tar/
pax.rs

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1#![allow(dead_code)]
2use std::io;
3use std::io::Write;
4use std::slice;
5use std::str;
6
7use crate::other;
8
9// Keywords for PAX extended header records.
10pub const PAX_NONE: &str = ""; // Indicates that no PAX key is suitable
11pub const PAX_PATH: &str = "path";
12pub const PAX_LINKPATH: &str = "linkpath";
13pub const PAX_SIZE: &str = "size";
14pub const PAX_UID: &str = "uid";
15pub const PAX_GID: &str = "gid";
16pub const PAX_UNAME: &str = "uname";
17pub const PAX_GNAME: &str = "gname";
18pub const PAX_MTIME: &str = "mtime";
19pub const PAX_ATIME: &str = "atime";
20pub const PAX_CTIME: &str = "ctime"; // Removed from later revision of PAX spec, but was valid
21pub const PAX_CHARSET: &str = "charset"; // Currently unused
22pub const PAX_COMMENT: &str = "comment"; // Currently unused
23
24pub const PAX_SCHILYXATTR: &str = "SCHILY.xattr.";
25
26// Keywords for GNU sparse files in a PAX extended header.
27pub const PAX_GNUSPARSE: &str = "GNU.sparse.";
28pub const PAX_GNUSPARSENUMBLOCKS: &str = "GNU.sparse.numblocks";
29pub const PAX_GNUSPARSEOFFSET: &str = "GNU.sparse.offset";
30pub const PAX_GNUSPARSENUMBYTES: &str = "GNU.sparse.numbytes";
31pub const PAX_GNUSPARSEMAP: &str = "GNU.sparse.map";
32pub const PAX_GNUSPARSENAME: &str = "GNU.sparse.name";
33pub const PAX_GNUSPARSEMAJOR: &str = "GNU.sparse.major";
34pub const PAX_GNUSPARSEMINOR: &str = "GNU.sparse.minor";
35pub const PAX_GNUSPARSESIZE: &str = "GNU.sparse.size";
36pub const PAX_GNUSPARSEREALSIZE: &str = "GNU.sparse.realsize";
37
38/// An iterator over the pax extensions in an archive entry.
39///
40/// This iterator yields structures which can themselves be parsed into
41/// key/value pairs.
42pub struct PaxExtensions<'entry> {
43    data: slice::Split<'entry, u8, fn(&u8) -> bool>,
44}
45
46impl<'entry> PaxExtensions<'entry> {
47    /// Create new pax extensions iterator from the given entry data.
48    pub fn new(a: &'entry [u8]) -> Self {
49        fn is_newline(a: &u8) -> bool {
50            *a == b'\n'
51        }
52        PaxExtensions {
53            data: a.split(is_newline),
54        }
55    }
56}
57
58/// A key/value pair corresponding to a pax extension.
59pub struct PaxExtension<'entry> {
60    key: &'entry [u8],
61    value: &'entry [u8],
62}
63
64pub fn pax_extensions_value(a: &[u8], key: &str) -> Option<u64> {
65    for extension in PaxExtensions::new(a) {
66        let current_extension = match extension {
67            Ok(ext) => ext,
68            Err(_) => return None,
69        };
70        if current_extension.key() != Ok(key) {
71            continue;
72        }
73
74        let value = match current_extension.value() {
75            Ok(value) => value,
76            Err(_) => return None,
77        };
78        let result = match value.parse::<u64>() {
79            Ok(result) => result,
80            Err(_) => return None,
81        };
82        return Some(result);
83    }
84    None
85}
86
87impl<'entry> Iterator for PaxExtensions<'entry> {
88    type Item = io::Result<PaxExtension<'entry>>;
89
90    fn next(&mut self) -> Option<io::Result<PaxExtension<'entry>>> {
91        let line = match self.data.next() {
92            Some(line) if line.is_empty() => return None,
93            Some(line) => line,
94            None => return None,
95        };
96
97        Some(
98            line.iter()
99                .position(|b| *b == b' ')
100                .and_then(|i| {
101                    str::from_utf8(&line[..i])
102                        .ok()
103                        .and_then(|len| len.parse::<usize>().ok().map(|j| (i + 1, j)))
104                })
105                .and_then(|(kvstart, reported_len)| {
106                    if line.len() + 1 == reported_len {
107                        line[kvstart..]
108                            .iter()
109                            .position(|b| *b == b'=')
110                            .map(|equals| (kvstart, equals))
111                    } else {
112                        None
113                    }
114                })
115                .map(|(kvstart, equals)| PaxExtension {
116                    key: &line[kvstart..kvstart + equals],
117                    value: &line[kvstart + equals + 1..],
118                })
119                .ok_or_else(|| other("malformed pax extension")),
120        )
121    }
122}
123
124impl<'entry> PaxExtension<'entry> {
125    /// Returns the key for this key/value pair parsed as a string.
126    ///
127    /// May fail if the key isn't actually utf-8.
128    pub fn key(&self) -> Result<&'entry str, str::Utf8Error> {
129        str::from_utf8(self.key)
130    }
131
132    /// Returns the underlying raw bytes for the key of this key/value pair.
133    pub fn key_bytes(&self) -> &'entry [u8] {
134        self.key
135    }
136
137    /// Returns the value for this key/value pair parsed as a string.
138    ///
139    /// May fail if the value isn't actually utf-8.
140    pub fn value(&self) -> Result<&'entry str, str::Utf8Error> {
141        str::from_utf8(self.value)
142    }
143
144    /// Returns the underlying raw bytes for this value of this key/value pair.
145    pub fn value_bytes(&self) -> &'entry [u8] {
146        self.value
147    }
148}
149
150/// Extension trait for `Builder` to append PAX extended headers.
151impl<T: Write> crate::Builder<T> {
152    /// Append PAX extended headers to the archive.
153    ///
154    /// Takes in an iterator over the list of headers to add to convert it into a header set formatted.
155    ///
156    /// Returns io::Error if an error occurs, else it returns ()
157    pub fn append_pax_extensions<'key, 'value>(
158        &mut self,
159        headers: impl IntoIterator<Item = (&'key str, &'value [u8])>,
160    ) -> Result<(), io::Error> {
161        // Store the headers formatted before write
162        let mut data: Vec<u8> = Vec::new();
163
164        // For each key in headers, convert into a sized space and add it to data.
165        // This will then be written in the file
166        for (key, value) in headers {
167            let mut len_len = 1;
168            let mut max_len = 10;
169            let rest_len = 3 + key.len() + value.len();
170            while rest_len + len_len >= max_len {
171                len_len += 1;
172                max_len *= 10;
173            }
174            let len = rest_len + len_len;
175            write!(&mut data, "{} {}=", len, key)?;
176            data.extend_from_slice(value);
177            data.push(b'\n');
178        }
179
180        // Ignore the header append if it's empty.
181        if data.is_empty() {
182            return Ok(());
183        }
184
185        // Create a header of type XHeader, set the size to the length of the
186        // data, set the entry type to XHeader, and set the checksum
187        // then append the header and the data to the archive.
188        let mut header = crate::Header::new_ustar();
189        let data_as_bytes: &[u8] = &data;
190        header.set_size(data_as_bytes.len() as u64);
191        header.set_entry_type(crate::EntryType::XHeader);
192        header.set_cksum();
193        self.append(&header, data_as_bytes)
194    }
195}
tar/pax.rs

tar/
pax.rs
