From b32be8ebf5e77c1ee9c8d6015a34e7e31b8423c8 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@mit.edu>
Date: Fri, 12 Feb 2016 22:18:46 -0500
Subject: Initial commit
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Create a utility to demonstrate scoville’s escaping scheme.
---
 src/scoville.cc | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 src/scoville.cc

(limited to 'src/scoville.cc')

diff --git a/src/scoville.cc b/src/scoville.cc
new file mode 100644
index 0000000..c0d4d79
--- /dev/null
+++ b/src/scoville.cc
@@ -0,0 +1,117 @@
+// Copyright 2016 Benjamin Barenblat
+//
+// 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.
+
+#include <array>
+#include <cstdlib>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+
+#include <glog/logging.h>
+
+namespace {
+
+class EncodingFailure : public std::logic_error {
+ public:
+  using std::logic_error::logic_error;
+};
+
+class DecodingFailure : public std::logic_error {
+ public:
+  using std::logic_error::logic_error;
+};
+
+void WriteAsciiAsHex(const char c, std::ostringstream* const out) {
+  if (1 < sizeof(c) && 0x100 <= c) {
+    // Not ASCII!
+    throw EncodingFailure("could not encode non-ASCII character '" +
+                          std::string(1, c) + "'");
+  }
+  *out << std::hex << static_cast<int>(c);
+}
+
+char ReadHexAsAscii(std::istringstream* const in) {
+  std::array<char, 3> hex_str;
+  in->get(hex_str.data(), hex_str.size());
+  char* decoded_end;
+  const char result =
+      static_cast<char>(std::strtol(hex_str.data(), &decoded_end, 16));
+  if (decoded_end == hex_str.data()) {
+    throw DecodingFailure("could not decode invalid hex");
+  }
+  return result;
+}
+
+bool IsVfatBadCharacter(const char c) noexcept {
+  return (0 <= c && c < 0x20) || c == '*' || c == '?' || c == '<' || c == '>' ||
+         c == '|' || c == '"' || c == ':' || c == '/' || c == '\\';
+}
+
+void Encode(std::istringstream* const in, std::ostringstream* const out) {
+  char c;
+  while (!in->get(c).eof()) {
+    if (IsVfatBadCharacter(c)) {
+      *out << '%';
+      WriteAsciiAsHex(c, out);
+    } else if (c == '%') {
+      *out << "%%";
+    } else {
+      *out << c;
+    }
+  }
+}
+
+void Decode(std::istringstream* const in, std::ostringstream* const out) {
+  char c;
+  while (!in->get(c).eof()) {
+    if (c == '%') {
+      if (in->peek() == '%') {
+        in->ignore();
+        *out << "%";
+      } else {
+        *out << ReadHexAsAscii(in);
+      }
+    } else {
+      *out << c;
+    }
+  }
+}
+
+}  // namespace
+
+int main(int, char* const argv[]) {
+  FLAGS_logtostderr = true;
+  google::InstallFailureSignalHandler();
+  google::InitGoogleLogging(argv[0]);
+
+  LOG(INFO) << "Got        " << argv[1];
+
+  std::string result;
+  {
+    std::istringstream in(argv[1]);
+    std::ostringstream out;
+    Encode(&in, &out);
+    result = out.str();
+  }
+  LOG(INFO) << "Encoded to " << result;
+
+  {
+    std::istringstream in(result);
+    std::ostringstream out;
+    Decode(&in, &out);
+    result = out.str();
+  }
+  LOG(INFO) << "Decoded to " << result;
+  return 0;
+}
-- 
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