1 /* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
31 #include "ovsdb-error.h"
33 #include "socket-util.h"
34 #include "transaction.h"
38 VLOG_DEFINE_THIS_MODULE(ovsdb_log);
49 struct lockfile *lockfile;
51 struct ovsdb_error *read_error;
52 struct ovsdb_error *write_error;
53 enum ovsdb_log_mode mode;
56 /* Attempts to open 'name' with the specified 'open_mode'. On success, stores
57 * the new log into '*filep' and returns NULL; otherwise returns NULL and
58 * stores NULL into '*filep'.
60 * Whether the file will be locked using lockfile_lock() depends on 'locking':
61 * use true to lock it, false not to lock it, or -1 to lock it only if
62 * 'open_mode' is a mode that allows writing.
65 ovsdb_log_open(const char *name, enum ovsdb_log_open_mode open_mode,
66 int locking, struct ovsdb_log **filep)
68 struct lockfile *lockfile;
69 struct ovsdb_error *error;
70 struct ovsdb_log *file;
78 assert(locking == -1 || locking == false || locking == true);
80 locking = open_mode != OVSDB_LOG_READ_ONLY;
83 int retval = lockfile_lock(name, 0, &lockfile);
85 error = ovsdb_io_error(retval, "%s: failed to lock lockfile",
93 if (open_mode == OVSDB_LOG_READ_ONLY) {
95 } else if (open_mode == OVSDB_LOG_READ_WRITE) {
97 } else if (open_mode == OVSDB_LOG_CREATE) {
98 if (stat(name, &s) == -1 && errno == ENOENT
99 && lstat(name, &s) == 0 && S_ISLNK(s.st_mode)) {
100 /* 'name' is a dangling symlink. We want to create the file that
101 * the symlink points to, but POSIX says that open() with O_EXCL
102 * must fail with EEXIST if the named file is a symlink. So, we
103 * have to leave off O_EXCL and accept the race. */
104 flags = O_RDWR | O_CREAT;
106 flags = O_RDWR | O_CREAT | O_EXCL;
111 fd = open(name, flags, 0666);
113 const char *op = open_mode == OVSDB_LOG_CREATE ? "create" : "open";
114 error = ovsdb_io_error(errno, "%s: %s failed", op, name);
118 if (!fstat(fd, &s) && s.st_size == 0) {
119 /* It's (probably) a new file so fsync() its parent directory to ensure
120 * that its directory entry is committed to disk. */
121 fsync_parent_dir(name);
124 stream = fdopen(fd, open_mode == OVSDB_LOG_READ_ONLY ? "rb" : "w+b");
126 error = ovsdb_io_error(errno, "%s: fdopen failed", name);
130 file = xmalloc(sizeof *file);
131 file->name = xstrdup(name);
132 file->lockfile = lockfile;
133 file->stream = stream;
134 file->prev_offset = 0;
136 file->read_error = NULL;
137 file->write_error = NULL;
138 file->mode = OVSDB_LOG_READ;
145 lockfile_unlock(lockfile);
151 ovsdb_log_close(struct ovsdb_log *file)
155 fclose(file->stream);
156 lockfile_unlock(file->lockfile);
157 ovsdb_error_destroy(file->read_error);
158 ovsdb_error_destroy(file->write_error);
163 static const char magic[] = "OVSDB JSON ";
166 parse_header(char *header, unsigned long int *length,
167 uint8_t sha1[SHA1_DIGEST_SIZE])
171 /* 'header' must consist of a magic string... */
172 if (strncmp(header, magic, strlen(magic))) {
176 /* ...followed by a length in bytes... */
177 *length = strtoul(header + strlen(magic), &p, 10);
178 if (!*length || *length == ULONG_MAX || *p != ' ') {
183 /* ...followed by a SHA-1 hash... */
184 if (!sha1_from_hex(sha1, p)) {
187 p += SHA1_HEX_DIGEST_LEN;
189 /* ...and ended by a new-line. */
197 struct ovsdb_log_read_cbdata {
199 struct ovsdb_log *file;
201 unsigned long length;
204 static struct ovsdb_error *
205 parse_body(struct ovsdb_log *file, off_t offset, unsigned long int length,
206 uint8_t sha1[SHA1_DIGEST_SIZE], struct json **jsonp)
208 struct json_parser *parser;
212 parser = json_parser_create(JSPF_TRAILER);
218 chunk = MIN(length, sizeof input);
219 if (fread(input, 1, chunk, file->stream) != chunk) {
220 json_parser_abort(parser);
221 return ovsdb_io_error(ferror(file->stream) ? errno : EOF,
222 "%s: error reading %lu bytes "
223 "starting at offset %lld", file->name,
224 length, (long long int) offset);
226 sha1_update(&ctx, input, chunk);
227 json_parser_feed(parser, input, chunk);
231 sha1_final(&ctx, sha1);
232 *jsonp = json_parser_finish(parser);
237 ovsdb_log_read(struct ovsdb_log *file, struct json **jsonp)
239 uint8_t expected_sha1[SHA1_DIGEST_SIZE];
240 uint8_t actual_sha1[SHA1_DIGEST_SIZE];
241 struct ovsdb_error *error;
243 unsigned long data_length;
247 *jsonp = json = NULL;
249 if (file->read_error) {
250 return ovsdb_error_clone(file->read_error);
251 } else if (file->mode == OVSDB_LOG_WRITE) {
252 return OVSDB_BUG("reading file in write mode");
255 if (!fgets(header, sizeof header, file->stream)) {
256 if (feof(file->stream)) {
259 error = ovsdb_io_error(errno, "%s: read failed", file->name);
264 if (!parse_header(header, &data_length, expected_sha1)) {
265 error = ovsdb_syntax_error(NULL, NULL, "%s: parse error at offset "
266 "%lld in header line \"%.*s\"",
267 file->name, (long long int) file->offset,
268 (int) strcspn(header, "\n"), header);
272 data_offset = file->offset + strlen(header);
273 error = parse_body(file, data_offset, data_length, actual_sha1, &json);
278 if (memcmp(expected_sha1, actual_sha1, SHA1_DIGEST_SIZE)) {
279 error = ovsdb_syntax_error(NULL, NULL, "%s: %lu bytes starting at "
280 "offset %lld have SHA-1 hash "SHA1_FMT" "
281 "but should have hash "SHA1_FMT,
282 file->name, data_length,
283 (long long int) data_offset,
284 SHA1_ARGS(actual_sha1),
285 SHA1_ARGS(expected_sha1));
289 if (json->type == JSON_STRING) {
290 error = ovsdb_syntax_error(NULL, NULL, "%s: %lu bytes starting at "
291 "offset %lld are not valid JSON (%s)",
292 file->name, data_length,
293 (long long int) data_offset,
298 file->prev_offset = file->offset;
299 file->offset = data_offset + data_length;
304 file->read_error = ovsdb_error_clone(error);
309 /* Causes the log record read by the previous call to ovsdb_log_read() to be
310 * effectively discarded. The next call to ovsdb_log_write() will overwrite
311 * that previously read record.
313 * Calling this function more than once has no additional effect.
315 * This function is useful when ovsdb_log_read() successfully reads a record
316 * but that record does not make sense at a higher level (e.g. it specifies an
317 * invalid transaction). */
319 ovsdb_log_unread(struct ovsdb_log *file)
321 assert(file->mode == OVSDB_LOG_READ);
322 file->offset = file->prev_offset;
326 ovsdb_log_write(struct ovsdb_log *file, struct json *json)
328 uint8_t sha1[SHA1_DIGEST_SIZE];
329 struct ovsdb_error *error;
336 if (file->write_error) {
337 return ovsdb_error_clone(file->write_error);
338 } else if (file->mode == OVSDB_LOG_READ) {
339 file->mode = OVSDB_LOG_WRITE;
340 if (fseeko(file->stream, file->offset, SEEK_SET)) {
341 error = ovsdb_io_error(errno, "%s: cannot seek to offset %lld",
342 file->name, (long long int) file->offset);
345 if (ftruncate(fileno(file->stream), file->offset)) {
346 error = ovsdb_io_error(errno, "%s: cannot truncate to length %lld",
347 file->name, (long long int) file->offset);
352 if (json->type != JSON_OBJECT && json->type != JSON_ARRAY) {
353 error = OVSDB_BUG("bad JSON type");
357 /* Compose content. Add a new-line (replacing the null terminator) to make
358 * the file easier to read, even though it has no semantic value. */
359 json_string = json_to_string(json, 0);
360 length = strlen(json_string) + 1;
361 json_string[length - 1] = '\n';
363 /* Compose header. */
364 sha1_bytes(json_string, length, sha1);
365 snprintf(header, sizeof header, "%s%zu "SHA1_FMT"\n",
366 magic, length, SHA1_ARGS(sha1));
369 if (fwrite(header, strlen(header), 1, file->stream) != 1
370 || fwrite(json_string, length, 1, file->stream) != 1
371 || fflush(file->stream))
373 error = ovsdb_io_error(errno, "%s: write failed", file->name);
375 /* Remove any partially written data, ignoring errors since there is
376 * nothing further we can do. */
377 ignore(ftruncate(fileno(file->stream), file->offset));
382 file->offset += strlen(header) + length;
387 file->write_error = ovsdb_error_clone(error);
393 ovsdb_log_commit(struct ovsdb_log *file)
395 if (fsync(fileno(file->stream))) {
396 return ovsdb_io_error(errno, "%s: fsync failed", file->name);
401 /* Returns the current offset into the file backing 'log', in bytes. This
402 * reflects the number of bytes that have been read or written in the file. If
403 * the whole file has been read, this is the file size. */
405 ovsdb_log_get_offset(const struct ovsdb_log *log)