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