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Auto merge of #1495 - samrat:fd-trait, r=oli-obk

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Add FileDescriptor trait to abstract fn's on File's and Stdin,Stdout,Stderr

Related issue: #1486

Instead of mapping FDs to `FileHandle`, map them to a `FileDescriptor` trait object. The goal is to eventually have both `FileHandle` as well as `Stdin`, `Stdout` and `Stderr` implement this trait so that syscalls involving FDs can handle both `File`s as well as the standard IO streams.

This PR adds the `FileDescriptor` trait and an `impl` for `FileHandle`. I'll open a separate PR for implementing the trait for the standard IO streams.
This commit is contained in:
bors 2020-08-03 15:50:30 +00:00
commit 69d050fb6b
2 changed files with 130 additions and 62 deletions
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2
src/machine.rs
View file

@ -250,7 +250,7 @@ pub struct Evaluator<'mir, 'tcx> {
/// Whether to enforce the validity invariant.
pub(crate) validate: bool,
pub(crate) file_handler: shims::posix::FileHandler,
pub(crate) file_handler: shims::posix::FileHandler<'tcx>,
pub(crate) dir_handler: shims::posix::DirHandler,
/// The temporary used for storing the argument of

190
src/shims/posix/fs.rs
View file

@ -1,7 +1,7 @@
use std::collections::BTreeMap;
use std::convert::{TryFrom, TryInto};
use std::fs::{read_dir, remove_dir, remove_file, rename, DirBuilder, File, FileType, OpenOptions, ReadDir};
use std::io::{Read, Seek, SeekFrom, Write};
use std::io::{self, Read, Seek, SeekFrom, Write};
use std::path::Path;
use std::time::SystemTime;
@ -22,15 +22,42 @@ struct FileHandle {
writable: bool,
}
#[derive(Debug, Default)]
pub struct FileHandler {
handles: BTreeMap<i32, FileHandle>,
trait FileDescriptor<'tcx> : std::fmt::Debug {
fn as_file_handle(&self) -> InterpResult<'tcx, &FileHandle>;
fn read(&mut self, bytes: &mut [u8]) -> InterpResult<'tcx, io::Result<usize>>;
fn write(&mut self, bytes: &[u8]) -> InterpResult<'tcx, io::Result<usize>>;
fn seek(&mut self, offset: SeekFrom) -> InterpResult<'tcx, io::Result<u64>>;
}
impl<'tcx> FileDescriptor<'tcx> for FileHandle {
fn as_file_handle(&self) -> InterpResult<'tcx, &FileHandle> {
Ok(&self)
}
fn read(&mut self, bytes: &mut [u8]) -> InterpResult<'tcx, io::Result<usize>> {
Ok(self.file.read(bytes))
}
fn write(&mut self, bytes: &[u8]) -> InterpResult<'tcx, io::Result<usize>> {
Ok(self.file.write(bytes))
}
fn seek(&mut self, offset: SeekFrom) -> InterpResult<'tcx, io::Result<u64>> {
Ok(self.file.seek(offset))
}
}
#[derive(Debug, Default)]
pub struct FileHandler<'tcx> {
handles: BTreeMap<i32, Box<dyn FileDescriptor<'tcx>>>,
}
// fd numbers 0, 1, and 2 are reserved for stdin, stdout, and stderr
const MIN_NORMAL_FILE_FD: i32 = 3;
impl FileHandler {
impl<'tcx> FileHandler<'tcx> {
fn insert_fd(&mut self, file_handle: FileHandle) -> i32 {
self.insert_fd_with_min_fd(file_handle, 0)
}
@ -62,7 +89,7 @@ impl FileHandler {
self.handles.last_key_value().map(|(fd, _)| fd.checked_add(1).unwrap()).unwrap_or(min_fd)
});
self.handles.insert(new_fd, file_handle).unwrap_none();
self.handles.insert(new_fd, Box::new(file_handle)).unwrap_none();
new_fd
}
}
@ -383,7 +410,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
}
let fh = &mut this.machine.file_handler;
let (file_result, writable) = match fh.handles.get(&fd) {
Some(FileHandle { file, writable }) => (file.try_clone(), *writable),
Some(file_descriptor) => match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => (file.try_clone(), *writable),
Err(_) => return this.handle_not_found(),
},
None => return this.handle_not_found(),
};
let fd_result = file_result.map(|duplicated| {
@ -394,9 +424,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
&& cmd == this.eval_libc_i32("F_FULLFSYNC")?
{
let &[_, _] = check_arg_count(args)?;
if let Some(FileHandle { file, writable }) = this.machine.file_handler.handles.get(&fd) {
let io_result = maybe_sync_file(file, *writable, File::sync_all);
this.try_unwrap_io_result(io_result)
if let Some(file_descriptor) = this.machine.file_handler.handles.get(&fd) {
match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => {
let io_result = maybe_sync_file(&file, *writable, File::sync_all);
this.try_unwrap_io_result(io_result)
},
Err(_) => this.handle_not_found(),
}
} else {
this.handle_not_found()
}
@ -412,24 +447,29 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
let fd = this.read_scalar(fd_op)?.to_i32()?;
if let Some(FileHandle { file, writable }) = this.machine.file_handler.handles.remove(&fd) {
// We sync the file if it was opened in a mode different than read-only.
if writable {
// `File::sync_all` does the checks that are done when closing a file. We do this to
// to handle possible errors correctly.
let result = this.try_unwrap_io_result(file.sync_all().map(|_| 0i32));
// Now we actually close the file.
drop(file);
// And return the result.
result
} else {
// We drop the file, this closes it but ignores any errors produced when closing
// it. This is done because `File::sync_all` cannot be done over files like
// `/dev/urandom` which are read-only. Check
// https://github.com/rust-lang/miri/issues/999#issuecomment-568920439 for a deeper
// discussion.
drop(file);
Ok(0)
if let Some(file_descriptor) = this.machine.file_handler.handles.remove(&fd) {
match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => {
// We sync the file if it was opened in a mode different than read-only.
if *writable {
// `File::sync_all` does the checks that are done when closing a file. We do this to
// to handle possible errors correctly.
let result = this.try_unwrap_io_result(file.sync_all().map(|_| 0i32));
// Now we actually close the file.
drop(file);
// And return the result.
result
} else {
// We drop the file, this closes it but ignores any errors produced when closing
// it. This is done because `File::sync_all` cannot be done over files like
// `/dev/urandom` which are read-only. Check
// https://github.com/rust-lang/miri/issues/999#issuecomment-568920439 for a deeper
// discussion.
drop(file);
Ok(0)
}
},
Err(_) => this.handle_not_found()
}
} else {
this.handle_not_found()
@ -460,15 +500,16 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
// host's and target's `isize`. This saves us from having to handle overflows later.
let count = count.min(this.machine_isize_max() as u64).min(isize::MAX as u64);
if let Some(FileHandle { file, writable: _ }) = this.machine.file_handler.handles.get_mut(&fd) {
trace!("read: FD mapped to {:?}", file);
if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
trace!("read: FD mapped to {:?}", file_descriptor);
// We want to read at most `count` bytes. We are sure that `count` is not negative
// because it was a target's `usize`. Also we are sure that its smaller than
// `usize::MAX` because it is a host's `isize`.
let mut bytes = vec![0; count as usize];
let result = file
.read(&mut bytes)
// `File::read` never returns a value larger than `count`, so this cannot fail.
// `File::read` never returns a value larger than `count`,
// so this cannot fail.
let result = file_descriptor
.read(&mut bytes)?
.map(|c| i64::try_from(c).unwrap());
match result {
@ -510,9 +551,11 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
// host's and target's `isize`. This saves us from having to handle overflows later.
let count = count.min(this.machine_isize_max() as u64).min(isize::MAX as u64);
if let Some(FileHandle { file, writable: _ }) = this.machine.file_handler.handles.get_mut(&fd) {
if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
let bytes = this.memory.read_bytes(buf, Size::from_bytes(count))?;
let result = file.write(&bytes).map(|c| i64::try_from(c).unwrap());
let result = file_descriptor
.write(&bytes)?
.map(|c| i64::try_from(c).unwrap());
this.try_unwrap_io_result(result)
} else {
this.handle_not_found()
@ -545,8 +588,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
return Ok(-1);
};
if let Some(FileHandle { file, writable: _ }) = this.machine.file_handler.handles.get_mut(&fd) {
let result = file.seek(seek_from).map(|offset| i64::try_from(offset).unwrap());
if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
let result = file_descriptor
.seek(seek_from)?
.map(|offset| i64::try_from(offset).unwrap());
this.try_unwrap_io_result(result)
} else {
this.handle_not_found()
@ -1103,21 +1148,26 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
let fd = this.read_scalar(fd_op)?.to_i32()?;
let length = this.read_scalar(length_op)?.to_i64()?;
if let Some(FileHandle { file, writable }) = this.machine.file_handler.handles.get_mut(&fd) {
if *writable {
if let Ok(length) = length.try_into() {
let result = file.set_len(length);
this.try_unwrap_io_result(result.map(|_| 0i32))
} else {
let einval = this.eval_libc("EINVAL")?;
this.set_last_error(einval)?;
Ok(-1)
if let Some(file_descriptor) = this.machine.file_handler.handles.get_mut(&fd) {
match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => {
if *writable {
if let Ok(length) = length.try_into() {
let result = file.set_len(length);
this.try_unwrap_io_result(result.map(|_| 0i32))
} else {
let einval = this.eval_libc("EINVAL")?;
this.set_last_error(einval)?;
Ok(-1)
}
} else {
// The file is not writable
let einval = this.eval_libc("EINVAL")?;
this.set_last_error(einval)?;
Ok(-1)
}
}
} else {
// The file is not writable
let einval = this.eval_libc("EINVAL")?;
this.set_last_error(einval)?;
Ok(-1)
Err(_) => this.handle_not_found()
}
} else {
this.handle_not_found()
@ -1135,9 +1185,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.check_no_isolation("fsync")?;
let fd = this.read_scalar(fd_op)?.to_i32()?;
if let Some(FileHandle { file, writable }) = this.machine.file_handler.handles.get(&fd) {
let io_result = maybe_sync_file(file, *writable, File::sync_all);
this.try_unwrap_io_result(io_result)
if let Some(file_descriptor) = this.machine.file_handler.handles.get(&fd) {
match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => {
let io_result = maybe_sync_file(&file, *writable, File::sync_all);
this.try_unwrap_io_result(io_result)
}
Err(_) => this.handle_not_found()
}
} else {
this.handle_not_found()
}
@ -1149,9 +1204,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.check_no_isolation("fdatasync")?;
let fd = this.read_scalar(fd_op)?.to_i32()?;
if let Some(FileHandle { file, writable }) = this.machine.file_handler.handles.get(&fd) {
let io_result = maybe_sync_file(file, *writable, File::sync_data);
this.try_unwrap_io_result(io_result)
if let Some(file_descriptor) = this.machine.file_handler.handles.get(&fd) {
match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => {
let io_result = maybe_sync_file(&file, *writable, File::sync_data);
this.try_unwrap_io_result(io_result)
}
Err(_) => this.handle_not_found()
}
} else {
this.handle_not_found()
}
@ -1187,9 +1247,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
return Ok(-1);
}
if let Some(FileHandle { file, writable }) = this.machine.file_handler.handles.get(&fd) {
let io_result = maybe_sync_file(file, *writable, File::sync_data);
this.try_unwrap_io_result(io_result)
if let Some(file_descriptor) = this.machine.file_handler.handles.get(&fd) {
match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable }) => {
let io_result = maybe_sync_file(&file, *writable, File::sync_data);
this.try_unwrap_io_result(io_result)
},
Err(_) => this.handle_not_found()
}
} else {
this.handle_not_found()
}
@ -1239,7 +1304,10 @@ impl FileMetadata {
) -> InterpResult<'tcx, Option<FileMetadata>> {
let option = ecx.machine.file_handler.handles.get(&fd);
let file = match option {
Some(FileHandle { file, writable: _ }) => file,
Some(file_descriptor) => match file_descriptor.as_file_handle() {
Ok(FileHandle { file, writable: _ }) => file,
Err(_) => return ecx.handle_not_found().map(|_: i32| None),
},
None => return ecx.handle_not_found().map(|_: i32| None),
};
let metadata = file.metadata();