rust/src/shims/env.rs

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use std::ffi::{OsString, OsStr};
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use std::env;
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use crate::stacked_borrows::Tag;
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use crate::rustc_target::abi::LayoutOf;
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use crate::*;
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use rustc_data_structures::fx::FxHashMap;
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use rustc::ty::layout::Size;
use rustc_mir::interpret::Pointer;
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#[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.
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map: FxHashMap<OsString, Pointer<Tag>>,
}
impl EnvVars {
pub(crate) fn init<'mir, 'tcx>(
ecx: &mut InterpCx<'mir, 'tcx, Evaluator<'tcx>>,
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excluded_env_vars: Vec<String>,
) {
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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) {
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let var_ptr =
alloc_env_var_as_c_str(name.as_ref(), value.as_ref(), ecx);
ecx.machine.env_vars.map.insert(OsString::from(name), var_ptr);
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}
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}
}
ecx.update_environ().unwrap();
}
}
fn alloc_env_var_as_c_str<'mir, 'tcx>(
name: &OsStr,
value: &OsStr,
ecx: &mut InterpCx<'mir, 'tcx, Evaluator<'tcx>>,
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) -> Pointer<Tag> {
let mut name_osstring = name.to_os_string();
name_osstring.push("=");
name_osstring.push(value);
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ecx.alloc_os_str_as_c_str(name_osstring.as_os_str(), MiriMemoryKind::Machine.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> {
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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.read_os_str_from_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::from(var_ptr.offset(Size::from_bytes(name.len() as u64 + 1), this)?)
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}
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> {
let mut this = self.eval_context_mut();
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let name_ptr = this.read_scalar(name_op)?.not_undef()?;
let value_ptr = this.read_scalar(value_op)?.not_undef()?;
let value = this.read_os_str_from_c_str(value_ptr)?;
let mut new = None;
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if !this.is_null(name_ptr)? {
let name = this.read_os_str_from_c_str(name_ptr)?;
if !name.is_empty() && !name.to_string_lossy().contains('=') {
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new = Some((name.to_owned(), value.to_owned()));
}
}
if let Some((name, value)) = new {
let var_ptr = alloc_env_var_as_c_str(&name, &value, &mut this);
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if let Some(var) = this.machine.env_vars.map.insert(name.to_owned(), var_ptr) {
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this.memory
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.deallocate(var, None, MiriMemoryKind::Machine.into())?;
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}
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this.update_environ()?;
Ok(0)
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} else {
Ok(-1)
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}
}
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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.read_os_str_from_c_str(name_ptr)?.to_owned();
if !name.is_empty() && !name.to_string_lossy().contains('=') {
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success = Some(this.machine.env_vars.map.remove(&name));
}
}
if let Some(old) = success {
if let Some(var) = old {
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this.memory
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.deallocate(var, None, MiriMemoryKind::Machine.into())?;
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}
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this.update_environ()?;
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();
this.check_no_isolation("getcwd")?;
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let buf = this.read_scalar(buf_op)?.not_undef()?;
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let size = this.read_scalar(size_op)?.to_machine_usize(&*this.tcx)?;
// If we cannot get the current directory, we return null
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match env::current_dir() {
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Ok(cwd) => {
if this.write_os_str_to_c_str(&OsString::from(cwd), buf, size)?.0 {
return Ok(buf);
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}
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let erange = this.eval_libc("ERANGE")?;
this.set_last_error(erange)?;
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}
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Err(e) => this.set_last_error_from_io_error(e)?,
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}
Ok(Scalar::ptr_null(&*this.tcx))
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}
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fn chdir(&mut self, path_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
let this = self.eval_context_mut();
this.check_no_isolation("chdir")?;
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let path = this.read_os_str_from_c_str(this.read_scalar(path_op)?.not_undef()?)?;
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match env::set_current_dir(path) {
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Ok(()) => Ok(0),
Err(e) => {
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this.set_last_error_from_io_error(e)?;
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Ok(-1)
}
}
}
fn update_environ(&mut self) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
// Collect all the pointers to each variable in a vector.
let mut vars: Vec<Scalar<Tag>> = this.machine.env_vars.map.values().map(|&ptr| ptr.into()).collect();
// Add the trailing null pointer.
vars.push(Scalar::from_int(0, this.pointer_size()));
// Make an array with all these pointers inside Miri.
let tcx = this.tcx;
let vars_layout =
this.layout_of(tcx.mk_array(tcx.types.usize, vars.len() as u64))?;
let vars_place = this.allocate(vars_layout, MiriMemoryKind::Machine.into());
for (idx, var) in vars.into_iter().enumerate() {
let place = this.mplace_field(vars_place, idx as u64)?;
this.write_scalar(var, place.into())?;
}
this.write_scalar(
vars_place.ptr,
this.memory.extra.environ.unwrap().into(),
)?;
Ok(())
}
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}