unpdf 0.4.5

High-performance PDF content extraction to Markdown, text, and JSON
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167

//! PDF format detection and validation.

use crate::error::{Error, Result};
use std::fs::File;
use std::io::{BufReader, Read};
use std::path::Path;

/// PDF format information.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PdfFormat {
    /// PDF version (e.g., "1.7", "2.0")
    pub version: String,
    /// Whether the file appears to be linearized (fast web view)
    pub linearized: bool,
}

impl std::fmt::Display for PdfFormat {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "PDF {}", self.version)
    }
}

/// PDF magic bytes: %PDF-
const PDF_MAGIC: &[u8] = b"%PDF-";
const PDF_MAGIC_LEN: usize = 5;
const VERSION_LEN: usize = 3; // e.g., "1.7"

/// Detect PDF format from a file path.
///
/// # Arguments
/// * `path` - Path to the PDF file
///
/// # Returns
/// * `Ok(PdfFormat)` if the file is a valid PDF
/// * `Err(Error::UnknownFormat)` if the file is not a PDF
///
/// # Example
/// ```no_run
/// use unpdf::detect::detect_format_from_path;
///
/// let format = detect_format_from_path("document.pdf").unwrap();
/// println!("PDF version: {}", format.version);
/// ```
pub fn detect_format_from_path<P: AsRef<Path>>(path: P) -> Result<PdfFormat> {
    let file = File::open(path)?;
    let mut reader = BufReader::new(file);
    let mut header = [0u8; 16];
    reader.read_exact(&mut header)?;
    detect_format_from_bytes(&header)
}

/// Detect PDF format from bytes.
///
/// # Arguments
/// * `data` - Byte slice containing at least the first 16 bytes of the file
///
/// # Returns
/// * `Ok(PdfFormat)` if the data starts with valid PDF header
/// * `Err(Error::UnknownFormat)` if the data is not a PDF
pub fn detect_format_from_bytes(data: &[u8]) -> Result<PdfFormat> {
    if data.len() < PDF_MAGIC_LEN + VERSION_LEN {
        return Err(Error::UnknownFormat);
    }

    // Check for PDF magic bytes
    if !data.starts_with(PDF_MAGIC) {
        return Err(Error::UnknownFormat);
    }

    // Extract version string (e.g., "1.7" from "%PDF-1.7")
    let version_bytes = &data[PDF_MAGIC_LEN..PDF_MAGIC_LEN + VERSION_LEN];
    let version = String::from_utf8_lossy(version_bytes).to_string();

    // Validate version format (should be like "1.0" to "2.0")
    if !is_valid_version(&version) {
        return Err(Error::UnsupportedVersion(version));
    }

    Ok(PdfFormat {
        version,
        linearized: false, // Would require parsing first indirect object for /Linearized key
    })
}

/// Check if a version string is valid.
fn is_valid_version(version: &str) -> bool {
    // Use chars().count() to count characters, not bytes.
    // version.len() counts bytes, which differs for multi-byte UTF-8 chars.
    let chars: Vec<char> = version.chars().collect();
    if chars.len() != 3 {
        return false;
    }

    chars[0].is_ascii_digit() && chars[1] == '.' && chars[2].is_ascii_digit()
}

/// Check if a file is a valid PDF.
///
/// # Arguments
/// * `path` - Path to the file
///
/// # Returns
/// * `true` if the file is a valid PDF
/// * `false` otherwise
pub fn is_pdf<P: AsRef<Path>>(path: P) -> bool {
    detect_format_from_path(path).is_ok()
}

/// Check if bytes represent a valid PDF.
///
/// # Arguments
/// * `data` - Byte slice to check
///
/// # Returns
/// * `true` if the data is a valid PDF header
/// * `false` otherwise
pub fn is_pdf_bytes(data: &[u8]) -> bool {
    detect_format_from_bytes(data).is_ok()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_detect_valid_pdf() {
        let data = b"%PDF-1.7\n%\xe2\xe3\xcf\xd3";
        let format = detect_format_from_bytes(data).unwrap();
        assert_eq!(format.version, "1.7");
    }

    #[test]
    fn test_detect_pdf_2_0() {
        let data = b"%PDF-2.0\n%\xe2\xe3\xcf\xd3";
        let format = detect_format_from_bytes(data).unwrap();
        assert_eq!(format.version, "2.0");
    }

    #[test]
    fn test_detect_invalid_format() {
        let data = b"<!DOCTYPE html>";
        let result = detect_format_from_bytes(data);
        assert!(matches!(result, Err(Error::UnknownFormat)));
    }

    #[test]
    fn test_detect_too_short() {
        let data = b"%PDF";
        let result = detect_format_from_bytes(data);
        assert!(matches!(result, Err(Error::UnknownFormat)));
    }

    #[test]
    fn test_is_pdf_bytes() {
        assert!(is_pdf_bytes(b"%PDF-1.4\n"));
        assert!(!is_pdf_bytes(b"Not a PDF"));
    }

    #[test]
    fn test_version_validation() {
        assert!(is_valid_version("1.0"));
        assert!(is_valid_version("1.7"));
        assert!(is_valid_version("2.0"));
        assert!(!is_valid_version("10.0"));
        assert!(!is_valid_version("abc"));
    }
}