Messages in this thread | | | Date | Tue, 18 Aug 2009 08:55:29 -0600 | Subject | Purpose of parameter in sysfs binary read | From | "Rick L. Vinyard, Jr." <> |
| |
The read function pointer of the sysfs bin_attribute structure has this signature:
ssize_t (*read)(struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t offset, size_t size);
I've figured out the purpose of all the parameters except the loff_t parameter.
Obviously it's an offset of some sort, but what is the meaning of the offset?
If I have binary data in a char* named bindata of size bsize, should it be copied into buf+offset in something like: memcpy(buf+offset, bindata, bsize);
Or, is it an offset from both buf and bindata in something like: memcpy(buf+offset, bindata+offset, bsize-offset);
Thanks,
Rick
| |