Re: fcntl v/s ioctl
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On 3/29/07, Rick Brown <rick.brown.3@xxxxxxxxx> wrote:
Hi, Could some one please explain me the differences and similarities between fcntl and ioctl? Is one built upon the other?
AFAIK, both are used for handling of very device specific commands by the driver.
not both, this goes well with ioctl as ioctl is customizable, there is an ioctl method in the struct file_operations. so a driver writer can define some device specific tasks & hook her own method to execute them via an ioctl http://lxr.linux.no/source/fs/ioctl.c#L159 fcntl is not customizable by a driver there are some fixed task which it performs like setting the close on exec flag duplicate fd set/get owner etc have a look at sys_fcntl http://lxr.linux.no/source/fs/fcntl.c#L385 & its worker do_fcntl http://lxr.linux.no/source/fs/fcntl.c#L315 we can say that fcntl dosen't bother if its a regular file or a device specific file where as ioctl changes its color in these case -- Milind Arun Choudhary - To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs