rust/src/shims/env.rs

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use std::collections::HashMap;
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use std::env;
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use rustc::ty::layout::{Size};
use rustc_mir::interpret::{Pointer, Memory};
use crate::stacked_borrows::Tag;
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use crate::*;
#[derive(Default)]
pub struct EnvVars {
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/// Stores pointers to the environment variables. These variables must be stored as
/// null-terminated C strings with the `"{name}={value}"` format.
map: HashMap<Vec<u8>, Pointer<Tag>>,
}
impl EnvVars {
pub(crate) fn init<'mir, 'tcx>(
ecx: &mut InterpCx<'mir, 'tcx, Evaluator<'tcx>>,
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mut excluded_env_vars: Vec<String>,
) {
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// Exclude `TERM` var to avoid terminfo trying to open the termcap file.
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excluded_env_vars.push("TERM".to_owned());
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if ecx.machine.communicate {
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for (name, value) in env::vars() {
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if !excluded_env_vars.contains(&name) {
let var_ptr = alloc_env_var(name.as_bytes(), value.as_bytes(), ecx.memory_mut());
ecx.machine.env_vars.map.insert(name.into_bytes(), var_ptr);
}
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}
}
}
}
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fn alloc_env_var<'mir, 'tcx>(
name: &[u8],
value: &[u8],
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memory: &mut Memory<'mir, 'tcx, Evaluator<'tcx>>,
) -> Pointer<Tag> {
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let mut bytes = name.to_vec();
bytes.push(b'=');
bytes.extend_from_slice(value);
bytes.push(0);
memory.allocate_static_bytes(bytes.as_slice(), MiriMemoryKind::Env.into())
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}
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impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
fn getenv(
&mut self,
name_op: OpTy<'tcx, Tag>,
) -> InterpResult<'tcx, Scalar<Tag>> {
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let this = self.eval_context_mut();
let name_ptr = this.read_scalar(name_op)?.not_undef()?;
let name = this.memory().read_c_str(name_ptr)?;
Ok(match this.machine.env_vars.map.get(name) {
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// The offset is used to strip the "{name}=" part of the string.
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Some(var_ptr) => Scalar::Ptr(var_ptr.offset(Size::from_bytes(name.len() as u64 + 1), this)?),
None => Scalar::ptr_null(&*this.tcx),
})
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}
fn setenv(
&mut self,
name_op: OpTy<'tcx, Tag>,
value_op: OpTy<'tcx, Tag>,
) -> InterpResult<'tcx, i32> {
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let this = self.eval_context_mut();
let name_ptr = this.read_scalar(name_op)?.not_undef()?;
let value_ptr = this.read_scalar(value_op)?.not_undef()?;
let value = this.memory().read_c_str(value_ptr)?;
let mut new = None;
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if !this.is_null(name_ptr)? {
let name = this.memory().read_c_str(name_ptr)?;
if !name.is_empty() && !name.contains(&b'=') {
new = Some((name.to_owned(), value.to_owned()));
}
}
if let Some((name, value)) = new {
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let var_ptr = alloc_env_var(&name, &value, this.memory_mut());
if let Some(var) = this.machine.env_vars.map.insert(name.to_owned(), var_ptr) {
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this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
}
Ok(0)
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} else {
Ok(-1)
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}
}
fn unsetenv(
&mut self,
name_op: OpTy<'tcx, Tag>,
) -> InterpResult<'tcx, i32> {
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let this = self.eval_context_mut();
let name_ptr = this.read_scalar(name_op)?.not_undef()?;
let mut success = None;
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if !this.is_null(name_ptr)? {
let name = this.memory().read_c_str(name_ptr)?.to_owned();
if !name.is_empty() && !name.contains(&b'=') {
success = Some(this.machine.env_vars.map.remove(&name));
}
}
if let Some(old) = success {
if let Some(var) = old {
this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
}
Ok(0)
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} else {
Ok(-1)
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}
}
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fn getcwd(
&mut self,
buf_op: OpTy<'tcx, Tag>,
size_op: OpTy<'tcx, Tag>,
) -> InterpResult<'tcx, Scalar<Tag>> {
let this = self.eval_context_mut();
if !this.machine.communicate {
throw_unsup_format!("Function not available when isolation is enabled")
}
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let tcx = &{this.tcx.tcx};
let buf = this.force_ptr(this.read_scalar(buf_op)?.not_undef()?)?;
let size = this.read_scalar(size_op)?.to_usize(&*this.tcx)?;
// If we cannot get the current directory, we return null
// FIXME: Technically we have to set the `errno` global too
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match env::current_dir() {
Ok(cwd) =>{
// It is not clear what happens with non-utf8 paths here
let mut bytes = cwd.display().to_string().into_bytes();
// If the buffer is smaller or equal than the path, we return null.
if (bytes.len() as u64) < size {
// We add a `/0` terminator
bytes.push(0);
// This is ok because the buffer is larger than the path with the null terminator.
this.memory_mut().get_mut(buf.alloc_id)?.write_bytes(tcx, buf, &bytes)?;
return Ok(Scalar::Ptr(buf))
}
this.machine.last_error = 34; // ERANGE
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}
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Err(e) => this.machine.last_error = e.raw_os_error().unwrap() as u32,
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}
Ok(Scalar::ptr_null(&*this.tcx))
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}
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}