tmolteno / openfat Goto Github PK

When files or directories are created with OpenFAT, long file name entries are written to the parent directory. These are visible to Linux and OpenFAT, but Windows only shows the short 8.3 filenames.

Hi, a warning:
../openfat/src/fat_core.c: In function '_fat_get_next_cluster':
../openfat/src/fat_core.c:86:9: warning: 'offset' may be used uninitialized in this function [-Wmaybe-uninitialized]
offset %= h->bytes_per_sector;

Firstly, thanks to the great work of openfat. I am using it in my own project.

Along my work with openfat, I met a error which was caused by bug here:

When "sector % h->fat->sectors_per_cluster == 0" is true, we want to get the next cluster, then get the first sector of that cluster. However, this condition is broken when h->fat->first_data_sector is not zero. For example, sector = 208, h->fat->sectors_per_cluster = 4 , h->fat->first_data_sector = 1, where "sector % h->fat->sectors_per_cluster == 0" is true, but we can't say this sector(208) is the end of cluster, right?

so we need to minus the offset. Bug fix seems like this:

uint32 tmpoff = h->fat->first_data_sector % h->fat->sectors_per_cluster;
if (((sector % h->fat->sectors_per_cluster) - tmpoff) == 0) {
  // .....
}

And I test above fix successfuly.