git.ozlabs.org Git - ccan/blob - ccan/tdb/test/external-transaction.c

   1 #include "external-transaction.h"
   2 #include <sys/types.h>
   3 #include <sys/wait.h>
   4 #include <unistd.h>
   5 #include <err.h>
   6 #include <fcntl.h>
   7 #include <stdlib.h>
   8 #include <limits.h>
   9 #include <string.h>
  10 #include <errno.h>
  11 #include <ccan/tdb/tdb.h>
  12 #include <ccan/tdb/tdb_private.h>
  13 #include <ccan/tap/tap.h>
  14 #include <stdio.h>
  15 #include <stdarg.h>
  16
  17 static struct tdb_context *tdb;
  18
  19 static volatile sig_atomic_t alarmed;
  20 static void do_alarm(int signum)
  21 {
  22         alarmed++;
  23 }
  24
  25 static void taplog(struct tdb_context *tdb,
  26                    enum tdb_debug_level level,
  27                    const char *fmt, ...)
  28 {
  29         va_list ap;
  30         char line[200];
  31
  32         va_start(ap, fmt);
  33         vsprintf(line, fmt, ap);
  34         va_end(ap);
  35
  36         diag("external: %s", line);
  37 }
  38
  39 static int do_operation(enum operation op, const char *name)
  40 {
  41         struct tdb_logging_context logctx = { taplog, NULL };
  42
  43         TDB_DATA k = { .dptr = (void *)"a", .dsize = 1 };
  44         TDB_DATA d = { .dptr = (void *)"b", .dsize = 1 };
  45
  46         if (op <= KEEP_OPENED) {
  47                 tdb = tdb_open_ex(name, 0, op == OPEN_WITH_CLEAR_IF_FIRST ?
  48                                   TDB_CLEAR_IF_FIRST : TDB_DEFAULT, O_RDWR, 0,
  49                                   &logctx, NULL);
  50                 if (!tdb)
  51                         return -1;
  52         }
  53
  54         if (op == KEEP_OPENED) {
  55                 return 0;
  56         } else if (op == OPEN || op == OPEN_WITH_CLEAR_IF_FIRST || op == CLOSE) {
  57                 tdb_close(tdb);
  58                 tdb = NULL;
  59                 return 1;
  60         } else if (op == STORE_KEEP_OPENED) {
  61                 if (tdb_store(tdb, k, d, 0) != 0)
  62                         return -2;
  63                 return 1;
  64         } else if (op == FETCH_KEEP_OPENED) {
  65                 TDB_DATA ret;
  66                 ret = tdb_fetch(tdb, k);
  67                 if (ret.dptr == NULL) {
  68                         if (tdb_error(tdb) == TDB_ERR_NOEXIST)
  69                                 return 1;
  70                         return -3;
  71                 }
  72                 if (ret.dsize != 1 || *(char *)ret.dptr != 'b')
  73                         return -4;
  74                 free(ret.dptr);
  75                 return 1;
  76         } else if (op == CHECK_KEEP_OPENED) {
  77                 return tdb_check(tdb, NULL, 0) == 0;
  78         } else if (op == NEEDS_RECOVERY_KEEP_OPENED) {
  79 #if 0
  80                 return tdb_maybe_needs_recovery(tdb);
  81 #else
  82                 return 0;
  83 #endif
  84         }
  85
  86         alarmed = 0;
  87         tdb_setalarm_sigptr(tdb, &alarmed);
  88
  89         alarm(1);
  90         if (tdb_transaction_start(tdb) != 0)
  91                 goto maybe_alarmed;
  92
  93         alarm(0);
  94         if (tdb_store(tdb, k, d, 0) != 0) {
  95                 tdb_transaction_cancel(tdb);
  96                 tdb_close(tdb);
  97                 tdb = NULL;
  98                 return -2;
  99         }
 100
 101         if (tdb_transaction_commit(tdb) == 0) {
 102                 tdb_delete(tdb, k);
 103                 if (op != TRANSACTION_KEEP_OPENED) {
 104                         tdb_close(tdb);
 105                         tdb = NULL;
 106                 }
 107                 return 1;
 108         }
 109
 110         tdb_delete(tdb, k);
 111 maybe_alarmed:
 112         if (op != TRANSACTION_KEEP_OPENED) {
 113                 tdb_close(tdb);
 114                 tdb = NULL;
 115         }
 116         if (alarmed)
 117                 return 0;
 118         return -3;
 119 }
 120
 121 struct agent {
 122         int cmdfd, responsefd;
 123 };
 124
 125 /* Do this before doing any tdb stuff.  Return handle, or NULL. */
 126 struct agent *prepare_external_agent(void)
 127 {
 128         int pid, ret;
 129         int command[2], response[2];
 130         struct sigaction act = { .sa_handler = do_alarm };
 131         char name[1+PATH_MAX];
 132
 133         if (pipe(command) != 0 || pipe(response) != 0)
 134                 return NULL;
 135
 136         pid = fork();
 137         if (pid < 0)
 138                 return NULL;
 139
 140         if (pid != 0) {
 141                 struct agent *agent = malloc(sizeof(*agent));
 142
 143                 close(command[0]);
 144                 close(response[1]);
 145                 agent->cmdfd = command[1];
 146                 agent->responsefd = response[0];
 147                 return agent;
 148         }
 149
 150         close(command[1]);
 151         close(response[0]);
 152         sigaction(SIGALRM, &act, NULL);
 153
 154         while ((ret = read(command[0], name, sizeof(name))) > 0) {
 155                 int result;
 156
 157                 result = do_operation(name[0], name+1);
 158                 if (write(response[1], &result, sizeof(result))
 159                     != sizeof(result))
 160                         err(1, "Writing response");
 161         }
 162         diag("external: read %i: %s", ret, strerror(errno));
 163         exit(0);
 164 }
 165
 166 /* Ask the external agent to try to do an operation. */
 167 int external_agent_operation(struct agent *agent,
 168                               enum operation op, const char *tdbname)
 169 {
 170         int res;
 171         char string[1 + strlen(tdbname) + 1];
 172
 173         string[0] = op;
 174         strcpy(string+1, tdbname);
 175
 176         if (write(agent->cmdfd, string, sizeof(string)) != sizeof(string))
 177                 err(1, "Writing to agent");
 178
 179         if (read(agent->responsefd, &res, sizeof(res)) != sizeof(res))
 180                 err(1, "Reading from agent");
 181
 182         if (res > 1)
 183                 errx(1, "Agent returned %u\n", res);
 184
 185         return res;
 186 }
 187
 188 void external_agent_operation_start(struct agent *agent,
 189                                     enum operation op, const char *tdbname)
 190 {
 191         char string[1 + strlen(tdbname) + 1];
 192
 193         string[0] = op;
 194         strcpy(string+1, tdbname);
 195
 196         if (write(agent->cmdfd, string, sizeof(string)) != sizeof(string))
 197                 err(1, "Writing to agent");
 198 }
 199
 200 bool external_agent_operation_check(struct agent *agent, bool block, int *res)
 201 {
 202         int flags = fcntl(agent->responsefd, F_GETFL);
 203
 204         if (block)
 205                 fcntl(agent->responsefd, F_SETFL, flags & ~O_NONBLOCK);
 206         else
 207                 fcntl(agent->responsefd, F_SETFL, flags | O_NONBLOCK);
 208
 209         switch (read(agent->responsefd, res, sizeof(*res))) {
 210         case sizeof(*res):
 211                 break;
 212         case 0:
 213                 errx(1, "Agent died?");
 214         default:
 215                 if (!block && (errno == EAGAIN || errno == EWOULDBLOCK))
 216                         return false;
 217                 err(1, "%slocking reading from agent", block ? "B" : "Non-b");
 218         }
 219
 220         if (*res > 1)
 221                 errx(1, "Agent returned %u\n", *res);
 222
 223         return true;
 224 }