From c49c6da80346c6d648afd94257ea2942489d3018 Mon Sep 17 00:00:00 2001 From: Wouter van Oortmerssen Date: Mon, 4 May 2015 13:36:27 -0700 Subject: [PATCH] Added extra checks for reading binaries in flatc By default, disallow reading binaries that do not correspond to the schema file_identifier. Override with --raw-binary Change-Id: I24822c0e4c80dab4e5a238ae2b6e601a09025c27 Tested: on Linux. --- docs/html/md__compiler.html | 1 + docs/source/Compiler.md | 3 ++ src/flatc.cpp | 81 ++++++++++++++++++++++++++++----------------- 3 files changed, 55 insertions(+), 30 deletions(-) diff --git a/docs/html/md__compiler.html b/docs/html/md__compiler.html index e6ee2b0..a372904 100644 --- a/docs/html/md__compiler.html +++ b/docs/html/md__compiler.html @@ -71,6 +71,7 @@ $(document).ready(function(){initNavTree('md__compiler.html','');});
  • --no-prefix : Don't prefix enum values in generated C++ by their enum type.
  • --gen-includes : Generate include statements for included schemas the generated file depends on (C++).
  • --gen-mutable : Generate additional non-const accessors for mutating FlatBuffers in-place.
    • +
  • --raw-binary : Allow binaries without a file_indentifier to be read. This may crash flatc given a mismatched schema.
  • --proto: Expect input files to be .proto files (protocol buffers). Output the corresponding .fbs file. Currently supports: package, message, enum. Does not support, but will skip without error: import, option. Does not support, will generate error: service, extend, extensions, oneof, group, custom options, nested declarations.
    • diff --git a/docs/source/Compiler.md b/docs/source/Compiler.md index 6a73bb7..cb0bb96 100755 --- a/docs/source/Compiler.md +++ b/docs/source/Compiler.md @@ -54,6 +54,9 @@ be generated for each file processed: - `--gen-mutable` : Generate additional non-const accessors for mutating FlatBuffers in-place. +- `--raw-binary` : Allow binaries without a file_indentifier to be read. + This may crash flatc given a mismatched schema. + - `--proto`: Expect input files to be .proto files (protocol buffers). Output the corresponding .fbs file. Currently supports: `package`, `message`, `enum`. diff --git a/src/flatc.cpp b/src/flatc.cpp index e22085e..4b570d2 100755 --- a/src/flatc.cpp +++ b/src/flatc.cpp @@ -18,8 +18,8 @@ #include "flatbuffers/idl.h" #include "flatbuffers/util.h" -static void Error(const char *err, const char *obj = nullptr, - bool usage = false, bool show_exe_name = true); +static void Error(const std::string &err, bool usage = false, + bool show_exe_name = true); // This struct allows us to create a table of all possible output generators // for the various programming languages and formats we support. @@ -68,12 +68,9 @@ const Generator generators[] = { const char *program_name = NULL; -static void Error(const char *err, const char *obj, bool usage, - bool show_exe_name) { +static void Error(const std::string &err, bool usage, bool show_exe_name) { if (show_exe_name) printf("%s: ", program_name); - printf("%s", err); - if (obj) printf(": %s", obj); - printf("\n"); + printf("%s\n", err.c_str()); if (usage) { printf("usage: %s [OPTION]... FILE... [-- FILE...]\n", program_name); for (size_t i = 0; i < sizeof(generators) / sizeof(generators[0]); ++i) @@ -90,6 +87,8 @@ static void Error(const char *err, const char *obj, bool usage, " --gen-includes Generate include statements for included schemas the\n" " generated file depends on (C++).\n" " --gen-mutable Generate accessors that can mutate buffers in-place.\n" + " --raw-binary Allow binaries without file_indentifier to be read.\n" + " This may crash flatc given a mismatched schema." " --proto Input is a .proto, translate to .fbs.\n" "FILEs may depend on declarations in earlier files.\n" "FILEs after the -- must be binary flatbuffer format files.\n" @@ -110,45 +109,47 @@ int main(int argc, const char *argv[]) { bool any_generator = false; bool print_make_rules = false; bool proto_mode = false; + bool raw_binary = false; std::vector filenames; std::vector include_directories; size_t binary_files_from = std::numeric_limits::max(); for (int argi = 1; argi < argc; argi++) { - const char *arg = argv[argi]; + std::string arg = argv[argi]; if (arg[0] == '-') { if (filenames.size() && arg[1] != '-') - Error("invalid option location", arg, true); - std::string opt = arg; - if (opt == "-o") { - if (++argi >= argc) Error("missing path following", arg, true); + Error("invalid option location: " + arg, true); + if (arg == "-o") { + if (++argi >= argc) Error("missing path following: " + arg, true); output_path = flatbuffers::ConCatPathFileName(argv[argi], ""); - } else if(opt == "-I") { - if (++argi >= argc) Error("missing path following", arg, true); + } else if(arg == "-I") { + if (++argi >= argc) Error("missing path following" + arg, true); include_directories.push_back(argv[argi]); - } else if(opt == "--strict-json") { + } else if(arg == "--strict-json") { opts.strict_json = true; - } else if(opt == "--no-prefix") { + } else if(arg == "--no-prefix") { opts.prefixed_enums = false; - } else if(opt == "--gen-mutable") { + } else if(arg == "--gen-mutable") { opts.mutable_buffer = true; - } else if(opt == "--gen-includes") { + } else if(arg == "--gen-includes") { opts.include_dependence_headers = true; - } else if(opt == "--") { // Separator between text and binary inputs. + } else if(arg == "--raw-binary") { + raw_binary = true; + } else if(arg == "--") { // Separator between text and binary inputs. binary_files_from = filenames.size(); - } else if(opt == "--proto") { + } else if(arg == "--proto") { proto_mode = true; any_generator = true; - } else if(opt == "-M") { + } else if(arg == "-M") { print_make_rules = true; } else { for (size_t i = 0; i < num_generators; ++i) { - if (opt == generators[i].generator_opt) { + if (arg == generators[i].generator_opt) { generator_enabled[i] = true; any_generator = true; goto found; } } - Error("unknown commandline argument", arg, true); + Error("unknown commandline argument" + arg, true); found:; } } else { @@ -159,7 +160,7 @@ int main(int argc, const char *argv[]) { if (!filenames.size()) Error("missing input files", nullptr, true); if (!any_generator) - Error("no options", "specify one of -c -g -j -t -b etc.", true); + Error("no options: specify one of -c -g -j -t -b etc.", true); // Now process the files: flatbuffers::Parser parser(opts.strict_json, proto_mode); @@ -168,7 +169,7 @@ int main(int argc, const char *argv[]) { ++file_it) { std::string contents; if (!flatbuffers::LoadFile(file_it->c_str(), true, &contents)) - Error("unable to load file", file_it->c_str()); + Error("unable to load file" + *file_it); bool is_binary = static_cast(file_it - filenames.begin()) >= binary_files_from; @@ -177,13 +178,33 @@ int main(int argc, const char *argv[]) { parser.builder_.PushBytes( reinterpret_cast(contents.c_str()), contents.length()); + if (!raw_binary) { + // Generally reading binaries that do not correspond to the schema + // will crash, and sadly there's no way around that when the binary + // does not contain a file identifier. + // We'd expect that typically any binary used as a file would have + // such an identifier, so by default we require them to match. + if (!parser.file_identifier_.length()) { + Error("current schema has no file_identifier: cannot test if \"" + + *file_it + + "\" matches the schema, use --raw-binary to read this file" + " anyway."); + } else if (!flatbuffers::BufferHasIdentifier(contents.c_str(), + parser.file_identifier_.c_str())) { + Error("binary \"" + + *file_it + + "\" does not have expected file_identifier \"" + + parser.file_identifier_ + + "\", use --raw-binary to read this file anyway."); + } + } } else { auto local_include_directory = flatbuffers::StripFileName(*file_it); include_directories.push_back(local_include_directory.c_str()); include_directories.push_back(nullptr); if (!parser.Parse(contents.c_str(), &include_directories[0], file_it->c_str())) - Error(parser.error_.c_str(), nullptr, false, false); + Error(parser.error_, false, false); include_directories.pop_back(); include_directories.pop_back(); } @@ -197,10 +218,10 @@ int main(int argc, const char *argv[]) { if (!print_make_rules) { flatbuffers::EnsureDirExists(output_path); if (!generators[i].generate(parser, output_path, filebase, opts)) { - Error((std::string("Unable to generate ") + - generators[i].lang_name + - " for " + - filebase).c_str()); + Error(std::string("Unable to generate ") + + generators[i].lang_name + + " for " + + filebase); } } else { std::string make_rule = generators[i].make_rule( -- 2.7.4