1 #include "external-agent.h"
3 #include "lock-tracking.h"
13 #include <ccan/tdb2/private.h>
14 #include <ccan/tap/tap.h>
18 static struct tdb_context *tdb;
20 static enum TDB_ERROR clear_if_first(int fd, void *arg)
22 /* We hold a lock offset 63 always, so we can tell if anyone is holding it. */
26 fl.l_whence = SEEK_SET;
30 if (fcntl(fd, F_SETLK, &fl) == 0) {
31 /* We must be first ones to open it! */
32 diag("agent truncating file!");
33 if (ftruncate(fd, 0) != 0) {
38 if (fcntl(fd, F_SETLKW, &fl) != 0) {
44 static enum agent_return do_operation(enum operation op, const char *name)
47 enum agent_return ret;
50 union tdb_attribute cif;
52 if (op != OPEN && op != OPEN_WITH_HOOK && !tdb) {
53 diag("external: No tdb open!");
57 diag("external: %s", operation_name(op));
59 k = tdb_mkdata(name, strlen(name));
61 locking_would_block = 0;
65 diag("Already have tdb %s open", tdb->name);
68 tdb = tdb_open(name, TDB_DEFAULT, O_RDWR, 0, &tap_log_attr);
70 if (!locking_would_block)
71 diag("Opening tdb gave %s", strerror(errno));
79 diag("Already have tdb %s open", tdb->name);
82 cif.openhook.base.attr = TDB_ATTRIBUTE_OPENHOOK;
83 cif.openhook.base.next = &tap_log_attr;
84 cif.openhook.fn = clear_if_first;
85 tdb = tdb_open(name, TDB_DEFAULT, O_RDWR, 0, &cif);
87 if (!locking_would_block)
88 diag("Opening tdb gave %s", strerror(errno));
95 ecode = tdb_fetch(tdb, k, &data);
96 if (ecode == TDB_ERR_NOEXIST) {
98 } else if (ecode < 0) {
100 } else if (!tdb_deq(data, k)) {
109 ret = tdb_store(tdb, k, k, 0) == 0 ? SUCCESS : OTHER_FAILURE;
111 case TRANSACTION_START:
112 ret = tdb_transaction_start(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
114 case TRANSACTION_COMMIT:
115 ret = tdb_transaction_commit(tdb)==0 ? SUCCESS : OTHER_FAILURE;
118 ret = tdb_needs_recovery(tdb) ? SUCCESS : FAILED;
121 ret = tdb_check(tdb, NULL, NULL) == 0 ? SUCCESS : OTHER_FAILURE;
124 ret = tdb_close(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
128 /* We do this async */
135 if (locking_would_block)
136 ret = WOULD_HAVE_BLOCKED;
142 int cmdfd, responsefd;
145 /* Do this before doing any tdb stuff. Return handle, or NULL. */
146 struct agent *prepare_external_agent(void)
149 int command[2], response[2];
150 char name[1+PATH_MAX];
152 if (pipe(command) != 0 || pipe(response) != 0)
160 struct agent *agent = malloc(sizeof(*agent));
164 agent->cmdfd = command[1];
165 agent->responsefd = response[0];
172 /* We want to fail, not block. */
173 nonblocking_locks = true;
174 log_prefix = "external: ";
175 while ((ret = read(command[0], name, sizeof(name))) > 0) {
176 enum agent_return result;
178 result = do_operation(name[0], name+1);
179 if (write(response[1], &result, sizeof(result))
181 err(1, "Writing response");
182 if (name[0] == SEND_SIGNAL) {
183 struct timeval ten_ms;
185 ten_ms.tv_usec = 10000;
186 select(0, NULL, NULL, NULL, &ten_ms);
187 kill(getppid(), SIGUSR1);
193 /* Ask the external agent to try to do an operation. */
194 enum agent_return external_agent_operation(struct agent *agent,
198 enum agent_return res;
204 len = 1 + strlen(name) + 1;
205 string = malloc(len);
208 strcpy(string+1, name);
210 if (write(agent->cmdfd, string, len) != len
211 || read(agent->responsefd, &res, sizeof(res)) != sizeof(res))
218 const char *agent_return_name(enum agent_return ret)
220 return ret == SUCCESS ? "SUCCESS"
221 : ret == WOULD_HAVE_BLOCKED ? "WOULD_HAVE_BLOCKED"
222 : ret == AGENT_DIED ? "AGENT_DIED"
223 : ret == FAILED ? "FAILED"
224 : ret == OTHER_FAILURE ? "OTHER_FAILURE"
228 const char *operation_name(enum operation op)
231 case OPEN: return "OPEN";
232 case OPEN_WITH_HOOK: return "OPEN_WITH_HOOK";
233 case FETCH: return "FETCH";
234 case STORE: return "STORE";
235 case CHECK: return "CHECK";
236 case TRANSACTION_START: return "TRANSACTION_START";
237 case TRANSACTION_COMMIT: return "TRANSACTION_COMMIT";
238 case NEEDS_RECOVERY: return "NEEDS_RECOVERY";
239 case SEND_SIGNAL: return "SEND_SIGNAL";
240 case CLOSE: return "CLOSE";
242 return "**INVALID**";
245 void free_external_agent(struct agent *agent)
248 close(agent->responsefd);