github.com/google/syzkaller@v0.0.0-20240517125934-c0f1611a36d6/executor/_include/flatbuffers/registry.h (about)

     1  /*
     2   * Copyright 2017 Google Inc. All rights reserved.
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  #ifndef FLATBUFFERS_REGISTRY_H_
    18  #define FLATBUFFERS_REGISTRY_H_
    19  
    20  #include "flatbuffers/base.h"
    21  #include "flatbuffers/idl.h"
    22  
    23  namespace flatbuffers {
    24  
    25  // Convenience class to easily parse or generate text for arbitrary FlatBuffers.
    26  // Simply pre-populate it with all schema filenames that may be in use, and
    27  // This class will look them up using the file_identifier declared in the
    28  // schema.
    29  class Registry {
    30   public:
    31    // Call this for all schemas that may be in use. The identifier has
    32    // a function in the generated code, e.g. MonsterIdentifier().
    33    void Register(const char *file_identifier, const char *schema_path) {
    34      Schema schema;
    35      schema.path_ = schema_path;
    36      schemas_[file_identifier] = schema;
    37    }
    38  
    39    // Generate text from an arbitrary FlatBuffer by looking up its
    40    // file_identifier in the registry.
    41    bool FlatBufferToText(const uint8_t *flatbuf, size_t len, std::string *dest) {
    42      // Get the identifier out of the buffer.
    43      // If the buffer is truncated, exit.
    44      if (len < sizeof(uoffset_t) + kFileIdentifierLength) {
    45        lasterror_ = "buffer truncated";
    46        return false;
    47      }
    48      std::string ident(
    49          reinterpret_cast<const char *>(flatbuf) + sizeof(uoffset_t),
    50          kFileIdentifierLength);
    51      // Load and parse the schema.
    52      Parser parser;
    53      if (!LoadSchema(ident, &parser)) return false;
    54      // Now we're ready to generate text.
    55      if (!GenerateText(parser, flatbuf, dest)) {
    56        lasterror_ = "unable to generate text for FlatBuffer binary";
    57        return false;
    58      }
    59      return true;
    60    }
    61  
    62    // Converts a binary buffer to text using one of the schemas in the registry,
    63    // use the file_identifier to indicate which.
    64    // If DetachedBuffer::data() is null then parsing failed.
    65    DetachedBuffer TextToFlatBuffer(const char *text,
    66                                    const char *file_identifier) {
    67      // Load and parse the schema.
    68      Parser parser;
    69      if (!LoadSchema(file_identifier, &parser)) return DetachedBuffer();
    70      // Parse the text.
    71      if (!parser.Parse(text)) {
    72        lasterror_ = parser.error_;
    73        return DetachedBuffer();
    74      }
    75      // We have a valid FlatBuffer. Detach it from the builder and return.
    76      return parser.builder_.Release();
    77    }
    78  
    79    // Modify any parsing / output options used by the other functions.
    80    void SetOptions(const IDLOptions &opts) { opts_ = opts; }
    81  
    82    // If schemas used contain include statements, call this function for every
    83    // directory the parser should search them for.
    84    void AddIncludeDirectory(const char *path) { include_paths_.push_back(path); }
    85  
    86    // Returns a human readable error if any of the above functions fail.
    87    const std::string &GetLastError() { return lasterror_; }
    88  
    89   private:
    90    bool LoadSchema(const std::string &ident, Parser *parser) {
    91      // Find the schema, if not, exit.
    92      auto it = schemas_.find(ident);
    93      if (it == schemas_.end()) {
    94        // Don't attach the identifier, since it may not be human readable.
    95        lasterror_ = "identifier for this buffer not in the registry";
    96        return false;
    97      }
    98      auto &schema = it->second;
    99      // Load the schema from disk. If not, exit.
   100      std::string schematext;
   101      if (!LoadFile(schema.path_.c_str(), false, &schematext)) {
   102        lasterror_ = "could not load schema: " + schema.path_;
   103        return false;
   104      }
   105      // Parse schema.
   106      parser->opts = opts_;
   107      if (!parser->Parse(schematext.c_str(), include_paths_.data(),
   108                         schema.path_.c_str())) {
   109        lasterror_ = parser->error_;
   110        return false;
   111      }
   112      return true;
   113    }
   114  
   115    struct Schema {
   116      std::string path_;
   117      // TODO(wvo) optionally cache schema file or parsed schema here.
   118    };
   119  
   120    std::string lasterror_;
   121    IDLOptions opts_;
   122    std::vector<const char *> include_paths_;
   123    std::map<std::string, Schema> schemas_;
   124  };
   125  
   126  }  // namespace flatbuffers
   127  
   128  #endif  // FLATBUFFERS_REGISTRY_H_