Handle invalid glibc FILE buffer

2025-07-06 08:58:22 -07:00
parent 513f978241
commit 300ce75ca6
2 changed files with 16 additions and 1 deletions
--- a/include/fmt/format-inl.h
+++ b/include/fmt/format-inl.h
@@ -1549,7 +1549,8 @@ template <typename F> class glibc_file : public file_base<F> {
  bool needs_flush() const {
    if ((this->file_->_flags & line_buffered) == 0) return false;
    char* end = this->file_->_IO_write_end;
-    return memchr(end, '\n', to_unsigned(this->file_->_IO_write_ptr - end));
+    auto size = max_of<ptrdiff_t>(this->file_->_IO_write_ptr - end, 0);
+    return memchr(end, '\n', static_cast<size_t>(size));
  }

  void flush() { fflush_unlocked(this->file_); }