timefs 0.1.0

Mount a Git repository as a read-only filesystem.
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
168

#[allow(dead_code)]
mod support;

use self::support::{with_mounted_timefs, RepositoryFixture};
use std::fs;
use std::os::unix::ffi::OsStringExt;
use std::thread;
use std::time::Duration;

#[test]
fn ref_snapshot_freezes_moving_references_and_history() {
    let live_fixture = release_fixture("timefs-task10-live");
    let (_value, live_mount) = with_mounted_timefs(live_fixture.path(), &[], &["-f"], |mounted| {
        assert_eq!(
            fs::read(mounted.path().join("now").join("README.md"))
                .expect("live now/README.md should be readable"),
            b"release v1\n"
        );

        advance_release_fixture(&live_fixture);
        thread::sleep(Duration::from_secs(2));

        assert_eq!(
            fs::read(mounted.path().join("now").join("fresh.txt"))
                .expect("live now/fresh.txt should appear after HEAD advances"),
            b"fresh from v2\n"
        );
        assert_eq!(
            fs::read(
                mounted
                    .path()
                    .join("refs")
                    .join("heads")
                    .join("main")
                    .join("fresh.txt"),
            )
            .expect("live refs/heads/main/fresh.txt should appear after HEAD advances"),
            b"fresh from v2\n"
        );
        assert_eq!(
            sorted_dir_entries(&mounted.path().join("history").join("README.md")).len(),
            2
        );
        assert_eq!(
            sorted_dir_entries(&mounted.path().join("history").join("fresh.txt")).len(),
            1
        );
    });
    assert!(
        live_mount.stderr.is_empty(),
        "live release mount emitted unexpected stderr: {}",
        live_mount.stderr
    );

    let snapshot_fixture = release_fixture("timefs-task10-snapshot");
    let before_head = snapshot_fixture.git_rev_parse("HEAD");
    let (_value, snapshot_mount) = with_mounted_timefs(
        snapshot_fixture.path(),
        &[],
        &["-f", "--ref-snapshot"],
        |mounted| {
            assert_eq!(
                fs::read(mounted.path().join("now").join("README.md"))
                    .expect("snapshotted now/README.md should be readable"),
                b"release v1\n"
            );

            advance_release_fixture(&snapshot_fixture);
            let after_head = snapshot_fixture.git_rev_parse("HEAD");
            thread::sleep(Duration::from_secs(2));

            assert_eq!(
                fs::read(mounted.path().join("now").join("README.md"))
                    .expect("snapshotted now/README.md should stay frozen"),
                b"release v1\n"
            );
            assert_eq!(
                fs::read(mounted.path().join("at").join("HEAD").join("README.md"),)
                    .expect("snapshotted at/HEAD/README.md should stay frozen"),
                b"release v1\n"
            );
            assert_eq!(
                fs::metadata(mounted.path().join("now").join("fresh.txt"))
                    .expect_err("snapshotted now/fresh.txt should stay absent")
                    .raw_os_error(),
                Some(libc::ENOENT)
            );
            assert_eq!(
                fs::metadata(
                    mounted
                        .path()
                        .join("refs")
                        .join("heads")
                        .join("main")
                        .join("fresh.txt"),
                )
                .expect_err("snapshotted refs/heads/main/fresh.txt should stay absent")
                .raw_os_error(),
                Some(libc::ENOENT)
            );
            assert_eq!(
                sorted_dir_entries(&mounted.path().join("history").join("README.md")).len(),
                1
            );
            assert_eq!(
                fs::metadata(mounted.path().join("history").join("fresh.txt"))
                    .expect_err("snapshotted history/fresh.txt should stay absent")
                    .raw_os_error(),
                Some(libc::ENOENT)
            );
            assert_eq!(
                fs::read(
                    mounted
                        .path()
                        .join("commits")
                        .join(before_head.as_str())
                        .join("README.md"),
                )
                .expect("commit-addressed snapshot should remain readable"),
                b"release v1\n"
            );
            assert_eq!(
                fs::read(
                    mounted
                        .path()
                        .join("commits")
                        .join(after_head.as_str())
                        .join("fresh.txt"),
                )
                .expect("commit-addressed fresh file should remain reachable by SHA"),
                b"fresh from v2\n"
            );
        },
    );
    assert!(
        snapshot_mount.stderr.is_empty(),
        "snapshot release mount emitted unexpected stderr: {}",
        snapshot_mount.stderr
    );
}

fn release_fixture(prefix: &str) -> RepositoryFixture {
    let fixture = RepositoryFixture::new(prefix);
    fs::write(fixture.path().join("README.md"), b"release v1\n")
        .expect("release fixture write should succeed");
    fixture.git(["add", "README.md"]);
    fixture.git(["commit", "-m", "Create release fixture"]);
    fixture
}

fn advance_release_fixture(fixture: &RepositoryFixture) {
    fs::write(fixture.path().join("README.md"), b"release v2\n")
        .expect("release fixture update should succeed");
    fs::write(fixture.path().join("fresh.txt"), b"fresh from v2\n")
        .expect("release fixture fresh file write should succeed");
    fixture.git(["add", "README.md", "fresh.txt"]);
    fixture.git(["commit", "-m", "Advance release fixture"]);
}

fn sorted_dir_entries(path: &std::path::Path) -> Vec<Vec<u8>> {
    let mut entries = fs::read_dir(path)
        .expect("directory should be readable")
        .filter_map(Result::ok)
        .map(|entry| entry.file_name().into_vec())
        .collect::<Vec<_>>();
    entries.sort();
    entries
}