Magic Number
The magic number tells the parser whether it is reading a parquet file. This is a 4-byte PAR1 and
is located at the beginning and at the end of a file.
Task
Implement the ensure_header_footer_magic function in src/magic.rs. It takes the entire file data
as Bytes and returns an error if this is not a parquet file.
pub fn ensure_header_footer_magic(data: Bytes) -> Result<()> {
todo!("step01: implement magic number")
}Test
To verify the implementation, uncomment the test in tests/integration/mod.rs.
-// mod step01_magic;
+mod step01_magic;
And run:
cargo test
Hints and Solution
Hint
You can use starts_with and ends_with functions to check whether the magic number is correctly
present at both ends of the file.
Solution
pub fn ensure_header_footer_magic(data: Bytes) -> Result<()> {
if data.len() < 8 || !data.starts_with(b"PAR1") || !data.ends_with(b"PAR1") {
bail!("Magic: not a parquet file")
}
Ok(())
}