scrambling key and value to escape ascii codes

example/example.cpp

@@ -404,5 +404,5 @@ void attribute_example() {
     std::string logfmt_pattern = "time=%Y-%m-%dT%H:%M:%S.%f%z, name=%n, level=%^%l%$, process=%P, thread=%t, message=\"%v\", ";
     logfmt_logger->set_pattern(logfmt_pattern);
 
-    logfmt_logger->log(spdlog::level::info, "logfmt structured logging", {{"key1", "value1"}, {"key2", "value2"}});
+    logfmt_logger->log(spdlog::level::info, "logfmt structured logging", {{"key\n1", "value\n1"}, {"key\r\n2", "value\r\n2"}});
 }

include/spdlog/details/attr_composer.h

@@ -0,0 +1,75 @@
+#pragma once
+
+#include <string>
+
+namespace spdlog {
+namespace details {
+
+inline void scramble(std::string& dst, std::string_view s)
+{
+    if (s.empty())
+        return;
+
+    auto start = s.data();
+    auto const end = s.data() + s.size();
+    auto cursor = start;
+
+    dst.reserve(dst.size() + s.size());
+
+    auto replace = [&](std::string_view with) {
+        dst.append(start, size_t(cursor - start));
+        ++cursor;
+        start = cursor;
+        dst.append(with);
+    };
+
+    while (cursor != end) {
+        auto c = static_cast<unsigned char>(*cursor);
+
+        switch (c) {
+        case '\b':
+            replace("\\b");
+            break;
+        case '\f':
+            replace("\\f");
+            break;
+        case '\n':
+            replace("\\n");
+            break;
+        case '\r':
+            replace("\\r");
+            break;
+        case '\t':
+            replace("\\t");
+            break;
+        case '\\':
+            replace("\\\\");
+            break;
+        case '"':
+            replace("\\\"");
+            break;
+        default:
+            if (c <= '\x0f') {
+                char buf[] = "\\u0000";
+                buf[5] += c;
+                if (c >= '\x0a')
+                    buf[5] += 'a' - ':';
+                replace(buf);
+            }
+            else if (c <= '\x1f' || c == 0x7f) {
+                char buf[] = "\\u0010";
+                buf[5] += c - 16;
+                if (c >= '\x1a')
+                    buf[5] += 'a' - ':';
+                replace(buf);
+            }
+            else
+                ++cursor;
+        }
+    }
+    if (cursor != start)
+        dst.append({start, size_t(cursor - start)});
+}
+
+}
+}

include/spdlog/details/log_attr.h

@@ -3,6 +3,7 @@
 #include <string>
 #include <string_view>
 #include <concepts>
+#include "attr_composer.h"
 
 namespace spdlog {
 namespace details {
@@ -12,15 +13,15 @@ namespace details {
 
 struct attr
 {
-    std::string_view key;
-    std::string_view value;
+    std::string key;
+    std::string value;
 
 public:
     attr(std::initializer_list<std::string_view> l) {
         if (l.size() != 2) return; // throw exception if not kv pair?
 
-        key = *l.begin();
-        value = *(l.begin()+1);
+        scramble(key, *l.begin());
+        scramble(value, *(l.begin()+1));
     }
 
     attr(std::string_view k, bool v)