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    SubjectPurpose of parameter in sysfs binary read
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    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



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