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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use crate::windows::windows_sys::{
RegCloseKey, RegEnumKeyExW, RegOpenKeyExW, RegQueryValueExW, ERROR_NO_MORE_ITEMS,
ERROR_SUCCESS, HKEY, HKEY_LOCAL_MACHINE, KEY_READ, KEY_WOW64_32KEY, REG_SZ,
};
use std::{
ffi::{OsStr, OsString},
io,
ops::RangeFrom,
os::windows::prelude::*,
ptr::null_mut,
};
/// Must never be `HKEY_PERFORMANCE_DATA`.
pub(crate) struct RegistryKey(Repr);
#[allow(clippy::upper_case_acronyms)]
type DWORD = u32;
struct OwnedKey(HKEY);
/// Note: must not encode `HKEY_PERFORMANCE_DATA` or one of its subkeys.
enum Repr {
/// `HKEY_LOCAL_MACHINE`.
LocalMachine,
/// A subkey of `HKEY_LOCAL_MACHINE`.
Owned(OwnedKey),
}
pub struct Iter<'a> {
idx: RangeFrom<DWORD>,
key: &'a RegistryKey,
}
unsafe impl Sync for Repr {}
unsafe impl Send for Repr {}
pub(crate) const LOCAL_MACHINE: RegistryKey = RegistryKey(Repr::LocalMachine);
impl RegistryKey {
fn raw(&self) -> HKEY {
match self.0 {
Repr::LocalMachine => HKEY_LOCAL_MACHINE,
Repr::Owned(ref val) => val.0,
}
}
/// Open a sub-key of `self`.
pub fn open(&self, key: &OsStr) -> io::Result<RegistryKey> {
let key = key.encode_wide().chain(Some(0)).collect::<Vec<_>>();
let mut ret = null_mut();
let err = unsafe {
RegOpenKeyExW(
self.raw(),
key.as_ptr(),
0,
KEY_READ | KEY_WOW64_32KEY,
&mut ret,
)
};
if err == ERROR_SUCCESS {
Ok(RegistryKey(Repr::Owned(OwnedKey(ret))))
} else {
Err(io::Error::from_raw_os_error(err as i32))
}
}
pub fn iter(&self) -> Iter {
Iter {
idx: 0..,
key: self,
}
}
pub fn query_str(&self, name: &str) -> io::Result<OsString> {
let name: &OsStr = name.as_ref();
let name = name.encode_wide().chain(Some(0)).collect::<Vec<_>>();
let mut len = 0;
let mut kind = 0;
unsafe {
let err = RegQueryValueExW(
self.raw(),
name.as_ptr(),
null_mut(),
&mut kind,
null_mut(),
&mut len,
);
if err != ERROR_SUCCESS {
return Err(io::Error::from_raw_os_error(err as i32));
}
if kind != REG_SZ {
return Err(io::Error::new(
io::ErrorKind::Other,
"registry key wasn't a string",
));
}
// The length here is the length in bytes, but we're using wide
// characters so we need to be sure to halve it for the length
// passed in.
assert!(len % 2 == 0, "impossible wide string size: {} bytes", len);
let vlen = len as usize / 2;
// Defensively initialized, see comment about
// `HKEY_PERFORMANCE_DATA` below.
let mut v = vec![0u16; vlen];
let err = RegQueryValueExW(
self.raw(),
name.as_ptr(),
null_mut(),
null_mut(),
v.as_mut_ptr() as *mut _,
&mut len,
);
// We don't check for `ERROR_MORE_DATA` (which would if the value
// grew between the first and second call to `RegQueryValueExW`),
// both because it's extremely unlikely, and this is a bit more
// defensive more defensive against weird types of registry keys.
if err != ERROR_SUCCESS {
return Err(io::Error::from_raw_os_error(err as i32));
}
// The length is allowed to change, but should still be even, as
// well as smaller.
assert!(len % 2 == 0, "impossible wide string size: {} bytes", len);
// If the length grew but returned a success code, it *probably*
// indicates we're `HKEY_PERFORMANCE_DATA` or a subkey(?). We
// consider this UB, since those keys write "undefined" or
// "unpredictable" values to len, and need to use a completely
// different loop structure. This should be impossible (and enforce
// it in the API to the best of our ability), but to mitigate the
// damage we do some smoke-checks on the len, and ensure `v` has
// been fully initialized (rather than trusting the result of
// `RegQueryValueExW`).
let actual_len = len as usize / 2;
assert!(actual_len <= v.len());
v.truncate(actual_len);
// Some registry keys may have a terminating nul character, but
// we're not interested in that, so chop it off if it's there.
if !v.is_empty() && v[v.len() - 1] == 0 {
v.pop();
}
Ok(OsString::from_wide(&v))
}
}
}
impl Drop for OwnedKey {
fn drop(&mut self) {
unsafe {
RegCloseKey(self.0);
}
}
}
impl<'a> Iterator for Iter<'a> {
type Item = io::Result<OsString>;
fn next(&mut self) -> Option<io::Result<OsString>> {
self.idx.next().and_then(|i| unsafe {
let mut v = Vec::with_capacity(256);
let mut len = v.capacity() as DWORD;
let ret = RegEnumKeyExW(
self.key.raw(),
i,
v.as_mut_ptr(),
&mut len,
null_mut(),
null_mut(),
null_mut(),
null_mut(),
);
if ret == ERROR_NO_MORE_ITEMS {
None
} else if ret != ERROR_SUCCESS {
Some(Err(io::Error::from_raw_os_error(ret as i32)))
} else {
v.set_len(len as usize);
Some(Ok(OsString::from_wide(&v)))
}
})
}
}
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