95e00bfed8
This commit applies rustfmt with default settings to files in src/libcore *that are not involved in any currently open PR* to minimize merge conflicts. The list of files involved in open PRs was determined by querying GitHub's GraphQL API with this script: https://gist.github.com/dtolnay/aa9c34993dc051a4f344d1b10e4487e8 With the list of files from the script in `outstanding_files`, the relevant commands were: $ find src/libcore -name '*.rs' | xargs rustfmt --edition=2018 $ rg libcore outstanding_files | xargs git checkout -- Repeating this process several months apart should get us coverage of most of the rest of libcore.
402 lines
12 KiB
Rust
402 lines
12 KiB
Rust
#![stable(feature = "", since = "1.30.0")]
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#![allow(non_camel_case_types)]
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//! Utilities related to FFI bindings.
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use crate::fmt;
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use crate::marker::PhantomData;
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use crate::ops::{Deref, DerefMut};
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/// Equivalent to C's `void` type when used as a [pointer].
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///
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/// In essence, `*const c_void` is equivalent to C's `const void*`
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/// and `*mut c_void` is equivalent to C's `void*`. That said, this is
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/// *not* the same as C's `void` return type, which is Rust's `()` type.
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///
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/// To model pointers to opaque types in FFI, until `extern type` is
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/// stabilized, it is recommended to use a newtype wrapper around an empty
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/// byte array. See the [Nomicon] for details.
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///
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/// One could use `std::os::raw::c_void` if they want to support old Rust
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/// compiler down to 1.1.0. After Rust 1.30.0, it was re-exported by
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/// this definition. For more information, please read [RFC 2521].
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///
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/// [pointer]: ../../std/primitive.pointer.html
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/// [Nomicon]: https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs
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/// [RFC 2521]: https://github.com/rust-lang/rfcs/blob/master/text/2521-c_void-reunification.md
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// N.B., for LLVM to recognize the void pointer type and by extension
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// functions like malloc(), we need to have it represented as i8* in
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// LLVM bitcode. The enum used here ensures this and prevents misuse
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// of the "raw" type by only having private variants. We need two
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// variants, because the compiler complains about the repr attribute
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// otherwise and we need at least one variant as otherwise the enum
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// would be uninhabited and at least dereferencing such pointers would
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// be UB.
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#[repr(u8)]
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#[stable(feature = "core_c_void", since = "1.30.0")]
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pub enum c_void {
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#[unstable(
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feature = "c_void_variant",
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reason = "temporary implementation detail",
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issue = "0"
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)]
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#[doc(hidden)]
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__variant1,
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#[unstable(
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feature = "c_void_variant",
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reason = "temporary implementation detail",
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issue = "0"
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)]
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#[doc(hidden)]
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__variant2,
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}
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#[stable(feature = "std_debug", since = "1.16.0")]
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impl fmt::Debug for c_void {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("c_void")
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}
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}
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/// Basic implementation of a `va_list`.
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// The name is WIP, using `VaListImpl` for now.
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#[cfg(any(
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all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")),
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all(target_arch = "aarch64", target_os = "ios"),
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target_arch = "wasm32",
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target_arch = "asmjs",
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windows
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))]
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#[repr(transparent)]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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#[lang = "va_list"]
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pub struct VaListImpl<'f> {
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ptr: *mut c_void,
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// Invariant over `'f`, so each `VaListImpl<'f>` object is tied to
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// the region of the function it's defined in
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_marker: PhantomData<&'f mut &'f c_void>,
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}
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#[cfg(any(
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all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")),
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all(target_arch = "aarch64", target_os = "ios"),
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target_arch = "wasm32",
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target_arch = "asmjs",
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windows
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))]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'f> fmt::Debug for VaListImpl<'f> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "va_list* {:p}", self.ptr)
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}
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}
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/// AArch64 ABI implementation of a `va_list`. See the
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/// [AArch64 Procedure Call Standard] for more details.
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///
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/// [AArch64 Procedure Call Standard]:
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/// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055b/IHI0055B_aapcs64.pdf
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#[cfg(all(target_arch = "aarch64", not(target_os = "ios"), not(windows)))]
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#[repr(C)]
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#[derive(Debug)]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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#[lang = "va_list"]
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pub struct VaListImpl<'f> {
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stack: *mut c_void,
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gr_top: *mut c_void,
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vr_top: *mut c_void,
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gr_offs: i32,
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vr_offs: i32,
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_marker: PhantomData<&'f mut &'f c_void>,
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}
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/// PowerPC ABI implementation of a `va_list`.
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#[cfg(all(target_arch = "powerpc", not(windows)))]
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#[repr(C)]
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#[derive(Debug)]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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#[lang = "va_list"]
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pub struct VaListImpl<'f> {
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gpr: u8,
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fpr: u8,
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reserved: u16,
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overflow_arg_area: *mut c_void,
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reg_save_area: *mut c_void,
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_marker: PhantomData<&'f mut &'f c_void>,
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}
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/// x86_64 ABI implementation of a `va_list`.
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#[cfg(all(target_arch = "x86_64", not(windows)))]
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#[repr(C)]
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#[derive(Debug)]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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#[lang = "va_list"]
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pub struct VaListImpl<'f> {
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gp_offset: i32,
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fp_offset: i32,
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overflow_arg_area: *mut c_void,
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reg_save_area: *mut c_void,
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_marker: PhantomData<&'f mut &'f c_void>,
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}
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/// A wrapper for a `va_list`
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#[repr(transparent)]
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#[derive(Debug)]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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pub struct VaList<'a, 'f: 'a> {
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#[cfg(any(
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all(
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not(target_arch = "aarch64"),
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not(target_arch = "powerpc"),
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not(target_arch = "x86_64")
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),
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all(target_arch = "aarch64", target_os = "ios"),
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target_arch = "wasm32",
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target_arch = "asmjs",
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windows
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))]
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inner: VaListImpl<'f>,
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#[cfg(all(
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any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"),
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any(not(target_arch = "aarch64"), not(target_os = "ios")),
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not(target_arch = "wasm32"),
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not(target_arch = "asmjs"),
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not(windows)
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))]
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inner: &'a mut VaListImpl<'f>,
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_marker: PhantomData<&'a mut VaListImpl<'f>>,
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}
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#[cfg(any(
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all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")),
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all(target_arch = "aarch64", target_os = "ios"),
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target_arch = "wasm32",
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target_arch = "asmjs",
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windows
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))]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'f> VaListImpl<'f> {
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/// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`.
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#[inline]
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pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> {
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VaList { inner: VaListImpl { ..*self }, _marker: PhantomData }
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}
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}
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#[cfg(all(
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any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"),
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any(not(target_arch = "aarch64"), not(target_os = "ios")),
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not(target_arch = "wasm32"),
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not(target_arch = "asmjs"),
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not(windows)
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))]
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'f> VaListImpl<'f> {
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/// Convert a `VaListImpl` into a `VaList` that is binary-compatible with C's `va_list`.
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#[inline]
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pub fn as_va_list<'a>(&'a mut self) -> VaList<'a, 'f> {
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VaList { inner: self, _marker: PhantomData }
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}
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}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'a, 'f: 'a> Deref for VaList<'a, 'f> {
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type Target = VaListImpl<'f>;
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#[inline]
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fn deref(&self) -> &VaListImpl<'f> {
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&self.inner
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}
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}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'a, 'f: 'a> DerefMut for VaList<'a, 'f> {
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#[inline]
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fn deref_mut(&mut self) -> &mut VaListImpl<'f> {
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&mut self.inner
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}
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}
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// The VaArgSafe trait needs to be used in public interfaces, however, the trait
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// itself must not be allowed to be used outside this module. Allowing users to
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// implement the trait for a new type (thereby allowing the va_arg intrinsic to
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// be used on a new type) is likely to cause undefined behavior.
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//
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// FIXME(dlrobertson): In order to use the VaArgSafe trait in a public interface
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// but also ensure it cannot be used elsewhere, the trait needs to be public
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// within a private module. Once RFC 2145 has been implemented look into
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// improving this.
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mod sealed_trait {
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/// Trait which whitelists the allowed types to be used with [VaList::arg]
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///
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/// [VaList::va_arg]: struct.VaList.html#method.arg
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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pub trait VaArgSafe {}
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}
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macro_rules! impl_va_arg_safe {
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($($t:ty),+) => {
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$(
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#[unstable(feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930")]
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impl sealed_trait::VaArgSafe for $t {}
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)+
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}
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}
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impl_va_arg_safe! {i8, i16, i32, i64, usize}
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impl_va_arg_safe! {u8, u16, u32, u64, isize}
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impl_va_arg_safe! {f64}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<T> sealed_trait::VaArgSafe for *mut T {}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<T> sealed_trait::VaArgSafe for *const T {}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'f> VaListImpl<'f> {
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/// Advance to the next arg.
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#[inline]
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pub unsafe fn arg<T: sealed_trait::VaArgSafe>(&mut self) -> T {
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va_arg(self)
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}
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/// Copies the `va_list` at the current location.
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pub unsafe fn with_copy<F, R>(&self, f: F) -> R
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where
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F: for<'copy> FnOnce(VaList<'copy, 'f>) -> R,
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{
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let mut ap = self.clone();
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let ret = f(ap.as_va_list());
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va_end(&mut ap);
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ret
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}
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}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'f> Clone for VaListImpl<'f> {
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#[inline]
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fn clone(&self) -> Self {
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let mut dest = crate::mem::MaybeUninit::uninit();
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// SAFETY: we write to the `MaybeUninit`, thus it is initialized and `assume_init` is legal
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unsafe {
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va_copy(dest.as_mut_ptr(), self);
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dest.assume_init()
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}
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}
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}
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#[unstable(
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feature = "c_variadic",
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reason = "the `c_variadic` feature has not been properly tested on \
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all supported platforms",
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issue = "44930"
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)]
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impl<'f> Drop for VaListImpl<'f> {
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fn drop(&mut self) {
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// FIXME: this should call `va_end`, but there's no clean way to
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// guarantee that `drop` always gets inlined into its caller,
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// so the `va_end` would get directly called from the same function as
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// the corresponding `va_copy`. `man va_end` states that C requires this,
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// and LLVM basically follows the C semantics, so we need to make sure
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// that `va_end` is always called from the same function as `va_copy`.
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// For more details, see https://github.com/rust-lang/rust/pull/59625
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// and https://llvm.org/docs/LangRef.html#llvm-va-end-intrinsic.
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//
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// This works for now, since `va_end` is a no-op on all current LLVM targets.
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}
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}
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extern "rust-intrinsic" {
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/// Destroy the arglist `ap` after initialization with `va_start` or
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/// `va_copy`.
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fn va_end(ap: &mut VaListImpl<'_>);
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/// Copies the current location of arglist `src` to the arglist `dst`.
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fn va_copy<'f>(dest: *mut VaListImpl<'f>, src: &VaListImpl<'f>);
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/// Loads an argument of type `T` from the `va_list` `ap` and increment the
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/// argument `ap` points to.
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fn va_arg<T: sealed_trait::VaArgSafe>(ap: &mut VaListImpl<'_>) -> T;
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}
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