[scudo][standalone] Add flags & related parsers

Summary:
As with other Sanitizers, and the current version of Scudo, we can
provide flags in differents way: at compile time, through a weak
function, through an environment variable.

This change adds support for the configuration flags, and the string
parsers. Those are fairly similar to the sanitizer_common way of doing
things.

Reviewers: morehouse, hctim, vitalybuka

Reviewed By: morehouse, vitalybuka

Subscribers: mgorny, delcypher, jdoerfert, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D59597

llvm-svn: 358011

1 files changed, 56 insertions, 0 deletions

diff --git a/compiler-rt/lib/scudo/standalone/flags_parser.h b/compiler-rt/lib/scudo/standalone/flags_parser.h
new file mode 100644
index 00000000000..d65bff7e785
--- /dev/null
+++ b/compiler-rt/lib/scudo/standalone/flags_parser.h
@@ -0,0 +1,56 @@
+//===-- flags_parser.h ------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SCUDO_FLAGS_PARSER_H_
+#define SCUDO_FLAGS_PARSER_H_
+
+#include "report.h"
+#include "string_utils.h"
+
+#include <stddef.h>
+#include <stdlib.h>
+
+namespace scudo {
+
+enum class FlagType : u8 {
+  FT_bool,
+  FT_int,
+};
+
+class FlagParser {
+public:
+  void registerFlag(const char *Name, const char *Desc, FlagType Type,
+                    void *Var);
+  void parseString(const char *S);
+  void printFlagDescriptions();
+
+private:
+  static const u32 MaxFlags = 12;
+  struct Flag {
+    const char *Name;
+    const char *Desc;
+    FlagType Type;
+    void *Var;
+  } Flags[MaxFlags];
+
+  u32 NumberOfFlags = 0;
+  const char *Buffer = nullptr;
+  uptr Pos = 0;
+
+  void reportFatalError(const char *Error);
+  void skipWhitespace();
+  void parseFlags();
+  void parseFlag();
+  bool runHandler(const char *Name, const char *Value);
+};
+
+void reportUnrecognizedFlags();
+
+} // namespace scudo
+
+#endif // SCUDO_FLAGS_PARSER_H_