ESP32 Forum

Hi to All!
I have an ESP-IDF project contained f_open(..) and f_puts(..)/f_gets(..).
Here is the part of my code:

if(f_open(&fil, u8GlobalNameOfFileName, FA_READ) == FR_OK)
{
f_gets(fileText, sizeof(FirstTextInCsv), &fil);
if(strcmp(fileText,FirstTextInCsv) == false)
{
PRINTF("The flash was populated\n");
ret = true;
}
}
else
{
PRINTF("Failed to open file for reading\n");
}
f_close(&fil);

After the compilation step, I get a linker errors:

c:/.espressif/tools/xtensa-esp32-elf/esp-2020r2-8.2.0/xtensa-esp32-elf/bin/../lib/gcc/xtensa-esp32-elf/8.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: esp-idf/main/libmain.a(sd_card.c.obj):(.literal.SDHC_CheckFirstWrite+0x8): undefined reference to `f_gets'

c:/.espressif/tools/xtensa-esp32-elf/esp-2020r2-8.2.0/xtensa-esp32-elf/bin/../lib/gcc/xtensa-esp32-elf/8.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: esp-idf/main/libmain.a(sd_card.c.obj):(.literal.SDHC_WriteFirstRowInCsv+0x0): undefined reference to `f_puts'

It is very strange that there are no errors for f_open (..) or f_close(..)!

I noticed that the functions f_open(), f_puts(), f_gets() are declared in the file {ESP-IDF}\components\fatfs\src\ff.h. And there are no “ifdefs” “separating” them. I also noticed that in the same directory there is a file ffconf.h, in which "FF_USE_STRFUNC 0" is defined with the following comments:

/* This option switches string functions, f_gets(), f_putc(), f_puts() and f_printf().
/
/ 0: Disable string functions.
/ 1: Enable without LF-CRLF conversion.
/ 2: Enable with LF-CRLF conversion. */

It is logical to assume that FF_USE_STRFUNC must be defined as 1 or 2 to be able to use f_puts() and f_gets(). But is it right for the user to make changes to the framework file?
Can you please tell me how to solve or "work around" this problem?

Hi olegboicenco,
Indeed we hadn't enabled FF_USE_STRFUNC option, as we assume that FATFS library will be used together with the VFS mechanism. That way you can use C standard library functions (fgets, fputs) to work with files.
If you have some existing code which uses FATFS APIs, you may enable FF_USE_STRFUNC. I don't think it will cause any side effects.

Now it's clear! Thank you, ESP_Igrr!!

Thanks from a troubled Keil + nordic semiconductor nrf52840-dk / nrf5 sdk user, and esp32 customer