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// Copyright 2015-2016 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
//! TODO: Module-level documentation.
macro_rules! define_type {
( $name:ident, $builtin:ty, $test_c_metrics:ident, $get_c_align_fn:ident,
$get_c_size_fn:ident, $doc:expr ) => {
#[allow(dead_code)] // Not all types are used in all configurations.
#[doc = $doc]
pub type $name = $builtin;
define_metrics_tests!($name, $test_c_metrics, $get_c_align_fn, $get_c_size_fn);
};
}
macro_rules! define_metrics_tests {
( $name:ident, $test_c_metrics:ident, $get_c_align_fn:ident,
$get_c_size_fn:ident ) => {
define_metrics_tests!($name, $test_c_metrics, $get_c_align_fn, $get_c_size_fn, 1);
};
( $name:ident, $test_c_metrics:ident, $c_align:ident, $c_size:ident,
$expected_align_factor:expr ) => {
#[cfg(test)]
extern "C" {
// We can't use `size_t` because we need to test that our
// definition of `size_t` is correct using this code! We use `u16`
// because even 8-bit and 16-bit microcontrollers have no trouble
// with it, and because `u16` is always as smaller or smaller than
// `usize`.
static $c_align: u16;
static $c_size: u16;
}
#[cfg(test)]
#[test]
fn $test_c_metrics() {
use std::mem;
let c_align = unsafe { $c_align };
let c_size = unsafe { $c_size };
// XXX: Remove these assertions and these uses of `as` when Rust
// supports implicit coercion of `u16` to `usize`.
assert!(mem::size_of_val(&c_align) <= mem::size_of::<usize>());
assert!(mem::size_of_val(&c_size) <= mem::size_of::<usize>());
// Rust uses 4 for the alignment of `i64` and `u64`. On Linux x86,
// GCC 5 uses 8 but earlier versions use 4 and so does Clang.
let rust_align =
if $expected_align_factor != 1 && mem::align_of::<$name>() != c_align as usize {
mem::align_of::<$name>() * $expected_align_factor
} else {
mem::align_of::<$name>()
};
assert_eq!(
(rust_align, mem::size_of::<$name>()),
(c_align as usize, c_size as usize)
);
}
};
}
define_type!(
int,
i32,
test_int_metrics,
GFp_int_align,
GFp_int_size,
"The C `int` type. Equivalent to `libc::c_int`."
);
define_type!(
uint,
u32,
test_uint_metrics,
GFp_uint_align,
GFp_uint_size,
"The C `unsigned int` type. Equivalent to `libc::c_uint`."
);
#[cfg(any(target_os = "windows", target_pointer_width = "32"))]
define_type!(
long,
i32,
test_long_metrics,
GFp_long_align,
GFp_long_size,
"The C `long` type. Equivalent to `libc::c_long`."
);
#[cfg(not(any(target_os = "windows", target_pointer_width = "32")))]
define_type!(
long,
i64,
test_long_metrics,
GFp_long_align,
GFp_long_size,
"The C `long` type. Equivalent to `libc::c_long`."
);
define_type!(
size_t,
usize,
test_size_t_metrics,
GFp_size_t_align,
GFp_size_t_size,
"The C `size_t` type from `<stdint.h>`.
ISO C's `size_t` is defined to be the type of the result of the
`sizeof` operator and the type of the size parameter to `malloc`. That
is, C's `size_t` is only required to hold the size of the largest object
that can be allocated. In particular, it is legal for a C implementation
to have a maximum object size smaller than the entire address space. For
example, a C implementation may have an maximum object size of 2^32
bytes with a 64-bit address space, and typedef `size_t` as `uint32_t` so
that `sizeof(size_t) == 4` and `sizeof(void*) == 8`.
Rust's `usize`, on the other hand, is defined to always be the same size
as a pointer. This means that it is possible, in theory, to have a platform
where `usize` can represent values that `size_t` cannot represent. However,
on the vast majority of systems, `usize` and `size_t` are represented the
same way. If it were required to explicitly cast `usize` to `size_t` on
common platforms, then many programmers would habitually write expressions
such as `my_slice.len() as libc::size_t` expecting this to always work and
be safe. But such a cast is *not* safe on the uncommon platforms where
`mem::sizeof(libc::size_t) < mem::size_t(usize)`. Consequently, to reduce
the chances of programmers becoming habituated to such casts that would be
unsafe on unusual platforms, we have adopted the following convention:
* On common platforms where C's `size_t` is the same size as `usize`,
`ring::c::size_t` must be a type alias of `usize`.
* On uncommon platforms where C's `size_t` is not the same size as `usize`,
`ring::c::size_t` must be a type alias for a type other than `usize`.
* Code that was written without consideration for the uncommon platforms
should not do any explicit casting between `size_t` and `usize`. Such
code will fail to compile on the uncommon platforms; this is better than
executing with unsafe truncations.
* Code that was written with full consideration of the uncommon platforms
should have explicit casts using `num::cast` or other methods that avoid
unintended truncation. Such code will then work on all platforms."
);
define_metrics_tests!(i8, test_i8_metrics, GFp_int8_t_align, GFp_int8_t_size);
define_metrics_tests!(u8, test_u8_metrics, GFp_uint8_t_align, GFp_uint8_t_size);
define_metrics_tests!(i16, test_i16_metrics, GFp_int16_t_align, GFp_int16_t_size);
define_metrics_tests!(u16, test_u16_metrics, GFp_uint16_t_align, GFp_uint16_t_size);
define_metrics_tests!(i32, test_i32_metrics, GFp_int32_t_align, GFp_int32_t_size);
define_metrics_tests!(u32, test_u32_metrics, GFp_uint32_t_align, GFp_uint32_t_size);
#[cfg(all(
test,
not(any(
all(target_arch = "x86", target_os = "linux"),
all(target_arch = "x86", target_os = "macos"),
all(target_arch = "x86", target_os = "ios"),
all(target_arch = "arm", target_os = "ios")
))
))]
const SIXTY_FOUR_BIT_ALIGNMENT_FACTOR: usize = 1;
#[cfg(all(
test,
any(
all(target_arch = "x86", target_os = "linux"),
all(target_arch = "x86", target_os = "macos"),
all(target_arch = "x86", target_os = "ios"),
all(target_arch = "arm", target_os = "ios")
)
))]
const SIXTY_FOUR_BIT_ALIGNMENT_FACTOR: usize = 2;
define_metrics_tests!(
i64,
test_i64_metrics,
GFp_int64_t_align,
GFp_int64_t_size,
SIXTY_FOUR_BIT_ALIGNMENT_FACTOR
);
define_metrics_tests!(
u64,
test_u64_metrics,
GFp_uint64_t_align,
GFp_uint64_t_size,
SIXTY_FOUR_BIT_ALIGNMENT_FACTOR
);
#[cfg(target_os = "windows")]
pub mod win32 {
define_type!(
ULONG,
u32,
test_ULONG_metrics,
GFp_ULONG_align,
GFp_ULONG_size,
"The win32 `ULONG` type."
);
define_type!(
BOOLEAN,
u8,
test_BOOLEAN_metrics,
GFp_BOOLEAN_align,
GFp_BOOLEAN_size,
"The win32 `BOOLEAN` type."
);
}