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Use TryFrom instead

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This commit is contained in:
Christian Poveda 2019-11-07 20:50:16 +01:00
parent f910ea135c
commit 4bbaa72dc9
2 changed files with 11 additions and 22 deletions
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14
src/helpers.rs
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@ -1,6 +1,5 @@
use std::{mem, iter};
use std::ffi::{OsStr, OsString};
use std::convert::TryFrom;
use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX};
use rustc::mir;
@ -460,16 +459,3 @@ fn bytes_to_os_str<'tcx, 'a>(bytes: &'a[u8]) -> InterpResult<'tcx, &'a OsStr> {
.map_err(|_| err_unsup_format!("{:?} is not a valid utf-8 string", bytes))?;
Ok(&OsStr::new(s))
}
pub fn try_into_host_usize(i: impl Into<u128>) -> Option<usize> {
let i: u128 = i.into();
if i > usize::max_value() as u128 {
None
} else {
Some(i as usize)
}
}
pub fn try_from_host_usize<T: TryFrom<u128>>(i: usize) -> Option<T> {
T::try_from(i as u128).ok()
}

19
src/shims/fs.rs
View File

@ -1,6 +1,7 @@
use std::collections::HashMap;
use std::fs::{remove_file, File, OpenOptions};
use std::io::{Read, Write};
use std::convert::TryFrom;
use rustc::ty::layout::Size;
@ -174,16 +175,18 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
let buf = this.read_scalar(buf_op)?.not_undef()?;
if let Some(handle) = this.machine.file_handler.handles.get_mut(&fd) {
let count = helpers::try_into_host_usize(count)
.ok_or_else(|| err_unsup_format!("Program tries to read into buffer too big for this host platform"))?;
// We want to read at most `count` bytes
let mut bytes = vec![0; count];
let count = isize::try_from(count)
.map_err(|_| err_unsup_format!("Program tries to read into buffer too big for this host platform"))?;
// 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_value()` because it is a host's `isize`.
let mut bytes = vec![0; count as usize];
let result = handle.file.read(&mut bytes);
match result {
Ok(c) => {
let read_bytes = helpers::try_from_host_usize::<i64>(c)
.ok_or_else(|| err_unsup_format!("Number of read bytes {} cannot be transformed to i64", c))?;
let read_bytes = i64::try_from(c)
.map_err(|_| err_unsup_format!("Number of read bytes {} cannot be transformed to i64", c))?;
// If reading to `bytes` did not fail, we write those bytes to the buffer.
this.memory.write_bytes(buf, bytes)?;
Ok(read_bytes)
@ -221,8 +224,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
let result = handle.file.write(&bytes);
match result {
Ok(c) => helpers::try_from_host_usize::<i64>(c)
.ok_or_else(|| err_unsup_format!("Number of written bytes {} cannot be transformed to i64", c).into()),
Ok(c) => i64::try_from(c)
.map_err(|_| err_unsup_format!("Number of written bytes {} cannot be transformed to i64", c).into()),
Err(e) => {
this.set_last_error_from_io_error(e)?;
Ok(-1)