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use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
use std::cmp::min;
use std::fmt;
use std::io;
/// VersionInfo is information about a Lucet module to allow the Lucet runtime to determine if or
/// how the module can be loaded, if so requested. The information here describes implementation
/// details in runtime support for `lucetc`-produced modules, and nothing higher level.
#[repr(C)]
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct VersionInfo {
major: u16,
minor: u16,
patch: u16,
reserved: u16,
/// `version_hash` is either all nulls or the first eight ascii characters of the git commit
/// hash of wherever this Version is coming from. In the case of a compiled lucet module, this
/// hash will come from the git commit that the lucetc producing it came from. In a runtime
/// context, it will be the git commit of lucet-runtime built into the embedder.
///
/// The version hash will typically populated only in release builds, but may blank even in
/// that case: if building from a packaged crate, or in a build environment that does not have
/// "git" installed, `lucetc` and `lucet-runtime` will fall back to an empty hash.
version_hash: [u8; 8],
}
impl fmt::Display for VersionInfo {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "{}.{}.{}", self.major, self.minor, self.patch)?;
if u64::from_ne_bytes(self.version_hash) != 0 {
write!(
fmt,
"-{}",
std::str::from_utf8(&self.version_hash).unwrap_or("INVALID")
)?;
}
Ok(())
}
}
impl VersionInfo {
pub fn new(major: u16, minor: u16, patch: u16, version_hash: [u8; 8]) -> VersionInfo {
VersionInfo {
major,
minor,
patch,
reserved: 0x8000,
version_hash,
}
}
/// A more permissive version check than for version equality. This check will allow an `other`
/// version that is more specific than `self`, but matches for data that is available.
pub fn compatible_with(&self, other: &VersionInfo) -> bool {
if !(self.valid() || other.valid()) {
return false;
}
if self.major == other.major && self.minor == other.minor && self.patch == other.patch {
if self.version_hash == [0u8; 8] {
// we aren't bound to a specific git commit, so anything goes.
true
} else {
self.version_hash == other.version_hash
}
} else {
false
}
}
pub fn write_to<W: WriteBytesExt>(&self, w: &mut W) -> io::Result<()> {
w.write_u16::<LittleEndian>(self.major)?;
w.write_u16::<LittleEndian>(self.minor)?;
w.write_u16::<LittleEndian>(self.patch)?;
w.write_u16::<LittleEndian>(self.reserved)?;
w.write(&self.version_hash).and_then(|written| {
if written != self.version_hash.len() {
Err(io::Error::new(
io::ErrorKind::Other,
"unable to write full version hash",
))
} else {
Ok(())
}
})
}
pub fn read_from<R: ReadBytesExt>(r: &mut R) -> io::Result<Self> {
let mut version_hash = [0u8; 8];
Ok(VersionInfo {
major: r.read_u16::<LittleEndian>()?,
minor: r.read_u16::<LittleEndian>()?,
patch: r.read_u16::<LittleEndian>()?,
reserved: r.read_u16::<LittleEndian>()?,
version_hash: {
r.read_exact(&mut version_hash)?;
version_hash
},
})
}
pub fn valid(&self) -> bool {
self.reserved == 0x8000
}
pub fn current(current_hash: &'static [u8]) -> Self {
let mut version_hash = [0u8; 8];
for i in 0..min(version_hash.len(), current_hash.len()) {
version_hash[i] = current_hash[i];
}
// The reasoning for this is as follows:
// `SerializedModule`, in version before version information was introduced, began with a
// pointer - `module_data_ptr`. This pointer would be relocated to somewhere in user space
// for the embedder of `lucet-runtime`. On x86_64, hopefully, that's userland code in some
// OS, meaning the pointer will be a pointer to user memory, and will be below
// 0x8000_0000_0000_0000. By setting `reserved` to `0x8000`, we set what would be the
// highest bit in `module_data_ptr` in an old `lucet-runtime` and guarantee a segmentation
// fault when loading these newer modules with version information.
VersionInfo::new(
env!("CARGO_PKG_VERSION_MAJOR").parse().unwrap(),
env!("CARGO_PKG_VERSION_MINOR").parse().unwrap(),
env!("CARGO_PKG_VERSION_PATCH").parse().unwrap(),
version_hash,
)
}
}