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Works on modern browsers again, updated readme to reflect this.

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Anselm Levskaya 2014-10-19 15:49:33 -07:00
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@ -3,37 +3,39 @@ De-obfuscated JSLinux
I wanted to understand how the amazing [JsLinux][1] worked. I wanted to understand how the amazing [JsLinux][1] worked.
However the original was passed through a minifier and was completely incomprehensible in that form. (Mr Bellard's standards for the code that he open sources is very high.) I couldn't wait for the proper release of the opus, so in a fit of mania I hand de-obfuscated the codebase (primarily the core cpu-emulation However the original was passed through a minifier and was completely incomprehensible in that form. (Mr Bellard's standards for the code that he open sources is very high.) I couldn't wait for the proper release of the opus, so in a fit of mania I hand de-obfuscated the codebase (primarily the core cpu-emulation routines and a bit of the rest as well) while studying it over a few days' time.
routines and a bit of the rest as well) while studying it over a few days' time.
In the off-chance someone else might be interested in this code as a In the off-chance someone else might be interested in this code as a basis for further weird in-browser x86 hacking I'm posting this
basis for further weird in-browser x86 hacking I'm posting this
redacted version of the code here, with permission of Mr. Bellard. redacted version of the code here, with permission of Mr. Bellard.
Note that there is a much more readable, ground-up project to build an open-source 386-style emulator in javascript called [jslm32][3]. Note that there is another ground-up project to build an open-source 386-style emulator in javascript called [jslm32][3].
I also recommend looking at the remarkable linux on [jor1k][5] emulator project.
### Status ### Status
The current codebase won't run on recent webkit browsers due to a breaking change in the way Synchronous [XHR][4] requests are handled. The binary loading routines need to be rewritten to be asynchronous, not terribly hard but annoying enough that I haven't just done it. (Fabrice's original online version has been patched and runs fine.) The current codebase should run on most modern versions of Chrome, Safari, and Firefox. If you're running it locally, you will need to load it via a local server to allow the XHR requests to load the binaries.
jslinux-deobfuscated is still a dense code base, it's an emulator of a rather jslinux-deobfuscated is still a dense, messy code base from any pedagogic point of view. However for those interested in Mr. Bellard's code,
complicated architecture, after all. However this version is nowhere this version is nowhere near so incomprehensible as the original. Nearly all of the global variables and function names have been named
near so incomprehensible as the original. Nearly all of the global variables somewhat sensibly. Many pointers to references have been added to the source.
and function names have been named somewhat sensibly. Many comments
have been added.
The core opcode execution loop has been autocommented to indicate what The core opcode execution loop has been commented to indicate what instruction the opcode refers to.
instruction operation the opcode refers to.
### Unresolved
One mystery is, why does CPUID(1) return 8 << 8 in EBX? EBX[15:8] is now used to indicate CLFLUSH line size, but that field must have been used for something else in the past. One mystery is, why does CPUID(1) return 8 << 8 in EBX? EBX[15:8] is now used to indicate CLFLUSH line size, but that field must have been used for something else in the past.
The CALL/RET/INT/IRET routines are still quite confused and haven't yet been rewritten. The code dealing with segmentation, and some of the code for real-mode remains relatively messy.
Any recommendations / clarifications are welcome!
### ETC ### ETC
I highly recommend, by the way, the excellent [JSShaper][2] library for transforming large javascript code bases. The hacks I made from it are in this repo: a little symbol-name-transformer node.js script and an emacs function for doing this in live buffers. I highly recommend, by the way, the excellent [JSShaper][2] library for transforming large javascript code bases. The hacks I made from it are in this repo: a little symbol-name-transformer node.js script and an emacs function for doing this in live buffers.
### License ### License
This is a pedagogical/aesthetic derivative of the original JSLinux code Copyright (c) 2011-2013 Fabrice Bellard. It is posted here with permission of the original author subject to his original constraints : Redistribution or commercial use is prohibited without the (original) author's permission. This is a pedagogical/aesthetic derivative of the original JSLinux code Copyright (c) 2011-2014 Fabrice Bellard. It is posted here with permission of the original author subject to his original constraints : Redistribution or commercial use is prohibited without the (original) author's permission.
### References ### References
Some other helpful references for understanding what's going on: Some other helpful references for understanding what's going on:
@ -59,3 +61,4 @@ Some other helpful references for understanding what's going on:
[2]: http://jsshaper.org [2]: http://jsshaper.org
[3]: https://github.com/ubercomp/jslm32 [3]: https://github.com/ubercomp/jslm32
[4]: https://bugs.webkit.org/show_bug.cgi?id=72154 [4]: https://bugs.webkit.org/show_bug.cgi?id=72154
[5]: https://github.com/s-macke/jor1k