Example of Boron write and read to memory using Filesystem

Tutorials
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Does anyone have working code for reading and writing to the Boron memory with the Filesystem. There are a few posts where comments indicate why the posted code doesn’t work (e.g. Unable to write then read successfully using Filesystem ) but I can not find any working code. Brief, working code for writing and reading would be a great help.

thanks, john

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@colemanjj did you review the Filesystem docs?

https://docs.particle.io/reference/device-os/api/file-system/

Also, @rickkas7 has a File Helper library you might find useful:

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Thanks for the suggestion. I studied that earlier today and understood it very little.

I’m good at muddling through working code and disassembling it into parts if I can see the output. But lonely code snippets or functions that I can’t test without a code framework I find very difficult to understand what they are up to.

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Also the file system API is POSIX based. The functions like open, read, write, close work basically the same as their counterparts on Unix-based operating systems.

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I developed working code based almost entirely on kelt’s post Unable to write then read successfully using Filesystem . I made some tweeks based on other posts and some suggestions from AI. I commented the code to the extent that I could. This compiles and runs on a Boron, OS 6.1.1. I hope it is useful as a very simplistic start to using the filesystem.

STARTUP(System.enableFeature(FEATURE_RETAINED_MEMORY)); // I'm not sure
STARTUP(System.enableFeature(FEATURE_RESET_INFO)); // these 4 lines are 
SYSTEM_THREAD(ENABLED);   // needed since I think they are the defaults
SYSTEM_MODE(SEMI_AUTOMATIC);   // these days
#include <fcntl.h>
#include <string>
#include <dirent.h>

SerialLogHandler logHandler;
#define buffSize 80     // defined this so that I could easily change the buffer size
void read_data_file()
{
  struct stat statbuf;   // the original code had "struct stat* statbuf" which didn't work
  int sd = stat("/data1.txt", &statbuf);  // I think this gets the return code from doing the commant stat
                                    // my understanding of &statbuf is minimal but it works
  if (sd != 0) {   // checks to see if the file exists. if sd=0 then file information successfully obtained
    return;
  }

  // 
  Log.info("statbuf %ld\n", statbuf.st_size); // publishes the size of the file

  // read the file
  int fd = open("/data1.txt", O_RDONLY); // opens the file read only

  Log.info("fd %d", fd); // prints the return code from opening the file for read only

  if (fd != -1) {
    //void* buffer;   // this did not seem to work in the original code so replaced it with the next line
    char buffer[buffSize];   // create a buffer of size "buffSize"
    int rd = read(fd, buffer, sizeof(buffer)-1);  // read sizeof(buffer)-1 bytes of the file into "buffer"
    char* content = static_cast<char*> (buffer);  // not sure what this is for

    Log.info("rd %d", rd); // print the return code for reading the file
    close(fd);  // close the file

    Log.info("got a msg buffer"); // a message to the console

    Log.info(content); // print the data read from the file
    Log.info(buffer);  // also print the data fromt eh file
  }
}

void write_data_file()
{
  int fd = open("/data1.txt", O_RDWR | O_CREAT | O_TRUNC); // open the file to write and set pointer to beginning of the file

  if (fd != -1) {  // if opening the file was successful write something
      write(fd, "foabar or somethign else \n", buffSize);   // write something up to 80 char
      close(fd);  // clos eth efile
      Log.info("writing a file out on event loop");  // message tot eh console
  }
}

void loop() {

  write_data_file(); // write the data file
  read_data_file();  // read the data file
  delay(5000);   // pause between write and reads before starting over
}

void setup() {

}
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