1 /* Copyright (c) 2009, 2010, 2011, 2012, 2013 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.
30 #include "ovsdb-error.h"
32 #include "socket-util.h"
33 #include "transaction.h"
45 struct lockfile *lockfile;
47 struct ovsdb_error *read_error;
49 enum ovsdb_log_mode mode;
52 /* Attempts to open 'name' with the specified 'open_mode'. On success, stores
53 * the new log into '*filep' and returns NULL; otherwise returns NULL and
54 * stores NULL into '*filep'.
56 * Whether the file will be locked using lockfile_lock() depends on 'locking':
57 * use true to lock it, false not to lock it, or -1 to lock it only if
58 * 'open_mode' is a mode that allows writing.
61 ovsdb_log_open(const char *name, enum ovsdb_log_open_mode open_mode,
62 int locking, struct ovsdb_log **filep)
64 struct lockfile *lockfile;
65 struct ovsdb_error *error;
66 struct ovsdb_log *file;
74 ovs_assert(locking == -1 || locking == false || locking == true);
76 locking = open_mode != OVSDB_LOG_READ_ONLY;
79 int retval = lockfile_lock(name, &lockfile);
81 error = ovsdb_io_error(retval, "%s: failed to lock lockfile",
89 if (open_mode == OVSDB_LOG_READ_ONLY) {
91 } else if (open_mode == OVSDB_LOG_READ_WRITE) {
93 } else if (open_mode == OVSDB_LOG_CREATE) {
94 if (stat(name, &s) == -1 && errno == ENOENT
95 && lstat(name, &s) == 0 && S_ISLNK(s.st_mode)) {
96 /* 'name' is a dangling symlink. We want to create the file that
97 * the symlink points to, but POSIX says that open() with O_EXCL
98 * must fail with EEXIST if the named file is a symlink. So, we
99 * have to leave off O_EXCL and accept the race. */
100 flags = O_RDWR | O_CREAT;
102 flags = O_RDWR | O_CREAT | O_EXCL;
107 fd = open(name, flags, 0666);
109 const char *op = open_mode == OVSDB_LOG_CREATE ? "create" : "open";
110 error = ovsdb_io_error(errno, "%s: %s failed", op, name);
114 if (!fstat(fd, &s) && s.st_size == 0) {
115 /* It's (probably) a new file so fsync() its parent directory to ensure
116 * that its directory entry is committed to disk. */
117 fsync_parent_dir(name);
120 stream = fdopen(fd, open_mode == OVSDB_LOG_READ_ONLY ? "rb" : "w+b");
122 error = ovsdb_io_error(errno, "%s: fdopen failed", name);
126 file = xmalloc(sizeof *file);
127 file->name = xstrdup(name);
128 file->lockfile = lockfile;
129 file->stream = stream;
130 file->prev_offset = 0;
132 file->read_error = NULL;
133 file->write_error = false;
134 file->mode = OVSDB_LOG_READ;
141 lockfile_unlock(lockfile);
147 ovsdb_log_close(struct ovsdb_log *file)
151 fclose(file->stream);
152 lockfile_unlock(file->lockfile);
153 ovsdb_error_destroy(file->read_error);
158 static const char magic[] = "OVSDB JSON ";
161 parse_header(char *header, unsigned long int *length,
162 uint8_t sha1[SHA1_DIGEST_SIZE])
166 /* 'header' must consist of a magic string... */
167 if (strncmp(header, magic, strlen(magic))) {
171 /* ...followed by a length in bytes... */
172 *length = strtoul(header + strlen(magic), &p, 10);
173 if (!*length || *length == ULONG_MAX || *p != ' ') {
178 /* ...followed by a SHA-1 hash... */
179 if (!sha1_from_hex(sha1, p)) {
182 p += SHA1_HEX_DIGEST_LEN;
184 /* ...and ended by a new-line. */
192 struct ovsdb_log_read_cbdata {
194 struct ovsdb_log *file;
196 unsigned long length;
199 static struct ovsdb_error *
200 parse_body(struct ovsdb_log *file, off_t offset, unsigned long int length,
201 uint8_t sha1[SHA1_DIGEST_SIZE], struct json **jsonp)
203 struct json_parser *parser;
207 parser = json_parser_create(JSPF_TRAILER);
213 chunk = MIN(length, sizeof input);
214 if (fread(input, 1, chunk, file->stream) != chunk) {
215 json_parser_abort(parser);
216 return ovsdb_io_error(ferror(file->stream) ? errno : EOF,
217 "%s: error reading %lu bytes "
218 "starting at offset %lld", file->name,
219 length, (long long int) offset);
221 sha1_update(&ctx, input, chunk);
222 json_parser_feed(parser, input, chunk);
226 sha1_final(&ctx, sha1);
227 *jsonp = json_parser_finish(parser);
232 ovsdb_log_read(struct ovsdb_log *file, struct json **jsonp)
234 uint8_t expected_sha1[SHA1_DIGEST_SIZE];
235 uint8_t actual_sha1[SHA1_DIGEST_SIZE];
236 struct ovsdb_error *error;
238 unsigned long data_length;
242 *jsonp = json = NULL;
244 if (file->read_error) {
245 return ovsdb_error_clone(file->read_error);
246 } else if (file->mode == OVSDB_LOG_WRITE) {
247 return OVSDB_BUG("reading file in write mode");
250 if (!fgets(header, sizeof header, file->stream)) {
251 if (feof(file->stream)) {
254 error = ovsdb_io_error(errno, "%s: read failed", file->name);
259 if (!parse_header(header, &data_length, expected_sha1)) {
260 error = ovsdb_syntax_error(NULL, NULL, "%s: parse error at offset "
261 "%lld in header line \"%.*s\"",
262 file->name, (long long int) file->offset,
263 (int) strcspn(header, "\n"), header);
267 data_offset = file->offset + strlen(header);
268 error = parse_body(file, data_offset, data_length, actual_sha1, &json);
273 if (memcmp(expected_sha1, actual_sha1, SHA1_DIGEST_SIZE)) {
274 error = ovsdb_syntax_error(NULL, NULL, "%s: %lu bytes starting at "
275 "offset %lld have SHA-1 hash "SHA1_FMT" "
276 "but should have hash "SHA1_FMT,
277 file->name, data_length,
278 (long long int) data_offset,
279 SHA1_ARGS(actual_sha1),
280 SHA1_ARGS(expected_sha1));
284 if (json->type == JSON_STRING) {
285 error = ovsdb_syntax_error(NULL, NULL, "%s: %lu bytes starting at "
286 "offset %lld are not valid JSON (%s)",
287 file->name, data_length,
288 (long long int) data_offset,
293 file->prev_offset = file->offset;
294 file->offset = data_offset + data_length;
299 file->read_error = ovsdb_error_clone(error);
304 /* Causes the log record read by the previous call to ovsdb_log_read() to be
305 * effectively discarded. The next call to ovsdb_log_write() will overwrite
306 * that previously read record.
308 * Calling this function more than once has no additional effect.
310 * This function is useful when ovsdb_log_read() successfully reads a record
311 * but that record does not make sense at a higher level (e.g. it specifies an
312 * invalid transaction). */
314 ovsdb_log_unread(struct ovsdb_log *file)
316 ovs_assert(file->mode == OVSDB_LOG_READ);
317 file->offset = file->prev_offset;
321 ovsdb_log_write(struct ovsdb_log *file, struct json *json)
323 uint8_t sha1[SHA1_DIGEST_SIZE];
324 struct ovsdb_error *error;
331 if (file->mode == OVSDB_LOG_READ || file->write_error) {
332 file->mode = OVSDB_LOG_WRITE;
333 file->write_error = false;
334 if (fseeko(file->stream, file->offset, SEEK_SET)) {
335 error = ovsdb_io_error(errno, "%s: cannot seek to offset %lld",
336 file->name, (long long int) file->offset);
339 if (ftruncate(fileno(file->stream), file->offset)) {
340 error = ovsdb_io_error(errno, "%s: cannot truncate to length %lld",
341 file->name, (long long int) file->offset);
346 if (json->type != JSON_OBJECT && json->type != JSON_ARRAY) {
347 error = OVSDB_BUG("bad JSON type");
351 /* Compose content. Add a new-line (replacing the null terminator) to make
352 * the file easier to read, even though it has no semantic value. */
353 json_string = json_to_string(json, 0);
354 length = strlen(json_string) + 1;
355 json_string[length - 1] = '\n';
357 /* Compose header. */
358 sha1_bytes(json_string, length, sha1);
359 snprintf(header, sizeof header, "%s%zu "SHA1_FMT"\n",
360 magic, length, SHA1_ARGS(sha1));
363 if (fwrite(header, strlen(header), 1, file->stream) != 1
364 || fwrite(json_string, length, 1, file->stream) != 1
365 || fflush(file->stream))
367 error = ovsdb_io_error(errno, "%s: write failed", file->name);
369 /* Remove any partially written data, ignoring errors since there is
370 * nothing further we can do. */
371 ignore(ftruncate(fileno(file->stream), file->offset));
376 file->offset += strlen(header) + length;
381 file->write_error = true;
387 ovsdb_log_commit(struct ovsdb_log *file)
389 if (fsync(fileno(file->stream))) {
390 return ovsdb_io_error(errno, "%s: fsync failed", file->name);
395 /* Returns the current offset into the file backing 'log', in bytes. This
396 * reflects the number of bytes that have been read or written in the file. If
397 * the whole file has been read, this is the file size. */
399 ovsdb_log_get_offset(const struct ovsdb_log *log)