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A few misc patches #5

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merged 4 commits into from
Jun 3, 2024
Merged

A few misc patches #5

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9eae4a2
lib: Rename RawLayerWriter -> GzipLayerWriter
cgwalters Jun 3, 2024
44bb48e
Fix duplicate tagged manifests
cgwalters Jun 3, 2024
a3dd5fd
Bump version to 0.2
cgwalters Jun 3, 2024
6f8ac5a
Add a helper to insert manifest and config
cgwalters Jun 3, 2024
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2 changes: 1 addition & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
[package]
name = "ocidir"
description = "A Rust library for reading and writing OCI (opencontainers) layout directories"
version = "0.1.0"
version = "0.2.0"
edition = "2021"
license = "MIT OR Apache-2.0"
repository = "https://github.com/containers/ocidir"
Expand Down
114 changes: 80 additions & 34 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ use cap_std_ext::dirext::CapStdExtDirExt;
use flate2::write::GzEncoder;
use fn_error_context::context;
use oci_image::MediaType;
use oci_spec::image::{self as oci_image, Descriptor};
use oci_spec::image::{self as oci_image, Descriptor, ImageIndex};
use olpc_cjson::CanonicalFormatter;
use openssl::hash::{Hasher, MessageDigest};
use serde::Serialize;
Expand Down Expand Up @@ -118,16 +118,16 @@ impl<'a> Debug for BlobWriter<'a> {
}
}

/// Create an OCI layer (also a blob).
pub struct RawLayerWriter<'a> {
/// Create an OCI tar+gzip layer.
pub struct GzipLayerWriter<'a> {
bw: BlobWriter<'a>,
uncompressed_hash: Hasher,
compressor: GzEncoder<Vec<u8>>,
}

impl<'a> Debug for RawLayerWriter<'a> {
impl<'a> Debug for GzipLayerWriter<'a> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("RawLayerWriter")
f.debug_struct("GzipLayerWriter")
.field("bw", &self.bw)
.field("compressor", &self.compressor)
.finish()
Expand Down Expand Up @@ -218,17 +218,18 @@ impl OciDir {
Ok(Self { dir })
}

/// Create a writer for a new blob (expected to be a tar stream)
pub fn create_raw_layer(&self, c: Option<flate2::Compression>) -> Result<RawLayerWriter> {
RawLayerWriter::new(&self.dir, c)
/// Create a writer for a new gzip+tar blob; the contents
/// are not parsed, but are expected to be a tarball.
pub fn create_gzip_layer(&self, c: Option<flate2::Compression>) -> Result<GzipLayerWriter> {
GzipLayerWriter::new(&self.dir, c)
}

/// Create a tar output stream, backed by a blob
pub fn create_layer(
&self,
c: Option<flate2::Compression>,
) -> Result<tar::Builder<RawLayerWriter>> {
Ok(tar::Builder::new(self.create_raw_layer(c)?))
) -> Result<tar::Builder<GzipLayerWriter>> {
Ok(tar::Builder::new(self.create_gzip_layer(c)?))
}

/// Add a layer to the top of the image stack. The firsh pushed layer becomes the root.
Expand Down Expand Up @@ -316,6 +317,16 @@ impl OciDir {
.unwrap())
}

/// Read the image index.
pub fn read_index(&self) -> Result<Option<ImageIndex>> {
let r = if let Some(index) = self.dir.open_optional("index.json")?.map(BufReader::new) {
Some(oci_image::ImageIndex::from_reader(index)?)
} else {
None
};
Ok(r)
}

/// Write a manifest as a blob, and replace the index with a reference to it.
pub fn insert_manifest(
&self,
Expand All @@ -334,20 +345,22 @@ impl OciDir {
manifest.set_annotations(Some(annotations));
}

let index = self.dir.open_optional("index.json")?.map(BufReader::new);
let index =
if let Some(mut index) = index.map(oci_image::ImageIndex::from_reader).transpose()? {
let mut manifests = index.manifests().clone();
manifests.push(manifest.clone());
index.set_manifests(manifests);
index
} else {
oci_image::ImageIndexBuilder::default()
.schema_version(oci_image::SCHEMA_VERSION)
.manifests(vec![manifest.clone()])
.build()
.unwrap()
};
let index = self.read_index()?;
let index = if let Some(mut index) = index {
let mut manifests = index.manifests().clone();
if let Some(tag) = tag {
manifests.retain(|d| !Self::descriptor_is_tagged(d, tag));
}
manifests.push(manifest.clone());
index.set_manifests(manifests);
index
} else {
oci_image::ImageIndexBuilder::default()
.schema_version(oci_image::SCHEMA_VERSION)
.manifests(vec![manifest.clone()])
.build()
.unwrap()
};

self.dir
.atomic_replace_with("index.json", |mut w| -> Result<()> {
Expand All @@ -359,6 +372,19 @@ impl OciDir {
Ok(manifest)
}

/// Convenience helper to write the provided config, update the manifest to use it, then call [`insert_manifest`].
pub fn insert_manifest_and_config(
&self,
mut manifest: oci_image::ImageManifest,
config: oci_image::ImageConfiguration,
tag: Option<&str>,
platform: oci_image::Platform,
) -> Result<Descriptor> {
let config = self.write_config(config)?;
manifest.set_config(config);
self.insert_manifest(manifest, tag, platform)
}

/// Write a manifest as a blob, and replace the index with a reference to it.
pub fn replace_with_single_manifest(
&self,
Expand Down Expand Up @@ -392,6 +418,14 @@ impl OciDir {
self.read_manifest_and_descriptor().map(|r| r.0)
}

fn descriptor_is_tagged(d: &Descriptor, tag: &str) -> bool {
d.annotations()
.as_ref()
.and_then(|annos| annos.get(OCI_TAG_ANNOTATION))
.filter(|tagval| tagval.as_str() == tag)
.is_some()
}

/// Find the manifest with the provided tag
pub fn find_manifest_with_tag(&self, tag: &str) -> Result<Option<oci_image::ImageManifest>> {
let f = self
Expand All @@ -400,13 +434,7 @@ impl OciDir {
.context("Failed to open index.json")?;
let idx: oci_image::ImageIndex = serde_json::from_reader(BufReader::new(f))?;
for img in idx.manifests() {
if img
.annotations()
.as_ref()
.and_then(|annos| annos.get(OCI_TAG_ANNOTATION))
.filter(|tagval| tagval.as_str() == tag)
.is_some()
{
if Self::descriptor_is_tagged(img, tag) {
return self.read_json_blob(img).map(Some);
}
}
Expand Down Expand Up @@ -471,7 +499,7 @@ impl<'a> std::io::Write for BlobWriter<'a> {
}
}

impl<'a> RawLayerWriter<'a> {
impl<'a> GzipLayerWriter<'a> {
/// Create a writer for a gzip compressed layer blob.
fn new(ocidir: &'a Dir, c: Option<flate2::Compression>) -> Result<Self> {
let bw = BlobWriter::new(ocidir)?;
Expand All @@ -497,7 +525,7 @@ impl<'a> RawLayerWriter<'a> {
}
}

impl<'a> std::io::Write for RawLayerWriter<'a> {
impl<'a> std::io::Write for GzipLayerWriter<'a> {
fn write(&mut self, srcbuf: &[u8]) -> std::io::Result<usize> {
self.compressor.get_mut().clear();
self.compressor.write_all(srcbuf).unwrap();
Expand Down Expand Up @@ -556,7 +584,7 @@ mod tests {
fn test_build() -> Result<()> {
let td = cap_tempfile::tempdir(cap_std::ambient_authority())?;
let w = OciDir::ensure(&td)?;
let mut layerw = w.create_raw_layer(None)?;
let mut layerw = w.create_gzip_layer(None)?;
layerw.write_all(b"pretend this is a tarball")?;
let root_layer = layerw.complete()?;
assert_eq!(
Expand All @@ -572,6 +600,7 @@ mod tests {
let config = w.write_config(config)?;
manifest.set_config(config);
w.replace_with_single_manifest(manifest.clone(), oci_image::Platform::default())?;
assert_eq!(w.read_index().unwrap().unwrap().manifests().len(), 1);

let read_manifest = w.read_manifest().unwrap();
assert_eq!(&read_manifest, &manifest);
Expand All @@ -580,10 +609,27 @@ mod tests {
w.insert_manifest(manifest, Some("latest"), oci_image::Platform::default())?;
// There's more than one now
assert!(w.read_manifest().is_err());
assert_eq!(w.read_index().unwrap().unwrap().manifests().len(), 2);

assert!(w.find_manifest_with_tag("noent").unwrap().is_none());
let found_via_tag = w.find_manifest_with_tag("latest").unwrap().unwrap();
assert_eq!(found_via_tag, read_manifest);

let mut layerw = w.create_gzip_layer(None)?;
layerw.write_all(b"pretend this is an updated tarball")?;
let root_layer = layerw.complete()?;
let mut manifest = new_empty_manifest().build().unwrap();
let mut config = oci_image::ImageConfigurationBuilder::default()
.build()
.unwrap();
w.push_layer(&mut manifest, &mut config, root_layer, "root", None);
let _: Descriptor = w.insert_manifest_and_config(
manifest,
config,
Some("latest"),
oci_image::Platform::default(),
)?;
assert_eq!(w.read_index().unwrap().unwrap().manifests().len(), 2);
Ok(())
}
}
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