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use std::{io::Write, process::Stdio};
use bstr::{BStr, BString, ByteSlice};
use super::Algorithm;
use crate::blob::{pipeline, Pipeline, Platform, ResourceKind};
/// A key to uniquely identify either a location in the worktree, or in the object database.
#[derive(Clone)]
pub(crate) struct CacheKey {
id: gix_hash::ObjectId,
location: BString,
/// If `true`, this is an `id` based key, otherwise it's location based.
use_id: bool,
/// Only relevant when `id` is not null, to further differentiate content and allow us to
/// keep track of both links and blobs with the same content (rare, but possible).
is_link: bool,
}
/// A stored value representing a diffable resource.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Debug)]
pub(crate) struct CacheValue {
/// The outcome of converting a resource into a diffable format using [Pipeline::convert_to_diffable()].
conversion: pipeline::Outcome,
/// The kind of the resource we are looking at. Only possible values are `Blob`, `BlobExecutable` and `Link`.
mode: gix_object::tree::EntryKind,
/// A possibly empty buffer, depending on `conversion.data` which may indicate the data is considered binary.
buffer: Vec<u8>,
}
impl std::hash::Hash for CacheKey {
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
if self.use_id {
self.id.hash(state);
self.is_link.hash(state)
} else {
self.location.hash(state)
}
}
}
impl PartialEq for CacheKey {
fn eq(&self, other: &Self) -> bool {
match (self.use_id, other.use_id) {
(false, false) => self.location.eq(&other.location),
(true, true) => self.id.eq(&other.id) && self.is_link.eq(&other.is_link),
_ => false,
}
}
}
impl Eq for CacheKey {}
impl Default for CacheKey {
fn default() -> Self {
CacheKey {
id: gix_hash::Kind::Sha1.null(),
use_id: false,
is_link: false,
location: BString::default(),
}
}
}
impl CacheKey {
fn set_location(&mut self, rela_path: &BStr) {
self.location.clear();
self.location.extend_from_slice(rela_path);
}
}
/// A resource ready to be diffed in one way or another.
#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct Resource<'a> {
/// If available, an index into the `drivers` field to access more diff-related information of the driver for items
/// at the given path, as previously determined by git-attributes.
///
/// Note that drivers are queried even if there is no object available.
pub driver_index: Option<usize>,
/// The data itself, suitable for diffing, and if the object or worktree item is present at all.
pub data: resource::Data<'a>,
/// The kind of the resource we are looking at. Only possible values are `Blob`, `BlobExecutable` and `Link`.
pub mode: gix_object::tree::EntryKind,
/// The location of the resource, relative to the working tree.
pub rela_path: &'a BStr,
/// The id of the content as it would be stored in `git`, or `null` if the content doesn't exist anymore at
/// `rela_path` or if it was never computed. This can happen with content read from the worktree, which has to
/// go through a filter to be converted back to what `git` would store.
pub id: &'a gix_hash::oid,
}
///
#[allow(clippy::empty_docs)]
pub mod resource {
use crate::blob::{
pipeline,
platform::{CacheKey, CacheValue, Resource},
};
impl<'a> Resource<'a> {
pub(crate) fn new(key: &'a CacheKey, value: &'a CacheValue) -> Self {
Resource {
driver_index: value.conversion.driver_index,
data: value.conversion.data.map_or(Data::Missing, |data| match data {
pipeline::Data::Buffer => Data::Buffer(&value.buffer),
pipeline::Data::Binary { size } => Data::Binary { size },
}),
mode: value.mode,
rela_path: key.location.as_ref(),
id: &key.id,
}
}
/// Produce an iterator over lines, separated by LF or CRLF, suitable to create tokens using
/// [`imara_diff::intern::InternedInput`].
pub fn intern_source(&self) -> imara_diff::sources::ByteLines<'a, true> {
crate::blob::sources::byte_lines_with_terminator(self.data.as_slice().unwrap_or_default())
}
}
/// The data of a diffable resource, as it could be determined and computed previously.
#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub enum Data<'a> {
/// The object is missing, either because it didn't exist in the working tree or because its `id` was null.
Missing,
/// The textual data as processed to be in a diffable state.
Buffer(&'a [u8]),
/// The size that the binary blob had at the given revision, without having applied filters, as it's either
/// considered binary or above the big-file threshold.
///
/// In this state, the binary file cannot be diffed.
Binary {
/// The size of the object prior to performing any filtering or as it was found on disk.
///
/// Note that technically, the size isn't always representative of the same 'state' of the
/// content, as once it can be the size of the blob in git, and once it's the size of file
/// in the worktree.
size: u64,
},
}
impl<'a> Data<'a> {
/// Return ourselves as slice of bytes if this instance stores data.
pub fn as_slice(&self) -> Option<&'a [u8]> {
match self {
Data::Buffer(d) => Some(d),
Data::Binary { .. } | Data::Missing => None,
}
}
}
}
///
#[allow(clippy::empty_docs)]
pub mod set_resource {
use bstr::BString;
use crate::blob::{pipeline, ResourceKind};
/// The error returned by [Platform::set_resource](super::Platform::set_resource).
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("Can only diff blobs and links, not {mode:?}")]
InvalidMode { mode: gix_object::tree::EntryKind },
#[error("Failed to read {kind} worktree data from '{rela_path}'")]
Io {
rela_path: BString,
kind: ResourceKind,
source: std::io::Error,
},
#[error("Failed to obtain attributes for {kind} resource at '{rela_path}'")]
Attributes {
rela_path: BString,
kind: ResourceKind,
source: std::io::Error,
},
#[error(transparent)]
ConvertToDiffable(#[from] pipeline::convert_to_diffable::Error),
}
}
///
#[allow(clippy::empty_docs)]
pub mod prepare_diff {
use bstr::BStr;
use crate::blob::platform::Resource;
/// The kind of operation that was performed during the [`diff`](super::Platform::prepare_diff()) operation.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum Operation<'a> {
/// The [internal diff algorithm](imara_diff::diff) should be called with the provided arguments.
/// This only happens if none of the resources are binary, and if there is no external diff program configured via git-attributes
/// *or* [Options::skip_internal_diff_if_external_is_configured](super::Options::skip_internal_diff_if_external_is_configured)
/// is `false`.
///
/// Use [`Outcome::interned_input()`] to easily obtain an interner for use with [`imara_diff::diff()`], or maintain one yourself
/// for greater reuse.
InternalDiff {
/// The algorithm we determined should be used, which is one of (in order, first set one wins):
///
/// * the driver's override
/// * the platforms own configuration (typically from git-config)
/// * the default algorithm
algorithm: imara_diff::Algorithm,
},
/// Run the external diff program according as configured in the `source`-resources driver.
/// This only happens if [Options::skip_internal_diff_if_external_is_configured](super::Options::skip_internal_diff_if_external_is_configured)
/// was `true`, preventing the usage of the internal diff implementation.
ExternalCommand {
/// The command as extracted from [Driver::command](super::super::Driver::command).
/// Use it in [`Platform::prepare_diff_command`](super::Platform::prepare_diff_command()) to easily prepare a compatible invocation.
command: &'a BStr,
},
/// One of the involved resources, [`old`](Outcome::old) or [`new`](Outcome::new), were binary and thus no diff
/// cannot be performed.
SourceOrDestinationIsBinary,
}
/// The outcome of a [`prepare_diff`](super::Platform::prepare_diff()) operation.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct Outcome<'a> {
/// The kind of diff that was actually performed. This may include skipping the internal diff as well.
pub operation: Operation<'a>,
/// The old or source of the diff operation.
pub old: Resource<'a>,
/// The new or destination of the diff operation.
pub new: Resource<'a>,
}
impl<'a> Outcome<'a> {
/// Produce an instance of an interner which `git` would use to perform diffs.
pub fn interned_input(&self) -> imara_diff::intern::InternedInput<&'a [u8]> {
crate::blob::intern::InternedInput::new(self.old.intern_source(), self.new.intern_source())
}
}
/// The error returned by [Platform::prepare_diff()](super::Platform::prepare_diff()).
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("Either the source or the destination of the diff operation were not set")]
SourceOrDestinationUnset,
#[error("Tried to diff resources that are both considered removed")]
SourceAndDestinationRemoved,
}
}
///
#[allow(clippy::empty_docs)]
pub mod prepare_diff_command {
use std::ops::{Deref, DerefMut};
use bstr::BString;
/// The error returned by [Platform::prepare_diff_command()](super::Platform::prepare_diff_command()).
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("Either the source or the destination of the diff operation were not set")]
SourceOrDestinationUnset,
#[error("Binary resources can't be diffed with an external command (as we don't have the data anymore)")]
SourceOrDestinationBinary,
#[error(
"Tempfile to store content of '{rela_path}' for passing to external diff command could not be created"
)]
CreateTempfile { rela_path: BString, source: std::io::Error },
#[error("Could not write content of '{rela_path}' to tempfile for passing to external diff command")]
WriteTempfile { rela_path: BString, source: std::io::Error },
}
/// The outcome of a [`prepare_diff_command`](super::Platform::prepare_diff_command()) operation.
///
/// This type acts like [`std::process::Command`], ready to run, with `stdin`, `stdout` and `stderr` set to *inherit*
/// all handles as this is expected to be for visual inspection.
pub struct Command {
pub(crate) cmd: std::process::Command,
/// Possibly a tempfile to be removed after the run, or `None` if there is no old version.
pub(crate) old: Option<gix_tempfile::Handle<gix_tempfile::handle::Closed>>,
/// Possibly a tempfile to be removed after the run, or `None` if there is no new version.
pub(crate) new: Option<gix_tempfile::Handle<gix_tempfile::handle::Closed>>,
}
impl Deref for Command {
type Target = std::process::Command;
fn deref(&self) -> &Self::Target {
&self.cmd
}
}
impl DerefMut for Command {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.cmd
}
}
}
/// Options for use in [Platform::new()].
#[derive(Default, Copy, Clone)]
pub struct Options {
/// The algorithm to use when diffing.
/// If unset, it uses the [default algorithm](Algorithm::default()).
pub algorithm: Option<Algorithm>,
/// If `true`, default `false`, then an external `diff` configured using gitattributes and drivers,
/// will cause the built-in diff [to be skipped](prepare_diff::Operation::ExternalCommand).
/// Otherwise, the internal diff is called despite the configured external diff, which is
/// typically what callers expect by default.
pub skip_internal_diff_if_external_is_configured: bool,
}
/// Lifecycle
impl Platform {
/// Create a new instance with `options`, and a way to `filter` data from the object database to data that is diff-able.
/// `filter_mode` decides how to do that specifically.
/// Use `attr_stack` to access attributes pertaining worktree filters and diff settings.
pub fn new(
options: Options,
filter: Pipeline,
filter_mode: pipeline::Mode,
attr_stack: gix_worktree::Stack,
) -> Self {
Platform {
old: None,
new: None,
diff_cache: Default::default(),
options,
filter,
filter_mode,
attr_stack,
}
}
}
/// Conversions
impl Platform {
/// Store enough information about a resource to eventually diff it, where…
///
/// * `id` is the hash of the resource. If it [is null](gix_hash::ObjectId::is_null()), it should either
/// be a resource in the worktree, or it's considered a non-existing, deleted object.
/// If an `id` is known, as the hash of the object as (would) be stored in `git`, then it should be provided
/// for completeness.
/// * `mode` is the kind of object (only blobs and links are allowed)
/// * `rela_path` is the relative path as seen from the (work)tree root.
/// * `kind` identifies the side of the diff this resource will be used for.
/// A diff needs both `OldOrSource` *and* `NewOrDestination`.
/// * `objects` provides access to the object database in case the resource can't be read from a worktree.
///
/// Note that it's assumed that either `id + mode (` or `rela_path` can serve as unique identifier for the resource,
/// depending on whether or not a [worktree root](pipeline::WorktreeRoots) is set for the resource of `kind`,
/// with resources with worktree roots using the `rela_path` as unique identifier.
///
/// ### Important
///
/// If an error occurs, the previous resource of `kind` will be cleared, preventing further diffs
/// unless another attempt succeeds.
pub fn set_resource(
&mut self,
id: gix_hash::ObjectId,
mode: gix_object::tree::EntryKind,
rela_path: &BStr,
kind: ResourceKind,
objects: &impl gix_object::FindObjectOrHeader, // TODO: make this `dyn` once https://github.com/rust-lang/rust/issues/65991 is stable, then also make tracker.rs `objects` dyn
) -> Result<(), set_resource::Error> {
let res = self.set_resource_inner(id, mode, rela_path, kind, objects);
if res.is_err() {
*match kind {
ResourceKind::OldOrSource => &mut self.old,
ResourceKind::NewOrDestination => &mut self.new,
} = None;
}
res
}
/// Given `diff_command` and `context`, typically obtained from git-configuration, and the currently set diff-resources,
/// prepare the invocation and temporary files needed to launch it according to protocol.
/// `count` / `total` are used for progress indication passed as environment variables `GIT_DIFF_PATH_(COUNTER|TOTAL)`
/// respectively (0-based), so the first path has `count=0` and `total=1` (assuming there is only one path).
/// Returns `None` if at least one resource is unset, see [`set_resource()`](Self::set_resource()).
///
/// Please note that this is an expensive operation this will always create up to two temporary files to hold the data
/// for the old and new resources.
///
/// ### Deviation
///
/// If one of the resources is binary, the operation reports an error as such resources don't make their data available
/// which is required for the external diff to run.
pub fn prepare_diff_command(
&self,
diff_command: BString,
context: gix_command::Context,
count: usize,
total: usize,
) -> Result<prepare_diff_command::Command, prepare_diff_command::Error> {
fn add_resource(
cmd: &mut std::process::Command,
res: Resource<'_>,
) -> Result<Option<gix_tempfile::Handle<gix_tempfile::handle::Closed>>, prepare_diff_command::Error> {
let tmpfile = match res.data {
resource::Data::Missing => {
cmd.args(["/dev/null", ".", "."]);
None
}
resource::Data::Buffer(buf) => {
let mut tmp = gix_tempfile::new(
std::env::temp_dir(),
gix_tempfile::ContainingDirectory::Exists,
gix_tempfile::AutoRemove::Tempfile,
)
.map_err(|err| prepare_diff_command::Error::CreateTempfile {
rela_path: res.rela_path.to_owned(),
source: err,
})?;
tmp.write_all(buf)
.map_err(|err| prepare_diff_command::Error::WriteTempfile {
rela_path: res.rela_path.to_owned(),
source: err,
})?;
tmp.with_mut(|f| {
cmd.arg(f.path());
})
.map_err(|err| prepare_diff_command::Error::WriteTempfile {
rela_path: res.rela_path.to_owned(),
source: err,
})?;
cmd.arg(res.id.to_string()).arg(res.mode.as_octal_str().to_string());
let tmp = tmp.close().map_err(|err| prepare_diff_command::Error::WriteTempfile {
rela_path: res.rela_path.to_owned(),
source: err,
})?;
Some(tmp)
}
resource::Data::Binary { .. } => return Err(prepare_diff_command::Error::SourceOrDestinationBinary),
};
Ok(tmpfile)
}
let (old, new) = self
.resources()
.ok_or(prepare_diff_command::Error::SourceOrDestinationUnset)?;
let mut cmd: std::process::Command = gix_command::prepare(gix_path::from_bstring(diff_command))
.with_context(context)
.env("GIT_DIFF_PATH_COUNTER", (count + 1).to_string())
.env("GIT_DIFF_PATH_TOTAL", total.to_string())
.stdin(Stdio::inherit())
.stdout(Stdio::inherit())
.stderr(Stdio::inherit())
.into();
cmd.arg(gix_path::from_bstr(old.rela_path).into_owned());
let mut out = prepare_diff_command::Command {
cmd,
old: None,
new: None,
};
out.old = add_resource(&mut out.cmd, old)?;
out.new = add_resource(&mut out.cmd, new)?;
if old.rela_path != new.rela_path {
out.cmd.arg(gix_path::from_bstr(new.rela_path).into_owned());
}
Ok(out)
}
/// Returns the resource of the given kind if it was set.
pub fn resource(&self, kind: ResourceKind) -> Option<Resource<'_>> {
let key = match kind {
ResourceKind::OldOrSource => self.old.as_ref(),
ResourceKind::NewOrDestination => self.new.as_ref(),
}?;
Resource::new(key, self.diff_cache.get(key)?).into()
}
/// Obtain the two resources that were previously set as `(OldOrSource, NewOrDestination)`, if both are set and available.
///
/// This is useful if one wishes to manually prepare the diff, maybe for invoking external programs, instead of relying on
/// [`Self::prepare_diff()`].
pub fn resources(&self) -> Option<(Resource<'_>, Resource<'_>)> {
let key = &self.old.as_ref()?;
let value = self.diff_cache.get(key)?;
let old = Resource::new(key, value);
let key = &self.new.as_ref()?;
let value = self.diff_cache.get(key)?;
let new = Resource::new(key, value);
Some((old, new))
}
/// Prepare a diff operation on the [previously set](Self::set_resource()) [old](ResourceKind::OldOrSource) and
/// [new](ResourceKind::NewOrDestination) resources.
///
/// The returned outcome allows to easily perform diff operations, based on the [`prepare_diff::Outcome::operation`] field,
/// which hints at what should be done.
pub fn prepare_diff(&mut self) -> Result<prepare_diff::Outcome<'_>, prepare_diff::Error> {
let old_key = &self.old.as_ref().ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
let old = self
.diff_cache
.get(old_key)
.ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
let new_key = &self.new.as_ref().ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
let new = self
.diff_cache
.get(new_key)
.ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
let mut out = prepare_diff::Outcome {
operation: prepare_diff::Operation::SourceOrDestinationIsBinary,
old: Resource::new(old_key, old),
new: Resource::new(new_key, new),
};
match (old.conversion.data, new.conversion.data) {
(None, None) => return Err(prepare_diff::Error::SourceAndDestinationRemoved),
(Some(pipeline::Data::Binary { .. }), _) | (_, Some(pipeline::Data::Binary { .. })) => return Ok(out),
_either_missing_or_non_binary => {
if let Some(command) = old
.conversion
.driver_index
.and_then(|idx| self.filter.drivers[idx].command.as_deref())
.filter(|_| self.options.skip_internal_diff_if_external_is_configured)
{
out.operation = prepare_diff::Operation::ExternalCommand {
command: command.as_bstr(),
};
return Ok(out);
}
}
}
out.operation = prepare_diff::Operation::InternalDiff {
algorithm: old
.conversion
.driver_index
.and_then(|idx| self.filter.drivers[idx].algorithm)
.or(self.options.algorithm)
.unwrap_or_default(),
};
Ok(out)
}
/// Every call to [set_resource()](Self::set_resource()) will keep the diffable data in memory, and that will never be cleared.
///
/// Use this method to clear the cache, releasing memory. Note that this will also loose all information about resources
/// which means diffs would fail unless the resources are set again.
///
/// Note that this also has to be called if the same resource is going to be diffed in different states, i.e. using different
/// `id`s, but the same `rela_path`.
pub fn clear_resource_cache(&mut self) {
self.old = None;
self.new = None;
self.diff_cache.clear();
}
}
impl Platform {
fn set_resource_inner(
&mut self,
id: gix_hash::ObjectId,
mode: gix_object::tree::EntryKind,
rela_path: &BStr,
kind: ResourceKind,
objects: &impl gix_object::FindObjectOrHeader,
) -> Result<(), set_resource::Error> {
if matches!(
mode,
gix_object::tree::EntryKind::Commit | gix_object::tree::EntryKind::Tree
) {
return Err(set_resource::Error::InvalidMode { mode });
}
let storage = match kind {
ResourceKind::OldOrSource => &mut self.old,
ResourceKind::NewOrDestination => &mut self.new,
}
.get_or_insert_with(Default::default);
storage.id = id;
storage.set_location(rela_path);
storage.is_link = matches!(mode, gix_object::tree::EntryKind::Link);
storage.use_id = self.filter.roots.by_kind(kind).is_none();
if self.diff_cache.contains_key(storage) {
return Ok(());
}
let entry =
self.attr_stack
.at_entry(rela_path, None, objects)
.map_err(|err| set_resource::Error::Attributes {
source: err,
kind,
rela_path: rela_path.to_owned(),
})?;
let mut buf = Vec::new();
let out = self.filter.convert_to_diffable(
&id,
mode,
rela_path,
kind,
&mut |_, out| {
let _ = entry.matching_attributes(out);
},
objects,
self.filter_mode,
&mut buf,
)?;
let key = storage.clone();
assert!(
self.diff_cache
.insert(
key,
CacheValue {
conversion: out,
mode,
buffer: buf,
},
)
.is_none(),
"The key impl makes clashes impossible with our usage"
);
Ok(())
}
}