Hi,
I know the file position is located in the file struct.
I know that during normal fork, copy_process copies these
structures and doesn't share them between father and son
(unless CLONE_FILES is used, like in threads).
still, in the following code, i get answers that explicitly
make me think that file pointer is shared, even accross normal
fork:
int fd = open("file",...);
int pid = fork();
if(pid)
{
lseek(fd,0,SEEK_SET);
write(fd,"bbbbb",..);
}
else
{
lseek(fd,0,SEEK_SET);
sleep(5);
write(fd,"aaaaa",..);
}
instead of "aaaaa" (the son should overwrite his fathers writings)
i get "bbbbbaaaaa". that means that during the father's writing,
the son's file position advanced, too !
why is that ?
why does all the kernel books i have state otherwise ?
what don't i understand here ?
thanks
S.
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