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         unsigned int i;
  90         int num;
  91         uint8_t *buffer;
  92
  93         *len = strlen(hex_in) / 2;
  94         buffer = talloc_array(mem_ctx, unsigned char, *len);
  95
  96         for (i=0; i<*len; i++) {
  97                 sscanf(&hex_in[i*2], "%02X", &num);
  98                 buffer[i] = (uint8_t)num;
  99         }
 100
 101         return buffer;
 102 }
 103
 104 static int lock_record(const char *dbpath, const char *dbflags,
 105                        const char *dbkey, struct lock_state *state)
 106 {
 107         int tdb_flags;
 108
 109         /* No error checking since CTDB always passes sane values */
 110         tdb_flags = strtol(dbflags, NULL, 0);
 111
 112         /* Convert hex key to key */
 113         if (strcmp(dbkey, "NULL") == 0) {
 114                 state->key.dptr = NULL;
 115                 state->key.dsize = 0;
 116         } else {
 117                 state->key.dptr = hex_decode_talloc(NULL, dbkey,
 118                                                     &state->key.dsize);
 119         }
 120
 121         state->tdb = tdb_open(dbpath, 0, tdb_flags, O_RDWR, 0600);
 122         if (state->tdb == NULL) {
 123                 fprintf(stderr, "locking: Error opening database %s\n", dbpath);
 124                 return 1;
 125         }
 126
 127         set_priority();
 128
 129         if (tdb_chainlock(state->tdb, state->key) < 0) {
 130                 fprintf(stderr, "locking: Error getting record lock (%s)\n",
 131                         tdb_errorstr(state->tdb));
 132                 return 1;
 133         }
 134
 135         reset_priority();
 136
 137         return 0;
 138
 139 }
 140
 141 static int lock_db(const char *dbpath, const char *dbflags,
 142                    struct lock_state *state)
 143 {
 144         int tdb_flags;
 145
 146         /* No error checking since CTDB always passes sane values */
 147         tdb_flags = strtol(dbflags, NULL, 0);
 148
 149         state->tdb = tdb_open(dbpath, 0, tdb_flags, O_RDWR, 0600);
 150         if (state->tdb == NULL) {
 151                 fprintf(stderr, "locking: Error opening database %s\n", dbpath);
 152                 return 1;
 153         }
 154
 155         set_priority();
 156
 157         if (tdb_lockall(state->tdb) < 0) {
 158                 fprintf(stderr, "locking: Error getting db lock (%s)\n",
 159                         tdb_errorstr(state->tdb));
 160                 return 1;
 161         }
 162
 163         reset_priority();
 164
 165         return 0;
 166 }
 167
 168 struct wait_for_parent_state {
 169         struct tevent_context *ev;
 170         pid_t ppid;
 171 };
 172
 173 static void wait_for_parent_check(struct tevent_req *subreq);
 174
 175 static struct tevent_req *wait_for_parent_send(TALLOC_CTX *mem_ctx,
 176                                                struct tevent_context *ev,
 177                                                pid_t ppid)
 178 {
 179         struct tevent_req *req, *subreq;
 180         struct wait_for_parent_state *state;
 181
 182         req = tevent_req_create(mem_ctx, &state, struct wait_for_parent_state);
 183         if (req == NULL) {
 184                 return NULL;
 185         }
 186
 187         state->ev = ev;
 188         state->ppid = ppid;
 189
 190         if (ppid == 1) {
 191                 tevent_req_done(req);
 192                 return tevent_req_post(req, ev);
 193         }
 194
 195         subreq = tevent_wakeup_send(state, ev,
 196                                     tevent_timeval_current_ofs(5,0));
 197         if (tevent_req_nomem(subreq, req)) {
 198                 return tevent_req_post(req, ev);
 199         }
 200         tevent_req_set_callback(subreq, wait_for_parent_check, req);
 201
 202         return req;
 203 }
 204
 205 static void wait_for_parent_check(struct tevent_req *subreq)
 206 {
 207         struct tevent_req *req = tevent_req_callback_data(
 208                 subreq, struct tevent_req);
 209         struct wait_for_parent_state *state = tevent_req_data(
 210                 req, struct wait_for_parent_state);
 211         bool status;
 212
 213         status = tevent_wakeup_recv(subreq);
 214         TALLOC_FREE(subreq);
 215         if (! status) {
 216                 /* Ignore error */
 217                 fprintf(stderr, "locking: tevent_wakeup_recv() failed\n");
 218         }
 219
 220         if (kill(state->ppid, 0) == -1 && errno == ESRCH) {
 221                 tevent_req_done(req);
 222                 return;
 223         }
 224
 225         subreq = tevent_wakeup_send(state, state->ev,
 226                                     tevent_timeval_current_ofs(5,0));
 227         if (tevent_req_nomem(subreq, req)) {
 228                 return;
 229         }
 230         tevent_req_set_callback(subreq, wait_for_parent_check, req);
 231 }
 232
 233 static bool wait_for_parent_recv(struct tevent_req *req)
 234 {
 235         if (tevent_req_is_unix_error(req, NULL)) {
 236                 return false;
 237         }
 238
 239         return true;
 240 }
 241
 242 static void cleanup(struct lock_state *state)
 243 {
 244         if (state->tdb != NULL) {
 245                 if (state->key.dsize == 0) {
 246                         tdb_unlockall(state->tdb);
 247                 } else {
 248                         tdb_chainunlock(state->tdb, state->key);
 249                 }
 250                 tdb_close(state->tdb);
 251         }
 252 }
 253
 254 static void signal_handler(struct tevent_context *ev,
 255                            struct tevent_signal *se,
 256                            int signum, int count, void *siginfo,
 257                            void *private_data)
 258 {
 259         struct lock_state *state = (struct lock_state *)private_data;
 260
 261         cleanup(state);
 262         exit(0);
 263 }
 264
 265 int main(int argc, char *argv[])
 266 {
 267         struct tevent_context *ev;
 268         struct tevent_signal *se;
 269         struct tevent_req *req;
 270         struct lock_state state = { 0 };
 271         int write_fd;
 272         char result = 0;
 273         int ppid;
 274         const char *lock_type;
 275         bool status;
 276
 277         reset_scheduler();
 278
 279         if (argc < 4) {
 280                 usage(argv[0]);
 281                 exit(1);
 282         }
 283
 284         ppid = atoi(argv[1]);
 285         write_fd = atoi(argv[2]);
 286         lock_type = argv[3];
 287
 288         ev = tevent_context_init(NULL);
 289         if (ev == NULL) {
 290                 fprintf(stderr, "locking: tevent_context_init() failed\n");
 291                 exit(1);
 292         }
 293
 294         se = tevent_add_signal(ev, ev, SIGTERM, 0,
 295                                signal_handler, &state);
 296         if (se == NULL) {
 297                 fprintf(stderr, "locking: tevent_add_signal() failed\n");
 298                 talloc_free(ev);
 299                 exit(1);
 300         }
 301
 302         if (strcmp(lock_type, "RECORD") == 0) {
 303                 if (argc != 7) {
 304                         fprintf(stderr,
 305                                 "locking: Invalid number of arguments (%d)\n",
 306                                 argc);
 307                         usage(argv[0]);
 308                         exit(1);
 309                 }
 310                 result = lock_record(argv[4], argv[5], argv[6], &state);
 311
 312         } else if (strcmp(lock_type, "DB") == 0) {
 313                 if (argc != 6) {
 314                         fprintf(stderr,
 315                                 "locking: Invalid number of arguments (%d)\n",
 316                                 argc);
 317                         usage(argv[0]);
 318                         exit(1);
 319                 }
 320                 result = lock_db(argv[4], argv[5], &state);
 321
 322         } else {
 323                 fprintf(stderr, "locking: Invalid lock-type '%s'\n", lock_type);
 324                 usage(argv[0]);
 325                 exit(1);
 326         }
 327
 328         send_result(write_fd, result);
 329
 330         req = wait_for_parent_send(ev, ev, ppid);
 331         if (req == NULL) {
 332                 fprintf(stderr, "locking: wait_for_parent_send() failed\n");
 333                 cleanup(&state);
 334                 exit(1);
 335         }
 336
 337         tevent_req_poll(req, ev);
 338
 339         status = wait_for_parent_recv(req);
 340         if (! status) {
 341                 fprintf(stderr, "locking: wait_for_parent_recv() failed\n");
 342         }
 343
 344         talloc_free(ev);
 345         cleanup(&state);
 346         return 0;
 347 }