vhdx-rs 0.2.0

VHDX (Virtual Hard Disk v2) library
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
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

use super::helpers::*;
use super::prelude::*;
use crc32c::crc32c;
use std::io::{Read, Seek, SeekFrom};

// -----------------------------------------------------------------------
// Replay overlay tests
// -----------------------------------------------------------------------

#[test]
fn build_overlay_single_data_descriptor() {
    let guid = test_log_guid();
    let entry = build_log_entry(1, 0, &[(true, 0x1000, 0)], 0xAA, &guid);
    let buf = build_log_buffer(vec![entry]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();
    let overlay = build_replay_overlay(&active).unwrap();

    assert_eq!(overlay.last_file_offset(), 0x2_0000_0000);
    assert!(overlay.sectors().contains_key(&0x1000));
    assert_eq!(overlay.sectors()[&0x1000].len(), 4096);

    // Verify the assembled sector: LeadingBytes(8) + Data(4084) + TrailingBytes(4)
    let sector = &overlay.sectors()[&0x1000];
    // Leading bytes: 0x0102030405060708
    assert_eq!(&sector[0..8], &0x0102_0304_0506_0708u64.to_le_bytes());
    // Middle 4084 bytes: fill_byte 0xAA
    assert_eq!(sector[8], 0xAA);
    assert_eq!(sector[4091], 0xAA);
    // Trailing bytes: 0xDEADBEEF
    assert_eq!(&sector[4092..4096], &0xDEAD_BEEFu32.to_le_bytes());
}

#[test]
fn build_overlay_zero_descriptor() {
    let guid = test_log_guid();
    let entry = build_log_entry(
        1,
        0,
        &[(false, 0x5000, 0x2000)], // zero: offset 0x5000, length 0x2000
        0,
        &guid,
    );
    let buf = build_log_buffer(vec![entry]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();
    let overlay = build_replay_overlay(&active).unwrap();

    assert_eq!(overlay.zeros().len(), 1);
    assert_eq!(overlay.zeros()[0], (0x5000, 0x2000));
    assert!(overlay.sectors().is_empty());
}

#[test]
fn build_overlay_mixed_descriptors() {
    let guid = test_log_guid();
    let entry = build_log_entry(
        1,
        0,
        &[
            (true, 0x1000, 0),       // data at 0x1000
            (false, 0x5000, 0x2000), // zero at 0x5000, len 0x2000
            (true, 0x2000, 0),       // data at 0x2000
        ],
        0xCC,
        &guid,
    );
    let buf = build_log_buffer(vec![entry]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();
    let overlay = build_replay_overlay(&active).unwrap();

    assert_eq!(overlay.sectors().len(), 2);
    assert!(overlay.sectors().contains_key(&0x1000));
    assert!(overlay.sectors().contains_key(&0x2000));
    assert_eq!(overlay.zeros().len(), 1);
    assert_eq!(overlay.zeros()[0], (0x5000, 0x2000));
}

#[test]
fn active_sequence_entries_are_in_replay_order() {
    let guid = test_log_guid();
    let e1 = build_log_entry(1, 0, &[(true, 0x1000, 0)], 0xAA, &guid);
    let e2 = build_log_entry(2, 0, &[(true, 0x2000, 0)], 0xBB, &guid);
    let e3 = build_log_entry(3, 0, &[(true, 0x3000, 0)], 0xCC, &guid);
    let buf = build_log_buffer(vec![e1, e2, e3]);

    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();

    // Replay order must be tail→head (1, 2, 3)
    let seqs: Vec<u64> = active
        .entries()
        .iter()
        .map(|e| e.entry.header().sequence_number())
        .collect();
    assert_eq!(seqs, vec![1, 2, 3]);
}

#[test]
fn entry_with_no_descriptors_replays_ok() {
    let guid = test_log_guid();
    let entry = build_log_entry(1, 0, &[], 0, &guid);
    let buf = build_log_buffer(vec![entry]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();
    let overlay = build_replay_overlay(&active).unwrap();
    assert_eq!(overlay.sectors().len(), 0);
    assert_eq!(overlay.zeros().len(), 0);
}

// -----------------------------------------------------------------------
// replay_to_file tests (write to temp file)
// -----------------------------------------------------------------------

#[test]
fn replay_to_file_writes_data() {
    let guid = test_log_guid();
    let entry = build_log_entry(1, 0, &[(true, 0x1000, 0)], 0xAA, &guid);
    let buf = build_log_buffer(vec![entry]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();

    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("replay_test.vhdx");
    let mut file = std::fs::OpenOptions::new()
        .read(true)
        .write(true)
        .create(true)
        .truncate(true)
        .open(&path)
        .unwrap();

    // Pre-size to avoid set_len on non-extended regions
    file.set_len(0x2_0000_0000).unwrap();

    replay_to_file(&mut file, &active).unwrap();

    // Read back the written sector
    let mut read_buf = [0u8; 4096];
    let mut f = std::fs::File::open(&path).unwrap();
    f.seek(SeekFrom::Start(0x1000)).unwrap();
    f.read_exact(&mut read_buf).unwrap();

    // Verify assembled sector
    assert_eq!(&read_buf[0..8], &0x0102_0304_0506_0708u64.to_le_bytes());
    assert_eq!(read_buf[8], 0xAA);
}

#[test]
fn active_sequence_flushed_and_last_file_offsets() {
    let guid = test_log_guid();
    let entry = build_log_entry(1, 0, &[(true, 0x1000, 0)], 0xAA, &guid);
    let buf = build_log_buffer(vec![entry]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();

    assert_eq!(active.flushed_file_offset(), 0x1_0000_0000);
    assert_eq!(active.last_file_offset(), 0x2_0000_0000);
}

#[test]
fn candidate_with_higher_seq_always_wins() {
    let guid = test_log_guid();
    // Build three separate 1-entry sequences with different seq numbers
    let e5 = build_log_entry(5, 0, &[(true, 0x1000, 0)], 0xAA, &guid);
    let mut e10 = build_log_entry(10, 0, &[(true, 0x2000, 0)], 0xBB, &guid);
    let mut e100 = build_log_entry(100, 0, &[(true, 0x3000, 0)], 0xCC, &guid);

    // Fix tail offsets so each entry points to itself (self-tail)
    // e5 is at offset 0, tail=0 is already correct
    let e5_len = e5.len();
    let e10_offset = e5_len;
    let e100_offset = e5_len + e10.len();

    // Fix e10 tail to point to itself (zero CRC field before recomputing)
    e10[12..16].copy_from_slice(
        &u32::try_from(e10_offset)
            .expect("offset fits u32")
            .to_le_bytes(),
    );
    e10[4..8].copy_from_slice(&0u32.to_le_bytes());
    let e10_crc = crc32c(&e10);
    e10[4..8].copy_from_slice(&e10_crc.to_le_bytes());

    // Fix e100 tail to point to itself (zero CRC field before recomputing)
    e100[12..16].copy_from_slice(
        &u32::try_from(e100_offset)
            .expect("offset fits u32")
            .to_le_bytes(),
    );
    e100[4..8].copy_from_slice(&0u32.to_le_bytes());
    let e100_checksum = crc32c(&e100);
    e100[4..8].copy_from_slice(&e100_checksum.to_le_bytes());

    // Place them in buffer; each with self-tail pointing to its own offset
    let buf = build_log_buffer(vec![e5, e10, e100]);
    let log = Log::new(&buf).unwrap();
    let active = detect_active_sequence(&log, &guid).unwrap();

    // Should pick the 1-entry sequence with seq=100
    assert_eq!(active.len(), 1);
    assert_eq!(active.entries()[0].entry.header().sequence_number(), 100);
}