软件再许可

在开源软件开发中，软件再许可指在软件模块的软件许可证不兼容并且需要兼容以进行更大的组合工作時的改變许可证操作。以二进制形式存在的，受版权保护的作品应用于软件源代码的许可证^[1]可以包含矛盾的条款。这些要求可能导致无法将多个软件作品的源代码或内容组合起来创建一个新的组合作品。^[2][3]

动机和描述

有时开源软件项目会陷入许可证不兼容的情况。通常，解决这种情况的唯一可行方法是重新许可所有参与的软件部分。为了成功地重新许可，需要得到所有相关版权所有者（通常是开发人员）的许可。虽然在免费和开源领域中，由于涉及许多贡献者，实现所有作者的 100% 覆盖通常是不可能的，但通常假设绝大多数就足够了。例如，Mozilla假设 95% 的作者覆盖率就足够了。^[4]自由和开源软件领域的其他人，例如Eric S. Raymond ，就整个代码库的重新许可要求得出了不同的结论。 ^[5]

案例

Mozilla项目和他们的Firefox浏览器是出于许可证兼容性原因成功重新授权的开源项目的早期示例。 Netscape的Communicator 4.0浏览器的源代码最初于 1998 年在Netscape Public License / Mozilla Public License^[6]下发布，但被FSF和OSI批评为不兼容。 ^{[7] [8]} 2001 年左右，时代华纳根据 Netscape 公共许可证行使其权利，并应 Mozilla 基金会的要求，将 Mozilla 中所有在 Netscape 公共许可证下的代码（包括其他贡献者的代码）重新许可^[9]为 MPL 1.1/ GPL 2.0/ LGPL 2.1 tri-license ，从而实现 GPL 兼容性。 ^[10]

Vorbis库最初被许可为 LGPL，但在 2001 年，在Richard Stallman的支持下，该许可被更改为BSD 许可，以鼓励他人采用該庫。^[11][12]

由于许可证兼容性，VLC项目还有一段复杂的许可证历史：2007 年，出于许可证兼容性的原因，它决定不將許可證升级到刚刚发布的GPLv3。^[13]在 2011 年初 VLC 从Apple App Store下架后，2011 年 10 月，VLC 项目将 VLC 库部分从 GPLv2 重新授权到 LGPLv2，以实现更好的兼容性。^[14][15]2013 年 7 月，VLC 应用程序可以重新提交到根据 Mozilla 公共许可证重新授权的iOS App Store。^[16]

7-Zip的LZMA SDK，最初在GNU LGPL和Common Public License下获得双重许可。^[17]链接二进制文件例外，由Igor Pavlov于 2008 年 12 月 2 日置于公共领域。 ^[18]

GNU TLS项目在2011年采用了 LGPLv3 许可证，但由于严重的许可证兼容性问题，在2013年将其代码重新授权回 LGPLv2.1。^{[19] [20] [21]}

GNU 自由文档许可证1.2版与广泛使用的知识共享署名-相同方式共享许可证不兼容，例如，对于維基百科来说，这是一个问题。^[22]因此，应维基媒体基金会的要求，FSF 在 GNU 自由文档许可证1.3版中添加了一个限时部分，允许使用 GFDL 的特定类型的网站在 CC BY-SA 许可下额外提供其工作。^[23]继 2009 年 6 月之后，除了先前使用的GFDL之外，维基媒体基金会通过双重许可将其项目（例如维基百科）迁移到知识共享署名-相同方式共享作为主要许可，^[24]改进了与更大的免费内容生态系统的许可兼容性。^[25][26]

2010 年，爲了簡化许可证文本，OGRE项目将其许可证从 LGPL 更改为MIT 许可证。^{[27] [28] [29]}

另一个案例是Google为他们的Android库Bionic将 GPLv2 许可的linux 内核头文件重新许可为 BSD 许可。为了摆脱 GPL，谷歌声称头文件已从任何具有版权的作品中清除，将它们减少为不可版权的“事实”。^{[30] [31]}但是，休斯顿大学法律中心的法学教授 Raymond Nimmer 对这种解释提出了质疑。 ^[32]

POV-Ray自 1991 年以来，根据 FOSS 不兼容、非商业来源可用的自定义POV-Ray 许可证分发。^[33][34]2013 年 11 月，其在Affero 通用公共许可证第3版（或更高版本）下重新获得许可。^[35]POV-Ray 是在 FOSS 许可证被广泛使用之前开发的，因此开发人员编写了自己的许可证，后来由于许可证与 FOSS 生态系统不兼容而成为问题。

2014 年，由于 GPLv3/GPLv2 出現兼容性問題， FreeCAD项目将其许可证从 GPL 更改为 LGPLv2。^{[36] [37]}

2014 年，Gang Garrison 2从 GPLv3 重新授权到MPL ，以提高库兼容性。^{[38] [39]}

此外，Dolphin项目在2015年5月将其许可证从“仅 GPLv2”更改为“GPLv2 或更高版本”，以实现更好的兼容性。^[40]

2015 年 6 月，mpv开始了项目的 GPL 许可源代码的重新许可过程，以提高 LGPLv2 下的许可兼容性，并获得了大多数（95%+）的贡献开发者的同意。^[41]2016年8月大约可以联系到 90% 的作者并表示同意。2017年10月，转换完成。 ^[42]

2015 年 7 月，为改进许可证兼容性，尤其是与Git的兼容性，Seafile从 GPLv3 切换到 GPLv2。^{[43] [44]}

2015 年，Natron从 MPL 重新授权到GPLv2 ，以实现更好的商业化。^[45]

2016 年，MAME在为自己的书面自定义许可和非商业许可条款苦苦挣扎多年后，实现了将代码库重新许可到 BSD/GPL^[46] 。 ^{[47] [48] [49] [50]}

2016 年 8 月，MariaDB公司将数据库代理服务器 MaxScale 从 GPL 重新授权给非 FOSS 但源可用且有时间限制的商业源许可证（英語：Business source license）^[51]，三年后默认返回 GPL。^[52][53]2017年发布了 1.1 版，并根据Bruce Perens的反馈进行了修订。^[54][55]

很长一段时间以来，D后端源代码都是可用的，但並非以開源許可證授權。^[56]因为它是在赛门铁克部分开发的，不能以开源許可證重新许可。^[57]2017年4月9日，后端部分也可以重新授权给开源的Boost Software License。^[58][59][60]

自2004年該遊戲開放以來，微软研究院的太空作战模拟器Allegiance的许可证爲MSR共享源许可证^[61][62]。2017 年 7 月 27 日，更改为 MIT 许可证。^[63][64]

參見

•  自由软件主题

• 许可证兼容性
• 向后兼容性
• 前向兼容性
• 许可证扩散

参考來源

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4. O’Riordan, Ciaran. (About GPLv3) Can the Linux Kernel Relicense?. fsfe.org. 2006-10-06 [2015-05-28]. （原始内容于2011-07-21）. Someone who works with many lawyers on free software copyright issues later told me that it is not necessary to get permission from 100% of the copyright holders. It would suffice if there was permission from the copyright holders of 95% of the source code and no objections from the holders of the other 5%. This, I’m told, is how Mozilla was able to relicense to the GPL in 2003 despite years of community contributions. 
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9. . mozilla.org. （原始内容存档于2010-05-13）. Some time ago mozilla.org announced its intent to seek relicensing of Mozilla code under a new licensing scheme that would address perceived incompatibilities of the Mozilla Public License (MPL) with the GNU General Public License (GPL) and GNU Lesser General Public License (LGPL). 
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43. switchin-from-gplv3-to-gplv2. ^{[失效連結]}
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