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doc(runtime-c-api) Improve error functions' documentations.

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This commit is contained in:
Ivan Enderlin
2020-01-20 14:23:52 +01:00
parent 9b483d3fe8
commit 384c501c93
1 changed files with 26 additions and 16 deletions
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42
lib/runtime-c-api/src/error.rs
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@ -22,16 +22,12 @@ pub(crate) fn take_last_error() -> Option<Box<dyn Error>> {
LAST_ERROR.with(|prev| prev.borrow_mut().take())
}
/// Gets the length in bytes of the last error.
/// Gets the length in bytes of the last error if any.
///
/// This can be used to dynamically allocate a buffer with the correct number of
/// bytes needed to store a message.
///
/// # Example
///
/// ```c
/// int error_len = wasmer_last_error_length();
/// char *error_str = malloc(error_len);
/// ```
/// See `wasmer_last_error_message()` to get a full example.
#[no_mangle]
pub extern "C" fn wasmer_last_error_length() -> c_int {
LAST_ERROR.with(|prev| match *prev.borrow() {
@ -40,19 +36,33 @@ pub extern "C" fn wasmer_last_error_length() -> c_int {
})
}
/// Stores the last error message into the provided buffer up to the given `length`.
/// The `length` parameter must be large enough to store the last error message.
/// Gets the last error message if any into the provided buffer
/// `buffer` up to the given `length`.
///
/// Returns the length of the string in bytes.
/// Returns `-1` if an error occurs.
/// The `length` parameter must be large enough to store the last
/// error message. Ideally, the value should come from
/// `wasmer_last_error_length()`.
///
/// # Example
/// The function returns the length of the string in bytes, `-1` if an
/// error occurs. Potential errors are:
///
/// * The buffer is a null pointer,
/// * The buffer is too smal to hold the error message.
///
/// Note: The error message always has a trailing null character.
///
/// Example:
///
/// ```c
/// int error_len = wasmer_last_error_length();
/// char *error_str = malloc(error_len);
/// wasmer_last_error_message(error_str, error_len);
/// printf("Error str: `%s`\n", error_str);
/// int error_length = wasmer_last_error_length();
///
/// if (error_length > 0) {
/// char *error_message = malloc(error_length);
/// wasmer_last_error_message(error_message, error_length);
/// printf("Error message: `%s`\n", error_message);
/// } else {
/// printf("No error message\n");
/// }
/// ```
#[no_mangle]
pub unsafe extern "C" fn wasmer_last_error_message(buffer: *mut c_char, length: c_int) -> c_int {