如何正确应用GNU GPLv3 和 LGPLv3 协议

前言

对于了解开源的朋友们，GNU GPL系列协议可谓是老朋友了。原来我基本上都是使用MIT License，应用简单。但是最近我计划做一个项目，使用到了GNU LGPLv3.0协议，但是其应用有点麻烦，所以在此记录一下。

GNU GPLv3.0

在应用之前我们先来了解一下GPLv3，这是非常必要的。GPL是一种copyleft类的协议，对于版权的保护力度很强，如果使用不当很可能扯上官司。另一方面，它又可以很好的帮助开发者维权。

Permissions(许可)

• Commercial use：被许可的材料和衍生产品可用于商业目的。
• Distribution：可以分发被许可的材料。
• Modification：可以修改被许可的材料。
• Patent use：明确授予贡献者的专利权。
• Private use：允许私人修改与使用被许可的材料。

Conditions(条件)

• Disclose source：分发许可材料时必须提供源代码。
• License and copyright notice：许可材料中必须包含许可证和版权声明的副本。
• Same license：分发许可材料时，必须在同一许可证下发布修改。在某些情况下，可以使用类似的相关许可证。
• State changes：必须记录对许可材料所做的更改。

Limitations(限制)

• Liability：本许可包括责任限制。
• Warranty：本许可证明确声明不提供任何担保。

GNU LGPLv3.0

LGPLv3基本与GPLv3相同，唯一不同的就是Same License不适用于Library。如何去理解呢？GPL的起草者Stallman是一个开源坚定的捍卫者，LGPL也是出于为了推广GPL类协议而无奈提出的。所以LGPL里说的都不是人话。大概意思就是如果你动态链接此库，GPL的传染性就此止步。因此，LGPL是商业友好的。

应用GPLv3.0

在项目文件夹里创建一个文件，一般按照GNU项目的惯例是COPYING，但是你也可以换成其他的，比如QT5项目文件夹的协议名就是LICENSE.GPL3。然后粘贴协议内容。

应用LGPLv3.0

在应用LGPLv3.0之前，你必须先应用GPLv3.0，所以LGPL更像是一种附加条款。要应用它，在项目文件夹里创建一个文件，同样按照惯例是COPYING.LESSER。然后粘贴协议内容。

建议的内容：添加文件头声明

我们建议在每个源文件开头添加文件头声明，样板可以在GPLv3的文件结尾部分找到，然后修改软件描述于版权声明即可：

	<one line to give the program's name and a brief idea of what it does.>Copyright (C) <year>  <name of author>This program is free software: you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation, either version 3 of the License, or(at your option) any later version.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program.  If not, see <https://www.gnu.org/licenses/>.

如果你的项目包含了控制台的二进制文件，GPL也提供了以下输出模板：

	<program>  Copyright (C) <year>  <name of author>This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.This is free software, and you are welcome to redistribute itunder certain conditions; type `show c' for details.

以上是GPLv3的版本，如果你是使用LGPLv3，则将GNU General Public License字段更改为GNU Lesser General Public License即可。

附录

GNU GPLv3.0原文

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THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
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SUCH DAMAGES.17. Interpretation of Sections 15 and 16.If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
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Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.END OF TERMS AND CONDITIONSHow to Apply These Terms to Your New ProgramsIf you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.To do so, attach the following notices to the program.  It is safest
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state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.<one line to give the program's name and a brief idea of what it does.>Copyright (C) <year>  <name of author>This program is free software: you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation, either version 3 of the License, or(at your option) any later version.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program.  If not, see <https://www.gnu.org/licenses/>.Also add information on how to contact you by electronic and paper mail.If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:<program>  Copyright (C) <year>  <name of author>This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.This is free software, and you are welcome to redistribute itunder certain conditions; type `show c' for details.The hypothetical commands `show w' and `show c' should show the appropriate
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might be different; for a GUI interface, you would use an "about box".You should also get your employer (if you work as a programmer) or school,
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For more information on this, and how to apply and follow the GNU GPL, see
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may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<https://www.gnu.org/licenses/why-not-lgpl.html>.

GNU LGPLv3.0 原文

                   GNU LESSER GENERAL PUBLIC LICENSEVersion 3, 29 June 2007Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>Everyone is permitted to copy and distribute verbatim copiesof this license document, but changing it is not allowed.This version of the GNU Lesser General Public License incorporates
the terms and conditions of version 3 of the GNU General Public
License, supplemented by the additional permissions listed below.0. Additional Definitions.As used herein, "this License" refers to version 3 of the GNU Lesser
General Public License, and the "GNU GPL" refers to version 3 of the GNU
General Public License."The Library" refers to a covered work governed by this License,
other than an Application or a Combined Work as defined below.An "Application" is any work that makes use of an interface provided
by the Library, but which is not otherwise based on the Library.
Defining a subclass of a class defined by the Library is deemed a mode
of using an interface provided by the Library.A "Combined Work" is a work produced by combining or linking an
Application with the Library.  The particular version of the Library
with which the Combined Work was made is also called the "Linked
Version".The "Minimal Corresponding Source" for a Combined Work means the
Corresponding Source for the Combined Work, excluding any source code
for portions of the Combined Work that, considered in isolation, are
based on the Application, and not on the Linked Version.The "Corresponding Application Code" for a Combined Work means the
object code and/or source code for the Application, including any data
and utility programs needed for reproducing the Combined Work from the
Application, but excluding the System Libraries of the Combined Work.1. Exception to Section 3 of the GNU GPL.You may convey a covered work under sections 3 and 4 of this License
without being bound by section 3 of the GNU GPL.2. Conveying Modified Versions.If you modify a copy of the Library, and, in your modifications, a
facility refers to a function or data to be supplied by an Application
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facility is invoked), then you may convey a copy of the modified
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a header file that is part of the Library.  You may convey such object
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Library side by side in a single library together with other library
facilities that are not Applications and are not covered by this
License, and convey such a combined library under terms of your
choice, if you do both of the following:a) Accompany the combined library with a copy of the same work basedon the Library, uncombined with any other library facilities,conveyed under the terms of this License.b) Give prominent notice with the combined library that part of itis a work based on the Library, and explaining where to find theaccompanying uncombined form of the same work.6. Revised Versions of the GNU Lesser General Public License.The Free Software Foundation may publish revised and/or new versions
of the GNU Lesser General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
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Library as you received it specifies that a certain numbered version
of the GNU Lesser General Public License "or any later version"
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conditions either of that published version or of any later version
published by the Free Software Foundation. If the Library as you
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General Public License ever published by the Free Software Foundation.If the Library as you received it specifies that a proxy can decide
whether future versions of the GNU Lesser General Public License shall
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permanent authorization for you to choose that version for the
Library.

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参考：
https://choosealicense.com/licenses/gpl-3.0/
https://choosealicense.com/licenses/lgpl-3.0/