTERM, 0,
 294                                signal_handler, &state);
 295         if (se == NULL) {
 296                 fprintf(stderr, "locking: tevent_add_signal() failed\n");
 297                 talloc_free(ev);
 298                 exit(1);
 299         }
 300
 301         if (strcmp(lock_type, "RECORD") == 0) {
 302                 if (argc != 7) {
 303                         fprintf(stderr,
 304                                 "locking: Invalid number of arguments (%d)\n",
 305                                 argc);
 306                         usage(argv[0]);
 307                         exit(1);
 308                 }
 309                 result = lock_record(argv[4], argv[5], argv[6], &state);
 310
 311         } else if (strcmp(lock_type, "DB") == 0) {
 312                 if (argc != 6) {
 313                         fprintf(stderr,
 314                                 "locking: Invalid number of arguments (%d)\n",
 315                                 argc);
 316                         usage(argv[0]);
 317                         exit(1);
 318                 }
 319                 result = lock_db(argv[4], argv[5], &state);
 320
 321         } else {
 322                 fprintf(stderr, "locking: Invalid lock-type '%s'\n", lock_type);
 323                 usage(argv[0]);
 324                 exit(1);
 325         }
 326
 327         send_result(write_fd, result);
 328
 329         req = wait_for_parent_send(ev, ev, ppid);
 330         if (req == NULL) {
 331                 fprintf(stderr, "locking: wait_for_parent_send() failed\n");
 332                 cleanup(&state);
 333                 exit(1);
 334         }
 335
 336         tevent_req_poll(req, ev);
 337
 338         status = wait_for_parent_recv(req);
 339         if (! status) {
 340                 fprintf(stderr, "locking: wait_for_parent_recv() failed\n");
 341         }
 342
 343         talloc_free(ev);
 344         cleanup(&state);
 345         return 0;
 346 }