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Merged
nunoplopes merged 4 commits into from
Oct 14, 2026
Merged

Translate address-of variadic function #533

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8503629
Update tests
lucic71 Oct 14, 2026
d70144b
Wrap [VaList] in Box to be able to use it as FnPtrArg
lucic71 Oct 14, 2026
deaf7cd
Update rules
lucic71 Oct 14, 2026
be4ef00
Merge branch 'master' into address-of-variadic-function
nunoplopes Oct 14, 2026
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15 changes: 11 additions & 4 deletions cpp2rust/converter/converter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -296,6 +296,9 @@ Converter::ConvertFunctionPointerType(const clang::FunctionProtoType *proto) {
result += ToString(p_ty);
result += ',';
}
if (proto->isVariadic()) {
result += "Box<[VaArg]>,";
}
result += ')';
if (!proto->getReturnType()->isVoidType()) {
result += std::format(" -> {}", ToString(proto->getReturnType()));
Expand Down Expand Up @@ -2234,8 +2237,9 @@ void Converter::EmitArgList(const CallInfo &info) {

if (info.is_variadic) {
if (!info.is_libc_passthrough) {
StrCat(token::kRef);
StrCat("Box::new");
}
PushParen box(*this, !info.is_libc_passthrough);
PushBracket push(*this, !info.is_libc_passthrough);
for (auto *arg : info.variadic_args) {
{
Expand Down Expand Up @@ -4069,6 +4073,9 @@ void Converter::ConvertLambdaClosure(const clang::CXXRecordDecl *decl,
ConvertVarDeclSkipInit(p);
StrCat(token::kComma);
}
if (call_operator->isVariadic()) {
StrCat("__args: Box<[VaArg]>", token::kComma);
}
in_function_formals_ = false;
StrCat('|');
ConvertFunctionReturnType(call_operator);
Expand Down Expand Up @@ -4626,7 +4633,7 @@ void Converter::ConvertFunctionParameters(clang::FunctionDecl *decl) {
StrCat(token::kComma);
}
if (decl->isVariadic()) {
StrCat("__args: &[VaArg]", token::kComma);
StrCat("__args: Box<[VaArg]>", token::kComma);
}
in_function_formals_ = false;
}
Expand Down Expand Up @@ -5321,15 +5328,15 @@ Converter::ConvertVariadicTail(clang::Expr *expr,
unsigned fixed = tgt_ir ? tgt_ir->params.size() : 0;

Buffer buf(*this);
StrCat("&[");
StrCat("Box::<[VaArg]>::from([");
for (unsigned i = fixed; i < all_args.size(); ++i) {
{
PushParen p(*this);
ConvertVariadicArg(all_args[i]);
}
StrCat(".into()", token::kComma);
}
StrCat("]");
StrCat("])");
return std::move(buf).str();
}

Expand Down
2 changes: 1 addition & 1 deletion docs/src/rules/conventions.md
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Expand Up @@ -11,7 +11,7 @@ fails the build; the notes below call out the ones that are not checked.
| Type rule | `t1`, `t2`, ... via `using`/`typedef` | `fn tN() -> RustType` with no arguments |
| Parameters | free-form (`o`, `it`, `key`, `dst`, `n`, ...) | must be `a0`, `a1`, ... consecutive from 0 |
| Generics | `T1`, `T2`, ... (type and non-type params) | `T1`, `T2`, ... consecutive from 1 |
| Variadic pack | `typename... Args` | trailing `va: &[VaArg]` |
| Variadic pack | `typename... Args` | trailing `va: Box<[VaArg]>` |
| Constructing pack | `Init<T, Args> &&...args` | trailing `init: RustType` |
| Locals in Rust bodies | | double-underscore prefix: `__v`, `__fd`, `__e`, ... |

Expand Down
4 changes: 2 additions & 2 deletions docs/src/rules/writing-rules.md
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Expand Up @@ -267,7 +267,7 @@ int f1(int a0, int a1, ...) { return fcntl(a0, a1, ...); }

is not expressible. A parameter pack can be forwarded (`args...`), which is
exactly what the rule body needs to do. The Rust side takes a trailing parameter
that must be typed `&[VaArg]` and named `va`:
that must be typed `Box<[VaArg]>` and named `va`:

```cpp
// rules/fcntl/src.cpp
Expand All @@ -279,7 +279,7 @@ int f1(int a0, int a1, Args... args) {

```rust
// rules/fcntl/tgt_refcount.rs
fn f1(a0: i32, a1: i32, va: &[VaArg]) -> i32 { ... }
fn f1(a0: i32, a1: i32, va: Box<[VaArg]>) -> i32 { ... }
```

Bodies read the arguments through the va-args API in `libcc2rs` (`VaArg`,
Expand Down
6 changes: 3 additions & 3 deletions docs/src/runtime/va-args.md
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Expand Up @@ -39,7 +39,7 @@ sum(3, 10, 20, 30);
```

```rust
pub fn sum_0(count: i32, __args: &[VaArg]) -> i32 {
pub fn sum_0(count: i32, __args: Box<[VaArg]>) -> i32 {
let ap: Value<VaList> = Rc::new(RefCell::new(VaList::default()));
(*ap.borrow_mut()) = VaList::new(__args);
let total: Value<i32> = Rc::new(RefCell::new(0));
Expand All @@ -48,7 +48,7 @@ pub fn sum_0(count: i32, __args: &[VaArg]) -> i32 {
// ...
}

sum_0(3, &[10.into(), 20.into(), 30.into()]);
sum_0(3, Box::new([10.into(), 20.into(), 30.into()]));
```

`arg::<T>()` goes through the `VaArgGet` trait, implemented for the integer and
Expand All @@ -59,5 +59,5 @@ panics, as does reading past the last argument.

Variadic libc functions such as `printf` and `fcntl` are handled by
[variadic rules](../rules/writing-rules.md#variadic-functions), whose bodies
receive the same `&[VaArg]` slice; `format_c` in the
receive the same `Box<[VaArg]>`; `format_c` in the
[format module](./io.md#formatting) consumes one to evaluate a format string.
11 changes: 11 additions & 0 deletions libcc2rs/src/fn_ptr_arg.rs
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Expand Up @@ -9,6 +9,7 @@ use std::rc::Rc;

use crate::rc::Ptr;
use crate::reinterpret::ByteRepr;
use crate::va_args::VaArg;
use crate::void::{AnyPtr, ErasedPtr};

pub enum ArgRepr {
Expand Down Expand Up @@ -126,6 +127,16 @@ impl FnPtrArg for AnyPtr {
}
}

impl FnPtrArg for Box<[VaArg]> {
#[inline]
fn to_repr(self) -> ArgRepr {
ArgRepr::Record(Box::new(self))
}
fn from_repr(r: ArgRepr) -> Self {
record_from_repr(r)
}
}

impl<T: ?Sized + 'static> FnPtrArg for *mut T {
#[inline]
fn to_repr(self) -> ArgRepr {
Expand Down
11 changes: 8 additions & 3 deletions rule-preprocessor/src/syntactic.rs
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Expand Up @@ -3,7 +3,7 @@

use cfg_expr::Expression;
use cfg_expr::expr::{Predicate, TargetPredicate};
use ra_ap_syntax::ast::{HasAttrs, HasGenericParams, HasName, HasTypeBounds};
use ra_ap_syntax::ast::{HasAttrs, HasGenericArgs, HasGenericParams, HasName, HasTypeBounds};
use ra_ap_syntax::{AstNode, SyntaxKind, ast, match_ast};
use std::collections::BTreeMap;
use std::path::{Path, PathBuf};
Expand Down Expand Up @@ -41,8 +41,13 @@ fn pointer_flags(ty: &ast::Type) -> (bool, bool) {
}

fn is_va_args_type(ty: &ast::Type) -> bool {
if let ast::Type::RefType(r) = ty
&& let Some(ast::Type::SliceType(slice)) = r.ty()
if let ast::Type::PathType(boxed) = ty
&& let Some(segment) = boxed.path().and_then(|p| p.segment())
&& segment.name_ref().is_some_and(|name| name.text() == "Box")
&& let Some(ast::GenericArg::TypeArg(arg)) = segment
.generic_arg_list()
.and_then(|args| args.generic_args().next())
&& let Some(ast::Type::SliceType(slice)) = arg.ty()
{
return matches!(slice.ty(), Some(ast::Type::PathType(path))
if path
Expand Down
4 changes: 2 additions & 2 deletions rules/fcntl/tgt_refcount.rs
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Expand Up @@ -3,7 +3,7 @@

use libcc2rs::*;

fn f1(a0: i32, a1: i32, va: &[VaArg]) -> i32 {
fn f1(a0: i32, a1: i32, va: Box<[VaArg]>) -> i32 {
let __res = match a1 {
::libc::F_GETFL => FdRegistry::with_fd(a0, |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFL)
Expand Down Expand Up @@ -34,7 +34,7 @@ fn f1(a0: i32, a1: i32, va: &[VaArg]) -> i32 {
}
}

fn f2(a0: Ptr<i8>, a1: i32, va: &[VaArg]) -> i32 {
fn f2(a0: Ptr<i8>, a1: i32, va: Box<[VaArg]>) -> i32 {
let __mode = match va.first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
Expand Down
2 changes: 1 addition & 1 deletion rules/ioctl/tgt_refcount.rs
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Expand Up @@ -3,7 +3,7 @@

use libcc2rs::*;

fn f1(a0: i32, a1: u64, va: &[VaArg]) -> i32 {
fn f1(a0: i32, a1: u64, va: Box<[VaArg]>) -> i32 {
panic!(
"ioctl is not supported in the refcount model (fd={}, request={}, varargs={})",
a0,
Expand Down
12 changes: 6 additions & 6 deletions rules/stdio/tgt_refcount.rs
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Expand Up @@ -161,8 +161,8 @@ fn f20(a0: i32, a1: Ptr<i8>) -> Ptr<CFile> {
Ptr::alloc(CFile::new(a0))
}

fn f21(a0: Ptr<i8>, a1: usize, a2: Ptr<i8>, va: &[VaArg]) -> i32 {
let __s = libcc2rs::format_c(&a2.to_rust_string(), va);
fn f21(a0: Ptr<i8>, a1: usize, a2: Ptr<i8>, va: Box<[VaArg]>) -> i32 {
let __s = libcc2rs::format_c(&a2.to_rust_string(), &va);
let __b = __s.as_bytes();
if a1 > 0 {
let __n = ::std::cmp::min(__b.len(), a1 - 1);
Expand Down Expand Up @@ -190,12 +190,12 @@ fn f24(a0: Ptr<CFile>, a1: Ptr<i8>, a2: i32, a3: usize) -> i32 {
0
}

fn f28(a0: Ptr<CFile>, a1: Ptr<i8>, va: &[VaArg]) -> i32 {
let __s = libcc2rs::format_c(&a1.to_rust_string(), va);
fn f28(a0: Ptr<CFile>, a1: Ptr<i8>, va: Box<[VaArg]>) -> i32 {
let __s = libcc2rs::format_c(&a1.to_rust_string(), &va);
a0.with_mut(|__f| __f.write(__s.as_bytes())) as i32
}

fn f29(a0: Ptr<i8>, va: &[VaArg]) -> i32 {
let __s = libcc2rs::format_c(&a0.to_rust_string(), va);
fn f29(a0: Ptr<i8>, va: Box<[VaArg]>) -> i32 {
let __s = libcc2rs::format_c(&a0.to_rust_string(), &va);
libcc2rs::c_stdout().with_mut(|__f| __f.write(__s.as_bytes())) as i32
}
2 changes: 1 addition & 1 deletion tests/ub/out/refcount/fd_double_close.rs
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Expand Up @@ -12,7 +12,7 @@ pub fn main() {
}
fn main_0() -> i32 {
let mut fd: i32 = {
let __mode = match &[].first() {
let __mode = match Box::<[VaArg]>::from([]).first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
};
Expand Down
2 changes: 1 addition & 1 deletion tests/ub/out/refcount/fd_use_after_close.rs
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Expand Up @@ -12,7 +12,7 @@ pub fn main() {
}
fn main_0() -> i32 {
let mut fd: i32 = {
let __mode = match &[].first() {
let __mode = match Box::<[VaArg]>::from([]).first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
};
Expand Down
44 changes: 32 additions & 12 deletions tests/unit/out/refcount/fcntl.rs
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Expand Up @@ -34,7 +34,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFL)
}),
::libc::F_SETFL => {
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFL(__flags))
})
Expand All @@ -43,7 +45,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFD)
}),
::libc::F_SETFD => {
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFD(__flags))
})
Expand All @@ -68,7 +72,7 @@ fn main_0() -> i32 {
}),
::libc::F_SETFL => {
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(
&&[(flags | ::libc::O_NONBLOCK).into()][0],
&Box::<[VaArg]>::from([(flags | ::libc::O_NONBLOCK).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFL(__flags))
Expand All @@ -79,7 +83,7 @@ fn main_0() -> i32 {
}),
::libc::F_SETFD => {
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(
&&[(flags | ::libc::O_NONBLOCK).into()][0],
&Box::<[VaArg]>::from([(flags | ::libc::O_NONBLOCK).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFD(__flags))
Expand All @@ -103,7 +107,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFL)
}),
::libc::F_SETFL => {
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFL(__flags))
})
Expand All @@ -112,7 +118,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFD)
}),
::libc::F_SETFD => {
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFD(__flags))
})
Expand Down Expand Up @@ -151,7 +159,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFL)
}),
::libc::F_SETFL => {
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFL(__flags))
})
Expand All @@ -160,7 +170,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFD)
}),
::libc::F_SETFD => {
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFD(__flags))
})
Expand All @@ -185,7 +197,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFL)
}),
::libc::F_SETFL => {
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(&&[(1).into()][0]));
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(1).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFL(__flags))
})
Expand All @@ -194,7 +208,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFD)
}),
::libc::F_SETFD => {
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(&&[(1).into()][0]));
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(1).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFD(__flags))
})
Expand All @@ -218,7 +234,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFL)
}),
::libc::F_SETFL => {
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::OFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFL(__flags))
})
Expand All @@ -227,7 +245,9 @@ fn main_0() -> i32 {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_GETFD)
}),
::libc::F_SETFD => {
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(&&[(0).into()][0]));
let __flags = nix::fcntl::FdFlag::from_bits_retain(i32::get(
&Box::<[VaArg]>::from([(0).into()])[0],
));
FdRegistry::with_fd((*fds.borrow())[(0) as usize], |__fd| {
nix::fcntl::fcntl(__fd, nix::fcntl::FcntlArg::F_SETFD(__flags))
})
Expand Down
4 changes: 2 additions & 2 deletions tests/unit/out/refcount/fd_io.rs
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Expand Up @@ -13,7 +13,7 @@ pub fn main() {
fn main_0() -> i32 {
let mut path: Ptr<i8> = Ptr::<i8>::from_string_literal(b"cpp2rust_fd_io_test.tmp");
let mut fd: i32 = {
let __mode = match &[(420).into()].first() {
let __mode = match Box::<[VaArg]>::from([(420).into()]).first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
};
Expand Down Expand Up @@ -49,7 +49,7 @@ fn main_0() -> i32 {
);
assert!((((FdRegistry::close(fd) == 0) as i32) != 0));
fd = {
let __mode = match &[].first() {
let __mode = match Box::<[VaArg]>::from([]).first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
};
Expand Down
2 changes: 1 addition & 1 deletion tests/unit/out/refcount/fstat.rs
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Expand Up @@ -13,7 +13,7 @@ pub fn main() {
fn main_0() -> i32 {
let mut path: Ptr<i8> = Ptr::<i8>::from_string_literal(b"cpp2rust_fstat_test.tmp");
let mut fd: i32 = {
let __mode = match &[(420).into()].first() {
let __mode = match Box::<[VaArg]>::from([(420).into()]).first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
};
Expand Down
2 changes: 1 addition & 1 deletion tests/unit/out/refcount/isatty.rs
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Expand Up @@ -13,7 +13,7 @@ pub fn main() {
fn main_0() -> i32 {
let mut path: Ptr<i8> = Ptr::<i8>::from_string_literal(b"cpp2rust_isatty_test.tmp");
let mut fd: i32 = {
let __mode = match &[(420).into()].first() {
let __mode = match Box::<[VaArg]>::from([(420).into()]).first() {
Some(__m) => nix::sys::stat::Mode::from_bits_truncate(i32::get(__m) as ::libc::mode_t),
None => nix::sys::stat::Mode::empty(),
};
Expand Down
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