Merge pull request #1357 from jonny5532/feature/improve-web-log

Make web log output show in correct order.

Software/src/devboard/webserver/debug_logging_html.cpp

@@ -4,8 +4,45 @@
 #include "index_html.h"
 
 #if defined(DEBUG_VIA_WEB) || defined(LOG_TO_SD)
+char* strnchr(const char* s, int c, size_t n) {
+  // Like strchr, but only searches the first 'n' bytes of the string.
+
+  if (s == NULL) {
+    return NULL;
+  }
+
+  // Iterate through the string up to 'n' characters or until a null terminator is found.
+  for (size_t i = 0; i < n && s[i] != '\0'; ++i) {
+    if (s[i] == c) {
+      // Character found, return a pointer to it.
+      return (char*)&s[i];
+    }
+  }
+
+  // If the character to be found is the null terminator, and we haven't exceeded
+  // 'n' bytes, check if the null terminator is at the current position.
+  if (c == '\0') {
+    for (size_t i = 0; i < n; ++i) {
+      if (s[i] == '\0') {
+        return (char*)&s[i];
+      }
+    }
+  }
+
+  // Character not found within the first 'n' bytes.
+  return NULL;
+}
+
 String debug_logger_processor(void) {
-  String content = String(index_html_header);
+  String content = String();
+  // Reserve enough space for the content to avoid reallocations.
+  if (!content.reserve(1000 + sizeof(datalayer.system.info.logged_can_messages))) {
+    if (content.reserve(15)) {
+      content += "Out of memory.";
+    }
+    return content;
+  }
+  content += index_html_header;
   // Page format
   content += "<style>";
   content += "body { background-color: black; color: white; font-family: Arial, sans-serif; }";
@@ -28,7 +65,34 @@ String debug_logger_processor(void) {
 
   // Start a new block for the debug log messages
   content += "<PRE style='text-align: left'>";
-  content += String(datalayer.system.info.logged_can_messages);
+  size_t offset = datalayer.system.info.logged_can_messages_offset;
+  // If we're mid-buffer, print the older part first.
+  if (offset > 0 && offset < (sizeof(datalayer.system.info.logged_can_messages) - 1)) {
+    // Find the next newline after the current offset. The offset will always be
+    // before the penultimate character, so (offset + 1) will be the final '\0'
+    // or earlier.
+
+    char* next_newline = strnchr(&datalayer.system.info.logged_can_messages[offset + 1], '\n',
+                                 sizeof(datalayer.system.info.logged_can_messages) - offset - 1);
+
+    if (next_newline != NULL) {
+      // We found a newline, so append from the character after that. We check
+      // the string length to ensure we don't add any intermediate '\0'
+      // characters.
+      content.concat(next_newline + 1,
+                     strnlen(next_newline + 1, sizeof(datalayer.system.info.logged_can_messages) - offset - 2));
+    } else {
+      // No newline found, so append from the next character after the offset to
+      // the end of the buffer. We check the string length to ensure we don't
+      // add any intermediate '\0' characters.
+      content.concat(&datalayer.system.info.logged_can_messages[offset + 1],
+                     strnlen(&datalayer.system.info.logged_can_messages[offset + 1],
+                             sizeof(datalayer.system.info.logged_can_messages) - offset - 1));
+    }
+  }
+  // Append the first part of the buffer up to the current write offset (which
+  // points to the first \0).
+  content.concat(datalayer.system.info.logged_can_messages, offset);
   content += "</PRE>";
 
   // Add JavaScript for navigation