Given a certain HDF5 file (HDF5 format), how can I know the version of the file format that has been used for its creation?
Context. It is said in the documentation that when you create/write a file the library the following applies for backward compatibility:
An HDF5 Library of any given release is designed to read all existing
HDF5 files from that or any prior release. Although major versions
sometimes contain features that require additions and/or changes to
the HDF5 file format, the library will by default write out files that
conform to a maximum compatibility principle. That is, files are
written with the earliest version of the file format that describes
the information, rather than always using the latest version possible.
This provides the best forward compatibility by allowing the maximum
number of older versions of the library to read new files.
I have tried tools like h5stat but it does not output the info that I want.
Thank you.
Here is an answer in the last question https://ftp.hdfgroup.org/hdf5-quest.html#h5dumpvers
Q: Can you add an option to h5dump or h5ls to print the version of a file ?
A: No, we do not plan on adding this option. Users should use attributes to specify the version of a file. There are many reasons why we shouldn't add this. For example, different objects in the file could be created or modified by different versions of the library.
Related
I would like to get the type of a file without using the extension, is there a way to use the metadata of a file to distinguish if it is a video file or if it isnt?
I have tried using extensions but I find searching each file extension and comparing it with a list of extensions is quite time consuming.
Yes it is possible to determine file type without using the file extension. You can do this by reading the file header also sometimes referred as file signature which occupies first few bytes of the file.
How many bytes do file header/signature occupy? This depends from file type to file type. So you should check the internet for more detailed information about the file header/signature for specific file type you want to identify.
You can find list of some more popular signatures List of file signatures - Wikipedia
PS: Most program stopped relying only on file signatures for determining file way back when first Windows came out. The main reason for this was the fact that since in the beginning file extensions were limited to three character length (limit of the old file systems like old FAT8 or FAT16) world quickly ran out of possible file extensions so multiple programs began to use same file extensions but used completely different file types. So by storing file header/signature at the beginning of the file you would no longer be limited by this file system limitation.
I created a data model file "ChatModel.xcdatamodeld" in my project. Then I merged branches on github. There're conflicts in "project.pbxproj". I fixed them. Then the error happened:
"/Users/mac/zhongqing-ios/Zhongqing/Zhongqing/Model/ChatModel.xcdatamodeld: Could not create bundle folder for versioned model at '/Users/mac/Library/Developer/Xcode/DerivedData/Zhongqing-chngcirectbawjenegkxtgdfgoux/Build/Products/Debug-iphonesimulator/Zhongqing.app/ChatModel.momd'".
"/Users/mac/zhongqing-ios/Zhongqing/ChatModel.xcdatamodeld: Unable to write VersionInfo.plist for versioned model at '/Users/mac/Library/Developer/Xcode/DerivedData/Zhongqing-chngcirectbawjenegkxtgdfgoux/Build/Products/Debug-iphonesimulator/Zhongqing.app/ChatModel.momd'".
Each time I have to delete the Derived Data so that the project can be run.
And then the error happen again.
Although some files are readable they should be treated like binary files. .pbxprojfiles are good example.
From pro-git
Some files look like text files but for all intents and purposes are to be treated as binary data. For instance, Xcode projects on the Mac contain a file that ends in .pbxproj, which is basically a JSON (plain text javascript data format) dataset written out to disk by the IDE that records your build settings and so on. Although it’s technically a text file, because it’s all ASCII, you don’t want to treat it as such because it’s really a lightweight database — you can’t merge the contents if two people changed it, and diffs generally aren’t helpful. The file is meant to be consumed by a machine. In essence, you want to treat it like a binary file.
I have a corrupted 7-zip archive that I am extracting manually using the method outlined by Igor Pavlov at this link. An intermediate result is a large file that is a bunch of files cat'ed together that must be separated manually. I understand that some file formats will need to be extracted manually by a human using discretion (text files, etc.) but many file formats encode the size of the file as part of the file itself (e.g. .zip). Furthermore, some files can be parsed and their size can be deduced with just a little information about the file format (e.g. .pdf). Let's say the large file consists of the following files concatenated together:
Key: <filename>(<contents>)
badfile(aaaaaaaaaaabbbbbbbbbcccccccdddddddd) -> zip1.zip(aaaaaaaaaaa)
badfile2(bbbbbbbbbcccccccdddddddd)
I am looking for a program that I can run on a large file (call it badfile) that can determine the type and size of the first logical file (let's say it's a .zip file) contained within and create a new file to hold the contents (e.g. zip1.zip since filenames are lost) and chop the file off the front of badfile. This would allow me to run the program in a loop to extract files with known types and/or pause and let the user handle the difficult cases. Does such a program exist? I know that the *nix command file(1) will do a lot of the work here, but there would be a lot of effort in encoding rules for sizing files (e.g. .pdf) that I would prefer to not duplicate.
I believe this question should be closed due to being off topic as it asks to find existing programs to solve the problem, but open bounty prevents close vote. However.
Does such a program exist?
Yes they exist is and are called data carving tools.
Some commom ones include scalpel and foremost and PhotoRec
A list of other tools is avaliable here
Is there a way to figure out what version of Xilinx was used to generate a bitfile just by looking in the bitfile? I've opened the bitfile in a hex editor, and only see the project name, date, and fpga model. See below.
Thanks!
Impossible, though this is not official: http://home.earthlink.net/~davesullins/software/bitinfo.html its README contains the following chunk.
Bitinfo is a simple utility that parses the header of a Xilinx bit file
and outputs all the information that can be obtained from that header.
This information includes the Xilinx FPGA the bit file was created for,
the NCD file the bit file was created from, the creation date and time,
and the bitstream length.
I guess you have to fallback on wildguess based on date/time. Good luck.
I have a huge text file in my application (version 1.0).
Lets assume that a new version (2.0) of this file was just released.
Most of the file remained the same but the new (2.0) version has a few modifications (some lines removed, others added).
I now wish to update the file (1.0) to the new version (2.0), but do not wish to download the whole file again.
I would love to just patch the file with the changes of the new file, thus saving bandwith from downloading the WHOLE new file from my server.
(Similar to the way versioning systems like git or svn act)
How can I do this programmatically? Are there any iOS libraries available?
Thank you
You need to implement some kind of Binary delta compression such as zdelta, or Remote Differential Compression such as the one in rsync.
Personally I'm not aware of such algorithm implemented specifically for iOS, but I'm sure it's possible to find one that is implemented in C/C++ which can be seamlessly used in the iOS environment.
Edit: I also recommend you to read this.
It's actually a big problem... if your API let you ask the data of a file in a specific range, you can just a ask the data range that you need to replace, and seek the file at the range and overwrite the specific data... this mean that you have to take trace about the changes every time you update the files... and your app update has to know the ranges to request... this is not a solution... I hope will be a start point to implement your own solution
to try to get partial conent in a range you need to add to your request header something like this:
Range: bytes=0-999
I think, you can do this by yourself without third party libraries. To achieve this, all you need is 1)Piece of code which will generate the metadata for joining versions of your file (offsets, lengths, and pointers to the data to be changed in older version); 2)piece of code which will do the hard work: read meta and put the parts on right places. Several days of struggling with offsets, and you are done ;) Good luck!