Add support for line buffering

2024-01-27 08:57:21 -08:00
parent 6f260455aa
commit 6435b169ec
2 changed files with 24 additions and 0 deletions
@@ -1517,6 +1517,12 @@ template <typename F> class apple_file : public file_base<F> {
    this->file_->_p += size;
    this->file_->_w -= size;
  }
+
+  bool needs_flush() const {
+    if ((this->file_->_flags & 1) == 0) return false;  // 1 is __SLBF.
+    return memchr(this->file_->_p + this->file_->_w, '\n',
+                  to_unsigned(-this->file_->_w));
+  }
 };

 // A fallback FILE wrapper.
@@ -1529,6 +1535,7 @@ template <typename F> class fallback_file : public file_base<F> {
  using file_base<F>::file_base;

  auto is_buffered() const -> bool { return false; }
+  auto needs_flush() const -> bool { return false; }

  auto get_read_buffer() const -> span<const char> {
    return {&next_, has_next_ ? 1u : 0u};
@@ -1581,7 +1588,9 @@ class file_print_buffer : public buffer<char> {
  }
  ~file_print_buffer() {
    file_.advance_write_buffer(size());
+    bool flush = file_.needs_flush();
    funlockfile(file_);
+    if (flush) fflush(file_);
  }
 };