Is there any C SQLite API for quoting/escaping the name of a table?
It's impossible to sqlite3_bind_text a table name because sqlite3_prepare_v2 fails to prepare a statement such as:
SELECT * FROM ? ;
I presume the table name is needed to parse the statement, so the quoting needs to have happened before sqlite3_prepare_v2.
Is there something like a sqlite3_quote_tablename? Maybe it already exists under a name I can't recognize, but I can't find anything in the functions list.
your proposed sqlite3_quote_tablename function could sanitize the input to prevent sql injection attacks. To do this it could parse the input to make sure it is a string literal. http://sqlite.org/lang_expr.html#litvalue
If a table name has invalid characters in it you can enclose the table name in double quotes, like this.
sqlite> create table "test table" (id); sqlite> insert into "test table" values (1); sqlite> select * from "test table"; id ---------- 1
Of course you should avoid using invalid characters whenever possible. It complicates development and is almost always unnecessary (IMO the only time it is necessary is when you inherit a project that is already done this way and it's too big to change).
When using SQLite prepared statements with parameters the parameter: "specifies a placeholder in the expression for a literal value that is filled in at runtime"
Before executing any SQL statement, SQLite "compiles" the SQL string into a series of opcodes that are executed by an internal Virtual Machine. The table names and column names upon which the SQL statement operates are a necessary part of the compilation process.
You can use parameters to bind "values" to prepared statements like this:
SELECT * FROM FOO WHERE name=?;
And then call sqlite3_bind_text() to bind the string gavinbeatty to the already compiled statement. However, this architecture means that you cannot use parameters like this:
SELECT * FROM ? WHERE name=?; // Can't bind table name as a parameter SELECT * FROM FOO WHERE ?=10; // Can't bind column name as a parameter
If SQLite doesn't accept table names as parameters, I don't think there is a solution for your problem...
Take into account that:
Parameters that are not assigned values using sqlite3_bind() are treated as NULL.
so in the case of your query, the table name would be NULL which of course is invalid.
I was looking for something like this too and couldn't find it either. In my case, the expected table names were always among a fixed set of tables (so those were easy to validate). The field names on the other hand weren't so I ended up filtering the string, pretty much removing everything that was not a letter, number, or underscore (I knew my fields would fit this parameters). That did the trick.
SQLite will escape identifiers for you with the %w format in the https://www.sqlite.org/printf.html family of functions.