-/* Copyright (c) 2009, 2010 Nicira Networks
+/* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/stat.h>
#include <unistd.h>
#include "json.h"
#include "socket-util.h"
#include "transaction.h"
#include "util.h"
-
-#define THIS_MODULE VLM_ovsdb_log
#include "vlog.h"
+VLOG_DEFINE_THIS_MODULE(ovsdb_log);
+
enum ovsdb_log_mode {
OVSDB_LOG_READ,
OVSDB_LOG_WRITE
};
struct ovsdb_log {
+ off_t prev_offset;
off_t offset;
char *name;
struct lockfile *lockfile;
locking = open_mode != OVSDB_LOG_READ_ONLY;
}
if (locking) {
- int retval = lockfile_lock(name, 0, &lockfile);
+ int retval = lockfile_lock(name, &lockfile);
if (retval) {
error = ovsdb_io_error(retval, "%s: failed to lock lockfile",
name);
} else if (open_mode == OVSDB_LOG_READ_WRITE) {
flags = O_RDWR;
} else if (open_mode == OVSDB_LOG_CREATE) {
- flags = O_RDWR | O_CREAT | O_EXCL;
+ if (stat(name, &s) == -1 && errno == ENOENT
+ && lstat(name, &s) == 0 && S_ISLNK(s.st_mode)) {
+ /* 'name' is a dangling symlink. We want to create the file that
+ * the symlink points to, but POSIX says that open() with O_EXCL
+ * must fail with EEXIST if the named file is a symlink. So, we
+ * have to leave off O_EXCL and accept the race. */
+ flags = O_RDWR | O_CREAT;
+ } else {
+ flags = O_RDWR | O_CREAT | O_EXCL;
+ }
} else {
NOT_REACHED();
}
file->name = xstrdup(name);
file->lockfile = lockfile;
file->stream = stream;
+ file->prev_offset = 0;
file->offset = 0;
file->read_error = NULL;
file->write_error = NULL;
goto error;
}
+ file->prev_offset = file->offset;
file->offset = data_offset + data_length;
*jsonp = json;
- return 0;
+ return NULL;
error:
file->read_error = ovsdb_error_clone(error);
return error;
}
+/* Causes the log record read by the previous call to ovsdb_log_read() to be
+ * effectively discarded. The next call to ovsdb_log_write() will overwrite
+ * that previously read record.
+ *
+ * Calling this function more than once has no additional effect.
+ *
+ * This function is useful when ovsdb_log_read() successfully reads a record
+ * but that record does not make sense at a higher level (e.g. it specifies an
+ * invalid transaction). */
+void
+ovsdb_log_unread(struct ovsdb_log *file)
+{
+ assert(file->mode == OVSDB_LOG_READ);
+ file->offset = file->prev_offset;
+}
+
struct ovsdb_error *
ovsdb_log_write(struct ovsdb_log *file, struct json *json)
{
file->offset += strlen(header) + length;
free(json_string);
- return 0;
+ return NULL;
error:
file->write_error = ovsdb_error_clone(error);
if (fsync(fileno(file->stream))) {
return ovsdb_io_error(errno, "%s: fsync failed", file->name);
}
- return 0;
+ return NULL;
}
/* Returns the current offset into the file backing 'log', in bytes. This