Re: New extension: Inotify

On Tue, Jul 8, 2008 at 3:31 PM, Antony Dovgal <tony@daylessday.org> wrote: > On 04.07.2008 22:19, Arnaud LB wrote: >>> >>> lnotify is a part of Linux kernel, which is GPL-licensed. >> >> The inotify functions are a set of syscalls, just like open() and >> close(). Using open() in your code does not force you to release it >> under the GPL ;) That's the same situation with inotify. > > open() and close() exist in other (non-GPL) systems, i.e. your code doesn't > depend on any certain kernel/library, hence its license doesn't affect your > code. > > In case of Inotify, you code was clearly done especially for Inotify and > fully depends on Inotify, which to my understanding means that this is a > "derivative work" and it should be GPLed, too, unfortunately. > > We've had an opposite case: ext/readline can link to both GPL-ed readline > and BSD-licensed libedit, which allows us to license it under PHP license. > > -- > Wbr, Antony Dovgal > I fully understand the purpose of these restrictions on the license of the extensions you host on PECL. But I think that my extension can be released under the PHP license without violating any license. It does not link to any user-land GPL'd library. Inotify is not a library like readline. Actually inotify is a set of 3 syscalls named inotify_init, inotify_add_watch and inotify_rm_watch. The only user-land code of inotify is in the glibc, and it may looks something like that: int inotify_init () { return syscall (SYS_inotify_init); } Where SYS_inotify_init is the number for the inotif_init syscall. This is so generic that the glibc writes these functions at compile time from a list of syscall names and numbers. So, yes, my code links and depends on the glibc (which is LGPL) because it uses these 3 convenience functions instead of using directly the syscall() function. I think it does not cause any problem to the PHP license, but if it does I may use syscall() directly or write these functions myself to not depend on any specific libc. However there are chances that other non-(L)GPL libcs export (or will export) the inotify functions, which would make my extension to not depend on any specific libc. And for the syscall part, Linux license [1] says: "NOTE! This copyright does *not* cover user programs that use kernel services by normal system calls - this is merely considered normal use of the kernel, and does *not* fall under the heading of "derived work". My extension is in this case, it uses only normal system calls, and is not a derived work of Linux or Inotify. [1] http://www.kernel.org/pub/linux/kernel/COPYING