sqlite_compressions/
bzip2.rs

1use std::io::{Read, Write};
2
3use bzip2::read::BzDecoder;
4use bzip2::write::BzEncoder;
5use bzip2::Compression;
6use rusqlite::Error::UserFunctionError;
7
8use crate::common::{register_compression, Encoder};
9use crate::rusqlite::{Connection, Result};
10
11/// Register the `bzip2` SQL functions with the given `SQLite` connection.
12/// The function takes a single argument and returns the [bzip2 compression](https://en.wikipedia.org/wiki/Bzip2) (blob) of that argument.
13/// The argument can be either a string or a blob.
14/// If the argument is `NULL`, the result is `NULL`.
15///
16/// # Example
17///
18/// ```
19/// # use sqlite_compressions::rusqlite::{Connection, Result};
20/// # use sqlite_compressions::register_bzip2_functions;
21/// # fn main() -> Result<()> {
22/// let db = Connection::open_in_memory()?;
23/// register_bzip2_functions(&db)?;
24/// let result: Vec<u8> = db.query_row("SELECT bzip2('hello')", [], |r| r.get(0))?;
25/// let expected = b"\x42\x5a\x68\x36\x31\x41\x59\x26\x53\x59\x19\x31\x65\x3d\x00\x00\x00\x81\x00\x02\x44\xa0\x00\x21\x9a\x68\x33\x4d\x07\x33\x8b\xb9\x22\x9c\x28\x48\x0c\x98\xb2\x9e\x80";
26/// assert_eq!(result, expected);
27/// let result: String = db.query_row("SELECT CAST(bzip2_decode(bzip2('world')) AS TEXT)", [], |r| r.get(0))?;
28/// let expected = "world";
29/// assert_eq!(result, expected);
30/// let result: bool = db.query_row("SELECT bzip2_test(bzip2('world'))", [], |r| r.get(0))?;
31/// let expected = true;
32/// assert_eq!(result, expected);
33/// # Ok(())
34/// # }
35/// ```
36pub fn register_bzip2_functions(conn: &Connection) -> Result<()> {
37    register_compression::<Bzip2Encoder>(conn)
38}
39
40pub struct Bzip2Encoder;
41
42impl Encoder for Bzip2Encoder {
43    fn enc_name() -> &'static str {
44        "bzip2"
45    }
46    fn dec_name() -> &'static str {
47        "bzip2_decode"
48    }
49    fn test_name() -> &'static str {
50        "bzip2_test"
51    }
52
53    fn encode(data: &[u8], quality: Option<u32>) -> Result<Vec<u8>> {
54        let quality = if let Some(param) = quality {
55            if param < Compression::fast().level() || param > Compression::best().level() {
56                return Err(UserFunctionError(
57                    format!(
58                        "The optional second argument to bzip2() must be between {} and {}",
59                        Compression::fast().level(),
60                        Compression::best().level()
61                    )
62                    .into(),
63                ));
64            }
65            Compression::new(param)
66        } else {
67            Compression::default()
68        };
69
70        let mut encoder = BzEncoder::new(Vec::new(), quality);
71        encoder
72            .write_all(data)
73            .map_err(|e| UserFunctionError(e.into()))?;
74        encoder.finish().map_err(|e| UserFunctionError(e.into()))
75    }
76
77    fn decode(data: &[u8]) -> Result<Vec<u8>> {
78        let mut decompressed = Vec::new();
79        BzDecoder::new(data)
80            .read_to_end(&mut decompressed)
81            .map_err(|e| UserFunctionError(e.into()))?;
82        Ok(decompressed)
83    }
84
85    fn test(data: &[u8]) -> bool {
86        // reuse the same buffer when decompressing
87        // ideally we should use some null buffer, but bzip2 doesn't seem to support that
88        // note that buffer size does affect performance and depend on the input data size
89        let mut buffer = [0u8; 1024];
90        let mut decoder = BzDecoder::new(data);
91        while let Ok(len) = decoder.read(&mut buffer) {
92            if len == 0 {
93                return true;
94            }
95        }
96        false
97    }
98}
sqlite_compressions/bzip2.rs

sqlite_compressions/
bzip2.rs
