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windows buffer size protocol: turns out std resets last_error to 0; let's require that in general

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This commit is contained in:
Ralf Jung 2024-04-23 09:41:55 +02:00
parent 342943bc77
commit 00acfabcee
2 changed files with 15 additions and 11 deletions
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23
src/tools/miri/src/shims/env.rs
View File

@ -160,10 +160,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
this.assert_target_os("windows", "GetEnvironmentVariableW");
let name_ptr = this.read_pointer(name_op)?;
let buf_ptr = this.read_pointer(buf_op)?;
let buf_size = this.read_scalar(size_op)?.to_u32()?; // in characters
let name = this.read_os_str_from_wide_str(name_ptr)?;
Ok(match this.machine.env_vars.map.get(&name) {
Some(&var_ptr) => {
this.set_last_error(Scalar::from_u32(0))?; // make sure this is unambiguously not an error
// The offset is used to strip the "{name}=" part of the string.
#[rustfmt::skip]
let name_offset_bytes = u64::try_from(name.len()).unwrap()
@ -172,14 +174,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
let var_ptr = var_ptr.offset(Size::from_bytes(name_offset_bytes), this)?;
let var = this.read_os_str_from_wide_str(var_ptr)?;
let buf_ptr = this.read_pointer(buf_op)?;
// `buf_size` represents the size in characters.
let buf_size = u64::from(this.read_scalar(size_op)?.to_u32()?);
Scalar::from_u32(windows_check_buffer_size(
this.write_os_str_to_wide_str(
&var, buf_ptr, buf_size, /*truncate*/ false,
)?,
))
Scalar::from_u32(windows_check_buffer_size(this.write_os_str_to_wide_str(
&var,
buf_ptr,
buf_size.into(),
/*truncate*/ false,
)?))
// This can in fact return 0. It is up to the caller to set last_error to 0
// beforehand and check it afterwards to exclude that case.
}
None => {
let envvar_not_found = this.eval_windows("c", "ERROR_ENVVAR_NOT_FOUND");
@ -375,7 +377,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
// If we cannot get the current directory, we return 0
match env::current_dir() {
Ok(cwd) => {
this.set_last_error(Scalar::from_u32(0))?; // make sure this is unambiguously not an error
// This can in fact return 0. It is up to the caller to set last_error to 0
// beforehand and check it afterwards to exclude that case.
return Ok(Scalar::from_u32(windows_check_buffer_size(
this.write_path_to_wide_str(&cwd, buf, size, /*truncate*/ false)?,
)));

3
src/tools/miri/src/shims/windows/foreign_items.rs
View File

@ -231,7 +231,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
Scalar::from_u32(0) // return zero upon failure
}
Ok(abs_filename) => {
this.set_last_error(Scalar::from_u32(0))?; // make sure this is unambiguously not an error
Scalar::from_u32(helpers::windows_check_buffer_size(
this.write_path_to_wide_str(
&abs_filename,
@ -240,6 +239,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
/*truncate*/ false,
)?,
))
// This can in fact return 0. It is up to the caller to set last_error to 0
// beforehand and check it afterwards to exclude that case.
}
};
this.write_scalar(result, dest)?;