fs-metadata

A filesystem representation, without the actual data.

The output of running fs-metadata . (after deleting the contents of node_modules/) looks like this:

{
  "name": ".",
  "type": "directory",
  "size": 476,
  "atime": 1452180519,
  "mtime": 1452180460,
  "ctime": 1452180460,
  "btime": 1452169219,
  "children": [
    {
      "name": "Makefile",
      "type": "file",
      "size": 197,
      "atime": 1452180519,
      "mtime": 1452169744,
      "ctime": 1452169744,
      "btime": 1452169709,
      "checksum": "91de0f6a8ae7606e2982efcfd2ec8dbd14abf4a7"
    },
    {
      "name": "README.md",
      "type": "file",
      "size": 125,
      "atime": 1452180519,
      "mtime": 1452180476,
      "ctime": 1452180476,
      "btime": 1439493444,
      "checksum": "bf1167ac8a71dc3a5f32443d711e997c0057ecf6"
    },
    {
      "name": "bin",
      "type": "directory",
      "size": 102,
      "atime": 1452180519,
      "mtime": 1452172424,
      "ctime": 1452172424,
      "btime": 1452172422,
      "children": [
        {
          "name": "fs-metadata",
          "type": "file",
          "size": 852,
          "atime": 1452180527,
          "mtime": 1452180391,
          "ctime": 1452180391,
          "btime": 1452172424,
          "checksum": "622be33e359b6e1ec4d213d6e3eeabc6adafc49b"
        }
      ]
    },
    {
      "name": "index.d.ts",
      "type": "file",
      "size": 1278,
      "atime": 1452180519,
      "mtime": 1452178736,
      "ctime": 1452178736,
      "btime": 1452169748,
      "checksum": "01edfb02bfacb1933c1d82ec3ce6afb8a8185740"
    },
    {
      "name": "index.js",
      "type": "file",
      "size": 3447,
      "atime": 1452180527,
      "mtime": 1452178736,
      "ctime": 1452178736,
      "btime": 1452169748,
      "checksum": "64acb0de678e599c29cd250c03b905f3bbc5b706"
    },
    {
      "name": "index.ts",
      "type": "file",
      "size": 4246,
      "atime": 1452180519,
      "mtime": 1452180254,
      "ctime": 1452180254,
      "btime": 1439563317,
      "checksum": "d616637460a7fbc4a1b9ea7880e53f2a453a56bd"
    },
    {
      "name": "node_modules",
      "type": "directory",
      "size": 340,
      "atime": 1452180519,
      "mtime": 1452175950,
      "ctime": 1452175950,
      "btime": 1452169510,
      "children": []
    },
    {
      "name": "package.json",
      "type": "file",
      "size": 621,
      "atime": 1452180519,
      "mtime": 1452171780,
      "ctime": 1452171780,
      "btime": 1432683185,
      "checksum": "513e768c831efac5d712baffa360312bc1b8fc74"
    },
    {
      "name": "tsconfig.json",
      "type": "file",
      "size": 208,
      "atime": 1452180519,
      "mtime": 1452172733,
      "ctime": 1452172733,
      "btime": 1448346772,
      "checksum": "56e09cc1671fd3c8a0271101fa1735e6c8fd80bb"
    }
  ]
}

Checksums

• Every file has a checksum generated from its content (the filename and any flags or extended attributes are ignored). This is a SHA-1 hash, and is equivalent to calling shasum at the command line.
  • Even empty files have a checksum, of course, namely, "da39a3ee5e6b4b0d3255bfef95601890afd80709".
• Every symlink has a checksum generated from its target. Again, it's a SHA-1 hash, equivalent to the output of readlink ur.lnk | tr -d '\n' | shasum.
• Every directory has a checksum generated from its children's names and checksums, using these steps:
  1. Lexicographically sort the children by name
  2. Append each child's checksum to its name, resulting in a single string for each child
  3. Join these strings with newlines, resulting in a single string for all the children
  4. Hash that resulting string with SHA-1
• Every other kind of file, like sockets and FIFOs, are given a checksum of "0000000000000000000000000000000000000000".

License

Copyright 2015 Christopher Brown. MIT Licensed.