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;
131 if (locking_would_block)
132 ret = WOULD_HAVE_BLOCKED;
138 int cmdfd, responsefd;
141 /* Do this before doing any tdb stuff. Return handle, or NULL. */
142 struct agent *prepare_external_agent(void)
145 int command[2], response[2];
146 char name[1+PATH_MAX];
148 if (pipe(command) != 0 || pipe(response) != 0)
156 struct agent *agent = malloc(sizeof(*agent));
160 agent->cmdfd = command[1];
161 agent->responsefd = response[0];
168 /* We want to fail, not block. */
169 nonblocking_locks = true;
170 log_prefix = "external: ";
171 while ((ret = read(command[0], name, sizeof(name))) > 0) {
172 enum agent_return result;
174 result = do_operation(name[0], name+1);
175 if (write(response[1], &result, sizeof(result))
177 err(1, "Writing response");
182 /* Ask the external agent to try to do an operation. */
183 enum agent_return external_agent_operation(struct agent *agent,
187 enum agent_return res;
193 len = 1 + strlen(name) + 1;
194 string = malloc(len);
197 strcpy(string+1, name);
199 if (write(agent->cmdfd, string, len) != len
200 || read(agent->responsefd, &res, sizeof(res)) != sizeof(res))
207 const char *agent_return_name(enum agent_return ret)
209 return ret == SUCCESS ? "SUCCESS"
210 : ret == WOULD_HAVE_BLOCKED ? "WOULD_HAVE_BLOCKED"
211 : ret == AGENT_DIED ? "AGENT_DIED"
212 : ret == FAILED ? "FAILED"
213 : ret == OTHER_FAILURE ? "OTHER_FAILURE"
217 const char *operation_name(enum operation op)
220 case OPEN: return "OPEN";
221 case OPEN_WITH_HOOK: return "OPEN_WITH_HOOK";
222 case FETCH: return "FETCH";
223 case STORE: return "STORE";
224 case CHECK: return "CHECK";
225 case TRANSACTION_START: return "TRANSACTION_START";
226 case TRANSACTION_COMMIT: return "TRANSACTION_COMMIT";
227 case NEEDS_RECOVERY: return "NEEDS_RECOVERY";
228 case CLOSE: return "CLOSE";
230 return "**INVALID**";
233 void free_external_agent(struct agent *agent)
236 close(agent->responsefd);