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Merged
merged 3 commits into from
Oct 1, 2024
Merged

Make returning io errors more uniform and convenient #3929

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07594af
move io error handling helpers to their own file
RalfJung Oct 1, 2024
c49845d
make set_last_error directly callable on a bunch of ways to represent…
RalfJung Oct 1, 2024
007573b
add set_last_error_and_return_i32 helper and use it in a few places
RalfJung Oct 1, 2024
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185 changes: 1 addition & 184 deletions src/helpers.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use std::collections::BTreeSet;
use std::num::NonZero;
use std::sync::Mutex;
use std::time::Duration;
use std::{cmp, io, iter};
use std::{cmp, iter};

use rand::RngCore;
use rustc_apfloat::Float;
Expand Down Expand Up @@ -31,65 +31,6 @@ pub enum AccessKind {
Write,
}

// This mapping should match `decode_error_kind` in
// <https://github.com/rust-lang/rust/blob/master/library/std/src/sys/pal/unix/mod.rs>.
const UNIX_IO_ERROR_TABLE: &[(&str, std::io::ErrorKind)] = {
use std::io::ErrorKind::*;
&[
("E2BIG", ArgumentListTooLong),
("EADDRINUSE", AddrInUse),
("EADDRNOTAVAIL", AddrNotAvailable),
("EBUSY", ResourceBusy),
("ECONNABORTED", ConnectionAborted),
("ECONNREFUSED", ConnectionRefused),
("ECONNRESET", ConnectionReset),
("EDEADLK", Deadlock),
("EDQUOT", FilesystemQuotaExceeded),
("EEXIST", AlreadyExists),
("EFBIG", FileTooLarge),
("EHOSTUNREACH", HostUnreachable),
("EINTR", Interrupted),
("EINVAL", InvalidInput),
("EISDIR", IsADirectory),
("ELOOP", FilesystemLoop),
("ENOENT", NotFound),
("ENOMEM", OutOfMemory),
("ENOSPC", StorageFull),
("ENOSYS", Unsupported),
("EMLINK", TooManyLinks),
("ENAMETOOLONG", InvalidFilename),
("ENETDOWN", NetworkDown),
("ENETUNREACH", NetworkUnreachable),
("ENOTCONN", NotConnected),
("ENOTDIR", NotADirectory),
("ENOTEMPTY", DirectoryNotEmpty),
("EPIPE", BrokenPipe),
("EROFS", ReadOnlyFilesystem),
("ESPIPE", NotSeekable),
("ESTALE", StaleNetworkFileHandle),
("ETIMEDOUT", TimedOut),
("ETXTBSY", ExecutableFileBusy),
("EXDEV", CrossesDevices),
// The following have two valid options. We have both for the forwards mapping; only the
// first one will be used for the backwards mapping.
("EPERM", PermissionDenied),
("EACCES", PermissionDenied),
("EWOULDBLOCK", WouldBlock),
("EAGAIN", WouldBlock),
]
};
// This mapping should match `decode_error_kind` in
// <https://github.com/rust-lang/rust/blob/master/library/std/src/sys/pal/windows/mod.rs>.
const WINDOWS_IO_ERROR_TABLE: &[(&str, std::io::ErrorKind)] = {
use std::io::ErrorKind::*;
// FIXME: this is still incomplete.
&[
("ERROR_ACCESS_DENIED", PermissionDenied),
("ERROR_FILE_NOT_FOUND", NotFound),
("ERROR_INVALID_PARAMETER", InvalidInput),
]
};

/// Gets an instance for a path.
///
/// A `None` namespace indicates we are looking for a module.
Expand Down Expand Up @@ -745,130 +686,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
self.eval_context_ref().tcx.sess.target.families.iter().any(|f| f == "unix")
}

/// Get last error variable as a place, lazily allocating thread-local storage for it if
/// necessary.
fn last_error_place(&mut self) -> InterpResult<'tcx, MPlaceTy<'tcx>> {
let this = self.eval_context_mut();
if let Some(errno_place) = this.active_thread_ref().last_error.as_ref() {
Ok(errno_place.clone())
} else {
// Allocate new place, set initial value to 0.
let errno_layout = this.machine.layouts.u32;
let errno_place = this.allocate(errno_layout, MiriMemoryKind::Machine.into())?;
this.write_scalar(Scalar::from_u32(0), &errno_place)?;
this.active_thread_mut().last_error = Some(errno_place.clone());
Ok(errno_place)
}
}

/// Sets the last error variable.
fn set_last_error(&mut self, scalar: Scalar) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
let errno_place = this.last_error_place()?;
this.write_scalar(scalar, &errno_place)
}

/// Gets the last error variable.
fn get_last_error(&mut self) -> InterpResult<'tcx, Scalar> {
let this = self.eval_context_mut();
let errno_place = this.last_error_place()?;
this.read_scalar(&errno_place)
}

/// This function tries to produce the most similar OS error from the `std::io::ErrorKind`
/// as a platform-specific errnum.
fn io_error_to_errnum(&self, err: std::io::Error) -> InterpResult<'tcx, Scalar> {
let this = self.eval_context_ref();
let target = &this.tcx.sess.target;
if target.families.iter().any(|f| f == "unix") {
for &(name, kind) in UNIX_IO_ERROR_TABLE {
if err.kind() == kind {
return Ok(this.eval_libc(name));
}
}
throw_unsup_format!("unsupported io error: {err}")
} else if target.families.iter().any(|f| f == "windows") {
for &(name, kind) in WINDOWS_IO_ERROR_TABLE {
if err.kind() == kind {
return Ok(this.eval_windows("c", name));
}
}
throw_unsup_format!("unsupported io error: {err}");
} else {
throw_unsup_format!(
"converting io::Error into errnum is unsupported for OS {}",
target.os
)
}
}

/// The inverse of `io_error_to_errnum`.
#[allow(clippy::needless_return)]
fn try_errnum_to_io_error(
&self,
errnum: Scalar,
) -> InterpResult<'tcx, Option<std::io::ErrorKind>> {
let this = self.eval_context_ref();
let target = &this.tcx.sess.target;
if target.families.iter().any(|f| f == "unix") {
let errnum = errnum.to_i32()?;
for &(name, kind) in UNIX_IO_ERROR_TABLE {
if errnum == this.eval_libc_i32(name) {
return Ok(Some(kind));
}
}
return Ok(None);
} else if target.families.iter().any(|f| f == "windows") {
let errnum = errnum.to_u32()?;
for &(name, kind) in WINDOWS_IO_ERROR_TABLE {
if errnum == this.eval_windows("c", name).to_u32()? {
return Ok(Some(kind));
}
}
return Ok(None);
} else {
throw_unsup_format!(
"converting errnum into io::Error is unsupported for OS {}",
target.os
)
}
}

/// Sets the last OS error using a `std::io::ErrorKind`.
fn set_last_error_from_io_error(&mut self, err: std::io::Error) -> InterpResult<'tcx> {
self.set_last_error(self.io_error_to_errnum(err)?)
}

/// Sets the last OS error using a `std::io::ErrorKind` and writes -1 to dest place.
fn set_last_error_and_return(
&mut self,
err: impl Into<io::Error>,
dest: &MPlaceTy<'tcx>,
) -> InterpResult<'tcx> {
self.set_last_error(self.io_error_to_errnum(err.into())?)?;
self.write_int(-1, dest)?;
Ok(())
}

/// Helper function that consumes an `std::io::Result<T>` and returns an
/// `InterpResult<'tcx,T>::Ok` instead. In case the result is an error, this function returns
/// `Ok(-1)` and sets the last OS error accordingly.
///
/// This function uses `T: From<i32>` instead of `i32` directly because some IO related
/// functions return different integer types (like `read`, that returns an `i64`).
fn try_unwrap_io_result<T: From<i32>>(
&mut self,
result: std::io::Result<T>,
) -> InterpResult<'tcx, T> {
match result {
Ok(ok) => Ok(ok),
Err(e) => {
self.eval_context_mut().set_last_error_from_io_error(e)?;
Ok((-1).into())
}
}
}

/// Dereference a pointer operand to a place using `layout` instead of the pointer's declared type
fn deref_pointer_as(
&self,
Expand Down
1 change: 1 addition & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,7 @@ pub use crate::range_map::RangeMap;
pub use crate::shims::EmulateItemResult;
pub use crate::shims::env::{EnvVars, EvalContextExt as _};
pub use crate::shims::foreign_items::{DynSym, EvalContextExt as _};
pub use crate::shims::io_error::{EvalContextExt as _, LibcError};
pub use crate::shims::os_str::EvalContextExt as _;
pub use crate::shims::panic::{CatchUnwindData, EvalContextExt as _};
pub use crate::shims::time::EvalContextExt as _;
Expand Down
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