MESSAGE
| DATE | 2004-04-20 |
| FROM | Ruben I Safir
|
| SUBJECT | Re: [hangout] Debugging cdparanoia in C
|
It's funny, but even as rusty as I am in C and clueless in Unix
functions in C, I'm still finding amature like mistakes in the
code for cdparanioa
Look at this snippet of code for example. This works, but it
should be programed more correctly (unless I'm missing something).
while(cdrom_devices[i]!=NULL){
/* is it a name or a pattern? */
char *pos;
if((pos=strchr(cdrom_devices[i],'?'))){
int j;
/* try first eight of each device */
for(j=0;j<4;j++){
char *buffer=copystring(cdrom_devices[i]);
/* number, then letter */
buffer[pos-(cdrom_devices[i])]=j+48;
if((d=cdda_identify(buffer,messagedest,messages)))
return(d);
idmessage(messagedest,messages,"",NULL);
buffer[pos-(cdrom_devices[i])]=j+97;
if((d=cdda_identify(buffer,messagedest,messages)))
return(d);
idmessage(messagedest,messages,"",NULL);
}
Breaking this function down -
cdrom[] is an array of char pointers to possible cdrom devices
if the array string has a '?' in it, then search for various devices by numbers and letter (such as /dev/hda1, /dev/hda2, ect)
pos is returned the position for the '?' in the string
from 0-4 then COPY the contents of the string in cdrom_device[i] into *buffer <<<=========== FOR EVERY TIME THROUGH THE LOOP.
***BOING****
They SHOULD copy the string into the buffer FIRST. I'd imagine that the optimizer fixes this, but this is the kind of mistakes in
coding which used to drive me NUTS. First, it adds a line into the loop. Second, your acking the system to do something over and
over again which needs to be done only ONCE. In a different situation, this kind of carelessness creates difficult to track bugs.
Ruben
On 2004.04.20 15:05 Billy wrote:
> On Tue, Apr 20, 2004 at 02:16:34PM -0400, Ruben I Safir wrote:
> >
> > Somebody might find it interesting.
> >
> >
> > > Is there a reason I should be?
> > >
> >
> > What is happening with this line:
> > if(lstat("/dev/cdrom",&s))
> >
> > lstat returns a 0 or a -1 and both are false
>
> any nonzero number is true in C.
>
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