server: Set maximum database size

1 files changed, 46 insertions, 15 deletions

diff --git a/db.c b/db.c
index f5f2572..f4c28f3 100644
--- a/db.c
+++ b/db.c
@@ -15,6 +15,8 @@
 #define PASSHASH_OPSLIMIT 3
 #define PASSHASH_MEMLIMIT crypto_pwhash_MEMLIMIT_INTERACTIVE
 
+#define MAX_DATABASE_SIZE_BYTES ((i64)2 * 1024 * 1024 * 1024)
+
 
 sqlite3 *database=NULL;
 
@@ -41,40 +43,69 @@ static struct hashed_password hash_password(const char *pass) {
 	return result;
 }
 
+// Returns whether successful
+bool select_simple_int(const char *query, i64 *out) {
+	sqlite3_stmt *stmt;
+	int res = sqlite3_prepare_v2(database, query, -1, &stmt, NULL);
+	bool retval = false;
+	if (res == SQLITE_OK) {
+		if (sqlite3_step(stmt) == SQLITE_ROW) {
+			*out = sqlite3_column_int64(stmt, 0);
+			retval = true;
+		}
+		SQLITE(finalize, stmt);
+	}
+	return retval;
+}
+
 
 void db_init(void){
-	SQLITE(config,SQLITE_CONFIG_SERIALIZED);
+	SQLITE(config, SQLITE_CONFIG_SERIALIZED);
 	SQLITE(initialize);
 
-	SQLITE(open_v2,"db.db",&database,SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE,NULL);
-	SQLITE(busy_timeout,database,500);
+	SQLITE(open_v2, "db.db", &database, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL);
+	SQLITE(busy_timeout, database, 500);
 
-	SQLITE(exec,database,"pragma foreign_keys = 1",NULL,NULL,NULL);
+	SQLITE(exec, database, "pragma foreign_keys = 1", NULL, NULL, NULL);
 
-	sqlite3_stmt *stmt;
-	int res = sqlite3_prepare_v2(database, "select version from Meta", -1, &stmt, NULL);
-	if (res == SQLITE_OK && sqlite3_step(stmt) == SQLITE_ROW) {
-		i64 version = sqlite3_column_int64(stmt, 0);
-		SQLITE(finalize, stmt);
+	i64 page_size, page_count;
+	if (select_simple_int("pragma page_size", &page_size) &&
+			select_simple_int("pragma page_count", &page_count)) {
+		i64 max_num_pages = MAX_DATABASE_SIZE_BYTES / page_size;
+		if (page_count >= max_num_pages - 1) {
+			fprintf(stderr, "WARNING: Database already at maximum size!\n");
+			max_num_pages = page_count + 2;
+		}
+
+		// SQLite doesn't allow preparing a pragma, so let's splice the integer in directly
+		char *str = NULL;
+		asprintf(&str, "pragma max_page_count = %" PRIi64, max_num_pages);
+		SQLITE(exec, database, str, NULL, NULL, NULL);
+		free(str);
+	} else {
+		die("Failed to query database page statistics: %s", sqlite3_errmsg(database));
+	}
 
+	i64 version;
+	if (select_simple_int("select version from Meta", &version)) {
 		if (version != DATABASE_VERSION) {
 			die("Database version incompatible: database %" PRIi64 ", application %d",
 				version, DATABASE_VERSION);
 		}
 	} else {
-		if (res == SQLITE_OK) SQLITE(finalize, stmt);
-
-		char *str=malloc(schema_sql_len+1,char);
-		memcpy(str,schema_sql,schema_sql_len);
-		str[schema_sql_len]='\0';
-		SQLITE(exec,database,str,NULL,NULL,NULL);
+		char *str = malloc(schema_sql_len+1, char);
+		memcpy(str, schema_sql, schema_sql_len);
+		str[schema_sql_len] = '\0';
+		SQLITE(exec, database, str, NULL, NULL, NULL);
 		free(str);
 
+		sqlite3_stmt *stmt;
 		SQLITE(prepare_v2, database, "insert into Meta (version) values (?)", -1, &stmt, NULL);
 		SQLITE(bind_int64, stmt, 1, DATABASE_VERSION);
 		if (sqlite3_step(stmt) != SQLITE_DONE) {
 			die("Could not set database version: %s", sqlite3_errmsg(database));
 		}
+		SQLITE(finalize, stmt);
 	}
 }