`

#### Excluding multiple resources from being packed

Given:
`
app
(a) ├── x1
(b) ├── x2
(c) ├── y3
(d) │   ├── x1
(e) │   └── z1
(f) │   └── x2
(g) └── z4
(h) └── w1
`

Exclude: a, b
`bash
$ asar pack app app.asar --unpack-dir "{x1,x2}"
`

Exclude: a, b, d, f
`bash
$ asar pack app app.asar --unpack-dir "**/{x1,x2}"
`

Exclude: a, b, d, f, h
`bash
$ asar pack app app.asar --unpack-dir "{/x1,/x2,z4/w1}"
`

Using programmatically

$3

`javascript
import { createPackage } from '@electron/asar';

const src = 'some/path/';
const dest = 'name.asar';

await createPackage(src, dest);
console.log('done.');
`

Please note that there is currently no error handling provided!

$3

`javascript
import { createPackageWithOptions } from '@electron/asar';

const src = 'some/path/';
const dest = 'name.asar';

function transform (filename) {
return new CustomTransformStream()
}

await createPackageWithOptions(src, dest, { transform: transform });
console.log('done.');
`

Format

Asar uses [Pickle][pickle] to safely serialize binary value to file.

The format of asar is very flat:

`
| UInt32: header_size | String: header | Bytes: file1 | ... | Bytes: file42 |
`

The header_size and header are serialized with [Pickle][pickle] class, and
header_size's [Pickle][pickle] object is 8 bytes.

The header is a JSON string, and the header_size is the size of header's
Pickle object.

Structure of header is something like this:

`json
{
"files": {
"tmp": {
"files": {}
},
"usr" : {
"files": {
"bin": {
"files": {
"ls": {
"offset": "0",
"size": 100,
"executable": true,
"integrity": {
"algorithm": "SHA256",
"hash": "...",
"blockSize": 1024,
"blocks": ["...", "..."]
}
},
"cd": {
"offset": "100",
"size": 100,
"executable": true,
"integrity": {
"algorithm": "SHA256",
"hash": "...",
"blockSize": 1024,
"blocks": ["...", "..."]
}
}
}
}
}
},
"etc": {
"files": {
"hosts": {
"offset": "200",
"size": 32,
"integrity": {
"algorithm": "SHA256",
"hash": "...",
"blockSize": 1024,
"blocks": ["...", "..."]
}
}
}
}
}
}
`

offset and size records the information to read the file from archive, the
offset starts from 0 so you have to manually add the size of header_size and
header to the offset to get the real offset of the file.

offset is a UINT64 number represented in string, because there is no way to
precisely represent UINT64 in JavaScript Number. size is a JavaScript
Number that is no larger than Number.MAX_SAFE_INTEGER, which has a value of
9007199254740991 and is about 8PB in size. We didn't store size in UINT64
because file size in Node.js is represented as Number and it is not safe to
convert Number to UINT64.

integrity is an object consisting of a few keys:
* A hashing algorithm, currently only SHA256 is supported.
* A hex encoded hash value representing the hash of the entire file.
* An array of hex encoded hashes for the blocks of the file. i.e. for a blockSize of 4KB this array contains the hash of every block if you split the file into N 4KB blocks.
* A integer value blockSize representing the size in bytes of each block in the blocks` hashes above

[pickle]: https://chromium.googlesource.com/chromium/src/+/main/base/pickle.h