[compiler-rt] [asan] Use InternalMmapVector for error_message_buffer, reallocate wh… (PR #77488)

[Vitaly Buka via llvm-commits]

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@@ -42,17 +41,15 @@ void AppendToErrorMessageBuffer(const char *buffer) {
   Lock l(&error_message_buf_mutex);
   if (!error_message_buffer) {
     error_message_buffer =
-      (char*)MmapOrDieQuietly(kErrorMessageBufferSize, __func__);
-    error_message_buffer_pos = 0;
+        new (GetGlobalLowLevelAllocator()) InternalMmapVector<char>();
+    error_message_buffer->reserve(kErrorMessageBufferSize);
+    error_message_buffer->push_back('\0');
   }
-  uptr length = internal_strlen(buffer);
-  RAW_CHECK(kErrorMessageBufferSize >= error_message_buffer_pos);
-  uptr remaining = kErrorMessageBufferSize - error_message_buffer_pos;
-  internal_strncpy(error_message_buffer + error_message_buffer_pos,
-                   buffer, remaining);
-  error_message_buffer[kErrorMessageBufferSize - 1] = '\0';
-  // FIXME: reallocate the buffer instead of truncating the message.
-  error_message_buffer_pos += Min(remaining, length);
+  uptr error_message_buffer_len = error_message_buffer->size() - 1;
+  uptr buffer_len = internal_strlen(buffer);
+  error_message_buffer->resize(error_message_buffer_len + buffer_len + 1);
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vitalybuka wrote:

error_message_buffer->Append() ? 

https://github.com/llvm/llvm-project/pull/77488