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// Copyright (C) 2017-2018 Baidu, Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in
//    the documentation and/or other materials provided with the
//    distribution.
//  * Neither the name of Baidu, Inc., nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use sgx_types::*;

pub type exception_handle = * const c_void;

///
/// rsgx_register_exception_handler registers an exception handler.
///
/// rsgx_register_exception_handler allows developers to register an exception handler, and specify whether to prepend
/// (when is_first_handler is equal to 1) or append the handler to the handler chain.
///
/// # Description
///
/// The Intel(R) SGX SDK supports the registration of custom exception handler functions. You can write your own code to
/// handle a limited set of hardware exceptions. For example, a CPUID instruction inside an enclave will effectively result
/// in a #UD fault (Invalid Opcode Exception). ISV enclave code can have an exception handler to prevent the enclave from
/// being trapped into an exception condition.
///
/// Calling rsgx_register_exception_handler allows you to register an exception handler, and specify whether to prepend
/// (when is_first_handler is nonzero) or append the handler to the handler chain.
///
/// After calling rsgx_register_exception_handler to prepend an exception handler, a subsequent call to this function may
/// add another exception handler at the beginning of the handler chain. Therefore the order in which exception handlers
/// are called does not only depend on the value of the is_first_handler parameter. It depends on the order
/// in which exception handlers are registered.
///
/// # Parameters
///
/// **is_first_handler**
///
/// Specify the order in which the handler should be called. If the parameter is nonzero, the handler is the first handler
/// to be called. If the parameter is zero, the handler is the last handler to be called.
///
/// **exception_handler**
///
/// The exception handler to be called
///
/// # Requirements
///
/// Library: libsgx_trts.a
///
/// # Return value
///
/// **Some(exception_handle)**
///
/// Indicates the exception handler is registered successfully. The return value is an open handle to the custom exception handler.
///
/// **None**
///
/// The exception handler was not registered.
///
pub fn rsgx_register_exception_handler(is_first_handler: u32, exception_handler: sgx_exception_handler_t) -> Option<exception_handle> {

    let handle = unsafe {
        sgx_register_exception_handler(is_first_handler, exception_handler)
    };

    if handle.is_null() { None } else { Some(handle) }
}

///
/// rsgx_unregister_exception_handler is used to unregister a custom exception handler.
///
/// # Description
///
/// The Intel(R) SGX SDK supports the registration of custom exception handler functions. An enclave developer
/// can write their own code to handle a limited set of hardware exceptions.
///
/// Calling rsgx_unregister_exception_handler allows developers to unregister an exception handler that was registered earlier.
///
/// # Parameters
///
/// **handle**
///
/// A handle to the custom exception handler previously registered using the rsgx_register_exception_handler function.
///
/// # Requirements
///
/// Library: libsgx_trts.a
///
/// # Return value
///
/// **true**
///
/// The custom exception handler is unregistered successfully.
///
/// **false**
///
/// The exception handler was not unregistered (not a valid pointer, handler not found).
///
pub fn rsgx_unregister_exception_handler(handle: exception_handle) -> bool {

    let ret = unsafe { sgx_unregister_exception_handler(handle) };
    if ret == 0 { false } else { true }
}