Is it legal for manufacturers to lock bootloaders on Android phones? Some backgroud : A bootloader is a very low level piece of software that runs first and loads an operating system of some other tool. On a lot of new Android devices the bootloader is "locked", that means that it checks if the digital signature of the installed OS and then only accepts to boot the device. Some phone manufacturers have started to lock bootloaders in order to prevent any system modification whether it is done by a legitimate user or not. My question : Android is an operating system based on Linux, and Linux is distributed under the GNU GPL v2 license. The GPL v2 grants some rights to the user, in particular being able to modify a program licensed under it. As bootloader locks prevent users from modifying an Android phone's software in some ways, is it legal for phones manufacturers to prevent the user from removing the bootloader lock ?
The Linux kernel is licensed under version 2 of the Gnu General Public License. You can demand the source code they used to build the kernel, but the license doesn't guarantee that you can change and replace any code. That caused some controversy, so the Free Software Foundation came up with version 3, which would require the company to allow users to reinstall changed software. Linux is not licensed under version 3. There are no license restriction on locking the kernel down on a specific device, and no laws I know of against doing it. If you want to change and reinstall the Linux kernel, you need to find a phone that will let you do that.
According to US law, the GPL is a license, not a contract. This means it is valid without consideration, it also means if you are in violation of the license, then you are committing copyright infringement, instead of being in breach of a contract. In Germany, the GPL is a contract. And that's fine, because German law doesn't require consideration for a contract to be valid. It's interesting in that the GPL license doesn't require you to state whether you agree to the license/contract or not. But if you don't agree to the contract then there is no contract, and you have no right to use the software.
What you're talking about is called black-box reverse engineering. It can be done, and as long as you are meticulous in your record keeping the fact that it has been done should be an appropriate defence against copyright infringement. But that doesn't help against patent claims - while in copyright cases the fact that code has or has not been directly copied is critical, in patent cases it its irrelevant: if you use a patented method, it's a violation. You therefore will need to be careful about any patents that may have been issued to the original author, as well as avoiding copying.
The idea for an app is not subject to copyright. Only the artifacts of the app itself (sourcecode, images, texts, sounds, etc.) can be. So if one only copies the idea and creates their own version of all the other assets, then they are not violating copyright. However, in some cases, ideas can be subject to patents. But patents on software are tricky. First of all, only new ideas can be patented. When a supposed new idea was already published before, then that's called &quot;prior art&quot; and you can not patent it. Then getting a patent means a lot of investment in money and time (which is very different from copyright which you get automatically the moment you make something copyright-worthy). So not everything that could theoretically be patented gets patented. And then, many jurisdictions do not recognize software patents at all, and those which do have different limits on what is and is not patentable when it comes to software. This means patents are rarely a concern when copying the app idea of someone else, but not never. And another possible concern is the third pillar of intellectual property: Trademarks. This protects the name of the app. Trademark law oversimplified forbids to create a competing product with a name which might confuse customers. So if you created StevesSuperCoolAppForCoolPeople and I create StevesSuperCoolAppForCoolPeople - Simplified Edition, then I would be violating your trademark, because my product name sounds as if it was your product, when it is in fact an unrelated product with a similar purpose.
Both. The user made an infringing copy with the upload, the developer did with the download. Further the ToS between the app owner and the user will not protect them from being sued by the owner of the copyright. They don't have any ToS with them.
Just assuming for the sake of this particular answer that everything happens in the U.S.: I'm not sure about the particular example of Open ZFS. The registration in the USPTO Records is in Oracle's name. Using OpenZFS for distributing the same kind of software as the now closed-source ZFS would seem to be infringing to me absent a license. Maybe Oracle just tolerates the use of the "ZFS" component by third-parties since they decided at some point to license the software under an open source license. In that case, they may have a dilution (http://www.inta.org/TrademarkBasics/FactSheets/Pages/TrademarkDilution.aspx) problem and the mark may be invalid. If the mark is invalid, anybody can pretty much do whatever they want with it. That said, assuming for sake of discussion that the mark is valid, there is indeed such a thing that is similar to the copyright fair use in trademarks (in the U.S. at least). It's called "nominative fair use". You can read more about it here: http://www.inta.org/TrademarkBasics/FactSheets/Pages/FairUse.aspx Bottom line is that under the nominative fair use doctrine it's generally ok for party A to use party B's trademark to refer to whatever party B is doing, even to sell products and services related to whatever party B is doing. As per the INTA document I just linked above, its for example ok to "use “iPhone” in non-stylized form on packaging for phone cases to indicate that it is usable with iPhone 6." Having a website (even with third-party ads) that discuss ZFS-related matters is similar to the iPhone example in my mind. Having a domain name that contains the mark seems riskier, but it's not necessarily downright forbidden. See: http://itlaw.wikia.com/wiki/Toyota_Motor_Sales,_U.S.A._v._Tabari
Whenever there is a license to share things, the license creator wants the license to be widely used, but absolutely does not want slightly different licenses that could be used to trick people, or that just cause legal problems when used. Normal copyright law applies. And for the reasons above, the GPL license as an example allows you to copy the license verbatim but absolutely doesn’t allow you to make any modifications other than changing who is the person licensing a work. I would be curious what happens legally if someone licenses something with a sneakily modified copy of the GPL and then makes claims against a licensee who assumed it was the original GPL.
I'm assuming that you are not seeking to change the license, and so it will remain GPLv3. As long as you've built on the original software, that license still applies. You also need to keep the previous copyright notices, including the names of the original people. Assuming that, everything you're doing is legal, which is what's on topic here. There is some etiquette around forks (which is what you're doing), which would be on topic at the Open Source Stack Exchange. I'm puzzled by your desire to have a different license text. You can't change the license from GPLv3, so that has to stay the same. (If the original has GPLv3 "or, at your option, any later version", you can drop the any other version text if you like.)