1 #include "external-agent.h"
3 #include "lock-tracking.h"
13 #include <ccan/tdb2/tdb1_private.h>
14 #include <ccan/tap/tap.h>
18 static struct tdb_context *tdb;
20 void (*external_agent_free)(void *) = free;
22 static enum TDB_ERROR clear_if_first(int fd, void *arg)
24 /* We hold a lock offset 4 always, so we can tell if anyone is holding it.
25 * (This is compatible with tdb1's TDB_CLEAR_IF_FIRST flag). */
29 fl.l_whence = SEEK_SET;
33 if (fcntl(fd, F_SETLK, &fl) == 0) {
34 /* We must be first ones to open it! */
35 diag("agent truncating file!");
36 if (ftruncate(fd, 0) != 0) {
41 if (fcntl(fd, F_SETLKW, &fl) != 0) {
47 static enum agent_return do_operation(enum operation op, const char *name)
50 enum agent_return ret;
53 union tdb_attribute cif;
55 if (op != OPEN && op != OPEN_WITH_HOOK && !tdb) {
56 diag("external: No tdb open!");
60 diag("external: %s", operation_name(op));
62 k = tdb_mkdata(name, strlen(name));
64 locking_would_block = 0;
68 diag("Already have tdb %s open", tdb->name);
71 tdb = tdb_open(name, TDB_DEFAULT, O_RDWR, 0, &tap_log_attr);
73 if (!locking_would_block)
74 diag("Opening tdb gave %s", strerror(errno));
82 diag("Already have tdb %s open", tdb->name);
85 cif.openhook.base.attr = TDB_ATTRIBUTE_OPENHOOK;
86 cif.openhook.base.next = &tap_log_attr;
87 cif.openhook.fn = clear_if_first;
88 tdb = tdb_open(name, TDB_DEFAULT, O_RDWR, 0, &cif);
90 if (!locking_would_block)
91 diag("Opening tdb gave %s", strerror(errno));
98 ecode = tdb_fetch(tdb, k, &data);
99 if (ecode == TDB_ERR_NOEXIST) {
101 } else if (ecode < 0) {
103 } else if (!tdb_deq(data, k)) {
105 external_agent_free(data.dptr);
108 external_agent_free(data.dptr);
112 ret = tdb_store(tdb, k, k, 0) == 0 ? SUCCESS : OTHER_FAILURE;
114 case TRANSACTION_START:
115 ret = tdb_transaction_start(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
117 case TRANSACTION_COMMIT:
118 ret = tdb_transaction_commit(tdb)==0 ? SUCCESS : OTHER_FAILURE;
121 if (tdb->flags & TDB_VERSION1)
122 ret = tdb1_needs_recovery(tdb) ? SUCCESS : FAILED;
124 ret = tdb_needs_recovery(tdb) ? SUCCESS : FAILED;
127 ret = tdb_check(tdb, NULL, NULL) == 0 ? SUCCESS : OTHER_FAILURE;
130 ret = tdb_close(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
134 /* We do this async */
141 if (locking_would_block)
142 ret = WOULD_HAVE_BLOCKED;
148 int cmdfd, responsefd;
151 /* Do this before doing any tdb stuff. Return handle, or NULL. */
152 struct agent *prepare_external_agent(void)
155 int command[2], response[2];
156 char name[1+PATH_MAX];
158 if (pipe(command) != 0 || pipe(response) != 0)
166 struct agent *agent = malloc(sizeof(*agent));
170 agent->cmdfd = command[1];
171 agent->responsefd = response[0];
178 /* We want to fail, not block. */
179 nonblocking_locks = true;
180 log_prefix = "external: ";
181 while ((ret = read(command[0], name, sizeof(name))) > 0) {
182 enum agent_return result;
184 result = do_operation(name[0], name+1);
185 if (write(response[1], &result, sizeof(result))
187 err(1, "Writing response");
188 if (name[0] == SEND_SIGNAL) {
189 struct timeval ten_ms;
191 ten_ms.tv_usec = 10000;
192 select(0, NULL, NULL, NULL, &ten_ms);
193 kill(getppid(), SIGUSR1);
199 /* Ask the external agent to try to do an operation. */
200 enum agent_return external_agent_operation(struct agent *agent,
204 enum agent_return res;
210 len = 1 + strlen(name) + 1;
211 string = malloc(len);
214 strcpy(string+1, name);
216 if (write(agent->cmdfd, string, len) != len
217 || read(agent->responsefd, &res, sizeof(res)) != sizeof(res))
224 const char *agent_return_name(enum agent_return ret)
226 return ret == SUCCESS ? "SUCCESS"
227 : ret == WOULD_HAVE_BLOCKED ? "WOULD_HAVE_BLOCKED"
228 : ret == AGENT_DIED ? "AGENT_DIED"
229 : ret == FAILED ? "FAILED"
230 : ret == OTHER_FAILURE ? "OTHER_FAILURE"
234 const char *operation_name(enum operation op)
237 case OPEN: return "OPEN";
238 case OPEN_WITH_HOOK: return "OPEN_WITH_HOOK";
239 case FETCH: return "FETCH";
240 case STORE: return "STORE";
241 case CHECK: return "CHECK";
242 case TRANSACTION_START: return "TRANSACTION_START";
243 case TRANSACTION_COMMIT: return "TRANSACTION_COMMIT";
244 case NEEDS_RECOVERY: return "NEEDS_RECOVERY";
245 case SEND_SIGNAL: return "SEND_SIGNAL";
246 case CLOSE: return "CLOSE";
248 return "**INVALID**";
251 void free_external_agent(struct agent *agent)
254 close(agent->responsefd);