binder/parcel/
file_descriptor.rs

1/*
2 * Copyright (C) 2020 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17use super::{
18    BorrowedParcel, Deserialize, DeserializeArray, DeserializeOption, Serialize, SerializeArray,
19    SerializeOption,
20};
21use crate::binder::AsNative;
22use crate::error::{status_result, Result, StatusCode};
23use crate::sys;
24
25use std::os::fd::{AsRawFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
26
27/// Rust version of the Java class android.os.ParcelFileDescriptor
28#[derive(Debug)]
29pub struct ParcelFileDescriptor(OwnedFd);
30
31impl ParcelFileDescriptor {
32    /// Create a new `ParcelFileDescriptor`
33    pub fn new<F: Into<OwnedFd>>(fd: F) -> Self {
34        Self(fd.into())
35    }
36}
37
38impl AsRef<OwnedFd> for ParcelFileDescriptor {
39    fn as_ref(&self) -> &OwnedFd {
40        &self.0
41    }
42}
43
44impl From<ParcelFileDescriptor> for OwnedFd {
45    fn from(fd: ParcelFileDescriptor) -> OwnedFd {
46        fd.0
47    }
48}
49
50impl AsRawFd for ParcelFileDescriptor {
51    fn as_raw_fd(&self) -> RawFd {
52        self.0.as_raw_fd()
53    }
54}
55
56impl IntoRawFd for ParcelFileDescriptor {
57    fn into_raw_fd(self) -> RawFd {
58        self.0.into_raw_fd()
59    }
60}
61
62impl PartialEq for ParcelFileDescriptor {
63    // Since ParcelFileDescriptors own the FD, if this function ever returns true (and it is used to
64    // compare two different objects), then it would imply that an FD is double-owned.
65    fn eq(&self, other: &Self) -> bool {
66        self.as_raw_fd() == other.as_raw_fd()
67    }
68}
69
70impl Eq for ParcelFileDescriptor {}
71
72impl Serialize for ParcelFileDescriptor {
73    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
74        let fd = self.0.as_raw_fd();
75        // Safety: `Parcel` always contains a valid pointer to an
76        // `AParcel`. Likewise, `ParcelFileDescriptor` always contains a
77        // valid file, so we can borrow a valid file
78        // descriptor. `AParcel_writeParcelFileDescriptor` does NOT take
79        // ownership of the fd, so we need not duplicate it first.
80        let status = unsafe { sys::AParcel_writeParcelFileDescriptor(parcel.as_native_mut(), fd) };
81        status_result(status)
82    }
83}
84
85impl SerializeArray for ParcelFileDescriptor {}
86
87impl SerializeOption for ParcelFileDescriptor {
88    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
89        if let Some(f) = this {
90            f.serialize(parcel)
91        } else {
92            let status =
93            // Safety: `Parcel` always contains a valid pointer to an
94            // `AParcel`. `AParcel_writeParcelFileDescriptor` accepts the
95            // value `-1` as the file descriptor to signify serializing a
96            // null file descriptor.
97                unsafe { sys::AParcel_writeParcelFileDescriptor(parcel.as_native_mut(), -1i32) };
98            status_result(status)
99        }
100    }
101}
102
103impl DeserializeOption for ParcelFileDescriptor {
104    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<Self>> {
105        let mut fd = -1i32;
106        // Safety: `Parcel` always contains a valid pointer to an
107        // `AParcel`. We pass a valid mutable pointer to an i32, which
108        // `AParcel_readParcelFileDescriptor` assigns the valid file
109        // descriptor into, or `-1` if deserializing a null file
110        // descriptor. The read function passes ownership of the file
111        // descriptor to its caller if it was non-null, so we must take
112        // ownership of the file and ensure that it is eventually closed.
113        unsafe {
114            status_result(sys::AParcel_readParcelFileDescriptor(parcel.as_native(), &mut fd))?;
115        }
116        if fd < 0 {
117            Ok(None)
118        } else {
119            // Safety: At this point, we know that the file descriptor was
120            // not -1, so must be a valid, owned file descriptor which we
121            // can safely turn into a `File`.
122            let file = unsafe { OwnedFd::from_raw_fd(fd) };
123            Ok(Some(ParcelFileDescriptor::new(file)))
124        }
125    }
126}
127
128impl Deserialize for ParcelFileDescriptor {
129    type UninitType = Option<Self>;
130    fn uninit() -> Self::UninitType {
131        Self::UninitType::default()
132    }
133    fn from_init(value: Self) -> Self::UninitType {
134        Some(value)
135    }
136
137    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
138        Deserialize::deserialize(parcel).transpose().unwrap_or(Err(StatusCode::UNEXPECTED_NULL))
139    }
140}
141
142impl DeserializeArray for ParcelFileDescriptor {}
binder/parcel/file_descriptor.rs

binder/parcel/
file_descriptor.rs
