OSS-Fuzz: Add new fuzzer targets help rendering process

fuzz/corpus/help_render_fuzzer/all-ff.seed

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+ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

fuzz/corpus/help_render_fuzzer/ascii-wide.seed

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+width zero narrow gutter indent help description choices default hidden

fuzz/corpus/help_render_fuzzer/choices.seed

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+red green blue fast slow verbose

fuzz/corpus/help_render_fuzzer/help-parse.seed

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+-h --help render after help request

fuzz/corpus/help_render_fuzzer/long-desc.seed

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+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

fuzz/corpus/help_render_fuzzer/newlines.seed

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+a
+b
+c description with newlines

fuzz/corpus/help_render_fuzzer/normal-width.seed

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+prog 80 6 40 2 1 normal terminal width

fuzz/corpus/help_render_fuzzer/random48.seed

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+þØNP³êßh]£Mæ¼û\AI»B^WI¡1_ô¶ÙÃêúÙ26
Ÿ7ÏÞ?*^”Y~J

fuzz/corpus/help_render_fuzzer/tiny.seed

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+x

fuzz/help_render_fuzzer.cpp

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+/*
+ * Fuzzer for the help rendering and text formatting machinery of args.hxx.
+ *
+ * The original OSS-Fuzz target (parse_args_fuzzer) only parses arguments
+ * and never renders help, so description building, word wrapping, prog
+ * lines, gutters, and choices/defaults rendering stayed untested.
+ *
+ * This harness:
+ *   - builds a schema with fuzzer-varied descriptions, defaults, choices,
+ *     hidden options, a validated group, and positionals,
+ *   - varies every ArgumentParser helpParams field, including pathological
+ *     narrow widths that historically caused unsigned underflow
+ *     (see test/help_underflow.cxx),
+ *   - parses a mix of recognized and arbitrary tokens so help rendering
+ *     runs against varied matched state, and
+ *   - renders help through all available paths: ArgumentParser::Help(),
+ *     operator<<(std::ostream&, const ArgumentParser&),
+ *     GetDescription()/GetProgramLine(), and the HelpFlag exception path.
+ */
+
+#include <cstddef>
+#include <cstdint>
+#include <sstream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include <fuzzer/FuzzedDataProvider.h>
+
+#include <args.hxx>
+
+namespace
+{
+
+// Prevent the rendered strings from being dead-code eliminated.
+unsigned long g_sink = 0;
+
+// Only combinations the setters accept: they throw on invalid input, and
+// schema setup exceptions would test the validators, not the formatting
+// code this harness targets.
+const char *const kLongPrefixes[] = {"--", "/", "-", "---"};
+const char *const kShortPrefixes[] = {"-", "/", ""};
+const char *const kTerminators[] = {"--", "-", ""};
+const char *const kLongSeparators[] = {"=", ":", "-", " "};
+
+bool (*const kGroupValidators[])(const args::Group &) = {
+    &args::Group::Validators::DontCare,
+    &args::Group::Validators::AtMostOne,
+    &args::Group::Validators::AtLeastOne,
+    &args::Group::Validators::Xor,
+    &args::Group::Validators::AllOrNone,
+};
+
+const char *const kTokens[] = {
+    "-h", "--help", "-a", "--alpha", "-b", "--beta", "-n", "7", "--number=42",
+    "--number=-3", "--number=x", "--number=", "-w", "one", "--words=two",
+    "-c", "red", "--colour=nope", "-g", "2.5", "--gamma=1e3", "-d", "--",
+    "positional", "-z", "--unknown", "",
+};
+
+template <typename T, size_t N>
+constexpr size_t ArraySize(T (&)[N])
+{
+    return N;
+}
+
+} // namespace
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+    FuzzedDataProvider fdp(data, size);
+
+    // -- Schema, with fuzzer-varied text --------------------------------------
+    args::ArgumentParser parser(fdp.ConsumeRandomLengthString(64),
+                                fdp.ConsumeRandomLengthString(64));
+
+    try
+    {
+        parser.LongPrefix(kLongPrefixes[fdp.ConsumeIntegralInRange<size_t>(0, ArraySize(kLongPrefixes) - 1)]);
+        parser.ShortPrefix(kShortPrefixes[fdp.ConsumeIntegralInRange<size_t>(0, ArraySize(kShortPrefixes) - 1)]);
+        parser.LongSeparator(kLongSeparators[fdp.ConsumeIntegralInRange<size_t>(0, ArraySize(kLongSeparators) - 1)]);
+        parser.Terminator(kTerminators[fdp.ConsumeIntegralInRange<size_t>(0, ArraySize(kTerminators) - 1)]);
+    }
+    catch (...)
+    {
+    }
+
+    args::HelpFlag help(parser, "help", "Displays this help menu", {'h', "help"});
+
+    args::Options flagOptions = args::Options::None;
+    switch (fdp.ConsumeIntegralInRange<unsigned>(0, 3))
+    {
+        case 1:
+            flagOptions = args::Options::HiddenFromDescription;
+            break;
+        case 2:
+            flagOptions = args::Options::HiddenFromUsage;
+            break;
+        case 3:
+            flagOptions = args::Options::Hidden;
+            break;
+        default:
+            break;
+    }
+
+    args::Flag alpha(parser, "alpha", fdp.ConsumeRandomLengthString(64), {'a', "alpha"}, flagOptions);
+    args::CounterFlag beta(parser, "beta", fdp.ConsumeRandomLengthString(64), {'b', "beta"}, 0, flagOptions);
+    args::ValueFlag<int> number(parser, "number", fdp.ConsumeRandomLengthString(64), {'n', "number"}, fdp.ConsumeIntegral<int>());
+    args::ValueFlag<std::string> text(parser, "text", fdp.ConsumeRandomLengthString(64), {"text"}, fdp.ConsumeRandomLengthString(24));
+    args::ValueFlagList<std::string> words(parser, "words", fdp.ConsumeRandomLengthString(64), {'w', "words"});
+
+    // Must be std::unordered_map: MapFlag's Map template parameter defaults
+    // to args::detail::unordered_map and std::map does not convert.
+    const std::unordered_map<std::string, int> choices{{"red", 1}, {"green", 2}, {"blue", 3}};
+    args::MapFlag<std::string, int> colour(parser, "colour", fdp.ConsumeRandomLengthString(64), {'c', "colour"}, choices);
+
+    args::Group group(parser, fdp.ConsumeRandomLengthString(32),
+                      kGroupValidators[fdp.ConsumeIntegralInRange<size_t>(0, ArraySize(kGroupValidators) - 1)]);
+    args::ValueFlag<double> gamma(group, "gamma", fdp.ConsumeRandomLengthString(64), {'g', "gamma"}, 0.5);
+    args::Flag delta(group, "delta", fdp.ConsumeRandomLengthString(64), {'d'});
+
+    args::Positional<std::string> source(parser, "source", fdp.ConsumeRandomLengthString(64));
+    args::PositionalList<std::string> extra(parser, "extra", fdp.ConsumeRandomLengthString(64));
+
+    // -- Every HelpParams field, including pathological narrow widths ---------
+    parser.helpParams.width = fdp.ConsumeIntegralInRange<unsigned>(0, 300);
+    parser.helpParams.progindent = fdp.ConsumeIntegralInRange<unsigned>(0, 16);
+    parser.helpParams.progtailindent = fdp.ConsumeIntegralInRange<unsigned>(0, 16);
+    parser.helpParams.descriptionindent = fdp.ConsumeIntegralInRange<unsigned>(0, 16);
+    parser.helpParams.flagindent = fdp.ConsumeIntegralInRange<unsigned>(0, 24);
+    parser.helpParams.helpindent = fdp.ConsumeIntegralInRange<unsigned>(0, 96);
+    parser.helpParams.eachgroupindent = fdp.ConsumeIntegralInRange<unsigned>(0, 8);
+    parser.helpParams.gutter = fdp.ConsumeIntegralInRange<unsigned>(0, 8);
+    parser.helpParams.showTerminator = fdp.ConsumeBool();
+    parser.helpParams.showProglineOptions = fdp.ConsumeBool();
+    parser.helpParams.showProglinePositionals = fdp.ConsumeBool();
+    parser.helpParams.showCommandChildren = fdp.ConsumeBool();
+    parser.helpParams.showCommandFullHelp = fdp.ConsumeBool();
+    parser.helpParams.proglineShowFlags = fdp.ConsumeBool();
+    parser.helpParams.proglinePreferShortFlags = fdp.ConsumeBool();
+    parser.helpParams.useValueNameOnce = fdp.ConsumeBool();
+    parser.helpParams.showValueName = fdp.ConsumeBool();
+    parser.helpParams.addNewlineBeforeDescription = fdp.ConsumeBool();
+    parser.helpParams.addChoices = fdp.ConsumeBool();
+    parser.helpParams.addDefault = fdp.ConsumeBool();
+    parser.helpParams.programName = fdp.ConsumeRandomLengthString(24);
+    parser.helpParams.usageString = fdp.ConsumeRandomLengthString(24);
+    parser.helpParams.optionsString = fdp.ConsumeRandomLengthString(24);
+    parser.helpParams.proglineOptions = fdp.ConsumeRandomLengthString(16);
+    parser.helpParams.proglineCommand = fdp.ConsumeRandomLengthString(16);
+    parser.helpParams.valueOpen = fdp.ConsumeRandomLengthString(8);
+    parser.helpParams.valueClose = fdp.ConsumeRandomLengthString(8);
+    parser.helpParams.choiceString = fdp.ConsumeRandomLengthString(16);
+    parser.helpParams.defaultString = fdp.ConsumeRandomLengthString(16);
+
+    // -- Parse a token mix so rendering runs against varied matched state -----
+    const size_t tokenCount = fdp.ConsumeIntegralInRange<size_t>(0, 8);
+    std::vector<std::string> argv;
+    argv.reserve(tokenCount);
+    for (size_t i = 0; i < tokenCount; ++i)
+    {
+        if (fdp.ConsumeBool())
+        {
+            argv.emplace_back(kTokens[fdp.ConsumeIntegralInRange<size_t>(0, ArraySize(kTokens) - 1)]);
+        }
+        else
+        {
+            argv.emplace_back(fdp.ConsumeRandomLengthString(16));
+        }
+    }
+
+    try
+    {
+        parser.ParseArgs(argv);
+    }
+    catch (...)
+    {
+    }
+
+    // -- Render through every help path ----------------------------------------
+    g_sink += parser.Help().size();
+
+    std::ostringstream stream;
+    stream << parser;
+    g_sink += stream.str().size();
+
+    g_sink += parser.GetDescription(parser.helpParams, 0).size();
+    g_sink += parser.GetProgramLine(parser.helpParams).size();
+
+    // Re-render with flipped boolean toggles to hit the alternate branches.
+    parser.helpParams.addChoices = !parser.helpParams.addChoices;
+    parser.helpParams.addDefault = !parser.helpParams.addDefault;
+    parser.helpParams.addNewlineBeforeDescription = !parser.helpParams.addNewlineBeforeDescription;
+    g_sink += parser.Help().size();
+
+    return 0;
+}