Update getFileBlock response parsing and error handling

This adds response error checking for getFileBlock and minor formatting fixes to make it similar to other methods

Author: fronders

src/SparkFun_u-blox_SARA-R5_Arduino_Library.cpp

@@ -5580,12 +5580,14 @@ SARA_R5_error_t SARA_R5::getFileContents(String filename, char *contents)
   return err;
 }
 
-SARA_R5_error_t SARA_R5::getFileBlock(const String& filename, char* buffer, size_t offset, size_t requested_length, size_t& bytes_read)
+SARA_R5_error_t SARA_R5::getFileBlock(const String& filename, char* buffer, size_t offset, size_t requestedLength, size_t& bytesRead)
 {
   SARA_R5_error_t err;
   char *command;
-  bytes_read = 0;
-  if (filename.length() < 1 || buffer == nullptr || requested_length < 1)
+  char *response;
+
+  bytesRead = 0;
+  if (filename.length() < 1 || buffer == nullptr || requestedLength < 1)
   {
       return SARA_R5_ERROR_UNEXPECTED_PARAM;
   }
@@ -5607,55 +5609,94 @@ SARA_R5_error_t SARA_R5::getFileBlock(const String& filename, char* buffer, size
     return SARA_R5_ERROR_OUT_OF_MEMORY;
   }
 #ifdef ULLONG_MAX
-  sprintf(command, "%s=\"%s\",%llu,%llu", SARA_R5_FILE_SYSTEM_READ_BLOCK, filename.c_str(), (unsigned long long) offset, (unsigned long long) requested_length);
+  sprintf(command, "%s=\"%s\",%llu,%llu", SARA_R5_FILE_SYSTEM_READ_BLOCK, filename.c_str(), (unsigned long long) offset, (unsigned long long) requestedLength);
 #else
-  sprintf(command, "%s=\"%s\",%lu,%lu", SARA_R5_FILE_SYSTEM_READ_BLOCK, filename.c_str(), (unsigned long) offset, (unsigned long) requested_length);
+  sprintf(command, "%s=\"%s\",%lu,%lu", SARA_R5_FILE_SYSTEM_READ_BLOCK, filename.c_str(), (unsigned long) offset, (unsigned long) requestedLength);
 #endif
+
+  response = sara_r5_calloc_char(minimumResponseAllocation);
+  if (response == nullptr)
+  {
+    if (_printDebug == true)
+    {
+      _debugPort->print(F("getFileBlock: response alloc failed: "));
+      _debugPort->println(minimumResponseAllocation);
+    }
+    free(command);
+    return SARA_R5_ERROR_OUT_OF_MEMORY;
+  }
+
+  // Send command and wait for some response
+  // Response format: \r\n+URDBLOCK: "filename",64000,"these bytes are the data of the file block"\r\n\r\nOK\r\n
   sendCommand(command, true);
+  err = waitForResponse(SARA_R5_FILE_SYSTEM_READ_BLOCK, SARA_R5_RESPONSE_ERROR, 5 * SARA_R5_STANDARD_RESPONSE_TIMEOUT);
+  if (err != SARA_R5_ERROR_SUCCESS)
+  {
+    if (_printDebug == true)
+    {
+      _debugPort->print(F("getFileBlock: waitForResponse returned err "));
+      _debugPort->println(err);
+    }
+    free(command);
+    free(response);
+    return err;
+  }
 
+  // Skip the filename in quotes and get the data length index
   int ich;
   char ch;
-  int quote_count = 0;
-  size_t comma_idx = 0;
-
-  while (quote_count < 3)
+  int quoteCount = 0;
+  size_t lengthIndex = 0;
+  while (quoteCount < 3 && bytesRead < minimumResponseAllocation)
   {
     ich = _hardSerial->read();
     if (ich < 0)
     {
       continue;
     }
     ch = (char)(ich & 0xFF);
-    command[bytes_read++] = ch;
+    response[bytesRead++] = ch;
     if (ch == '"')
     {
-      quote_count++;
+      quoteCount++;
     }
-    else if (ch == ',' && quote_count == 2)
+    else if (ch == ',' && lengthIndex == 0 && quoteCount == 2)
     {
-      comma_idx = bytes_read;
+      lengthIndex = bytesRead;
     }
   }
+  response[bytesRead] = 0; // Make response a null-terminated string
+  response[bytesRead - 2] = 0; // Terminate response string right after block length
+  size_t data_length = strtoul(&response[lengthIndex], nullptr, 10);
 
-  command[bytes_read] = 0;
-  command[bytes_read - 2] = 0;
-
-  // Example response:
-  // +URDBLOCK: "wombat.bin",64000,"<data starts here>... "<cr><lf>
-  size_t data_length = strtoul(&command[comma_idx], nullptr, 10);
-  free(command);
-
-  bytes_read = 0;
-  size_t bytes_remaining = data_length;
-  while (bytes_read < data_length)
+  // Read file block data directly into supplied buffer
+  bytesRead = 0;
+  size_t bytesRemaining = data_length;
+  while (bytesRead < data_length)
   {
     // This method seems more reliable than reading a byte at a time.
-    size_t rc = _hardSerial->readBytes(&buffer[bytes_read], bytes_remaining);
-    bytes_read += rc;
-    bytes_remaining -= rc;
+    size_t rc = _hardSerial->readBytes(&buffer[bytesRead], bytesRemaining);
+    bytesRead += rc;
+    bytesRemaining -= rc;
   }
 
-  return SARA_R5_ERROR_SUCCESS;
+  // Read rest of response until \r\nOK\r\n
+  err = waitForResponse(SARA_R5_RESPONSE_OK, SARA_R5_RESPONSE_ERROR, SARA_R5_STANDARD_RESPONSE_TIMEOUT);
+  if (err != SARA_R5_ERROR_SUCCESS)
+  {
+    if (_printDebug == true)
+    {
+      _debugPort->print(F("getFileBlock: waitForResponse returned err "));
+      _debugPort->println(err);
+    }
+    free(command);
+    free(response);
+    return err;
+  }
+
+  free(command);
+  free(response);
+  return err;
 }
 
 SARA_R5_error_t SARA_R5::getFileSize(String filename, int *size)

src/SparkFun_u-blox_SARA-R5_Arduino_Library.h

@@ -1010,7 +1010,7 @@ class SARA_R5 : public Print
   // TO DO: add full support for file tags. Default tag to USER
   SARA_R5_error_t getFileContents(String filename, String *contents); // OK for text files. But will fail with binary files (containing \0) on some platforms.
   SARA_R5_error_t getFileContents(String filename, char *contents); // OK for binary files. Make sure contents can hold the entire file. Get the size first with getFileSize.
-  SARA_R5_error_t getFileBlock(const String& filename, char* buffer, size_t offset, size_t length, size_t& bytes_read); // OK for binary files. Make sure buffer can hold the requested block size.
+  SARA_R5_error_t getFileBlock(const String& filename, char* buffer, size_t offset, size_t requestedLength, size_t& bytesRead); // OK for binary files. Make sure buffer can hold the requested block size.
 
   // Append data to a file, delete file first to not appends the data.
   SARA_R5_error_t appendFileContents(String filename, String str);