cache_manager_config_lib/
cache_manager_config_lib_rust_config_lib_source.rs

1use fidl::unpersist;
2use fidl_cf_sc_internal_cachemanagerconfiglib::Config as FidlConfig;
3use fuchsia_inspect::Node;
4use fuchsia_runtime::{take_startup_handle, HandleInfo, HandleType};
5use std::convert::TryInto;
6const EXPECTED_CHECKSUM: &[u8] = &[
7    0xee, 0xc7, 0xc3, 0x22, 0xf2, 0xb0, 0x79, 0x6d, 0x7d, 0x07, 0x77, 0x52, 0x8f, 0x01, 0x54, 0xa2,
8    0xaa, 0x69, 0xe1, 0xa9, 0xf1, 0xb7, 0x80, 0xc0, 0xfe, 0x0a, 0xca, 0x3e, 0xd8, 0xfc, 0x25, 0xd8,
9];
10#[derive(Debug)]
11pub struct Config {
12    pub cache_clearing_threshold: u64,
13    pub storage_checking_frequency: u64,
14}
15impl Config {
16    #[doc = r" Take the config startup handle and parse its contents."]
17    #[doc = r""]
18    #[doc = r" # Panics"]
19    #[doc = r""]
20    #[doc = r" If the config startup handle was already taken or if it is not valid."]
21    pub fn take_from_startup_handle() -> Self {
22        let handle_info = HandleInfo::new(HandleType::ComponentConfigVmo, 0);
23        let config_vmo: zx::Vmo =
24            take_startup_handle(handle_info).expect("Config VMO handle must be present.").into();
25        Self::from_vmo(&config_vmo).expect("Config VMO handle must be valid.")
26    }
27    #[doc = r" Parse `Self` from `vmo`."]
28    pub fn from_vmo(vmo: &zx::Vmo) -> Result<Self, Error> {
29        let config_size = vmo.get_content_size().map_err(Error::GettingContentSize)?;
30        let config_bytes = vmo.read_to_vec(0, config_size).map_err(Error::ReadingConfigBytes)?;
31        Self::from_bytes(&config_bytes)
32    }
33    #[doc = r" Parse `Self` from `bytes`."]
34    pub fn from_bytes(bytes: &[u8]) -> Result<Self, Error> {
35        let (checksum_len_bytes, bytes) = bytes.split_at_checked(2).ok_or(Error::TooFewBytes)?;
36        let checksum_len_bytes: [u8; 2] =
37            checksum_len_bytes.try_into().expect("previous call guaranteed 2 element slice");
38        let checksum_length = u16::from_le_bytes(checksum_len_bytes) as usize;
39        let (observed_checksum, bytes) =
40            bytes.split_at_checked(checksum_length).ok_or(Error::TooFewBytes)?;
41        if observed_checksum != EXPECTED_CHECKSUM {
42            return Err(Error::ChecksumMismatch { observed_checksum: observed_checksum.to_vec() });
43        }
44        let fidl_config: FidlConfig = unpersist(bytes).map_err(Error::Unpersist)?;
45        Ok(Self {
46            cache_clearing_threshold: fidl_config.cache_clearing_threshold,
47            storage_checking_frequency: fidl_config.storage_checking_frequency,
48        })
49    }
50    pub fn record_inspect(&self, inspector_node: &Node) {
51        inspector_node.record_uint("cache_clearing_threshold", self.cache_clearing_threshold);
52        inspector_node.record_uint("storage_checking_frequency", self.storage_checking_frequency);
53    }
54}
55#[derive(Debug)]
56pub enum Error {
57    #[doc = r" Failed to read the content size of the VMO."]
58    GettingContentSize(zx::Status),
59    #[doc = r" Failed to read the content of the VMO."]
60    ReadingConfigBytes(zx::Status),
61    #[doc = r" The VMO was too small for this config library."]
62    TooFewBytes,
63    #[doc = r" The VMO's config ABI checksum did not match this library's."]
64    ChecksumMismatch { observed_checksum: Vec<u8> },
65    #[doc = r" Failed to parse the non-checksum bytes of the VMO as this library's FIDL type."]
66    Unpersist(fidl::Error),
67}
68impl std::fmt::Display for Error {
69    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
70        match self {
71            Self::GettingContentSize(status) => {
72                write!(f, "Failed to get content size: {status}")
73            }
74            Self::ReadingConfigBytes(status) => {
75                write!(f, "Failed to read VMO content: {status}")
76            }
77            Self::TooFewBytes => {
78                write!(f, "VMO content is not large enough for this config library.")
79            }
80            Self::ChecksumMismatch { observed_checksum } => {
81                write!(
82                    f,
83                    "ABI checksum mismatch, expected {:?}, got {:?}",
84                    EXPECTED_CHECKSUM, observed_checksum,
85                )
86            }
87            Self::Unpersist(fidl_error) => {
88                write!(f, "Failed to parse contents of config VMO: {fidl_error}")
89            }
90        }
91    }
92}
93impl std::error::Error for Error {
94    #[allow(unused_parens, reason = "rustfmt errors without parens here")]
95    fn source(&self) -> Option<(&'_ (dyn std::error::Error + 'static))> {
96        match self {
97            Self::GettingContentSize(ref status) | Self::ReadingConfigBytes(ref status) => {
98                Some(status)
99            }
100            Self::TooFewBytes => None,
101            Self::ChecksumMismatch { .. } => None,
102            Self::Unpersist(ref fidl_error) => Some(fidl_error),
103        }
104    }
105    fn description(&self) -> &str {
106        match self {
107            Self::GettingContentSize(_) => "getting content size",
108            Self::ReadingConfigBytes(_) => "reading VMO contents",
109            Self::TooFewBytes => "VMO contents too small",
110            Self::ChecksumMismatch { .. } => "ABI checksum mismatch",
111            Self::Unpersist(_) => "FIDL parsing error",
112        }
113    }
114}
cache_manager_config_lib/cache_manager_config_lib_rust_config_lib_source.rs

cache_manager_config_lib/
cache_manager_config_lib_rust_config_lib_source.rs
