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#include "external-agent.h"
#include "logging.h"
#include "lock-tracking.h"
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <err.h>
#include <fcntl.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <errno.h>
#include <ccan/tdb2/private.h>
#include <ccan/tap/tap.h>
#include <stdio.h>
#include <stdarg.h>
static struct tdb_context *tdb;
static enum TDB_ERROR clear_if_first(int fd, void *arg)
{
/* We hold a lock offset 63 always, so we can tell if anyone is holding it. */
struct flock fl;
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
fl.l_start = 63;
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 TDB_ERR_IO;
}
}
fl.l_type = F_RDLCK;
if (fcntl(fd, F_SETLKW, &fl) != 0) {
return TDB_ERR_IO;
}
return TDB_SUCCESS;
}
static enum agent_return do_operation(enum operation op, const char *name)
{
TDB_DATA k;
enum agent_return ret;
TDB_DATA data;
enum TDB_ERROR ecode;
union tdb_attribute cif;
if (op != OPEN && op != OPEN_WITH_HOOK && !tdb) {
diag("external: No tdb open!");
return OTHER_FAILURE;
}
diag("external: %s", operation_name(op));
k = tdb_mkdata(name, strlen(name));
locking_would_block = 0;
switch (op) {
case OPEN:
if (tdb) {
diag("Already have tdb %s open", tdb->name);
return OTHER_FAILURE;
}
tdb = tdb_open(name, TDB_DEFAULT, O_RDWR, 0, &tap_log_attr);
if (!tdb) {
if (!locking_would_block)
diag("Opening tdb gave %s", strerror(errno));
forget_locking();
ret = OTHER_FAILURE;
} else
ret = SUCCESS;
break;
case OPEN_WITH_HOOK:
if (tdb) {
diag("Already have tdb %s open", tdb->name);
return OTHER_FAILURE;
}
cif.openhook.base.attr = TDB_ATTRIBUTE_OPENHOOK;
cif.openhook.base.next = &tap_log_attr;
cif.openhook.fn = clear_if_first;
tdb = tdb_open(name, TDB_DEFAULT, O_RDWR, 0, &cif);
if (!tdb) {
if (!locking_would_block)
diag("Opening tdb gave %s", strerror(errno));
forget_locking();
ret = OTHER_FAILURE;
} else
ret = SUCCESS;
break;
case FETCH:
ecode = tdb_fetch(tdb, k, &data);
if (ecode == TDB_ERR_NOEXIST) {
ret = FAILED;
} else if (ecode < 0) {
ret = OTHER_FAILURE;
} else if (!tdb_deq(data, k)) {
ret = OTHER_FAILURE;
free(data.dptr);
} else {
ret = SUCCESS;
free(data.dptr);
}
break;
case STORE:
ret = tdb_store(tdb, k, k, 0) == 0 ? SUCCESS : OTHER_FAILURE;
break;
case TRANSACTION_START:
ret = tdb_transaction_start(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
break;
case TRANSACTION_COMMIT:
ret = tdb_transaction_commit(tdb)==0 ? SUCCESS : OTHER_FAILURE;
break;
case NEEDS_RECOVERY:
ret = tdb_needs_recovery(tdb) ? SUCCESS : FAILED;
break;
case CHECK:
ret = tdb_check(tdb, NULL, NULL) == 0 ? SUCCESS : OTHER_FAILURE;
break;
case CLOSE:
ret = tdb_close(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
tdb = 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 tdb 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);
}
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