Function pact_matching_ffi::error::get_error_message[−][src]

#[no_mangle]
pub extern "C" fn get_error_message(
    buffer: *mut c_char, 
    length: c_int
) -> c_int
Expand description

Provide the error message from LAST_ERROR to the calling C code.

This function should be called after any other function in the pact_matching FFI indicates a failure with its own error message, if the caller wants to get more context on why the error happened.

Do note that this error-reporting mechanism only reports the top-level error message, not any source information embedded in the original Rust error type. If you want more detailed information for debugging purposes, use the logging interface.

Params

  • buffer: a pointer to an array of char of sufficient length to hold the error message.
  • length: an int providing the length of the buffer.

Return Codes

  • The number of bytes written to the provided buffer, which may be zero if there is no last error.
  • -1 if the provided buffer is a null pointer.
  • -2 if the provided buffer length is too small for the error message.
  • -3 if the write failed for some other reason.
  • -4 if the error message had an interior NULL

Notes

Note that this function zeroes out any excess in the provided buffer.

Error Handling

The return code must be checked for one of the negative number error codes before the buffer is used. If an error code is present, the buffer may not be in a usable state.

If the buffer is longer than needed for the error message, the excess space will be zeroed as a safety mechanism. This is slightly less efficient than leaving the contents of the buffer alone, but the difference is expected to be negligible in practice.