ocibuilder/header.py at main · xl2002/ocibuilder · GitHub

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
import tarfile
import os
import struct
import gzip
def read_tar_metadata(tar_gz_path):
    with tarfile.open(tar_gz_path, "r:gz") as tar:
        print(f"\n📦 解析镜像层: {tar_gz_path}\n")

        for member in tar.getmembers():
            # 计算 tar 头部大小（POSIX 标准，每个文件 512 字节头）
            tar_header_size = 512

            # 获取文件路径、模式、大小、UID、GID、修改时间等
            print(f"📂 文件名: {member.name}")
            print(f"├── 类型: {'目录' if member.isdir() else '普通文件' if member.isfile() else '其他'}")
            print(f"├── 文件大小: {member.size} 字节")
            print(f"├── 头部大小: {tar_header_size} 字节")
            print(f"├── 权限: {oct(member.mode)}")
            print(f"├── 所有者 UID: {member.uid}")
            print(f"├── 所有者 GID: {member.gid}")
            print(f"├── 修改时间: {member.mtime}")
            print(f"└── 设备 (devmajor: {member.devmajor}, devminor: {member.devminor})")
            print("-" * 60)

def extract_tar_headers(tar_gz_path):
    headers = []
    with gzip.open(tar_gz_path, 'rb') as f:
        with tarfile.open(fileobj=f, mode='r|') as tar:
            for member in tar:
                headers.append({
                    'name': member.name,
                    'size': member.size,
                    'mtime': member.mtime,
                    'mode': member.mode,
                    'uid': member.uid,
                    'gid': member.gid,
                    'uname': member.uname,
                    'gname': member.gname,
                    'type': member.type,
                    'linkname': member.linkname,
                    'tarinfo': member
                })
    return headers

def compare_headers(file1, file2):
    h1 = extract_tar_headers(file1)
    h2 = extract_tar_headers(file2)

    print(f"\n📁 比较镜像层: \n  - 文件1: {file1}\n  - 文件2: {file2}")
    if len(h1) != len(h2):
        print(f"❌ 文件条目数量不同: {len(h1)} vs {len(h2)}")
    else:
        print(f"✅ 条目数量一致: {len(h1)}")

    for i, (entry1, entry2) in enumerate(zip(h1, h2)):
        print(f"\n🧾 比较文件 {i+1}: {entry1['name']}")
        for key in ['name', 'size', 'mtime', 'mode', 'uid', 'gid', 'uname', 'gname', 'type', 'linkname']:
            v1 = entry1.get(key)
            v2 = entry2.get(key)
            if v1 != v2:
                print(f"  ❗ 差异字段: {key}")
                print(f"    文件1: {v1}")
                print(f"    文件2: {v2}")

def read_gzip_header(filepath):
    with open(filepath, "rb") as f:
        header = f.read(16)

        # 提取基本的 gzip 文件头字段
        metadata = {
            "ID1": header[0],  # 0x1f
            "ID2": header[1],  # 0x8b
            "CompressionMethod": header[2],  # 0x08 (deflate)
            "Flags": header[3],  # 标志
            "MTIME": int.from_bytes(header[4:8], "little"),  # 时间戳
            "XFL": header[8],  # 压缩标志
            "OS": header[9],  # 操作系统类型
        }

        # 如果Flags的第0位设置为1，表示文件名和注释字段存在
        if metadata["Flags"] & 0x08:
            # 读取文件名
            file_name = b""
            while True:
                byte = f.read(1)
                if byte == b"\0":
                    break
                file_name += byte
            metadata["FileName"] = file_name.decode("utf-8", errors="ignore")

        # 如果Flags的第1位设置为1，表示注释字段存在
        if metadata["Flags"] & 0x04:
            # 读取注释
            comment = b""
            while True:
                byte = f.read(1)
                if byte == b"\0":
                    break
                comment += byte
            metadata["Comment"] = comment.decode("utf-8", errors="ignore")

        # 如果Flags的第2位设置为1，表示校验和存在
        if metadata["Flags"] & 0x02:
            # 读取校验和（2字节）
            f.read(2)  # 可以在这里读取并验证校验和，如果需要的话

        return metadata

def compare_gzip_headers(file1, file2):
    header1 = read_gzip_header(file1)
    header2 = read_gzip_header(file2)

    print(f"{'Field':<20} {'File 1':<10} {'File 2':<10} {'Match'}")
    print("-" * 50)
    for key in header1:
        value1 = header1[key]
        value2 = header2[key]
        match = "✔️" if value1 == value2 else "❌"
        print(f"{key:<20} {value1!s:<10} {value2!s:<10} {match}")

# 测试读取 OCI/Docker 镜像层 tar.gz
dirpath="./oci_images/oci_registry/blobs/sha256/"
tar_gz_file1 = "46e63dc23e391afc2f22255d63e73620b0c533616e43ffb7726626194068f981"  # 你的镜像层路径
tar_gz_file2 = "48481cb17f9a96b4a2a6d64d765fe2962e2acbd6461d48c7a98f426882f253c2"
# read_tar_metadata(os.path.join(dirpath, tar_gz_file1))
# compare_headers(os.path.join(dirpath, tar_gz_file1),os.path.join(dirpath, tar_gz_file2))
compare_gzip_headers(os.path.join(dirpath, tar_gz_file1),os.path.join(dirpath, tar_gz_file2))
# # 解压前查看头部
# gzip -cd 52714d37428a60069772b38d67b528a0caecd3fe48d6974ca6b2477be17eb9c4 | head -c 512 | hexdump -C > before1.hex
# gzip -cd 48481cb17f9a96b4a2a6d64d765fe2962e2acbd6461d48c7a98f426882f253c2 | head -c 512 | hexdump -C > before2.hex
# # 解压为 .tar
# gunzip -c 52714d37428a60069772b38d67b528a0caecd3fe48d6974ca6b2477be17eb9c4 > yourfile1.tar
# gunzip -c 48481cb17f9a96b4a2a6d64d765fe2962e2acbd6461d48c7a98f426882f253c2 > yourfile2.tar
# shasum -a 256 yourfile1.tar
# shasum -a 256 yourfile2.tar

# gzip -lv 52714d37428a60069772b38d67b528a0caecd3fe48d6974ca6b2477be17eb9c4
# gzip -lv 48481cb17f9a96b4a2a6d64d765fe2962e2acbd6461d48c7a98f426882f253c2
# gzip -c yourfile1.tar > yourfile1.tar.gz
# gzip -c yourfile2.tar > yourfile3.tar.gz
# # 解压后查看头部
# head -c 512 yourfile.tar | hexdump -C > after.hex

# # 对比
# diff before.hex after.hex
# diff before1.hex before2.hex