vault_audit_tools/utils/
reader.rs

1//! Smart file reader with automatic decompression support.
2//!
3//! Provides transparent decompression for .gz and .zst files,
4//! allowing analysis of compressed audit logs without manual extraction.
5//!
6//! # Supported Formats
7//!
8//! - Plain text files
9//! - Gzip compressed files (.gz)
10//! - Zstandard compressed files (.zst)
11//!
12//! # Examples
13//!
14//! ```no_run
15//! use vault_audit_tools::utils::reader::open_file;
16//! use std::io::{BufRead, BufReader};
17//!
18//! // Automatically handles .gz, .zst, or plain text
19//! let reader = open_file("audit.log.gz").unwrap();
20//! let buf_reader = BufReader::new(reader);
21//!
22//! for line in buf_reader.lines() {
23//!     let line = line.unwrap();
24//!     // Process line...
25//! }
26//! ```
27
28use anyhow::{Context, Result};
29use flate2::read::GzDecoder;
30use std::fs::File;
31use std::io::Read;
32use std::path::Path;
33
34/// Opens a file with automatic decompression based on extension.
35///
36/// Detects file type by extension:
37/// - `.gz` → Gzip decompression
38/// - `.zst` → Zstandard decompression
39/// - Otherwise → Plain file
40///
41/// # Arguments
42///
43/// * `path` - Path to the file (compressed or uncompressed)
44///
45/// # Returns
46///
47/// A `Read` trait object that transparently handles decompression
48///
49/// # Examples
50///
51/// ```no_run
52/// use vault_audit_tools::utils::reader::open_file;
53/// use std::io::Read;
54///
55/// let mut reader = open_file("audit.log.gz").unwrap();
56/// let mut contents = String::new();
57/// reader.read_to_string(&mut contents).unwrap();
58/// ```
59pub fn open_file(path: impl AsRef<Path>) -> Result<Box<dyn Read + Send>> {
60    let path = path.as_ref();
61    let file =
62        File::open(path).with_context(|| format!("Failed to open file: {}", path.display()))?;
63
64    let extension = path.extension().and_then(|e| e.to_str()).unwrap_or("");
65
66    match extension {
67        "gz" => {
68            let decoder = GzDecoder::new(file);
69            Ok(Box::new(decoder))
70        }
71        "zst" => {
72            let decoder = zstd::Decoder::new(file).with_context(|| {
73                format!("Failed to create zstd decoder for: {}", path.display())
74            })?;
75            Ok(Box::new(decoder))
76        }
77        _ => Ok(Box::new(file)),
78    }
79}
80
81#[cfg(test)]
82mod tests {
83    use super::*;
84    use std::io::{BufRead, BufReader, Write};
85    use tempfile::TempDir;
86
87    #[test]
88    fn test_plain_file() {
89        let dir = TempDir::new().unwrap();
90        let path = dir.path().join("test.txt");
91        {
92            let mut file = std::fs::File::create(&path).unwrap();
93            writeln!(file, "test line 1").unwrap();
94            writeln!(file, "test line 2").unwrap();
95        }
96
97        let reader = open_file(&path).unwrap();
98        let buf_reader = BufReader::new(reader);
99        let lines: Vec<String> = buf_reader.lines().collect::<Result<_, _>>().unwrap();
100
101        assert_eq!(lines.len(), 2);
102        assert_eq!(lines[0], "test line 1");
103        assert_eq!(lines[1], "test line 2");
104    }
105
106    #[test]
107    fn test_gzip_file() {
108        use flate2::write::GzEncoder;
109        use flate2::Compression;
110
111        let dir = TempDir::new().unwrap();
112        let path = dir.path().join("test.gz");
113        {
114            let file = std::fs::File::create(&path).unwrap();
115            let mut encoder = GzEncoder::new(file, Compression::default());
116            writeln!(encoder, "compressed line 1").unwrap();
117            writeln!(encoder, "compressed line 2").unwrap();
118            encoder.finish().unwrap();
119        }
120
121        let reader = open_file(&path).unwrap();
122        let buf_reader = BufReader::new(reader);
123        let lines: Vec<String> = buf_reader.lines().collect::<Result<_, _>>().unwrap();
124
125        assert_eq!(lines.len(), 2);
126        assert_eq!(lines[0], "compressed line 1");
127        assert_eq!(lines[1], "compressed line 2");
128    }
129
130    #[test]
131    fn test_zstd_file() {
132        let dir = TempDir::new().unwrap();
133        let path = dir.path().join("test.zst");
134        {
135            let file = std::fs::File::create(&path).unwrap();
136            let mut encoder = zstd::Encoder::new(file, 3).unwrap();
137            writeln!(encoder, "zstd line 1").unwrap();
138            writeln!(encoder, "zstd line 2").unwrap();
139            encoder.finish().unwrap();
140        }
141
142        let reader = open_file(&path).unwrap();
143        let buf_reader = BufReader::new(reader);
144        let lines: Vec<String> = buf_reader.lines().collect::<Result<_, _>>().unwrap();
145
146        assert_eq!(lines.len(), 2);
147        assert_eq!(lines[0], "zstd line 1");
148        assert_eq!(lines[1], "zstd line 2");
149    }
150}
vault_audit_tools/utils/reader.rs

vault_audit_tools/utils/
reader.rs
