The reexport database code is designed to support multiple ways
to store the state.
So far only SQlite is implemented.
Signed-off-by: Richard Weinberger <richard@xxxxxx>
---
support/reexport/backend_sqlite.c | 267 ++++++++++++++++++++++++++++
support/reexport/reexport_backend.h | 47 +++++
2 files changed, 314 insertions(+)
create mode 100644 support/reexport/backend_sqlite.c
create mode 100644 support/reexport/reexport_backend.h
diff --git a/support/reexport/backend_sqlite.c b/support/reexport/backend_sqlite.c
new file mode 100644
index 00000000..132f30c4
--- /dev/null
+++ b/support/reexport/backend_sqlite.c
@@ -0,0 +1,267 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sqlite3.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/random.h>
+#include <unistd.h>
+
+#include "conffile.h"
+#include "reexport_backend.h"
+#include "xlog.h"
+
+#define REEXPDB_DBFILE NFS_STATEDIR "/reexpdb.sqlite3"
+#define REEXPDB_DBFILE_WAIT_USEC (5000)
+
+static sqlite3 *db;
+static int init_done;
+
+static int prng_init(void)
+{
+ int seed;
+
+ if (getrandom(&seed, sizeof(seed), 0) != sizeof(seed)) {
+ xlog(L_ERROR, "Unable to obtain seed for PRNG via getrandom()");
+ return -1;
+ }
+
+ srand(seed);
+ return 0;
+}
+
+static void wait_for_dbaccess(void)
+{
+ usleep(REEXPDB_DBFILE_WAIT_USEC + (rand() % REEXPDB_DBFILE_WAIT_USEC));
+}
+
+static bool sqlite_plug_init(void)
+{
+ char *sqlerr;
+ int ret;
+
+ if (init_done)
+ return true;
+
+ if (prng_init() != 0)
+ return false;
+
+ ret = sqlite3_open_v2(conf_get_str_with_def("reexport", "sqlitedb", REEXPDB_DBFILE),
+ &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_FULLMUTEX,
+ NULL);
+ if (ret != SQLITE_OK) {
+ xlog(L_ERROR, "Unable to open reexport database: %s", sqlite3_errstr(ret));
+ return false;
+ }
+
+again:
+ ret = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS fsidnums (num INTEGER PRIMARY KEY CHECK (num > 0 AND num < 4294967296), path TEXT UNIQUE); CREATE INDEX IF NOT EXISTS idx_ids_path ON fsidnums (path);", NULL, NULL, &sqlerr);
+ switch (ret) {
+ case SQLITE_OK:
+ init_done = 1;
+ ret = 0;
+ break;
+ case SQLITE_BUSY:
+ case SQLITE_LOCKED:
+ wait_for_dbaccess();
+ goto again;
+ default:
+ xlog(L_ERROR, "Unable to init reexport database: %s", sqlite3_errstr(ret));
+ sqlite3_free(sqlerr);
+ sqlite3_close_v2(db);
+ ret = -1;
+ }
+
+ return ret == 0 ? true : false;
+}
+
+static void sqlite_plug_destroy(void)
+{
+ if (!init_done)
+ return;
+
+ sqlite3_close_v2(db);
+}
+
+static bool get_fsidnum_by_path(char *path, uint32_t *fsidnum, bool *found)
+{
+ static const char fsidnum_by_path_sql[] = "SELECT num FROM fsidnums WHERE path = ?1;";
+ sqlite3_stmt *stmt = NULL;
+ bool success = false;
+ int ret;
+
+ *found = false;
+
+ ret = sqlite3_prepare_v2(db, fsidnum_by_path_sql, sizeof(fsidnum_by_path_sql), &stmt, NULL);
+ if (ret != SQLITE_OK) {
+ xlog(L_WARNING, "Unable to prepare SQL query '%s': %s", fsidnum_by_path_sql, sqlite3_errstr(ret));
+ goto out;
+ }
+
+ ret = sqlite3_bind_text(stmt, 1, path, -1, NULL);
+ if (ret != SQLITE_OK) {
+ xlog(L_WARNING, "Unable to bind SQL query '%s': %s", fsidnum_by_path_sql, sqlite3_errstr(ret));
+ goto out;
+ }
+
+again:
+ ret = sqlite3_step(stmt);
+ switch (ret) {
+ case SQLITE_ROW:
+ *fsidnum = sqlite3_column_int(stmt, 0);
+ success = true;
+ *found = true;
+ break;
+ case SQLITE_DONE:
+ /* No hit */
+ success = true;
+ *found = false;
+ break;
+ case SQLITE_BUSY:
+ case SQLITE_LOCKED:
+ wait_for_dbaccess();
+ goto again;
+ default:
+ xlog(L_WARNING, "Error while looking up '%s' in database: %s", path, sqlite3_errstr(ret));
+ }
+
+out:
+ sqlite3_finalize(stmt);
+ return success;
+}
+
+static bool sqlite_plug_path_by_fsidnum(uint32_t fsidnum, char **path, bool *found)
+{
+ static const char path_by_fsidnum_sql[] = "SELECT path FROM fsidnums WHERE num = ?1;";
+ sqlite3_stmt *stmt = NULL;
+ bool success = false;
+ int ret;
+
+ *found = false;
+
+ ret = sqlite3_prepare_v2(db, path_by_fsidnum_sql, sizeof(path_by_fsidnum_sql), &stmt, NULL);
+ if (ret != SQLITE_OK) {
+ xlog(L_WARNING, "Unable to prepare SQL query '%s': %s", path_by_fsidnum_sql, sqlite3_errstr(ret));
+ goto out;
+ }
+
+ ret = sqlite3_bind_int(stmt, 1, fsidnum);
+ if (ret != SQLITE_OK) {
+ xlog(L_WARNING, "Unable to bind SQL query '%s': %s", path_by_fsidnum_sql, sqlite3_errstr(ret));
+ goto out;
+ }
+
+again:
+ ret = sqlite3_step(stmt);
+ switch (ret) {
+ case SQLITE_ROW:
+ *path = strdup((char *)sqlite3_column_text(stmt, 0));
+ if (*path) {
+ *found = true;
+ success = true;
+ } else {
+ xlog(L_WARNING, "Out of memory");
+ }
+ break;
+ case SQLITE_DONE:
+ /* No hit */
+ *found = false;
+ success = true;
+ break;
+ case SQLITE_BUSY:
+ case SQLITE_LOCKED:
+ wait_for_dbaccess();
+ goto again;
+ default:
+ xlog(L_WARNING, "Error while looking up '%i' in database: %s", fsidnum, sqlite3_errstr(ret));
+ }
+
+out:
+ sqlite3_finalize(stmt);
+ return success;
+}
+
+static bool new_fsidnum_by_path(char *path, uint32_t *fsidnum)
+{
+ /*
+ * This query is a little tricky. We use SQL to find and claim the smallest free fsid number.
+ * To find a free fsid the fsidnums is left joined to itself but with an offset of 1.
+ * Everything after the UNION statement is to handle the corner case where fsidnums
+ * is empty. In this case we want 1 as first fsid number.
+ */
+ static const char new_fsidnum_by_path_sql[] = "INSERT INTO fsidnums VALUES ((SELECT ids1.num + 1 FROM fsidnums AS ids1 LEFT JOIN fsidnums AS ids2 ON ids2.num = ids1.num + 1 WHERE ids2.num IS NULL UNION SELECT 1 WHERE NOT EXISTS (SELECT NULL FROM fsidnums WHERE num = 1) LIMIT 1), ?1) RETURNING num;";
+
+ sqlite3_stmt *stmt = NULL;
+ int ret, check = 0;
+ bool success = false;
+
+ ret = sqlite3_prepare_v2(db, new_fsidnum_by_path_sql, sizeof(new_fsidnum_by_path_sql), &stmt, NULL);
+ if (ret != SQLITE_OK) {
+ xlog(L_WARNING, "Unable to prepare SQL query '%s': %s", new_fsidnum_by_path_sql, sqlite3_errstr(ret));
+ goto out;
+ }
+
+ ret = sqlite3_bind_text(stmt, 1, path, -1, NULL);
+ if (ret != SQLITE_OK) {
+ xlog(L_WARNING, "Unable to bind SQL query '%s': %s", new_fsidnum_by_path_sql, sqlite3_errstr(ret));
+ goto out;
+ }
+
+again:
+ ret = sqlite3_step(stmt);
+ switch (ret) {
+ case SQLITE_ROW:
+ *fsidnum = sqlite3_column_int(stmt, 0);
+ success = true;
+ break;
+ case SQLITE_CONSTRAINT:
+ /* Maybe we lost the race against another writer and the path is now present. */
+ check = 1;
+ break;
+ case SQLITE_BUSY:
+ case SQLITE_LOCKED:
+ wait_for_dbaccess();
+ goto again;
+ default:
+ xlog(L_WARNING, "Error while looking up '%s' in database: %s", path, sqlite3_errstr(ret));
+ }
+
+out:
+ sqlite3_finalize(stmt);
+
+ if (check) {
+ bool found = false;
+
+ get_fsidnum_by_path(path, fsidnum, &found);
+ if (!found)
+ xlog(L_WARNING, "SQLITE_CONSTRAINT error while inserting '%s' in database", path);
+ }
+
+ return success;
+}
+
+static bool sqlite_plug_fsidnum_by_path(char *path, uint32_t *fsidnum, int may_create, bool *found)
+{
+ bool success;
+
+ success = get_fsidnum_by_path(path, fsidnum, found);
+ if (success) {
+ if (!*found && may_create) {
+ success = new_fsidnum_by_path(path, fsidnum);
+ if (success)
+ *found = true;
+ }
+ }
+
+ return success;
+}
+
+struct reexpdb_backend_plugin sqlite_plug_ops = {
+ .fsidnum_by_path = sqlite_plug_fsidnum_by_path,
+ .path_by_fsidnum = sqlite_plug_path_by_fsidnum,
+ .initdb = sqlite_plug_init,
+ .destroydb = sqlite_plug_destroy,
+};
diff --git a/support/reexport/reexport_backend.h b/support/reexport/reexport_backend.h
new file mode 100644
index 00000000..4940f06f
--- /dev/null
+++ b/support/reexport/reexport_backend.h
@@ -0,0 +1,47 @@
+#ifndef REEXPORT_BACKEND_H
+#define REEXPORT_BACKEND_H
+
+extern struct reexpdb_backend_plugin sqlite_plug_ops;
+
+struct reexpdb_backend_plugin {
+ /*
+ * Find or allocate a fsidnum for a given path.
+ *
+ * @path: Path to look for
+ * @fsidnum: Pointer to an uint32_t variable
+ * @may_create: If non-zero, a fsidnum will be allocated if none was found
+ *
+ * Returns true if either an fsidnum was found or successfully allocated,
+ * false otherwise.
+ * On success, the fsidnum will be stored into @fsidnum.
+ * Upon errors, false is returned and errors are logged.
+ */
+ bool (*fsidnum_by_path)(char *path, uint32_t *fsidnum, int may_create, bool *found);
+
+ /*
+ * Lookup path by a given fsidnum
+ *
+ * @fsidnum: fsidnum to look for
+ * @path: address of a char pointer
+ *
+ * Returns true if a path was found, false otherwise.
+ * Upon errors, false is returned and errors are logged.
+ * In case of success, the function returns the found path
+ * via @path, @path will point to a freshly allocated buffer
+ * which is free()'able.
+ */
+ bool (*path_by_fsidnum)(uint32_t fsidnum, char **path, bool *found);
+
+ /*
+ * Init database connection, can get called multiple times.
+ * Returns true on success, false otherwise.
+ */
+ bool (*initdb)(void);
+
+ /*
+ * Undoes initdb().
+ */
+ void (*destroydb)(void);
+};
+
+#endif /* REEXPORT_BACKEND_H */
--
2.31.1
