fwrite cannot handle more than 4095 chars.

[Tomas Brambora]

fwrite sets ferror to 1 when attempting to write > 4095 chars. This should not be caused by reaching DATA_XFER_LIMIT as this is set to 64KB.

#include <stdio.h>
#include <errno.h>
#include <vfs/vfs.h>
#include <fcntl.h>

#define BUFSIZE 5000

int main(int argc, char **argv)
{
	int i;

	char buffer[BUFSIZE];
	for (i=0; i<BUFSIZE; ++i)
		buffer[i] = 'a';

	FILE *f = fopen("/data/tmp", "w");
	errno = 0;
	printf("ferror: %i\n", ferror(f));
	int cnt = fwrite(buffer, sizeof(char), BUFSIZE, f);
	printf("cnt: %i, errno: %i, ferror: %i", cnt, errno, ferror(f));
	fclose(f);

	return 0;
}

[Jiri Svoboda]

Are you sure you have enough free space on the file system? Root FAT fs has less than 4 kB of free space.

[Jakub Jermář]

I am closing this because in my case the reproducible test case is caused by a too small root file system.