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/*
* (C) 2015,2017 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_FFI_UTILS_H_
#define BOTAN_FFI_UTILS_H_
#include <cstdint>
#include <memory>
#include <stdexcept>
#include <functional>
#include <botan/exceptn.h>
#include <botan/mem_ops.h>
namespace Botan_FFI {
class BOTAN_UNSTABLE_API FFI_Error final : public Botan::Exception
{
public:
FFI_Error(const std::string& what, int err_code) :
Exception("FFI error", what),
m_err_code(err_code)
{}
int error_code() const noexcept override { return m_err_code; }
Botan::ErrorType error_type() const noexcept override { return Botan::ErrorType::InvalidArgument; }
private:
int m_err_code;
};
template<typename T, uint32_t MAGIC>
struct botan_struct
{
public:
botan_struct(T* obj) : m_magic(MAGIC), m_obj(obj) {}
virtual ~botan_struct() { m_magic = 0; m_obj.reset(); }
bool magic_ok() const { return (m_magic == MAGIC); }
T* unsafe_get() const
{
return m_obj.get();
}
private:
uint32_t m_magic = 0;
std::unique_ptr<T> m_obj;
};
#define BOTAN_FFI_DECLARE_STRUCT(NAME, TYPE, MAGIC) \
struct NAME final : public Botan_FFI::botan_struct<TYPE, MAGIC> { explicit NAME(TYPE* x) : botan_struct(x) {} }
// Declared in ffi.cpp
int ffi_error_exception_thrown(const char* func_name, const char* exn,
int rc = BOTAN_FFI_ERROR_EXCEPTION_THROWN);
template<typename T, uint32_t M>
T& safe_get(botan_struct<T,M>* p)
{
if(!p)
throw FFI_Error("Null pointer argument", BOTAN_FFI_ERROR_NULL_POINTER);
if(p->magic_ok() == false)
throw FFI_Error("Bad magic in ffi object", BOTAN_FFI_ERROR_INVALID_OBJECT);
if(T* t = p->unsafe_get())
return *t;
throw FFI_Error("Invalid object pointer", BOTAN_FFI_ERROR_INVALID_OBJECT);
}
int ffi_guard_thunk(const char* func_name, std::function<int ()>);
template<typename T, uint32_t M, typename F>
int apply_fn(botan_struct<T, M>* o, const char* func_name, F func)
{
if(!o)
return BOTAN_FFI_ERROR_NULL_POINTER;
if(o->magic_ok() == false)
return BOTAN_FFI_ERROR_INVALID_OBJECT;
T* p = o->unsafe_get();
if(p == nullptr)
return BOTAN_FFI_ERROR_INVALID_OBJECT;
return ffi_guard_thunk(func_name, [&]() { return func(*p); });
}
#define BOTAN_FFI_DO(T, obj, param, block) \
apply_fn(obj, __func__, \
[=](T& param) -> int { do { block } while(0); return BOTAN_FFI_SUCCESS; })
/*
* Like BOTAN_FFI_DO but with no trailing return with the expectation
* that the block always returns a value. This exists because otherwise
* MSVC warns about the dead return after the block in FFI_DO.
*/
#define BOTAN_FFI_RETURNING(T, obj, param, block) \
apply_fn(obj, __func__, \
[=](T& param) -> int { do { block } while(0); })
template<typename T, uint32_t M>
int ffi_delete_object(botan_struct<T, M>* obj, const char* func_name)
{
try
{
if(obj == nullptr)
return BOTAN_FFI_SUCCESS; // ignore delete of null objects
if(obj->magic_ok() == false)
return BOTAN_FFI_ERROR_INVALID_OBJECT;
delete obj;
return BOTAN_FFI_SUCCESS;
}
catch(std::exception& e)
{
return ffi_error_exception_thrown(func_name, e.what());
}
catch(...)
{
return ffi_error_exception_thrown(func_name, "unknown exception");
}
}
#define BOTAN_FFI_CHECKED_DELETE(o) ffi_delete_object(o, __func__)
inline int write_output(uint8_t out[], size_t* out_len, const uint8_t buf[], size_t buf_len)
{
if(out_len == nullptr)
return BOTAN_FFI_ERROR_NULL_POINTER;
const size_t avail = *out_len;
*out_len = buf_len;
if((avail >= buf_len) && (out != nullptr))
{
Botan::copy_mem(out, buf, buf_len);
return BOTAN_FFI_SUCCESS;
}
else
{
if(out != nullptr)
{
Botan::clear_mem(out, avail);
}
return BOTAN_FFI_ERROR_INSUFFICIENT_BUFFER_SPACE;
}
}
template<typename Alloc>
int write_vec_output(uint8_t out[], size_t* out_len, const std::vector<uint8_t, Alloc>& buf)
{
return write_output(out, out_len, buf.data(), buf.size());
}
inline int write_str_output(uint8_t out[], size_t* out_len, const std::string& str)
{
return write_output(out, out_len,
Botan::cast_char_ptr_to_uint8(str.data()),
str.size() + 1);
}
inline int write_str_output(char out[], size_t* out_len, const std::string& str)
{
return write_str_output(Botan::cast_char_ptr_to_uint8(out), out_len, str);
}
inline int write_str_output(char out[], size_t* out_len, const std::vector<uint8_t>& str_vec)
{
return write_output(Botan::cast_char_ptr_to_uint8(out),
out_len,
str_vec.data(),
str_vec.size());
}
}
#endif
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