I need a microcontroller to read a data file that's been stored in a Zip file (actually a custom OPC-based file format, but that's irrelevant). The data file has a known name, path, and size, and is guaranteed to be stored uncompressed. What is the simplest & fastest way to find the start of the file data within the Zip file without writing a complete Zip parser?
NOTE: I'm aware of the Zip comment section, but the data file in question is too big to fit in it.
I ended up writing a simple parser that finds the file data in question using the central directory.
Related
I'm looking for a tool that can extract files by searching aggressively through a ZIP archive. The compressed files are preceded with LFHs but no CDHs are present. Unzip outputs an empty folder.
I found one called 'binwalk' but even though it finds the hidden files inside ZIP archives it seems not to know how to extract them.
Thank You in advance.
You can try sunzip. It reads the zip file as a stream, and will extract files as it encounters the local headers and compressed data.
Use the -r option to retain the files decompressed in the event of an error. You will be left with a temporary directory starting with _z containing the extracted files, but with temporary, random names.
My question is: Is there a way to extract the flexray singals from Mf4 using dbc/arxml file and save to MDF format
Not until somebody releases a reliable parser for the Fibex and Arxml database formats for Flexray.
How can I store multiple files in one file using python?
I mean my own file format not a zip or a rar.
For e.g I want to create an archive from a folder but with my own file format. ( like 'Files.HR' )
Or just storing files in one file without any dictionary or file format. ( 'Files' No file format )
You may want to use "tar" files. In python, you can use the tarfile module to write files in the file and then later extract them back into real files.
You do not have to name the file *.tar. You can name it something else related to your specific application, such as naming it Files.HR.
Please see this nice tutorial or read the official docs to see how to use tarfile.
HI and thanks for any help. Is there a way to work with files larger than 10mg? I have to check for updates on items in a file that would be uploaded, but the file contains all items in the system and is approximately 20MG. This 10MG limit is killing me. I see streaming for file save and appending but not for file reading. So I am open to any suggestions. The provider in this instance doesn't offer the facility to chunk the files. thanks in advance for your help.
If you are using SS2 to process a file from the file cabinet then if you use file.lines.iterator() to process a file the size limit is 10MB per line.
I believe returning a file object from a map reduce script's getInputStage automatically parses the file into lines.
The 10MB file size limit comes into play if you try to create a file larger than 10MB.
If you are trying to read in a an external file via script then one approach that I've used is to proxy the call via an external service. e.g. query an AWS lambda function that checks for and saves the file to S3. Return the file path and size to your SuiteScript. The SuiteScript then asks for "pages" of the file that are less than 10MB and saves those. If you are uploading something like a .csv then the lambda function can send the header with each paged request.
While reading a ZIP file, can we safely assume that all file structures (by that I mean Local File Header + file data (compressed or stored) + Data Descriptor) are exactly consecutive? Can there be any irrelevant data in between?
PkWare Appnote tells that
"Immediately following the local header for a file is the compressed
or stored data for the file. The series of [local file header][file
data][data descriptor] repeats for each file in the .ZIP archive."
So there should be no gaps between them.
However, I would recommend to parse and read central directory, not go through local file headers (except that you need streamed processing).