Added license and readme, renamed a class and changed main to generat…

…e jars.

LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

README.md

@@ -0,0 +1,99 @@
+# Mappings Hasher
+This is a tool that creates a hashed mapping from a given mapping.
+There are multiple reasons why you'd want to use this mapping rather than the raw mappings:
+- If the raw mappings are under a more restrictive license,
+  the hashed mappings contain only very little information about them.
+  Keep in mind that this doesn't necessarily mean you'll have rights to the hashed mappings.
+  I am not a lawyer.
+- The hashed mapping are likely more stable than the original ones.
+  This is mostly because of built-in hardening against package renames and descriptor changes.
+- The hashed mappings look distinct from the original mappings.
+  This is useful if you want to use the hashed mappings as a base for another mapping set.
+- You can always create these mappings from scratch and automatically.
+  Other intermediary mappings need to be kept updated manually starting at some base version.
+
+## Generating mappings
+The repository as is, is designed for generating hashed Minecraft mappings.
+You simply invoke the jar with the version id from the version manifest as the argument.
+For example, in order to create the hashed mappings for the first release candidate for 1.17.1 you run:
+
+    java <jar-file> 1.17.1-rc1
+
+This will download the mappings, the client jar and all required libraries and cache them for future runs.
+Then it will create the output jar in `out/mappings/hashed-<version>.jar`.
+
+## Hashing rules
+This section describes how the program generates the hashed names.
+
+### Hash format
+The generated hashed names are of the following form:
+- Classes: `C_<hash>`
+- Methods: `m_<hash>`
+- Fields: `f_<hash>`
+
+The `<hash>` are the least significant 8 characters of the base-26 representation of the members "raw name".
+
+If a class, method or field is unobfuscated, no mapping is generated.
+
+### Raw names
+The raw name is string created from the original mapping.
+The formatting was chosen in a way to harden against instability in the original raw mapping set.
+
+#### Classes
+The raw name of a class is its full name from the original mapping, e.g. `net/example/Outer$Inner`.
+The use of slashed names is natural since that is how the class names are in JVM bytecode.
+
+In order to harden the mapping set against package names, the package name is stripped wherever possible.
+If the simple class name is unique in the provided jar, the raw name is instead its simple name, e.g. `Outer$Inner`.
+Conversely, if there is a class `net/example/A` and a class `net/test/A`, the full name must be used.
+
+If the class is unobfuscated, that means annotated as such, the raw name equals its name in the original mapping.
+
+#### Methods
+The raw name of a method is `m;<raw-class-name>.<method-name>;<method-descriptor>`.
+The `<raw-class-name>` is described above, the method name and descriptor are taken from the original mapping.
+The `m;` prefix is required since methods and fields look otherwise identical if the descriptor is stripped.
+
+In order to harden the mapping set against descriptor changes, the descriptor is stripped wherever possible.
+If the method name is unique in its containing class, the descriptor in the raw name is left empty.
+
+If the method is unobfuscated, that means annotated as such, the raw name equals its name in the original mapping.
+The special method names "<init>" and "<clinit>" are also treated as unobfuscated.
+
+Methods require additional logic since they can override methods in other classes.
+If a method overrides another, it is required that their raw names are equal.
+If a method overrides *multiple* other methods, they all need to have the same name.
+For this reason, a "name set" is formed.
+This set contains the raw names of all "top level methods" that need to have the same name.
+"Top level" means that those methods don't override another method.
+From this set the lexically biggest name is chosen and used as the raw name for all other methods in the set.
+
+#### Fields
+The raw name of a field is `f;<raw-class-name>.<field-name>;<field-descriptor>`.
+The `<raw-class-name>` is described above, the field name and descriptor are taken from the original mapping.
+The `f;` prefix is required since methods and fields look otherwise identical if the descriptor is stripped.
+
+In order to harden the mapping set against descriptor changes, the descriptor is stripped wherever possible.
+If the field name is unique in its containing class, the descriptor in the raw name is left empty.
+
+> Note that while java doesn't allow fields to only differ in their descriptor, the JVM does.
+
+## Inner workings
+Internally, the `MappingsHasher` class does most of the heavy-lifting.
+It is supplied with a `MappingSet` and a default package for all obfuscated classes.
+
+Next, all the libraries have to be added via `MappingsHasher.addLibrary(JarFile library)`.
+This is necessary in order for the hasher to correctly detect when methods override library methods.
+The hasher will treat these methods as unobfuscated.
+
+One can specify additional annotations that mark classes, methods and fields as unobfuscated.
+Annotating a method, field or nested class will also mark the containing class as unobfuscated.
+Annotating a class will mark all its methods and fields (but not nested classes) as unobfuscated.
+Note that these annotations should be specified in their hashed form.
+
+Finally, invoking `MappingsHasher.generate(JarFile jar)` with the obfuscated jar will return a new `MappingSet`.
+First, it extracts all the class and member information from the jar,
+while recursively resolving super classes and interfaces.
+This considers all provided jars, as well as the classpath (mostly for the java platform).
+Then the hasher iterates all classes and their members again and creates the hashe mappings.
+

src/main/java/org/quiltmc/mappings_hasher/Main.java

@@ -15,6 +15,8 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.jar.JarFile;
+import java.util.jar.JarOutputStream;
+import java.util.zip.ZipEntry;
 
 public class Main {
     public static void main(String[] args) throws IOException {
@@ -47,32 +49,34 @@ public static void main(String[] args) throws IOException {
         InputStream mojmapStream = Files.newInputStream(mojmapFile.toPath());
         TextMappingsReader mappingsReader = new ProGuardReader(new InputStreamReader(mojmapStream));
         MappingSet obf_to_mojmap = mappingsReader.read().reverse();
-        MappingHasher mappingHasher = new MappingHasher(obf_to_mojmap, "net/minecraft/unmapped");
+        MappingsHasher mappingsHasher = new MappingsHasher(obf_to_mojmap, "net/minecraft/unmapped");
 
         System.out.println("Loading libs...");
         for (LibraryEntry lib : version.libraries()) {
             JarFile libJar = new JarFile(lib.getOrDownload());
-            mappingHasher.addLibrary(libJar);
+            mappingsHasher.addLibrary(libJar);
         }
 
         System.out.println("Loading client jar...");
         JarFile clientJar = new JarFile(version.downloads().get("client").getOrDownload());
 
         System.out.println("Generating mappings...");
-        mappingHasher.addDontObfuscateAnnotation("net/minecraft/unmapped/C_qwuptkcl", true);
-        mappingHasher.addDontObfuscateAnnotation("net/minecraft/unmapped/C_prlazzma", true);
-        MappingSet obf_to_hashed = mappingHasher.generate(clientJar);
+        mappingsHasher.addDontObfuscateAnnotation("net/minecraft/unmapped/C_qwuptkcl", true);
+        mappingsHasher.addDontObfuscateAnnotation("net/minecraft/unmapped/C_prlazzma", true);
+        MappingSet obf_to_hashed = mappingsHasher.generate(clientJar);
 
         System.out.println("Writing mappings to file...");
-        Path outPath = Paths.get("mappings", version.id() + ".tiny");
+        Path outPath = Paths.get("mappings", "hashed-" + version.id() + ".jar");
         Files.createDirectories(outPath.getParent());
         Files.deleteIfExists(outPath);
         Files.createFile(outPath);
-        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(Files.newOutputStream(outPath)));
+
+        JarOutputStream outJar = new JarOutputStream(Files.newOutputStream(outPath));
+        outJar.putNextEntry(new ZipEntry("hashed/mappings.tiny"));
+        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outJar));
         TinyMappingsWriter mappingsWriter = new TinyMappingsWriter(writer, "official", "hashed");
         mappingsWriter.write(obf_to_hashed);
         writer.flush();
-        writer.close();
-
+        outJar.close();
     }
 }