Initial implementation of OVSDB.

1 files changed, 360 insertions, 0 deletions

diff --git a/ovsdb/file.c b/ovsdb/file.c
new file mode 100644
index 000000000..4883d76f1
--- /dev/null
+++ b/ovsdb/file.c
@@ -0,0 +1,360 @@
+/* Copyright (c) 2009 Nicira Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include "file.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "json.h"
+#include "lockfile.h"
+#include "ovsdb-error.h"
+#include "sha1.h"
+#include "util.h"
+
+#define THIS_MODULE VLM_ovsdb_file
+#include "vlog.h"
+
+enum ovsdb_file_mode {
+    OVSDB_FILE_READ,
+    OVSDB_FILE_WRITE
+};
+
+struct ovsdb_file {
+    off_t offset;
+    char *name;
+    struct lockfile *lockfile;
+    FILE *stream;
+    struct ovsdb_error *read_error;
+    struct ovsdb_error *write_error;
+    enum ovsdb_file_mode mode;
+};
+
+struct ovsdb_error *
+ovsdb_file_open(const char *name, int flags, struct ovsdb_file **filep)
+{
+    struct lockfile *lockfile;
+    struct ovsdb_error *error;
+    struct ovsdb_file *file;
+    struct stat s;
+    FILE *stream;
+    int accmode;
+    int fd;
+
+    *filep = NULL;
+
+    accmode = flags & O_ACCMODE;
+    if (accmode == O_RDWR || accmode == O_WRONLY) {
+        int retval = lockfile_lock(name, 0, &lockfile);
+        if (retval) {
+            error = ovsdb_io_error(retval, "%s: failed to lock lockfile",
+                                   name);
+            goto error;
+        }
+    } else {
+        lockfile = NULL;
+    }
+
+    fd = open(name, flags, 0666);
+    if (fd < 0) {
+        const char *op = flags & O_CREAT && flags & O_EXCL ? "create" : "open";
+        error = ovsdb_io_error(errno, "%s: %s failed", op, name);
+        goto error_unlock;
+    }
+
+    if (!fstat(fd, &s) && s.st_size == 0) {
+        /* It's (probably) a new file so fsync() its parent directory to ensure
+         * that its directory entry is committed to disk. */
+        char *dir = dir_name(name);
+        int dirfd = open(dir, O_RDONLY);
+        if (dirfd >= 0) {
+            if (fsync(dirfd) && errno != EINVAL) {
+                VLOG_ERR("%s: fsync failed (%s)", dir, strerror(errno));
+            }
+            close(dirfd);
+        } else {
+            VLOG_ERR("%s: open failed (%s)", dir, strerror(errno));
+        }
+        free(dir);
+    }
+
+    stream = fdopen(fd, (accmode == O_RDONLY ? "rb"
+                         : accmode == O_WRONLY ? "wb"
+                         : "w+b"));
+    if (!stream) {
+        error = ovsdb_io_error(errno, "%s: fdopen failed", name);
+        goto error_close;
+    }
+
+    file = xmalloc(sizeof *file);
+    file->name = xstrdup(name);
+    file->lockfile = lockfile;
+    file->stream = stream;
+    file->offset = 0;
+    file->read_error = NULL;
+    file->write_error = NULL;
+    file->mode = OVSDB_FILE_READ;
+    *filep = file;
+    return NULL;
+
+error_close:
+    close(fd);
+error_unlock:
+    lockfile_unlock(lockfile);
+error:
+    return error;
+}
+
+void
+ovsdb_file_close(struct ovsdb_file *file)
+{
+    if (file) {
+        free(file->name);
+        fclose(file->stream);
+        lockfile_unlock(file->lockfile);
+        ovsdb_error_destroy(file->read_error);
+        ovsdb_error_destroy(file->write_error);
+        free(file);
+    }
+}
+
+static const char magic[] = "OVSDB JSON ";
+
+static bool
+parse_header(char *header, unsigned long int *length,
+             uint8_t sha1[SHA1_DIGEST_SIZE])
+{
+    char *p;
+
+    /* 'header' must consist of a magic string... */
+    if (strncmp(header, magic, strlen(magic))) {
+        return false;
+    }
+
+    /* ...followed by a length in bytes... */
+    *length = strtoul(header + strlen(magic), &p, 10);
+    if (!*length || *length == ULONG_MAX || *p != ' ') {
+        return false;
+    }
+    p++;
+
+    /* ...followed by a SHA-1 hash... */
+    if (!sha1_from_hex(sha1, p)) {
+        return false;
+    }
+    p += SHA1_HEX_DIGEST_LEN;
+
+    /* ...and ended by a new-line. */
+    if (*p != '\n') {
+        return false;
+    }
+
+    return true;
+}
+
+struct ovsdb_file_read_cbdata {
+    char input[4096];
+    struct ovsdb_file *file;
+    int error;
+    unsigned long length;
+};
+
+static struct ovsdb_error *
+parse_body(struct ovsdb_file *file, off_t offset, unsigned long int length,
+           uint8_t sha1[SHA1_DIGEST_SIZE], struct json **jsonp)
+{
+    unsigned long int bytes_left;
+    struct json_parser *parser;
+    struct sha1_ctx ctx;
+
+    sha1_init(&ctx);
+    parser = json_parser_create(JSPF_TRAILER);
+
+    bytes_left = length;
+    while (length > 0) {
+        char input[BUFSIZ];
+        int chunk;
+
+        chunk = MIN(length, sizeof input);
+        if (fread(input, 1, chunk, file->stream) != chunk) {
+            json_parser_abort(parser);
+            return ovsdb_io_error(ferror(file->stream) ? errno : EOF,
+                                  "%s: error reading %lu bytes "
+                                  "starting at offset %lld", file->name,
+                                  length, (long long int) offset);
+        }
+        sha1_update(&ctx, input, chunk);
+        json_parser_feed(parser, input, chunk);
+        length -= chunk;
+    }
+
+    sha1_final(&ctx, sha1);
+    *jsonp = json_parser_finish(parser);
+    return NULL;
+}
+
+struct ovsdb_error *
+ovsdb_file_read(struct ovsdb_file *file, struct json **jsonp)
+{
+    uint8_t expected_sha1[SHA1_DIGEST_SIZE];
+    uint8_t actual_sha1[SHA1_DIGEST_SIZE];
+    struct ovsdb_error *error;
+    off_t data_offset;
+    unsigned long data_length;
+    struct json *json;
+    char header[128];
+
+    *jsonp = json = NULL;
+
+    if (file->read_error) {
+        return ovsdb_error_clone(file->read_error);
+    } else if (file->mode == OVSDB_FILE_WRITE) {
+        return OVSDB_BUG("reading file in write mode");
+    }
+
+    if (!fgets(header, sizeof header, file->stream)) {
+        if (feof(file->stream)) {
+            error = NULL;
+        } else {
+            error = ovsdb_io_error(errno, "%s: read failed", file->name);
+        }
+        goto error;
+    }
+
+    if (!parse_header(header, &data_length, expected_sha1)) {
+        error = ovsdb_syntax_error(NULL, NULL, "%s: parse error at offset "
+                                   "%lld in header line \"%.*s\"",
+                                   file->name, (long long int) file->offset,
+                                   (int) strcspn(header, "\n"), header);
+        goto error;
+    }
+
+    data_offset = file->offset + strlen(header);
+    error = parse_body(file, data_offset, data_length, actual_sha1, &json);
+    if (error) {
+        goto error;
+    }
+
+    if (memcmp(expected_sha1, actual_sha1, SHA1_DIGEST_SIZE)) {
+        error = ovsdb_syntax_error(NULL, NULL, "%s: %lu bytes starting at "
+                                   "offset %lld have SHA-1 hash "SHA1_FMT" "
+                                   "but should have hash "SHA1_FMT,
+                                   file->name, data_length,
+                                   (long long int) data_offset,
+                                   SHA1_ARGS(actual_sha1),
+                                   SHA1_ARGS(expected_sha1));
+        goto error;
+    }
+
+    if (json->type == JSON_STRING) {
+        error = ovsdb_syntax_error(NULL, NULL, "%s: %lu bytes starting at "
+                                   "offset %lld are not valid JSON (%s)",
+                                   file->name, data_length,
+                                   (long long int) data_offset,
+                                   json->u.string);
+        goto error;
+    }
+
+    file->offset = data_offset + data_length;
+    *jsonp = json;
+    return 0;
+
+error:
+    file->read_error = ovsdb_error_clone(error);
+    json_destroy(json);
+    return error;
+}
+
+struct ovsdb_error *
+ovsdb_file_write(struct ovsdb_file *file, struct json *json)
+{
+    uint8_t sha1[SHA1_DIGEST_SIZE];
+    struct ovsdb_error *error;
+    char *json_string;
+    char header[128];
+    size_t length;
+
+    json_string = NULL;
+
+    if (file->write_error) {
+        return ovsdb_error_clone(file->write_error);
+    } else if (file->mode == OVSDB_FILE_READ) {
+        file->mode = OVSDB_FILE_WRITE;
+        if (fseeko(file->stream, file->offset, SEEK_SET)) {
+            error = ovsdb_io_error(errno, "%s: cannot seek to offset %lld",
+                                   file->name, (long long int) file->offset);
+            goto error;
+        }
+        if (ftruncate(fileno(file->stream), file->offset)) {
+            error = ovsdb_io_error(errno, "%s: cannot truncate to length %lld",
+                                   file->name, (long long int) file->offset);
+            goto error;
+        }
+    }
+
+    if (json->type != JSON_OBJECT && json->type != JSON_ARRAY) {
+        error = OVSDB_BUG("bad JSON type");
+        goto error;
+    }
+
+    /* Compose content.  Add a new-line (replacing the null terminator) to make
+     * the file easier to read, even though it has no semantic value.  */
+    json_string = json_to_string(json, 0);
+    length = strlen(json_string) + 1;
+    json_string[length - 1] = '\n';
+
+    /* Compose header. */
+    sha1_bytes(json_string, length, sha1);
+    snprintf(header, sizeof header, "%s%zu "SHA1_FMT"\n",
+             magic, length, SHA1_ARGS(sha1));
+
+    /* Write. */
+    if (fwrite(header, strlen(header), 1, file->stream) != 1
+        || fwrite(json_string, length, 1, file->stream) != 1
+        || fflush(file->stream))
+    {
+        error = ovsdb_io_error(errno, "%s: write failed", file->name);
+
+        /* Remove any partially written data, ignoring errors since there is
+         * nothing further we can do. */
+        ftruncate(fileno(file->stream), file->offset);
+
+        goto error;
+    }
+
+    file->offset += strlen(header) + length;
+    free(json_string);
+    return 0;
+
+error:
+    file->write_error = ovsdb_error_clone(error);
+    free(json_string);
+    return error;
+}
+
+struct ovsdb_error *
+ovsdb_file_commit(struct ovsdb_file *file)
+{
+    if (fsync(fileno(file->stream))) {
+        return ovsdb_io_error(errno, "%s: fsync failed", file->name);
+    }
+    return 0;
+}