[lkml]   [2004]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: question on common error-handling idiom
    >There's something I've been wondering about for a while.  There is a lot of code
    >in linux that looks something like this:
    >err = -ERRORCODE
    >if (error condition)
    > goto out;

    That's because there might something as:

    err = -EPERM;
    if(error) { goto out; }
    do something;
    if(error2) { goto out; }
    do something more;
    if(error3) { goto out; }

    Is shorter than:

    if(error) { err = -EPERM; goto out; }
    do something;
    if(error2) { err = -EPERM; goto out; }
    do something more;
    if(error3) { err = -EPERM; goto out; }

    >Is there any particular reason why the former is preferred? Is the compiler

    To keep it short. Because it might have been worse than just err =xxx:

    if(error) {
    do this and that;
    and more;
    even more;
    more more;
    goto out;

    Repeating that over and over is not that good. So we wrap it a little bit to do
    a "staircase" deinitialization:

    err = -EPERM;
    if(error) { goto this_didnot_work; }
    err = -ENOSPC;
    if(error) { goto that_didnot_work; }

    all uninitializations needed

    all other uninit's

    return err;

    So to summarize, it's done to reduce code whilst keeping the error code around
    until we actually leave the function.

    My € 0.02!

    Jan Engelhardt
    Gesellschaft für Wissenschaftliche Datenverarbeitung
    Am Fassberg, 37077 Göttingen,
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 14:07    [W:0.021 / U:81.456 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site