Cannot Reencode ASAR

[tscs37]

I've found that opening an ASAR file and attempting to reencode it directly leads to issues on the archive format.

When attempting to decode an ASAR generated with this library, I get the following error;

invalid character '\x00' looking for beginning of value

Electron doesn't want to open this file either and asar crashes with a stack error.

I suspect the header might be wrongly encoded.

[ghost]

Are you able to attach a minimal ASAR file with which you are experiencing this bug?

[tscs37]

Sadly not, the only ASAR I've been able to reproduce this on is a 13MB large file.

However, I have found that the error changes from invalid character '\x00' looking for beginning of value
to invalid character '\'' looking for beginning of value when switching from copying strings to copying byte slices, additionally, it seems that these characters appear after the header in the ASAR.

It looks like the header size is not correctly encoded by some offset.

[tscs37]

The header_size section is as follows:

0400 0000 884A 0700 844A 0700 805A 0700

The header starts at 0x000010 and ends at 0x074A80, making it 0x74A70 or 477808 bytes long

According to header_size however it should end at 00075A80, making it 0x75A70 or 481905 bytes long

That means the encoder is miscalculating the header_size values by 4097 bytes.

[yyq2013]

I have the same issue.
Finally change the code to work:
I copy it here and change some code
https://github.com/yyq2013/asar
Hope someone fix it.

[ghost]

@yyq2013 Do you have an ASAR file that I can test this with?

[yyq2013]

@bontibon
Please change the zip to asar:
test.zip
out.zip

The first file test.asar is genereate by nodejs command "asar pack ...."
The second file out.asar is generated by the go asar lib from test.asar
code:

f:=test.asar
archive ,err := asar.Decode(f)
if err != nil {
glog.Error(err)
return
}
out:=out.asar
archive.EncodeTo(out)

And then:
Use go asar lib to read the out.asar you will get the error
Maybe not the same error out there, but there are the same type error(header size or other error ocurrs it).