[DOC] Error in ff_fopen() documentation

[carlk3]

Describe the issue
Please describe the issue and expected clarification in concise language.

At ff_fopen, pcMode, Letter "w", Mode, it says "Open a file for reading and writing." This in incorrect. It is only opened for writing. If you try to read, permission is denied.

Reference
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https://www.freertos.org/FreeRTOS-Plus/FreeRTOS_Plus_FAT/stdio_API/ff_fopen.html

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• Version: [e.g. 80.0.3987.132]

[htibosch]

@carlk3 wrote:

At ff_fopen, pcMode, Letter "w", Mode, it says "Open a file for reading and writing." This in incorrect. If you try to read, permission is denied.

Out of curiosity, I tried the same under Linux and Windows: both fseek() and fread() return zero when the files was created with the "w"-flag:

    FILE *fp = fopen (fname, "w");
    if (fp != NULL) {
        fprintf(fp, "Hello world\n");
        int rc = fseek (fp, 0, SEEK_SET);
        if (rc == 0) {
            char contents[ 32 ];
            rc = fread (contents, 1, sizeof contents - 1, fp);
        }
        fclose (fp);
    }

I also tried to create the file with "w+", that does allow to write and read from the same hand.e

So let's change the documentation:

-    Open a file for reading and writing. If the file ...
+    Open a file for writing. If the file ...

Thank for your suggestion!

[carlk3]

I also tried to create the file with "w+", that does allow to write and read from the same hand.e

Of course, "w+" is not explicitly documented, although "r+" is. Looking at the code for uint8_t FF_GetModeBits( const char * pcMode ) (in ff_file.c), apparently you can mix and match individual characters in the string and order is not important. So, "+" could be documented separately.

I have found that the pcMode string "rw" works well in this case.

[kar-rahul-aws]

Hi @carlk3, thanks for catching this for us. The documentation should be updated shortly. Will close the issue once the pages are updated. We will be updating the content as @htibosch suggested for now.

[kar-rahul-aws]

We have updated the content in the page

[AniruddhaKanhere]

I cannot see the change on the official page: https://freertos.org/FreeRTOS-Plus/FreeRTOS_Plus_FAT/stdio_API/ff_fopen.html.

Once that is fixed, the issue can be closed.

[moninom1]

Thank you @AniruddhaKanhere for pointing it out, working on updating it the official page, will update once done.

[moninom1]

The change is updated on the official page, Hence closing the issue. Thank you