How can we read executable files in memory and then manipulate them , does NSFileHandle can works with executable files and how so ?!
Thank you.
Sure, NSFileHandle can manipulate anything you can read and write with a file descriptor. It just gives you raw access to the data in the file though, so to work with executables you would need to implement things like a Mach-O parser if you want to actually do anything that requires you to do anything that requires semantic understanding of the file,
On the other hand, if you just want to do something like checksum the file you don't need much more infrastructure than NSFileHandle.
Related
Alright, here's what I'm dealing with (you can skip to TLDR if all you need to see is what I want to run):
I'm having an issue with file formatting for a nasty conglomeration of several ancient programs I've strung together. I have some data in .CSV format, and I need to put it into .SPC format. I've tried a set of proprietary MATLAB programs called 'GS tools' for fast and easy conversion, but fast and easy doesn't look like its gonna happen here since there are discrepancies in how .spc files are organized now and how they were organized back when my ancient programs were written.
If I could find the source code for the old programs I could probably alter the GS tools code to write my .spc files appropriately, but all I can find are broken links circa 2002 and earlier. Seeing as I don't know what my programs are looking for, I have no choice but to try resaving my data with other programs until one of them produces something workable.
I found my Cinderella program: if I open the data I have in a program called Spekwin and save the file with a .spc extension... viola! Everything else runs on those files. The problem is that I have hundreds of these files and I'd like to automate the conversion process.
I either need to extract the writing rubric Spekwin uses for .spc files (I believe that info is stored in a dll file within the program, but I'm not sure if that actually makes sense) and use it as a rule to write a file from my input data, or I need a piece of code that will open a file with Spekwin, tell Spekwin to save that file under the .spc extension, and terminate Spekwin.
TLDR: Need a command that tells the computer to open a file with a certain program, save that file under a different extension through that program (essentially open*.csv>save as>*.spc), then terminate the program.
OR--I need a way to tell MATLAB to write a file according to rules specified by a .dll, but I'm not sure I fully understand what that entails.
Of course I'm open to suggestions on other ways to handle this.
I need to replace a file on a zip using iOS. I tried many libraries with no results. The only one that kind of did the trick was zipzap (https://github.com/pixelglow/zipzap) but this one is no good for me, because what really do is re-zip the file again with the change and besides of this process be to slow for me, also do something that loads the whole file on memory and make my application crash.
PS: If this is not possible or way to complicated, I can settle for rename or delete an specific file.
You need to find a framework where you can modify how data is read and written. You would then use some form of mmap to essentially read and write small chunks. Searching on NSData and mmap resulted in this Post, however you can use mmap from the posix level too. Ps it will be slower than using pure memory no way around that.
Got it WORKING!! JXZip (https://github.com/JanX2/JXZip) has made exactly what I need, they link to libzip (http://www.nih.at/libzip/) that is a fully equiped library for working with ZIP files and JXZip have all the necessary Objective-C wrapper code. Thanks for all the replys.
For archive purposes, as the author of zipzap:
Actually zipzap does exactly what you want. If you replace an entry within a zip file, zipzap will do the minimum necessary to update it: it will skip writing all entries before the replaced entry, then write out the entry, then write out all entries after the replaced entry without recompressing. At the moment, it does require sufficient memory for the entries after the replaced entry though.
I have several files in a GridFS Document Store and what I'd like to do is to pipe this data into a zip file via stdin in NodeJS. So that I will end up with a zip file containing all these files.
Now my question is how can I give the files a valid filename inside of the zip file. I think I need to emulate/fake a file header containing the filename?
Any help is appreciated!
Thanks
I had problems when writing zip files with Node.js not long ago. I ended up doing something similar to what is described in Zip archives in node.js
I can't help you directly with your problem, but at least I hope I can point out some things:
Don't try to use node-archive. Even if the description says it allows to create zip files, the moment I read the source code (since documentation is unexistant) I realized that's just a lie. It only exposes methods for reading.
Using zip by spawning a process, like recommended on the provided link, seems to be the best way. Something that would work is copying the files to a local folder with whatever name you desire and then calling the zip command, just to delete the files afterwards.
The other option, which seems ok, is to use zipper (https://github.com/rubenv/zipper, although better just use npm). The reason I'm not really wishing to use it is because there's not that much flexibility, it seems to have been done in a day and it hasn't been modified since the first commit, so I'm not sure it will receive maintenance (sure, you could just fork it...).
I swear the day I have an entire free weekend with no work I will write a freaking module that does this as complete as possible. It's silly that there isn't and it shouldn't be that much struggle. blablablarant.
Edit:
Not sure if it was there before, but now I've been using the node-compress module (also using gzippo). It works fine.
I'm trying to write a 3D OBJ file parser for the iPhone/iPad and am trying to figure out the absolute fastest method to do this. I'm not super familiar with c++ but have a few ideas. Some of the ideas I had on how to approach this were to read the whole file into a string then parse from there. Another idea was to read the file line by line and put it into vectors, but that sounds like it might be slower. I know there are a lot of tricks to make c++ extremely fast. Anyone want to take a stab at this? After I parse the file, I'm going to re-save it as a binary file for fast loading on subsequent startups. Thanks.
Check this source: http://code.google.com/p/iphonewavefrontloader/
It works pretty fast, so you can learn how it is implemented.
I've found a couple of libs (LiteZip and ZipArchive) that allow to unzip files on iPhone. But both of them require an input as a file. Is there a library that allows to directly unzip NSData containing zip-archived data without writing it to temporary file?
I've tried to adopt mentioned above libs for that, but with no success so far.
In this answer to this question, I point out the CocoaDev wiki category on NSData which adds zip / unzip support to that class. This would let you do this entirely in memory.
From what I understand, the zip format stores files separately and each stored file is compressed using a compression algorithm (generally it's the DEFLATE algorithm).
If you're only interested in uncompressing data that was compressed using the DEFLATE algorithm you could use this zlib addition to NSData from Google Toolbox For Mac
It doesn't need temporary files.