/*
 * CAmkES backing for Rust Read and Write traits.
 *
 * Copyright 2021, Google LLC
 * Apache License 2.0
 *
 * These CAmkES interfaces express the standard Rust read() and write()
 * signatures, assuming two separate, externally defined, and implicitly
 * associated dataports for each of read and write.
 *
 * It is intended that Rust code be able to use extern "C" declarations
 * referencing the camkes.h that this will generate as the core of
 * implementations of the Read and Write traits.
 */

procedure rust_read_inf {
  // Reads up to limit bytes into the read dataport.
  //
  // Returns the number of bytes read or a negative value if there is any
  // error.
  int read(in size_t limit);
};

procedure rust_write_inf {
  // Writes up to a given number of bytes from the write dataport.
  //
  // Returns the number of bytes actually written or a negative value if there
  // is any error. For non-negative return values < available, the caller is
  // reponsible for retrying with the remaining bytes at the beginning of the
  // write dataport.
  int write(in size_t available);

  // Blocks until all bytes so far written have been pushed to the real sink.
  //
  // The semantics are the same as Rust's Write::flush. Returns 0 on success
  // and a negative value if there is any error.
  int flush();
}