--- /dev/null
+#include "external-agent.h"
+#include "logging.h"
+#include "lock-tracking.h"
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <ccan/err/err.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <string.h>
+#include <errno.h>
+#include "tap-interface.h"
+#include <stdio.h>
+#include <stdarg.h>
+
+static struct ntdb_context *ntdb;
+
+void (*external_agent_free)(void *) = free;
+
+static enum NTDB_ERROR clear_if_first(int fd, void *arg)
+{
+/* We hold a lock offset 4 always, so we can tell if anyone is holding it.
+ * (This is compatible with tdb's TDB_CLEAR_IF_FIRST flag). */
+ struct flock fl;
+
+ fl.l_type = F_WRLCK;
+ fl.l_whence = SEEK_SET;
+ fl.l_start = 4;
+ fl.l_len = 1;
+
+ if (fcntl(fd, F_SETLK, &fl) == 0) {
+ /* We must be first ones to open it! */
+ diag("agent truncating file!");
+ if (ftruncate(fd, 0) != 0) {
+ return NTDB_ERR_IO;
+ }
+ }
+ fl.l_type = F_RDLCK;
+ if (fcntl(fd, F_SETLKW, &fl) != 0) {
+ return NTDB_ERR_IO;
+ }
+ return NTDB_SUCCESS;
+}
+
+static enum agent_return do_operation(enum operation op, const char *name)
+{
+ NTDB_DATA k, d;
+ enum agent_return ret;
+ NTDB_DATA data;
+ enum NTDB_ERROR ecode;
+ union ntdb_attribute cif;
+ const char *eq;
+
+ if (op != OPEN && op != OPEN_WITH_HOOK && !ntdb) {
+ diag("external: No ntdb open!");
+ return OTHER_FAILURE;
+ }
+
+ diag("external: %s", operation_name(op));
+
+ eq = strchr(name, '=');
+ if (eq) {
+ k = ntdb_mkdata(name, eq - name);
+ d = ntdb_mkdata(eq + 1, strlen(eq+1));
+ } else {
+ k = ntdb_mkdata(name, strlen(name));
+ d.dsize = 0;
+ d.dptr = NULL;
+ }
+
+ locking_would_block = 0;
+ switch (op) {
+ case OPEN:
+ if (ntdb) {
+ diag("Already have ntdb %s open", ntdb_name(ntdb));
+ return OTHER_FAILURE;
+ }
+ ntdb = ntdb_open(name, MAYBE_NOSYNC, O_RDWR, 0, &tap_log_attr);
+ if (!ntdb) {
+ if (!locking_would_block)
+ diag("Opening ntdb gave %s", strerror(errno));
+ forget_locking();
+ ret = OTHER_FAILURE;
+ } else
+ ret = SUCCESS;
+ break;
+ case OPEN_WITH_HOOK:
+ if (ntdb) {
+ diag("Already have ntdb %s open", ntdb_name(ntdb));
+ return OTHER_FAILURE;
+ }
+ cif.openhook.base.attr = NTDB_ATTRIBUTE_OPENHOOK;
+ cif.openhook.base.next = &tap_log_attr;
+ cif.openhook.fn = clear_if_first;
+ ntdb = ntdb_open(name, MAYBE_NOSYNC, O_RDWR, 0, &cif);
+ if (!ntdb) {
+ if (!locking_would_block)
+ diag("Opening ntdb gave %s", strerror(errno));
+ forget_locking();
+ ret = OTHER_FAILURE;
+ } else
+ ret = SUCCESS;
+ break;
+ case FETCH:
+ ecode = ntdb_fetch(ntdb, k, &data);
+ if (ecode == NTDB_ERR_NOEXIST) {
+ ret = FAILED;
+ } else if (ecode < 0) {
+ ret = OTHER_FAILURE;
+ } else if (!ntdb_deq(data, d)) {
+ ret = OTHER_FAILURE;
+ external_agent_free(data.dptr);
+ } else {
+ ret = SUCCESS;
+ external_agent_free(data.dptr);
+ }
+ break;
+ case STORE:
+ ret = ntdb_store(ntdb, k, d, 0) == 0 ? SUCCESS : OTHER_FAILURE;
+ break;
+ case TRANSACTION_START:
+ ret = ntdb_transaction_start(ntdb) == 0 ? SUCCESS : OTHER_FAILURE;
+ break;
+ case TRANSACTION_COMMIT:
+ ret = ntdb_transaction_commit(ntdb)==0 ? SUCCESS : OTHER_FAILURE;
+ break;
+ case NEEDS_RECOVERY:
+ ret = external_agent_needs_rec(ntdb);
+ break;
+ case CHECK:
+ ret = ntdb_check(ntdb, NULL, NULL) == 0 ? SUCCESS : OTHER_FAILURE;
+ break;
+ case CLOSE:
+ ret = ntdb_close(ntdb) == 0 ? SUCCESS : OTHER_FAILURE;
+ ntdb = NULL;
+ break;
+ case SEND_SIGNAL:
+ /* We do this async */
+ ret = SUCCESS;
+ break;
+ default:
+ ret = OTHER_FAILURE;
+ }
+
+ if (locking_would_block)
+ ret = WOULD_HAVE_BLOCKED;
+
+ return ret;
+}
+
+struct agent {
+ int cmdfd, responsefd;
+};
+
+/* Do this before doing any ntdb stuff. Return handle, or NULL. */
+struct agent *prepare_external_agent(void)
+{
+ int pid, ret;
+ int command[2], response[2];
+ char name[1+PATH_MAX];
+
+ if (pipe(command) != 0 || pipe(response) != 0)
+ return NULL;
+
+ pid = fork();
+ if (pid < 0)
+ return NULL;
+
+ if (pid != 0) {
+ struct agent *agent = malloc(sizeof(*agent));
+
+ close(command[0]);
+ close(response[1]);
+ agent->cmdfd = command[1];
+ agent->responsefd = response[0];
+ return agent;
+ }
+
+ close(command[1]);
+ close(response[0]);
+
+ /* We want to fail, not block. */
+ nonblocking_locks = true;
+ log_prefix = "external: ";
+ while ((ret = read(command[0], name, sizeof(name))) > 0) {
+ enum agent_return result;
+
+ result = do_operation(name[0], name+1);
+ if (write(response[1], &result, sizeof(result))
+ != sizeof(result))
+ err(1, "Writing response");
+ if (name[0] == SEND_SIGNAL) {
+ struct timeval ten_ms;
+ ten_ms.tv_sec = 0;
+ ten_ms.tv_usec = 10000;
+ select(0, NULL, NULL, NULL, &ten_ms);
+ kill(getppid(), SIGUSR1);
+ }
+ }
+ exit(0);
+}
+
+/* Ask the external agent to try to do an operation. */
+enum agent_return external_agent_operation(struct agent *agent,
+ enum operation op,
+ const char *name)
+{
+ enum agent_return res;
+ unsigned int len;
+ char *string;
+
+ if (!name)
+ name = "";
+ len = 1 + strlen(name) + 1;
+ string = malloc(len);
+
+ string[0] = op;
+ strcpy(string+1, name);
+
+ if (write(agent->cmdfd, string, len) != len
+ || read(agent->responsefd, &res, sizeof(res)) != sizeof(res))
+ res = AGENT_DIED;
+
+ free(string);
+ return res;
+}
+
+const char *agent_return_name(enum agent_return ret)
+{
+ return ret == SUCCESS ? "SUCCESS"
+ : ret == WOULD_HAVE_BLOCKED ? "WOULD_HAVE_BLOCKED"
+ : ret == AGENT_DIED ? "AGENT_DIED"
+ : ret == FAILED ? "FAILED"
+ : ret == OTHER_FAILURE ? "OTHER_FAILURE"
+ : "**INVALID**";
+}
+
+const char *operation_name(enum operation op)
+{
+ switch (op) {
+ case OPEN: return "OPEN";
+ case OPEN_WITH_HOOK: return "OPEN_WITH_HOOK";
+ case FETCH: return "FETCH";
+ case STORE: return "STORE";
+ case CHECK: return "CHECK";
+ case TRANSACTION_START: return "TRANSACTION_START";
+ case TRANSACTION_COMMIT: return "TRANSACTION_COMMIT";
+ case NEEDS_RECOVERY: return "NEEDS_RECOVERY";
+ case SEND_SIGNAL: return "SEND_SIGNAL";
+ case CLOSE: return "CLOSE";
+ }
+ return "**INVALID**";
+}
+
+void free_external_agent(struct agent *agent)
+{
+ close(agent->cmdfd);
+ close(agent->responsefd);
+ free(agent);
+}
projects / ccan / blobdiff