在 UBI 文件系统中将文件从源复制到目标

Question

I want to copy file from source to destination. But in case of destination folder size is small compare to source file. It does not fail write, always return success and this behaviour I have observed in UBI file system only.

while ((size = fread(buffer, 1, BUFSIZ, source)) > 0)
{
    size_t size_2 = fwrite(buffer, 1, size, destination);
    if (size_2 != size)
    {
        retval = -1;
        break;
    }
}

In UBIFS supports write-back, In which file changes are cached and go to the flash later. Any one know how to verify write status for this.

Answer 1

You can use fsync to verify the write-back status.

To quote from the following source:

transfers ("flushes") all modified in-core data of ... the file referred to by the file descriptor fd to the disk device (or other permanent storage device) so that all changed information can be retrieved even if the system crashes or is rebooted. This includes writing through or flushing a disk cache if present

http://man7.org/linux/man-pages/man2/fdatasync.2.html