[HN Gopher] Making our own executable packer, part 13, Thread-lo...
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Making our own executable packer, part 13, Thread-local storage
Author : lukastyrychtr
Score : 35 points
Date : 2020-06-25 17:38 UTC (5 hours ago)
(HTM) web link (fasterthanli.me)
(TXT) w3m dump (fasterthanli.me)
| platz wrote:
| Would someone explain what the primary intent and current best-
| case usages of thread-local storage are?
|
| Is this more suited for certain languages than others?
| Someone wrote:
| https://en.wikipedia.org/wiki/Thread-local_storage mentions the
| two most common uses: _errno_ (historically a global variable,
| but on modern Unixes thread-local) and having separate threads
| accumulate a value, to only merge them at the end, thus
| decreasing contention for the merged value.
| platz wrote:
| > having separate threads accumulate a value, to only merge
| them at the end, thus decreasing contention for the merged
| value.
|
| That sounds like just having scoped state in each thread that
| isn't global.
| drudru11 wrote:
| Why is he making a packer?
| chrisseaton wrote:
| I don't understand what a 'packer' is - is it a linker?
| rustybolt wrote:
| From what I understand, it's something that 'packs' an
| application, either to preserve space or to obfuscate it
| (making it a little bit harder to reverse engineer it since
| you have to peek at the extracted contents in the memory
| instead of at the file contents).
|
| So when you would run a packed application, there application
| would essentially start to unpack an encrypted/compressed
| blob of memory, and then jump to it once it's unpacked.
| killercup wrote:
| > I don't understand what a 'packer' is
|
| You've found the right series of articles then!
| chrisseaton wrote:
| I read it - I did't find an explanation of what it was that
| he was building, just how he was building it.
| saagarjha wrote:
| Think of it of decompression software bundled along with
| a compressed version of the program you actually want to
| run. So execution starts in the uncompression part, it
| unzips all the code into memory, and then starts running
| the program you actually cared about.
| haecceity wrote:
| It compresses executables.
| scintill76 wrote:
| > amos loves to tinker
| killercup wrote:
| Start at part 1.
|
| No, he doesn't give you an answer, but you might just find it
| interesting enough to no longer have the qusstion.
| royjacobs wrote:
| The better question is, why not?
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