Introduce a `fmt!` macro which wraps all arguments in `kernel::fmt::Adapter` This enables formatting of foreign types (like `core::ffi::CStr`) that do not implement `fmt::Display` due to concerns around lossy conversions which do not apply in the kernel.
Replace all direct calls to `format_args!` with `fmt!`. In preparation for replacing our `CStr` with `core::ffi::CStr`, move its `fmt::Display` implementation to `kernel::fmt::Adapter<&CStr>`. Suggested-by: Alice Ryhl <alicer...@google.com> Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/with/516476467 Signed-off-by: Tamir Duberstein <tam...@gmail.com> --- drivers/block/rnull.rs | 2 +- rust/kernel/block/mq.rs | 2 +- rust/kernel/device.rs | 2 +- rust/kernel/fmt.rs | 77 +++++++++++++++++++++++++++++ rust/kernel/kunit.rs | 6 +-- rust/kernel/lib.rs | 1 + rust/kernel/prelude.rs | 3 +- rust/kernel/print.rs | 4 +- rust/kernel/seq_file.rs | 2 +- rust/kernel/str.rs | 23 ++++----- rust/macros/fmt.rs | 118 ++++++++++++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 19 +++++++ scripts/rustdoc_test_gen.rs | 2 +- 13 files changed, 235 insertions(+), 26 deletions(-) diff --git a/drivers/block/rnull.rs b/drivers/block/rnull.rs index d07e76ae2c13..6366da12c5a5 100644 --- a/drivers/block/rnull.rs +++ b/drivers/block/rnull.rs @@ -51,7 +51,7 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> { .logical_block_size(4096)? .physical_block_size(4096)? .rotational(false) - .build(format_args!("rnullb{}", 0), tagset) + .build(fmt!("rnullb{}", 0), tagset) })(); try_pin_init!(Self { diff --git a/rust/kernel/block/mq.rs b/rust/kernel/block/mq.rs index fb0f393c1cea..842be88aa1cf 100644 --- a/rust/kernel/block/mq.rs +++ b/rust/kernel/block/mq.rs @@ -82,7 +82,7 @@ //! Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?; //! let mut disk = gen_disk::GenDiskBuilder::new() //! .capacity_sectors(4096) -//! .build(format_args!("myblk"), tagset)?; +//! .build(fmt!("myblk"), tagset)?; //! //! # Ok::<(), kernel::error::Error>(()) //! ``` diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 5c372cf27ed0..99d99a76934c 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -240,7 +240,7 @@ impl DeviceContext for Normal {} macro_rules! dev_printk { ($method:ident, $dev:expr, $($f:tt)*) => { { - ($dev).$method(core::format_args!($($f)*)); + ($dev).$method($crate::prelude::fmt!($($f)*)); } } } diff --git a/rust/kernel/fmt.rs b/rust/kernel/fmt.rs new file mode 100644 index 000000000000..12b08debc3b3 --- /dev/null +++ b/rust/kernel/fmt.rs @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Formatting utilities. + +use core::fmt; + +/// Internal adapter used to route allow implementations of formatting traits for foreign types. +/// +/// It is inserted automatically by the [`fmt!`] macro and is not meant to be used directly. +/// +/// [`fmt!`]: crate::prelude::fmt! +#[doc(hidden)] +pub struct Adapter<T>(pub T); + +macro_rules! impl_fmt_adapter_forward { + ($($trait:ident),* $(,)?) => { + $( + impl<T: fmt::$trait> fmt::$trait for Adapter<T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let Self(t) = self; + fmt::$trait::fmt(t, f) + } + } + )* + }; +} + +impl_fmt_adapter_forward!(Debug, LowerHex, UpperHex, Octal, Binary, Pointer, LowerExp, UpperExp); + +macro_rules! impl_display_forward { + ($( + $( { $($generics:tt)* } )? $ty:ty $( { where $($where:tt)* } )? + ),* $(,)?) => { + $( + impl$($($generics)*)? fmt::Display for Adapter<&$ty> + $(where $($where)*)? { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let Self(t) = self; + fmt::Display::fmt(t, f) + } + } + )* + }; +} + +impl<T: ?Sized> fmt::Display for Adapter<&&T> +where + for<'a> Adapter<&'a T>: fmt::Display, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let Self(t) = self; + Adapter::<&T>(**t).fmt(f) + } +} + +impl_display_forward!( + bool, + char, + core::panic::PanicInfo<'_>, + crate::str::BStr, + fmt::Arguments<'_>, + i128, + i16, + i32, + i64, + i8, + isize, + str, + u128, + u16, + u32, + u64, + u8, + usize, + {<T: ?Sized>} crate::sync::Arc<T> {where crate::sync::Arc<T>: fmt::Display}, + {<T: ?Sized>} crate::sync::UniqueArc<T> {where crate::sync::UniqueArc<T>: fmt::Display}, +); diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 1604fb6a5b1b..c29e34192553 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -72,14 +72,14 @@ macro_rules! kunit_assert { // mistake (it is hidden to prevent that). // // This mimics KUnit's failed assertion format. - $crate::kunit::err(format_args!( + $crate::kunit::err($crate::prelude::fmt!( " # {}: ASSERTION FAILED at {FILE}:{LINE}\n", $name )); - $crate::kunit::err(format_args!( + $crate::kunit::err($crate::prelude::fmt!( " Expected {CONDITION} to be true, but is false\n" )); - $crate::kunit::err(format_args!( + $crate::kunit::err($crate::prelude::fmt!( " Failure not reported to KUnit since this is a non-KUnit task\n" )); break 'out; diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 6e9287136cac..ec48c818d512 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -66,6 +66,7 @@ pub mod faux; #[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)] pub mod firmware; +pub mod fmt; pub mod fs; pub mod init; pub mod io; diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index baa774a351ce..ef1efcb9d945 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -17,7 +17,7 @@ pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec, Vec}; #[doc(no_inline)] -pub use macros::{export, module, vtable}; +pub use macros::{export, fmt, module, vtable}; pub use pin_init::{init, pin_data, pin_init, pinned_drop, InPlaceWrite, Init, PinInit, Zeroable}; @@ -26,7 +26,6 @@ // `super::std_vendor` is hidden, which makes the macro inline for some reason. #[doc(no_inline)] pub use super::dbg; -pub use super::fmt; pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn}; pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn}; diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs index 9783d960a97a..0f5e15128005 100644 --- a/rust/kernel/print.rs +++ b/rust/kernel/print.rs @@ -149,7 +149,7 @@ macro_rules! print_macro ( // takes borrows on the arguments, but does not extend the scope of temporaries. // Therefore, a `match` expression is used to keep them around, since // the scrutinee is kept until the end of the `match`. - match format_args!($($arg)+) { + match $crate::prelude::fmt!($($arg)+) { // SAFETY: This hidden macro should only be called by the documented // printing macros which ensure the format string is one of the fixed // ones. All `__LOG_PREFIX`s are null-terminated as they are generated @@ -168,7 +168,7 @@ macro_rules! print_macro ( // The `CONT` case. ($format_string:path, true, $($arg:tt)+) => ( $crate::print::call_printk_cont( - format_args!($($arg)+), + $crate::prelude::fmt!($($arg)+), ); ); ); diff --git a/rust/kernel/seq_file.rs b/rust/kernel/seq_file.rs index 7a9403eb6e5b..627bc2f7b3d2 100644 --- a/rust/kernel/seq_file.rs +++ b/rust/kernel/seq_file.rs @@ -47,7 +47,7 @@ pub fn call_printf(&self, args: core::fmt::Arguments<'_>) { #[macro_export] macro_rules! seq_print { ($m:expr, $($arg:tt)+) => ( - $m.call_printf(format_args!($($arg)+)) + $m.call_printf($crate::prelude::fmt!($($arg)+)) ); } pub use seq_print; diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 98d5c74ec4f7..302423ca5eb0 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -54,7 +54,7 @@ impl fmt::Display for BStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` - /// # use kernel::{fmt, b_str, str::{BStr, CString}}; + /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// let ascii = b_str!("Hello, BStr!"); /// let s = CString::try_from_fmt(fmt!("{}", ascii))?; /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes()); @@ -85,7 +85,7 @@ impl fmt::Debug for BStr { /// escaping the rest. /// /// ``` - /// # use kernel::{fmt, b_str, str::{BStr, CString}}; + /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// // Embedded double quotes are escaped. /// let ascii = b_str!("Hello, \"BStr\"!"); /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?; @@ -424,12 +424,12 @@ pub fn to_ascii_uppercase(&self) -> Result<CString, AllocError> { } } -impl fmt::Display for CStr { +impl fmt::Display for crate::fmt::Adapter<&CStr> { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::c_str; - /// # use kernel::fmt; + /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("🐧"); @@ -442,7 +442,8 @@ impl fmt::Display for CStr { /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - for &c in self.as_bytes() { + let Self(cstr) = self; + for &c in cstr.as_bytes() { if (0x20..0x7f).contains(&c) { // Printable character. f.write_char(c as char)?; @@ -459,7 +460,7 @@ impl fmt::Debug for CStr { /// /// ``` /// # use kernel::c_str; - /// # use kernel::fmt; + /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("🐧"); @@ -595,7 +596,7 @@ fn deref(&self) -> &str { macro_rules! format { ($($f:tt)*) => ({ - &*String::from_fmt(kernel::fmt!($($f)*)) + &*String::from_fmt(crate::prelude::fmt!($($f)*)) }) } @@ -850,7 +851,7 @@ fn write_str(&mut self, s: &str) -> fmt::Result { /// # Examples /// /// ``` -/// use kernel::{str::CString, fmt}; +/// use kernel::{str::CString, prelude::fmt}; /// /// let s = CString::try_from_fmt(fmt!("{}{}{}", "abc", 10, 20))?; /// assert_eq!(s.as_bytes_with_nul(), "abc1020\0".as_bytes()); @@ -940,9 +941,3 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&**self, f) } } - -/// A convenience alias for [`core::format_args`]. -#[macro_export] -macro_rules! fmt { - ($($f:tt)*) => ( core::format_args!($($f)*) ) -} diff --git a/rust/macros/fmt.rs b/rust/macros/fmt.rs new file mode 100644 index 000000000000..6b6bd9295d18 --- /dev/null +++ b/rust/macros/fmt.rs @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 + +use proc_macro::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree}; +use std::collections::BTreeSet; + +/// Please see [`crate::fmt`] for documentation. +pub(crate) fn fmt(input: TokenStream) -> TokenStream { + let mut input = input.into_iter(); + + let first_opt = input.next(); + let first_owned_str; + let mut names = BTreeSet::new(); + let first_lit = { + let Some((mut first_str, first_lit)) = (match first_opt.as_ref() { + Some(TokenTree::Literal(first_lit)) => { + first_owned_str = first_lit.to_string(); + Some(first_owned_str.as_str()).and_then(|first| { + let first = first.strip_prefix('"')?; + let first = first.strip_suffix('"')?; + Some((first, first_lit)) + }) + } + _ => None, + }) else { + return first_opt.into_iter().chain(input).collect(); + }; + while let Some((_, rest)) = first_str.split_once('{') { + first_str = rest; + if let Some(rest) = first_str.strip_prefix('{') { + first_str = rest; + continue; + } + while let Some((name, rest)) = first_str.split_once('}') { + first_str = rest; + if let Some(rest) = first_str.strip_prefix('}') { + first_str = rest; + continue; + } + let name = name.split_once(':').map_or(name, |(name, _)| name); + if !name.is_empty() && !name.chars().all(|c| c.is_ascii_digit()) { + names.insert(name); + } + break; + } + } + first_lit + }; + + let first_span = first_lit.span(); + let adapt = |expr| { + let mut borrow = + TokenStream::from_iter([TokenTree::Punct(Punct::new('&', Spacing::Alone))]); + borrow.extend(expr); + make_ident(first_span, ["kernel", "fmt", "Adapter"]) + .chain([TokenTree::Group(Group::new(Delimiter::Parenthesis, borrow))]) + }; + + let flush = |args: &mut TokenStream, current: &mut TokenStream| { + let current = std::mem::take(current); + if !current.is_empty() { + args.extend(adapt(current)); + } + }; + + let mut args = TokenStream::from_iter(first_opt); + { + let mut current = TokenStream::new(); + for tt in input { + match &tt { + TokenTree::Punct(p) => match p.as_char() { + ',' => { + flush(&mut args, &mut current); + &mut args + } + '=' => { + names.remove(current.to_string().as_str()); + args.extend(std::mem::take(&mut current)); + &mut args + } + _ => &mut current, + }, + _ => &mut current, + } + .extend([tt]); + } + flush(&mut args, &mut current); + } + + for name in names { + args.extend( + [ + TokenTree::Punct(Punct::new(',', Spacing::Alone)), + TokenTree::Ident(Ident::new(name, first_span)), + TokenTree::Punct(Punct::new('=', Spacing::Alone)), + ] + .into_iter() + .chain(adapt(TokenTree::Ident(Ident::new(name, first_span)).into())), + ); + } + + TokenStream::from_iter(make_ident(first_span, ["core", "format_args"]).chain([ + TokenTree::Punct(Punct::new('!', Spacing::Alone)), + TokenTree::Group(Group::new(Delimiter::Parenthesis, args)), + ])) +} + +fn make_ident<'a, T: IntoIterator<Item = &'a str>>( + span: Span, + names: T, +) -> impl Iterator<Item = TokenTree> + use<'a, T> { + names.into_iter().flat_map(move |name| { + [ + TokenTree::Punct(Punct::new(':', Spacing::Joint)), + TokenTree::Punct(Punct::new(':', Spacing::Alone)), + TokenTree::Ident(Ident::new(name, span)), + ] + }) +} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index d31e50c446b0..fa956eaa3ba7 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -10,6 +10,7 @@ mod quote; mod concat_idents; mod export; +mod fmt; mod helpers; mod kunit; mod module; @@ -196,6 +197,24 @@ pub fn export(attr: TokenStream, ts: TokenStream) -> TokenStream { export::export(attr, ts) } +/// Like [`core::format_args!`], but automatically wraps arguments in [`kernel::fmt::Adapter`]. +/// +/// This macro allows generating `core::fmt::Arguments` while ensuring that each argument is wrapped +/// with `::kernel::fmt::Adapter`, which customizes formatting behavior for kernel logging. +/// +/// Named arguments used in the format string (e.g. `{foo}`) are detected and resolved from local +/// bindings. All positional and named arguments are automatically wrapped. +/// +/// This macro is an implementation detail of other kernel logging macros like [`pr_info!`] and +/// should not typically be used directly. +/// +/// [`kernel::fmt::Adapter`]: ../kernel/fmt/struct.Adapter.html +/// [`pr_info!`]: ../kernel/macro.pr_info.html +#[proc_macro] +pub fn fmt(input: TokenStream) -> TokenStream { + fmt::fmt(input) +} + /// Concatenate two identifiers. /// /// This is useful in macros that need to declare or reference items with names diff --git a/scripts/rustdoc_test_gen.rs b/scripts/rustdoc_test_gen.rs index ec8d70ac888b..22ed9ee14053 100644 --- a/scripts/rustdoc_test_gen.rs +++ b/scripts/rustdoc_test_gen.rs @@ -197,7 +197,7 @@ macro_rules! assert_eq {{ // This follows the syntax for declaring test metadata in the proposed KTAP v2 spec, which may // be used for the proposed KUnit test attributes API. Thus hopefully this will make migration // easier later on. - kernel::kunit::info(format_args!(" # {kunit_name}.location: {real_path}:{line}\n")); + kernel::kunit::info(fmt!(" # {kunit_name}.location: {real_path}:{line}\n")); /// The anchor where the test code body starts. #[allow(unused)] -- 2.49.0
