Closes #3 Validate DBC frame definitions and report error locations

dbc_parser.cpp

@@ -15,8 +15,21 @@
 #include <sstream>
 #include <stdexcept>
 #include <cctype>
+#include <charconv>
+#include <limits>
 
 namespace {
+  std::uint32_t ParseDecimal (const std::string &text,
+                              std::uint32_t maximum,
+                              const char *field) {
+    std::uint32_t value = 0U;
+    const auto parsed = std::from_chars (text.data(), text.data() + text.size(), value);
+    if (text.empty() || parsed.ec != std::errc() ||
+        parsed.ptr != text.data() + text.size() || value > maximum)
+      throw std::runtime_error (std::string ("Invalid ") + field + ": " + text);
+    return value;
+  }
+
   /**
    * @brief Remove leading and trailing spaces.
    * @param text Input text.
@@ -45,31 +58,39 @@ DbcDatabase DbcParser::ParseFile (const std::string &filePath) const {
   DbcDatabase database;
   FrameInfo *currentFrame = nullptr;
 
+  std::size_t lineNumber = 0U;
   std::string line;
   while (std::getline (input, line)) {
+    ++lineNumber;
     line = Trim (line);
     if (line.empty())
       continue;
 
-    if (IsFrameLine (line)) {
-      FrameInfo frame = ParseFrameLine (line);
-      database.frames.push_back (frame);
-      currentFrame = &database.frames.back();
-    } else if (IsSignalLine (line)) {
-      if (currentFrame == nullptr)
-        throw std::runtime_error ("Signal found before any frame definition.");
+    try {
+      if (IsFrameLine (line)) {
+        FrameInfo frame = ParseFrameLine (line);
+        database.frames.push_back (frame);
+        currentFrame = &database.frames.back();
+      } else if (IsSignalLine (line)) {
+        if (currentFrame == nullptr)
+          throw std::runtime_error ("Signal found before any frame definition.");
 
-      SignalInfo signal = ParseSignalLine (line);
-      currentFrame->signals.push_back (signal);
-    } else if (IsCommentLine (line))
-      ParseCommentLine (line, database);
+        SignalInfo signal = ParseSignalLine (line);
+        currentFrame->signals.push_back (signal);
+      } else if (IsCommentLine (line))
+        ParseCommentLine (line, database);
+    } catch (const std::exception &error) {
+      throw std::runtime_error (filePath + ":" + std::to_string (lineNumber) +
+                                ": " + error.what());
+    }
   }
 
   return database;
 }
 
 bool DbcParser::IsFrameLine (const std::string &line) {
-  return (line.size() >= 4U) && (line.compare (0U, 4U, "BO_ ") == 0);
+  return (line.compare (0U, 3U, "BO_") == 0) &&
+    ((line.size() == 3U) || std::isspace (static_cast<unsigned char> (line[3U])));
 }
 
 bool DbcParser::IsSignalLine (const std::string &line) {
@@ -146,33 +167,37 @@ FrameInfo DbcParser::ParseFrameLine (const std::string &line) {
    */
 
   std::istringstream stream (line);
-  std::string token;
+  std::string keyword;
+  std::string idText;
+  if (!(stream >> keyword >> idText) || keyword != "BO_")
+    throw std::runtime_error ("Missing CAN ID in frame definition.");
+
+  const std::uint32_t rawCanId = ParseDecimal (
+    idText, std::numeric_limits<std::uint32_t>::max(), "CAN ID");
+  // Only bit 31 may accompany the actual 29-bit identifier.
+  if ((rawCanId & 0x60000000U) != 0U)
+    throw std::runtime_error ("CAN ID exceeds the 29-bit identifier range.");
+
+  std::string nameText;
+  if (!std::getline (stream, nameText, ':') || stream.eof())
+    throw std::runtime_error ("Missing ':' in frame definition.");
+  std::istringstream nameStream (nameText);
   FrameInfo frame;
-  std::uint32_t rawCanId = 0U;
+  std::string extra;
+  if (!(nameStream >> frame.name) || (nameStream >> extra))
+    throw std::runtime_error ("Missing or invalid frame name.");
 
-  stream >> token;
-  if (token != "BO_")
-    throw std::runtime_error ("Invalid frame line: " + line);
+  std::string lengthText;
+  if (!(stream >> lengthText))
+    throw std::runtime_error ("Missing payload length in frame definition.");
+  frame.dlc = static_cast<std::uint8_t> (ParseDecimal (
+    lengthText, std::numeric_limits<std::uint8_t>::max(), "payload length"));
+  if (!(stream >> frame.transmitter))
+    throw std::runtime_error ("Missing transmitter in frame definition.");
+  if (stream >> extra)
+    throw std::runtime_error ("Unexpected trailing field in frame definition: " + extra);
 
-  stream >> rawCanId;
   NormalizeCanId (rawCanId, frame.canId, frame.isExtended);
-
-  stream >> token;
-  if (token.empty())
-    throw std::runtime_error ("Missing frame name: " + line);
-
-  if (token[token.size() - 1U] == ':')
-    token.erase (token.size() - 1U, 1U);
-
-  frame.name = token;
-
-  {
-    unsigned int dlcValue = 0U;
-    stream >> dlcValue;
-    frame.dlc = static_cast<std::uint8_t> (dlcValue);
-  }
-
-  stream >> frame.transmitter;
   frame.pgn = TryExtractPgn (frame.canId, frame.isExtended, frame.hasPgn);
 
   return frame;