lib/tdb/test/external-agent.c

   1 #include "external-agent.h"
   2 #include "lock-tracking.h"
   3 #include "logging.h"
   4 #include <sys/types.h>
   5 #include <sys/wait.h>
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8 #include <stdlib.h>
   9 #include <limits.h>
  10 #include <string.h>
  11 #include <errno.h>
  12 #include "../common/tdb_private.h"
  13 #include "tap-interface.h"
  14 #include <stdio.h>
  15 #include <stdarg.h>
  16
  17 static struct tdb_context *tdb;
  18
  19 static enum agent_return do_operation(enum operation op, const char *name)
  20 {
  21         TDB_DATA k;
  22         enum agent_return ret;
  23         TDB_DATA data;
  24
  25         if (op != OPEN && op != OPEN_WITH_CLEAR_IF_FIRST && !tdb) {
  26                 diag("external: No tdb open!");
  27                 return OTHER_FAILURE;
  28         }
  29
  30         k.dptr = discard_const_p(uint8_t, name);
  31         k.dsize = strlen(name);
  32
  33         locking_would_block = 0;
  34         switch (op) {
  35         case OPEN:
  36                 if (tdb) {
  37                         diag("Already have tdb %s open", tdb_name(tdb));
  38                         return OTHER_FAILURE;
  39                 }
  40                 tdb = tdb_open_ex(name, 0, TDB_DEFAULT, O_RDWR, 0,
  41                                   &taplogctx, NULL);
  42                 if (!tdb) {
  43                         if (!locking_would_block)
  44                                 diag("Opening tdb gave %s", strerror(errno));
  45                         ret = OTHER_FAILURE;
  46                 } else
  47                         ret = SUCCESS;
  48                 break;
  49         case OPEN_WITH_CLEAR_IF_FIRST:
  50                 if (tdb)
  51                         return OTHER_FAILURE;
  52                 tdb = tdb_open_ex(name, 0, TDB_CLEAR_IF_FIRST, O_RDWR, 0,
  53                                   &taplogctx, NULL);
  54                 ret = tdb ? SUCCESS : OTHER_FAILURE;
  55                 break;
  56         case TRANSACTION_START:
  57                 ret = tdb_transaction_start(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
  58                 break;
  59         case FETCH:
  60                 data = tdb_fetch(tdb, k);
  61                 if (data.dptr == NULL) {
  62                         if (tdb_error(tdb) == TDB_ERR_NOEXIST)
  63                                 ret = FAILED;
  64                         else
  65                                 ret = OTHER_FAILURE;
  66                 } else if (data.dsize != k.dsize
  67                            || memcmp(data.dptr, k.dptr, k.dsize) != 0) {
  68                         ret = OTHER_FAILURE;
  69                 } else {
  70                         ret = SUCCESS;
  71                 }
  72                 free(data.dptr);
  73                 break;
  74         case STORE:
  75                 ret = tdb_store(tdb, k, k, 0) == 0 ? SUCCESS : OTHER_FAILURE;
  76                 break;
  77         case TRANSACTION_COMMIT:
  78                 ret = tdb_transaction_commit(tdb)==0 ? SUCCESS : OTHER_FAILURE;
  79                 break;
  80         case CHECK:
  81                 ret = tdb_check(tdb, NULL, NULL) == 0 ? SUCCESS : OTHER_FAILURE;
  82                 break;
  83         case NEEDS_RECOVERY:
  84                 ret = tdb_needs_recovery(tdb) ? SUCCESS : FAILED;
  85                 break;
  86         case CLOSE:
  87                 ret = tdb_close(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
  88                 tdb = NULL;
  89                 break;
  90         default:
  91                 ret = OTHER_FAILURE;
  92         }
  93
  94         if (locking_would_block)
  95                 ret = WOULD_HAVE_BLOCKED;
  96
  97         return ret;
  98 }
  99
 100 struct agent {
 101         int cmdfd, responsefd;
 102         pid_t pid;
 103 };
 104
 105 /* Do this before doing any tdb stuff.  Return handle, or NULL. */
 106 struct agent *prepare_external_agent(void)
 107 {
 108         int ret;
 109         int command[2], response[2];
 110         char name[1+PATH_MAX];
 111         struct agent *agent = malloc(sizeof(*agent));
 112
 113         if (pipe(command) != 0 || pipe(response) != 0) {
 114                 fprintf(stderr, "pipe failed: %s\n", strerror(errno));
 115                 exit(1);
 116         }
 117
 118         agent->pid = fork();
 119         if (agent->pid < 0) {
 120                 fprintf(stderr, "fork failed: %s\n", strerror(errno));
 121                 exit(1);
 122         }
 123
 124         if (agent->pid != 0) {
 125                 close(command[0]);
 126                 close(response[1]);
 127                 agent->cmdfd = command[1];
 128                 agent->responsefd = response[0];
 129                 return agent;
 130         }
 131
 132         close(command[1]);
 133         close(response[0]);
 134
 135         /* We want to fail, not block. */
 136         nonblocking_locks = true;
 137         log_prefix = "external: ";
 138         while ((ret = read(command[0], name, sizeof(name))) > 0) {
 139                 enum agent_return result;
 140
 141                 result = do_operation(name[0], name+1);
 142                 if (write(response[1], &result, sizeof(result))
 143                     != sizeof(result))
 144                         abort();
 145         }
 146         exit(0);
 147 }
 148
 149 void shutdown_agent(struct agent *agent)
 150 {
 151         pid_t p;
 152
 153         close(agent->cmdfd);
 154         close(agent->responsefd);
 155         p = waitpid(agent->pid, NULL, WNOHANG);
 156         if (p == 0) {
 157                 kill(agent->pid, SIGKILL);
 158         }
 159         waitpid(agent->pid, NULL, 0);
 160         free(agent);
 161 }
 162
 163 /* Ask the external agent to try to do an operation. */
 164 enum agent_return external_agent_operation(struct agent *agent,
 165                                            enum operation op,
 166                                            const char *name)
 167 {
 168         enum agent_return res;
 169         unsigned int len;
 170         char *string;
 171
 172         if (!name)
 173                 name = "";
 174         len = 1 + strlen(name) + 1;
 175         string = malloc(len);
 176
 177         string[0] = op;
 178         strcpy(string+1, name);
 179
 180         if (write(agent->cmdfd, string, len) != len
 181             || read(agent->responsefd, &res, sizeof(res)) != sizeof(res))
 182                 res = AGENT_DIED;
 183
 184         free(string);
 185         return res;
 186 }
 187
 188 const char *agent_return_name(enum agent_return ret)
 189 {
 190         return ret == SUCCESS ? "SUCCESS"
 191                 : ret == WOULD_HAVE_BLOCKED ? "WOULD_HAVE_BLOCKED"
 192                 : ret == AGENT_DIED ? "AGENT_DIED"
 193                 : ret == FAILED ? "FAILED"
 194                 : ret == OTHER_FAILURE ? "OTHER_FAILURE"
 195                 : "**INVALID**";
 196 }
 197
 198 const char *operation_name(enum operation op)
 199 {
 200         switch (op) {
 201         case OPEN: return "OPEN";
 202         case OPEN_WITH_CLEAR_IF_FIRST: return "OPEN_WITH_CLEAR_IF_FIRST";
 203         case TRANSACTION_START: return "TRANSACTION_START";
 204         case FETCH: return "FETCH";
 205         case STORE: return "STORE";
 206         case TRANSACTION_COMMIT: return "TRANSACTION_COMMIT";
 207         case CHECK: return "CHECK";
 208         case NEEDS_RECOVERY: return "NEEDS_RECOVERY";
 209         case CLOSE: return "CLOSE";
 210         }
 211         return "**INVALID**";
 212 }