Feat improve read tests

include/libserial/serial.hpp

@@ -302,6 +302,26 @@ void setMinNumberCharRead(uint16_t);
  */
 void setBaudRate(BaudRate baud_rate);
 
+/**
+ * @brief Sets the maximum safe read size
+ *
+ * Configures the maximum number of bytes that can be read
+ * in a single read operation to prevent excessive memory usage.
+ *
+ * @param size The desired maximum safe read size in bytes
+ */
+void setMaxSafeReadSize(size_t size);
+
+/**
+ * @brief Gets the maximum safe read size
+ *
+ * Retrieves the maximum number of bytes that can be read
+ * in a single read operation to prevent excessive memory usage.
+ *
+ * @return The maximum safe read size in bytes
+ */
+size_t getMaxSafeReadSize() const;
+
 /**
  * @brief Gets the current baud rate
  *
@@ -318,8 +338,9 @@ int getBaudRate() const;
 void setFdForTest(int fd) {
   fd_serial_port_ = fd;
 }
-
-// For testing - allow injection of mock functions
+// WARNING: Test helper only! This function allows injection of custom
+// system call functions for testing error handling. It should NEVER be
+// used in production code.
 void setSystemCallFunctions(
   std::function<int(struct pollfd*, nfds_t, int)> poll_func,
   std::function<ssize_t(int, void*, size_t)> read_func) {
@@ -410,8 +431,9 @@ std::chrono::milliseconds write_timeout_ms_{1000};    ///< Write timeout in mill
  *
  * Defines the maximum number of bytes that can be read
  * in a single read operation to prevent excessive memory usage.
+ * Default is 2048 bytes (2KB).
  */
-static constexpr size_t kMaxSafeReadSize = 2048;  // 2KB limit
+size_t max_safe_read_size_{2048};  // 2KB limit
 
 /**
  * @brief Timeout value in milliseconds

src/serial.cpp

@@ -65,7 +65,7 @@ size_t Serial::read(std::shared_ptr<std::string> buffer) {
   }
 
   buffer->clear();
-  buffer->resize(kMaxSafeReadSize);
+  buffer->resize(max_safe_read_size_);
 
   struct pollfd fd_poll;
   fd_poll.fd = fd_serial_port_;
@@ -83,7 +83,8 @@ size_t Serial::read(std::shared_ptr<std::string> buffer) {
   }
 
   // Data available: do the read
-  ssize_t bytes_read = read_(fd_serial_port_, const_cast<char*>(buffer->data()), kMaxSafeReadSize);
+  ssize_t bytes_read = read_(fd_serial_port_, const_cast<char*>(buffer->data()),
+                             max_safe_read_size_);
   if (bytes_read < 0) {
     throw IOException(std::string("Error reading from serial port: ") + strerror(errno));
   }
@@ -108,7 +109,7 @@ size_t Serial::readBytes(std::shared_ptr<std::string> buffer, size_t num_bytes)
   buffer->clear();
   buffer->resize(num_bytes);
 
-  ssize_t bytes_read = ::read(fd_serial_port_, buffer->data(), num_bytes);  // codacy-ignore[buffer-boundary]
+  ssize_t bytes_read = read_(fd_serial_port_, buffer->data(), num_bytes);  // codacy-ignore[buffer-boundary]
 
   if (bytes_read < 0) {
     throw IOException("Error reading from serial port: " + std::string(strerror(errno)));
@@ -130,9 +131,9 @@ size_t Serial::readUntil(std::shared_ptr<std::string> buffer, char terminator) {
 
   while (temp_char != terminator) {
     // Check buffer size limit to prevent excessive memory usage
-    if (buffer->size() >= kMaxSafeReadSize) {
+    if (buffer->size() >= max_safe_read_size_) {
       throw IOException("Read buffer exceeded maximum size limit of " +
-                        std::to_string(kMaxSafeReadSize) +
+                        std::to_string(max_safe_read_size_) +
                         " bytes without finding terminator");
     }
     // Check timeout if enabled (0 means no timeout)
@@ -344,6 +345,14 @@ void Serial::setMinNumberCharRead(uint16_t num) {
   this->setTermios2();
 }
 
+void Serial::setMaxSafeReadSize(size_t size) {
+  max_safe_read_size_ = size;
+}
+
+size_t Serial::getMaxSafeReadSize() const {
+  return max_safe_read_size_;
+}
+
 int Serial::getAvailableData() const {
   int bytes_available;
   if (ioctl(fd_serial_port_, FIONREAD, &bytes_available) < 0) {

test/test_serial_pty.cpp

@@ -426,6 +426,39 @@ TEST_F(PseudoTerminalTest, ReadBytesWithInvalidNumBytes) {
   }, libserial::IOException);
 }
 
+TEST_F(PseudoTerminalTest, ReadBytesWithReadFail) {
+  libserial::Serial serial_port;
+
+  serial_port.open(slave_port_);
+  serial_port.setBaudRate(9600);
+  serial_port.setCanonicalMode(libserial::CanonicalMode::DISABLE);
+
+  auto read_buffer = std::make_shared<std::string>();
+
+  for (const auto& [error_num, error_msg] : errors_read_) {
+    serial_port.setSystemCallFunctions(
+      [](struct pollfd*, nfds_t, int) -> int {
+      return 1;
+    },
+      [error_num](int, void*, size_t) -> ssize_t {
+      errno = error_num;
+      return -1;
+    });
+
+    auto expected_what = "Error reading from serial port: " + error_msg;
+
+    EXPECT_THROW({
+      try {
+        serial_port.readBytes(read_buffer, 10);
+      }
+      catch (const libserial::IOException& e) {
+        EXPECT_STREQ(expected_what.c_str(), e.what());
+        throw;
+      }
+    }, libserial::IOException);
+  }
+}
+
 TEST_F(PseudoTerminalTest, ReadBytesCanonicalMode) {
   libserial::Serial serial_port;
 
@@ -472,6 +505,25 @@ TEST_F(PseudoTerminalTest, ReadUntil) {
   EXPECT_EQ(*read_buffer, "Read Until!");
 }
 
+TEST_F(PseudoTerminalTest, ReadUntilWithNullBuffer) {
+  libserial::Serial serial_port;
+
+  serial_port.open(slave_port_);
+  serial_port.setBaudRate(9600);
+
+  std::shared_ptr<std::string> null_buffer;
+
+  EXPECT_THROW({
+    try {
+      serial_port.readUntil(null_buffer, '!');
+    }
+    catch (const libserial::IOException& e) {
+      EXPECT_STREQ("Null pointer passed to readUntil function", e.what());
+      throw;
+    }
+  }, libserial::IOException);
+}
+
 TEST_F(PseudoTerminalTest, ReadUntilTimeout) {
   libserial::Serial serial_port;
 
@@ -552,3 +604,38 @@ TEST_F(PseudoTerminalTest, ReadUntilWithPollFail) {
     }, libserial::IOException);
   }
 }
+
+TEST_F(PseudoTerminalTest, ReadUntilWithOverflowBuffer) {
+  libserial::Serial serial_port;
+
+  serial_port.open(slave_port_);
+  serial_port.setBaudRate(9600);
+  EXPECT_NO_THROW(serial_port.setMaxSafeReadSize(10));  // Set max safe read size to 10 bytes
+
+  std::string test_message(15, 'a');
+  test_message.push_back('\n');
+
+  ssize_t bytes_written = write(master_fd_, test_message.c_str(), test_message.length());
+  ASSERT_GT(bytes_written, 0) << "Failed to write to master end";
+
+  // Give time for data to propagate
+  fsync(master_fd_);
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+  // Test reading with shared pointer - only read what's available
+  auto read_buffer = std::make_shared<std::string>();
+
+  auto expected_what = "Read buffer exceeded maximum size limit of " +
+                       std::to_string(serial_port.getMaxSafeReadSize()) +
+                       " bytes without finding terminator";
+
+  EXPECT_THROW({
+    try {
+      serial_port.readUntil(read_buffer, '!');
+    }
+    catch (const libserial::IOException& e) {
+      EXPECT_STREQ(expected_what.c_str(), e.what());
+      throw;
+    }
+  }, libserial::IOException);
+}