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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:
>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,
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