1 files changed, 18 insertions, 12 deletions

diff --git a/src/buffer.cc b/src/buffer.cc
index 65c6757..3073a45 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -20,7 +20,7 @@ class FixedBuffer : public Buffer {
       avail = 0;
     } else {
       avail = (data_.get() + size_) - rptr_;
-      if (avail < need) {
+      if (avail < need && rptr_ > data_.get()) {
         rotate();
         return rptr(avail, need);
       }
@@ -36,7 +36,7 @@ class FixedBuffer : public Buffer {
       if (rptr_ == wptr_)
         reset();
     } else {
-      assert(rptr_ != wptr_ || !full_);
+      assert(rptr_ != wptr_ || full_);
       assert(std::cmp_greater_equal((data_.get() + size_) - rptr_, size));
       rptr_ += size;
       if (rptr_ == data_.get() + size_) {
@@ -59,7 +59,7 @@ class FixedBuffer : public Buffer {
       avail = 0;
     } else {
       avail = (data_.get() + size_) - wptr_;
-      if (avail < need) {
+      if (avail < need && rptr_ > data_.get()) {
         rotate();
         return wptr(avail, need);
       }
@@ -102,18 +102,24 @@ class FixedBuffer : public Buffer {
   }
 
   void rotate() {
-    size_t to_move = (data_.get() + size_) - rptr_;
-    if (wptr_ + to_move > rptr_) {
-      auto tmp = std::make_unique_for_overwrite<char[]>(to_move);
-      memcpy(tmp.get(), rptr_, to_move);
-      memmove(data_.get() + to_move, data_.get(), wptr_ - data_.get());
-      memcpy(data_.get(), tmp.get(), to_move);
+    if (rptr_ < wptr_) {
+      size_t size = wptr_ - rptr_;
+      memmove(data_.get(), rptr_, size);
+      wptr_ = data_.get() + size;
     } else {
-      memmove(data_.get() + to_move, data_.get(), wptr_ - data_.get());
-      memcpy(data_.get(), rptr_, to_move);
+      size_t to_move = (data_.get() + size_) - rptr_;
+      if (wptr_ + to_move > rptr_) {
+        auto tmp = std::make_unique_for_overwrite<char[]>(to_move);
+        memcpy(tmp.get(), rptr_, to_move);
+        memmove(data_.get() + to_move, data_.get(), wptr_ - data_.get());
+        memcpy(data_.get(), tmp.get(), to_move);
+      } else {
+        memmove(data_.get() + to_move, data_.get(), wptr_ - data_.get());
+        memcpy(data_.get(), rptr_, to_move);
+      }
+      wptr_ += to_move;
     }
     rptr_ = data_.get();
-    wptr_ += to_move;
   }
 
   size_t const size_;