lance_file/
lib.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright The Lance Authors
3
4pub mod datatypes;
5pub mod format;
6pub(crate) mod io;
7pub mod reader;
8pub mod testing;
9pub mod version;
10pub mod versions;
11pub mod writer;
12
13#[cfg(test)]
14mod compatibility_tests;
15
16pub use io::LanceEncodingsIo;
17
18use format::MAGIC;
19use lance_core::{Error, Result};
20use lance_io::object_store::ObjectStore;
21use object_store::path::Path;
22use version::{ConcreteFileVersion, LanceFileVersion};
23
24pub async fn determine_file_version(
25    store: &ObjectStore,
26    path: &Path,
27    known_size: Option<usize>,
28) -> Result<LanceFileVersion> {
29    let size = match known_size {
30        None => store.size(path).await.unwrap() as usize,
31        Some(size) => size,
32    };
33    if size < 8 {
34        return Err(Error::invalid_input_source(
35            format!(
36                "the file {} does not appear to be a lance file (too small)",
37                path
38            )
39            .into(),
40        ));
41    }
42    let reader = store.open_with_size(path, size).await?;
43    let footer = reader.get_range((size - 8)..size).await?;
44    if &footer[4..] != MAGIC {
45        return Err(Error::invalid_input_source(
46            format!(
47                "the file {} does not appear to be a lance file (magic mismatch)",
48                path
49            )
50            .into(),
51        ));
52    }
53    let major_version = u16::from_le_bytes([footer[0], footer[1]]);
54    let minor_version = u16::from_le_bytes([footer[2], footer[3]]);
55
56    ConcreteFileVersion::from_footer_numbers(major_version, minor_version).map(Into::into)
57}
lance_file/lib.rs

lance_file/
lib.rs
