Judging by the lib_v1.0.2 library, access to the file system is implemented in Toit. May be can give some simple examples, which would include:
Create a file,
Writing data to file,
Reading data from a file,
Deleting a file,
Is there support for folders, and if so, what is the nesting level and how to get a list of files in the folder?
Update 2022-12-20: the host package's filesystem functionality (host.file and host.directory) is now supported for sdcards.
The filesystem libraries are not supported on ESP32 devices. They were implemented for host machines (like Linux), but that version isn't released.
The libraries will likely move soon and then not be accessible anymore.
If you want to store data on the device, maybe the device flashstore works for you:
import device
main:
store := device.FlashStore
store.set "key" "data"
Related
I am tying to scan usb msc in stm32 for audio files. This mp3 files are scattered in many folders which are unknown to the application.
First I scan for directories in the root folder and find folders then I scan folders for mp3 files.
This is very time consuming and for depth of 8 folders with many files in each folder.
Is there any Way to Scan for just for folders which have mp3 file in them using a better approach.
Directory structure for testing is something like this:
It is not clear what your problem might be since you have not provided any code to see how you are scanning, or quantative information on the file/folder structure ("many files" is rather vague), or even specified the media type used.
However a solution that might overcome all the variables of filesystem performance, hardware I/O, driver implementation and media type and make access more deterministic regardless, is to maintain a separate index file or database in a single file in the root directory to map each MP3 file to its path so you need only search the index/database for the MP3 you need (or use it to directly list all MP3's without scanning the file system).
If you maintain that file sorted (or a separate index file that is sorted) then you can use a binary search to find a specific file. Or simply use a real database - though that might be a rather heavyweight solution for this purpose. You might even load the metadata into memory for even faster access, and write it to the filesystem only if it changes.
Either way, the solution I suggest is to isolate your application from the variability of the filesystem/media, and the lack of scalability of FAT in general by maintaining your own "metadata" file(s) indicating what is stored and where so that you can use that to access the files directly without file system scanning using findfirst/findnext semantics, and recursion which is always best avoided, but is the obvious way to scan a directory tree.
Incidentally this is precisely how iTunes works for example. The "iTunes Library.xml" contains meta-data about "songs" including their location. Clearly you need not have anything quite that detailed, but the principle is the same and there may be merit in using XML or JSON for your application given a suitable library for updating and accessing such a file.
By doing that, the performance is more directly within your control rather than dependent on the filesystem, media and/or device driver level. However you still have some control/responsibility over the media and its interface (SPI, SDIO, USB or whatever), and the device I/O layer (DMA, interrupts, polled, bit-banged), and while you may have little control over the choice of FAT and the ELM FatFs implementation, you can certainly impact its performance greatly at the device driver, hardware interface and physical media level.
At some point in my C program I have to deal with something like this.
FILE * fptr = fopen("/Parent/child/.../file.dat");
Which means in order to access any file I need to know it's location. That's all understandable.
But, how can I make this generic? In my computer "/Parent/child/.../file.dat" will work because that's where the file is stored, but I'm making a software to distribute to other users so the path obviously differs. My question is, how can I install a specific file into the user's computer such that I can know and get the location of that file. I a but confused about this concept so any resources that could help me understand it better would be greatly appreciated.
In Linux the default path to application files should be hardcoded. There is a standard which applications should follow. For example, architecture-independent files should go to /usr/share/ and then either your application name or, if you expect the data to be shared between applications, a generic category such as images. User-specific configuration files should go $HOME/.config/<app-name>. Older applications place their default configuration in $HOME/.<app-name> instead.
You should also provide an ability to override the default path to the data with a command line switch and/or an environment variable and/or a user configuration file (the location of the latter should also be overridable with a command line switch and/or an environment variable).
Some applications search for their data directory relatively to the executable position. An executable can know its own absolute path by reading /proc/self/exe symbolic link. For example, if an executable finds itself in /usr/local/bin/somename, it can look for /usr/local/share/<app-name> (two levels up from the executable name and down to share/<app-name>.).
Finally, if you distribute source code for the users to build, the file locations should be configuration parameters.
In a course I am enrolled in, I was tasked to create a filesystem with some custom features. I simply created an image of zeroes using dd, and created my filesystem by creating superblock, inodes, stat files, etc. for it. It can read/write files, import and export files and directories, with proper directory hierarchy.
Now I want to make this work with an actual physical partition. I looked at many places, and saw that file descriptors can be read as plain files. But I want to know if it relies on existing filesystem in the partition. Can I bypass everything and simply get a block-wise read/write interface, and with ability to seek to bytes or blocks? What would be the overhead on that?
Also, I want to turn it into a linux module so that my filesystem can work with file managers. What is the standard API interface that I need to implement to make it happen?
Please guide me to the right direction.
You have a lot of options; integration into the kernel is relatively hard, whereas integrating with a user space file system framework (libfuse on github) is a good intermediate step. At the end, you will have a usable file system.
I am confused a bit about .bin files. Basically in Linux we use elf, .ko type of files for upgrading the box or to copy in it . But, while upgrading a NAND flash in router or any Networking Gaint products why always .bin files is preferred. Is this is something like converged mix of all the OS related files. Does it possible to see the contents of a bin file. How to play with it. It is something like contents of BootROM. How is is prepared? How do we create and test on this. How Linux support for this. Any historical reasons behind this?
Speaking about routers, those files are usually just snapshots of a router's flash memory, probably compressed and with some headers added. Typical things are a compressed squashfs image or simply gzip'ed snapshot of memory.
There is no such thing as .bin format, it's just a custom array of bytes and every vendor interprets it in some vendor-specific way. Basically this extension means “it's not your business what's in the file, our device/software will handle it”. You can try to identify (thnk, reverse-engineer) what's actually in those files by using file utility or just looking at those files through a hex editor and trying to guess what's going on.
I want to essentially make it so that you never need to unzip/unrar any files. Currently, I have a Dokan filesystem which can do it given a specific zip file but I wanted to know how I can make it apply to all files. Meaning, I want to be able to compile a program that has "fopen("test.zip/1.jpg", "rb");". I think that a Shell Extension would work for dynamically loading the file into the filesystem IF I were browsing in the shell explorer but that doesnt help me with the fopen example. Any ideas?
What you want to do can be used with help of file system filter driver, which would track directory enumeration requests and report directories in place of ZIP files. Then this driver would create virtual files and take the data from ZIP archives. Quite a lot of kernel-mode work, I should say. And file system filter driver is not a file system driver, so dokan won't help you at all.