RL-FlashFS - File overwrite?

Hello,

I'm wondering if it's possible, and if so if someone has an example, to overwrite a portion of a file using the RL-FlashFS library.

Basically I have a working setup and I have a small file system on NOR flash. I have a fixed size file and I want to overwrite a middle section of this file.

If I try something like:

            if(f = fopen("my_test_file", "a"))
            {
                int j = 38;
                rewind(f);
                fseek(f, header.head_index-1 * (4 * sizeof(uint32_t)), SEEK_SET);
                fwrite(&j, sizeof(uint32_t), 1, f);
                fwrite(&j, sizeof(uint32_t), 1, f);
                fwrite(&j, sizeof(uint32_t), 1, f);
                fwrite(&j, sizeof(uint32_t), 1, f);
                fseek (f, -1L, SEEK_END);
                fclose(f);
            }

The rewind doesn't seem to do anything and it just appends the 4 ints to the end of the file.

Any ideas? Am I doing something wrong?

Thanks.

M