getdirentries_args and other kernel syscall structures

From: Daniel Rudy (dr2867_at_pacbell.net)
Date: 11/23/05

  • Next message: Thierry Herbelot: "Re: Xen dom0 support" 
    Date: Tue, 22 Nov 2005 20:32:10 -0800
To: freebsd-hackers@freebsd.org

    Ok, I'va got a little question here. In the structure
    getdirentries_args, there seems to be duplicated fields that I'm not
    entirely sure what they do. Here's the definition of a structure
    verbatim from sys/sysproto.h:

    struct getdirentries_args {
            char fd_l_[PADL_(int)]; int fd; char fd_r_[PADR_(int)];
            char buf_l_[PADL_(char *)]; char * buf; char buf_r_[PADR_(char *)];
            char count_l_[PADL_(u_int)]; u_int count; char
    count_r_[PADR_(u_int)];
            char basep_l_[PADL_(long *)]; long * basep; char
    basep_r_[PADR_(long *)];
    };

    Now my question is what does the l and r variables do? It seems that
    they do something with padding the data based on the endian of the
    machine? I look through this header file, and I see all the structures
    have similar constructs. Is it something that can be safely ignored? 

    -- 
Daniel Rudy
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