summaryrefslogtreecommitdiff
path: root/src/fsentry.rs
blob: 90afd702f39cc7fd3af7b5bddf6aec792ed71022 (plain)
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
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
//! An entry in the file system.

use log::{debug, error};
use serde::{Deserialize, Serialize};
use std::ffi::OsString;
use std::fs::read_link;
use std::fs::{FileType, Metadata};
use std::os::unix::ffi::OsStringExt;
use std::os::unix::fs::FileTypeExt;
use std::path::{Path, PathBuf};
use users::{Groups, Users, UsersCache};

#[cfg(target_os = "linux")]
use std::os::linux::fs::MetadataExt;

#[cfg(target_os = "macos")]
use std::os::macos::fs::MetadataExt;

/// A file system entry.
///
/// Represent all backup-relevant the metadata about a file system
/// object: fully qualified pathname, type, length (if applicable),
/// etc. Everything except the content of a regular file or the
/// contents of a directory.
///
/// This is everything Obnam cares about each file system object, when
/// making a backup.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FilesystemEntry {
    kind: FilesystemKind,
    path: Vec<u8>,
    len: u64,

    // 16 bits should be enough for a Unix mode_t.
    // https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html
    //  However, it's 32 bits on Linux, so that's what we store.
    mode: u32,

    // Linux can store file system time stamps in nanosecond
    // resolution. We store them as two 64-bit integers.
    mtime: i64,
    mtime_ns: i64,
    atime: i64,
    atime_ns: i64,

    // The target of a symbolic link, if any.
    symlink_target: Option<PathBuf>,

    // User and group owning the file. We store them as both the
    // numeric id and the textual name corresponding to the numeric id
    // at the time of the backup.
    uid: u32,
    gid: u32,
    user: String,
    group: String,
}

/// Possible errors related to file system entries.
#[derive(Debug, thiserror::Error)]
pub enum FsEntryError {
    /// File kind numeric representation is unknown.
    #[error("Unknown file kind {0}")]
    UnknownFileKindCode(u8),

    /// Failed to read a symbolic link's target.
    #[error("failed to read symbolic link target {0}: {1}")]
    ReadLink(PathBuf, std::io::Error),
}

#[allow(clippy::len_without_is_empty)]
impl FilesystemEntry {
    /// Create an `FsEntry` from a file's metadata.
    pub fn from_metadata(
        path: &Path,
        meta: &Metadata,
        cache: &mut UsersCache,
    ) -> Result<Self, FsEntryError> {
        let kind = FilesystemKind::from_file_type(meta.file_type());
        let symlink_target = if kind == FilesystemKind::Symlink {
            debug!("reading symlink target for {:?}", path);
            let target =
                read_link(path).map_err(|err| FsEntryError::ReadLink(path.to_path_buf(), err))?;
            Some(target)
        } else {
            None
        };

        let uid = meta.st_uid();
        let gid = meta.st_gid();
        let user: String = if let Some(user) = cache.get_user_by_uid(uid) {
            user.name().to_string_lossy().to_string()
        } else {
            "".to_string()
        };
        let group = if let Some(group) = cache.get_group_by_gid(gid) {
            group.name().to_string_lossy().to_string()
        } else {
            "".to_string()
        };

        Ok(Self {
            path: path.to_path_buf().into_os_string().into_vec(),
            kind: FilesystemKind::from_file_type(meta.file_type()),
            len: meta.len(),
            mode: meta.st_mode(),
            mtime: meta.st_mtime(),
            mtime_ns: meta.st_mtime_nsec(),
            atime: meta.st_atime(),
            atime_ns: meta.st_atime_nsec(),
            symlink_target,
            uid,
            gid,
            user,
            group,
        })
    }

    /// Return the kind of file the entry refers to.
    pub fn kind(&self) -> FilesystemKind {
        self.kind
    }

    /// Return full path to the entry.
    pub fn pathbuf(&self) -> PathBuf {
        let path = self.path.clone();
        PathBuf::from(OsString::from_vec(path))
    }

    /// Return number of bytes for the entity represented by the entry.
    pub fn len(&self) -> u64 {
        self.len
    }

    /// Return the entry's mode bits.
    pub fn mode(&self) -> u32 {
        self.mode
    }

    /// Return the entry's access time, whole seconds.
    pub fn atime(&self) -> i64 {
        self.atime
    }

    /// Return the entry's access time, nanoseconds since the last full second.
    pub fn atime_ns(&self) -> i64 {
        self.atime_ns
    }

    /// Return the entry's modification time, whole seconds.
    pub fn mtime(&self) -> i64 {
        self.mtime
    }

    /// Return the entry's modification time, nanoseconds since the last full second.
    pub fn mtime_ns(&self) -> i64 {
        self.mtime_ns
    }

    /// Does the entry represent a directory?
    pub fn is_dir(&self) -> bool {
        self.kind() == FilesystemKind::Directory
    }

    /// Return target of the symlink the entry represents.
    pub fn symlink_target(&self) -> Option<PathBuf> {
        self.symlink_target.clone()
    }
}

/// Different types of file system entries.
#[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize)]
pub enum FilesystemKind {
    /// Regular file, including a hard link to one.
    Regular,
    /// A directory.
    Directory,
    /// A symbolic link.
    Symlink,
    /// A UNIX domain socket.
    Socket,
    /// A UNIX named pipe.
    Fifo,
}

impl FilesystemKind {
    /// Create a kind from a file type.
    pub fn from_file_type(file_type: FileType) -> Self {
        if file_type.is_file() {
            FilesystemKind::Regular
        } else if file_type.is_dir() {
            FilesystemKind::Directory
        } else if file_type.is_symlink() {
            FilesystemKind::Symlink
        } else if file_type.is_socket() {
            FilesystemKind::Socket
        } else if file_type.is_fifo() {
            FilesystemKind::Fifo
        } else {
            panic!("unknown file type {:?}", file_type);
        }
    }

    /// Represent a kind as a numeric code.
    pub fn as_code(&self) -> u8 {
        match self {
            FilesystemKind::Regular => 0,
            FilesystemKind::Directory => 1,
            FilesystemKind::Symlink => 2,
            FilesystemKind::Socket => 3,
            FilesystemKind::Fifo => 4,
        }
    }

    /// Create a kind from a numeric code.
    pub fn from_code(code: u8) -> Result<Self, FsEntryError> {
        match code {
            0 => Ok(FilesystemKind::Regular),
            1 => Ok(FilesystemKind::Directory),
            2 => Ok(FilesystemKind::Symlink),
            3 => Ok(FilesystemKind::Socket),
            4 => Ok(FilesystemKind::Fifo),
            _ => Err(FsEntryError::UnknownFileKindCode(code)),
        }
    }
}

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

    #[test]
    fn file_kind_regular_round_trips() {
        one_file_kind_round_trip(FilesystemKind::Regular);
        one_file_kind_round_trip(FilesystemKind::Directory);
        one_file_kind_round_trip(FilesystemKind::Symlink);
        one_file_kind_round_trip(FilesystemKind::Socket);
        one_file_kind_round_trip(FilesystemKind::Fifo);
    }

    fn one_file_kind_round_trip(kind: FilesystemKind) {
        assert_eq!(kind, FilesystemKind::from_code(kind.as_code()).unwrap());
    }
}