1[I have snipped the snail mail address of the FSF because it has 2changed in the past and is likely to change again. The current 3address should be at http://www.gnu.org/] 4 5 GNU LIBRARY GENERAL PUBLIC LICENSE 6 Version 2, June 1991 7 8 Copyright (C) 1991 Free Software Foundation, Inc. 9 Everyone is permitted to copy and distribute verbatim copies 10 of this license document, but changing it is not allowed. 11 12[This is the first released version of the library GPL. It is 13 numbered 2 because it goes with version 2 of the ordinary GPL.] 14 15 Preamble 16 17 The licenses for most software are designed to take away your 18freedom to share and change it. By contrast, the GNU General Public 19Licenses are intended to guarantee your freedom to share and change 20free software--to make sure the software is free for all its users. 21 22 This license, the Library General Public License, applies to some 23specially designated Free Software Foundation software, and to any 24other libraries whose authors decide to use it. You can use it for 25your libraries, too. 26 27 When we speak of free software, we are referring to freedom, not 28price. Our General Public Licenses are designed to make sure that you 29have the freedom to distribute copies of free software (and charge for 30this service if you wish), that you receive source code or can get it 31if you want it, that you can change the software or use pieces of it 32in new free programs; and that you know you can do these things. 33 34 To protect your rights, we need to make restrictions that forbid 35anyone to deny you these rights or to ask you to surrender the rights. 36These restrictions translate to certain responsibilities for you if 37you distribute copies of the library, or if you modify it. 38 39 For example, if you distribute copies of the library, whether gratis 40or for a fee, you must give the recipients all the rights that we gave 41you. You must make sure that they, too, receive or can get the source 42code. If you link a program with the library, you must provide 43complete object files to the recipients so that they can relink them 44with the library, after making changes to the library and recompiling 45it. And you must show them these terms so they know their rights. 46 47 Our method of protecting your rights has two steps: (1) copyright 48the library, and (2) offer you this license which gives you legal 49permission to copy, distribute and/or modify the library. 50 51 Also, for each distributor's protection, we want to make certain 52that everyone understands that there is no warranty for this free 53library. If the library is modified by someone else and passed on, we 54want its recipients to know that what they have is not the original 55version, so that any problems introduced by others will not reflect on 56the original authors' reputations. 57 58 Finally, any free program is threatened constantly by software 59patents. We wish to avoid the danger that companies distributing free 60software will individually obtain patent licenses, thus in effect 61transforming the program into proprietary software. To prevent this, 62we have made it clear that any patent must be licensed for everyone's 63free use or not licensed at all. 64 65 Most GNU software, including some libraries, is covered by the ordinary 66GNU General Public License, which was designed for utility programs. This 67license, the GNU Library General Public License, applies to certain 68designated libraries. This license is quite different from the ordinary 69one; be sure to read it in full, and don't assume that anything in it is 70the same as in the ordinary license. 71 72 The reason we have a separate public license for some libraries is that 73they blur the distinction we usually make between modifying or adding to a 74program and simply using it. Linking a program with a library, without 75changing the library, is in some sense simply using the library, and is 76analogous to running a utility program or application program. However, in 77a textual and legal sense, the linked executable is a combined work, a 78derivative of the original library, and the ordinary General Public License 79treats it as such. 80 81 Because of this blurred distinction, using the ordinary General 82Public License for libraries did not effectively promote software 83sharing, because most developers did not use the libraries. We 84concluded that weaker conditions might promote sharing better. 85 86 However, unrestricted linking of non-free programs would deprive the 87users of those programs of all benefit from the free status of the 88libraries themselves. This Library General Public License is intended to 89permit developers of non-free programs to use free libraries, while 90preserving your freedom as a user of such programs to change the free 91libraries that are incorporated in them. (We have not seen how to achieve 92this as regards changes in header files, but we have achieved it as regards 93changes in the actual functions of the Library.) The hope is that this 94will lead to faster development of free libraries. 95 96 The precise terms and conditions for copying, distribution and 97modification follow. Pay close attention to the difference between a 98"work based on the library" and a "work that uses the library". The 99former contains code derived from the library, while the latter only 100works together with the library. 101 102 Note that it is possible for a library to be covered by the ordinary 103General Public License rather than by this special one. 104 105 GNU LIBRARY GENERAL PUBLIC LICENSE 106 TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 107 108 0. This License Agreement applies to any software library which 109contains a notice placed by the copyright holder or other authorized 110party saying it may be distributed under the terms of this Library 111General Public License (also called "this License"). Each licensee is 112addressed as "you". 113 114 A "library" means a collection of software functions and/or data 115prepared so as to be conveniently linked with application programs 116(which use some of those functions and data) to form executables. 117 118 The "Library", below, refers to any such software library or work 119which has been distributed under these terms. A "work based on the 120Library" means either the Library or any derivative work under 121copyright law: that is to say, a work containing the Library or a 122portion of it, either verbatim or with modifications and/or translated 123straightforwardly into another language. (Hereinafter, translation is 124included without limitation in the term "modification".) 125 126 "Source code" for a work means the preferred form of the work for 127making modifications to it. For a library, complete source code means 128all the source code for all modules it contains, plus any associated 129interface definition files, plus the scripts used to control compilation 130and installation of the library. 131 132 Activities other than copying, distribution and modification are not 133covered by this License; they are outside its scope. The act of 134running a program using the Library is not restricted, and output from 135such a program is covered only if its contents constitute a work based 136on the Library (independent of the use of the Library in a tool for 137writing it). Whether that is true depends on what the Library does 138and what the program that uses the Library does. 139 140 1. You may copy and distribute verbatim copies of the Library's 141complete source code as you receive it, in any medium, provided that 142you conspicuously and appropriately publish on each copy an 143appropriate copyright notice and disclaimer of warranty; keep intact 144all the notices that refer to this License and to the absence of any 145warranty; and distribute a copy of this License along with the 146Library. 147 148 You may charge a fee for the physical act of transferring a copy, 149and you may at your option offer warranty protection in exchange for a 150fee. 151 152 2. You may modify your copy or copies of the Library or any portion 153of it, thus forming a work based on the Library, and copy and 154distribute such modifications or work under the terms of Section 1 155above, provided that you also meet all of these conditions: 156 157 a) The modified work must itself be a software library. 158 159 b) You must cause the files modified to carry prominent notices 160 stating that you changed the files and the date of any change. 161 162 c) You must cause the whole of the work to be licensed at no 163 charge to all third parties under the terms of this License. 164 165 d) If a facility in the modified Library refers to a function or a 166 table of data to be supplied by an application program that uses 167 the facility, other than as an argument passed when the facility 168 is invoked, then you must make a good faith effort to ensure that, 169 in the event an application does not supply such function or 170 table, the facility still operates, and performs whatever part of 171 its purpose remains meaningful. 172 173 (For example, a function in a library to compute square roots has 174 a purpose that is entirely well-defined independent of the 175 application. Therefore, Subsection 2d requires that any 176 application-supplied function or table used by this function must 177 be optional: if the application does not supply it, the square 178 root function must still compute square roots.) 179 180These requirements apply to the modified work as a whole. If 181identifiable sections of that work are not derived from the Library, 182and can be reasonably considered independent and separate works in 183themselves, then this License, and its terms, do not apply to those 184sections when you distribute them as separate works. But when you 185distribute the same sections as part of a whole which is a work based 186on the Library, the distribution of the whole must be on the terms of 187this License, whose permissions for other licensees extend to the 188entire whole, and thus to each and every part regardless of who wrote 189it. 190 191Thus, it is not the intent of this section to claim rights or contest 192your rights to work written entirely by you; rather, the intent is to 193exercise the right to control the distribution of derivative or 194collective works based on the Library. 195 196In addition, mere aggregation of another work not based on the Library 197with the Library (or with a work based on the Library) on a volume of 198a storage or distribution medium does not bring the other work under 199the scope of this License. 200 201 3. You may opt to apply the terms of the ordinary GNU General Public 202License instead of this License to a given copy of the Library. To do 203this, you must alter all the notices that refer to this License, so 204that they refer to the ordinary GNU General Public License, version 2, 205instead of to this License. (If a newer version than version 2 of the 206ordinary GNU General Public License has appeared, then you can specify 207that version instead if you wish.) Do not make any other change in 208these notices. 209 210 Once this change is made in a given copy, it is irreversible for 211that copy, so the ordinary GNU General Public License applies to all 212subsequent copies and derivative works made from that copy. 213 214 This option is useful when you wish to copy part of the code of 215the Library into a program that is not a library. 216 217 4. You may copy and distribute the Library (or a portion or 218derivative of it, under Section 2) in object code or executable form 219under the terms of Sections 1 and 2 above provided that you accompany 220it with the complete corresponding machine-readable source code, which 221must be distributed under the terms of Sections 1 and 2 above on a 222medium customarily used for software interchange. 223 224 If distribution of object code is made by offering access to copy 225from a designated place, then offering equivalent access to copy the 226source code from the same place satisfies the requirement to 227distribute the source code, even though third parties are not 228compelled to copy the source along with the object code. 229 230 5. A program that contains no derivative of any portion of the 231Library, but is designed to work with the Library by being compiled or 232linked with it, is called a "work that uses the Library". Such a 233work, in isolation, is not a derivative work of the Library, and 234therefore falls outside the scope of this License. 235 236 However, linking a "work that uses the Library" with the Library 237creates an executable that is a derivative of the Library (because it 238contains portions of the Library), rather than a "work that uses the 239library". The executable is therefore covered by this License. 240Section 6 states terms for distribution of such executables. 241 242 When a "work that uses the Library" uses material from a header file 243that is part of the Library, the object code for the work may be a 244derivative work of the Library even though the source code is not. 245Whether this is true is especially significant if the work can be 246linked without the Library, or if the work is itself a library. The 247threshold for this to be true is not precisely defined by law. 248 249 If such an object file uses only numerical parameters, data 250structure layouts and accessors, and small macros and small inline 251functions (ten lines or less in length), then the use of the object 252file is unrestricted, regardless of whether it is legally a derivative 253work. (Executables containing this object code plus portions of the 254Library will still fall under Section 6.) 255 256 Otherwise, if the work is a derivative of the Library, you may 257distribute the object code for the work under the terms of Section 6. 258Any executables containing that work also fall under Section 6, 259whether or not they are linked directly with the Library itself. 260 261 6. As an exception to the Sections above, you may also compile or 262link a "work that uses the Library" with the Library to produce a 263work containing portions of the Library, and distribute that work 264under terms of your choice, provided that the terms permit 265modification of the work for the customer's own use and reverse 266engineering for debugging such modifications. 267 268 You must give prominent notice with each copy of the work that the 269Library is used in it and that the Library and its use are covered by 270this License. You must supply a copy of this License. If the work 271during execution displays copyright notices, you must include the 272copyright notice for the Library among them, as well as a reference 273directing the user to the copy of this License. Also, you must do one 274of these things: 275 276 a) Accompany the work with the complete corresponding 277 machine-readable source code for the Library including whatever 278 changes were used in the work (which must be distributed under 279 Sections 1 and 2 above); and, if the work is an executable linked 280 with the Library, with the complete machine-readable "work that 281 uses the Library", as object code and/or source code, so that the 282 user can modify the Library and then relink to produce a modified 283 executable containing the modified Library. (It is understood 284 that the user who changes the contents of definitions files in the 285 Library will not necessarily be able to recompile the application 286 to use the modified definitions.) 287 288 b) Accompany the work with a written offer, valid for at 289 least three years, to give the same user the materials 290 specified in Subsection 6a, above, for a charge no more 291 than the cost of performing this distribution. 292 293 c) If distribution of the work is made by offering access to copy 294 from a designated place, offer equivalent access to copy the above 295 specified materials from the same place. 296 297 d) Verify that the user has already received a copy of these 298 materials or that you have already sent this user a copy. 299 300 For an executable, the required form of the "work that uses the 301Library" must include any data and utility programs needed for 302reproducing the executable from it. However, as a special exception, 303the source code distributed need not include anything that is normally 304distributed (in either source or binary form) with the major 305components (compiler, kernel, and so on) of the operating system on 306which the executable runs, unless that component itself accompanies 307the executable. 308 309 It may happen that this requirement contradicts the license 310restrictions of other proprietary libraries that do not normally 311accompany the operating system. Such a contradiction means you cannot 312use both them and the Library together in an executable that you 313distribute. 314 315 7. You may place library facilities that are a work based on the 316Library side-by-side in a single library together with other library 317facilities not covered by this License, and distribute such a combined 318library, provided that the separate distribution of the work based on 319the Library and of the other library facilities is otherwise 320permitted, and provided that you do these two things: 321 322 a) Accompany the combined library with a copy of the same work 323 based on the Library, uncombined with any other library 324 facilities. This must be distributed under the terms of the 325 Sections above. 326 327 b) Give prominent notice with the combined library of the fact 328 that part of it is a work based on the Library, and explaining 329 where to find the accompanying uncombined form of the same work. 330 331 8. You may not copy, modify, sublicense, link with, or distribute 332the Library except as expressly provided under this License. Any 333attempt otherwise to copy, modify, sublicense, link with, or 334distribute the Library is void, and will automatically terminate your 335rights under this License. However, parties who have received copies, 336or rights, from you under this License will not have their licenses 337terminated so long as such parties remain in full compliance. 338 339 9. You are not required to accept this License, since you have not 340signed it. However, nothing else grants you permission to modify or 341distribute the Library or its derivative works. These actions are 342prohibited by law if you do not accept this License. Therefore, by 343modifying or distributing the Library (or any work based on the 344Library), you indicate your acceptance of this License to do so, and 345all its terms and conditions for copying, distributing or modifying 346the Library or works based on it. 347 348 10. Each time you redistribute the Library (or any work based on the 349Library), the recipient automatically receives a license from the 350original licensor to copy, distribute, link with or modify the Library 351subject to these terms and conditions. You may not impose any further 352restrictions on the recipients' exercise of the rights granted herein. 353You are not responsible for enforcing compliance by third parties to 354this License. 355 356 11. If, as a consequence of a court judgment or allegation of patent 357infringement or for any other reason (not limited to patent issues), 358conditions are imposed on you (whether by court order, agreement or 359otherwise) that contradict the conditions of this License, they do not 360excuse you from the conditions of this License. If you cannot 361distribute so as to satisfy simultaneously your obligations under this 362License and any other pertinent obligations, then as a consequence you 363may not distribute the Library at all. For example, if a patent 364license would not permit royalty-free redistribution of the Library by 365all those who receive copies directly or indirectly through you, then 366the only way you could satisfy both it and this License would be to 367refrain entirely from distribution of the Library. 368 369If any portion of this section is held invalid or unenforceable under any 370particular circumstance, the balance of the section is intended to apply, 371and the section as a whole is intended to apply in other circumstances. 372 373It is not the purpose of this section to induce you to infringe any 374patents or other property right claims or to contest validity of any 375such claims; this section has the sole purpose of protecting the 376integrity of the free software distribution system which is 377implemented by public license practices. Many people have made 378generous contributions to the wide range of software distributed 379through that system in reliance on consistent application of that 380system; it is up to the author/donor to decide if he or she is willing 381to distribute software through any other system and a licensee cannot 382impose that choice. 383 384This section is intended to make thoroughly clear what is believed to 385be a consequence of the rest of this License. 386 387 12. If the distribution and/or use of the Library is restricted in 388certain countries either by patents or by copyrighted interfaces, the 389original copyright holder who places the Library under this License may add 390an explicit geographical distribution limitation excluding those countries, 391so that distribution is permitted only in or among countries not thus 392excluded. In such case, this License incorporates the limitation as if 393written in the body of this License. 394 395 13. The Free Software Foundation may publish revised and/or new 396versions of the Library General Public License from time to time. 397Such new versions will be similar in spirit to the present version, 398but may differ in detail to address new problems or concerns. 399 400Each version is given a distinguishing version number. If the Library 401specifies a version number of this License which applies to it and 402"any later version", you have the option of following the terms and 403conditions either of that version or of any later version published by 404the Free Software Foundation. If the Library does not specify a 405license version number, you may choose any version ever published by 406the Free Software Foundation. 407 408 14. If you wish to incorporate parts of the Library into other free 409programs whose distribution conditions are incompatible with these, 410write to the author to ask for permission. For software which is 411copyrighted by the Free Software Foundation, write to the Free 412Software Foundation; we sometimes make exceptions for this. Our 413decision will be guided by the two goals of preserving the free status 414of all derivatives of our free software and of promoting the sharing 415and reuse of software generally. 416 417 NO WARRANTY 418 419 15. BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE, THERE IS NO 420WARRANTY FOR THE LIBRARY, TO THE EXTENT PERMITTED BY APPLICABLE LAW. 421EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR 422OTHER PARTIES PROVIDE THE LIBRARY "AS IS" WITHOUT WARRANTY OF ANY 423KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE 424IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 425PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE 426LIBRARY IS WITH YOU. SHOULD THE LIBRARY PROVE DEFECTIVE, YOU ASSUME 427THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 428 429 16. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN 430WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY 431AND/OR REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE, BE LIABLE TO YOU 432FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR 433CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE 434LIBRARY (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING 435RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A 436FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF 437SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH 438DAMAGES. 439 440 END OF TERMS AND CONDITIONS 441 442 Appendix: How to Apply These Terms to Your New Libraries 443 444 If you develop a new library, and you want it to be of the greatest 445possible use to the public, we recommend making it free software that 446everyone can redistribute and change. You can do so by permitting 447redistribution under these terms (or, alternatively, under the terms of the 448ordinary General Public License). 449 450 To apply these terms, attach the following notices to the library. It is 451safest to attach them to the start of each source file to most effectively 452convey the exclusion of warranty; and each file should have at least the 453"copyright" line and a pointer to where the full notice is found. 454 455 <one line to give the library's name and a brief idea of what it does.> 456 Copyright (C) <year> <name of author> 457 458 This library is free software; you can redistribute it and/or 459 modify it under the terms of the GNU Library General Public 460 License as published by the Free Software Foundation; either 461 version 2 of the License, or (at your option) any later version. 462 463 This library is distributed in the hope that it will be useful, 464 but WITHOUT ANY WARRANTY; without even the implied warranty of 465 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 466 Library General Public License for more details. 467 468 You should have received a copy of the GNU Library General Public 469 License along with this library; if not, write to the Free 470 Software Foundation, Inc. 471 472Also add information on how to contact you by electronic and paper mail. 473 474You should also get your employer (if you work as a programmer) or your 475school, if any, to sign a "copyright disclaimer" for the library, if 476necessary. Here is a sample; alter the names: 477 478 Yoyodyne, Inc., hereby disclaims all copyright interest in the 479 library `Frob' (a library for tweaking knobs) written by James Random Hacker. 480 481 <signature of Ty Coon>, 1 April 1990 482 Ty Coon, President of Vice 483 484That's all there is to it! 485