Add OCI Image Specs support

CMakeLists.txt

@@ -23,6 +23,7 @@ set(CMAKE_C_EXTENSIONS OFF)
 option(BFC_WITH_FUSE "Build with FUSE support for mounting" OFF)
 option(BFC_WITH_ZSTD "Build with Zstd compression support" OFF)
 option(BFC_WITH_SODIUM "Build with libsodium encryption support" OFF)
+option(BFC_WITH_OCI "Build with OCI Image Specs support" OFF)
 option(BFC_COVERAGE "Enable coverage reporting" OFF)
 option(BFC_BUILD_BENCHMARKS "Build benchmarks" ON)
 option(BFC_BUILD_EXAMPLES "Build examples" ON)

OCI_SUPPORT.md

@@ -0,0 +1,193 @@
+# BFC OCI Image Specs Support
+
+This document describes the OCI (Open Container Initiative) Image Specs support added to BFC (Binary File Container).
+
+## Overview
+
+BFC now supports storing and managing OCI container images in its efficient single-file format. This allows BFC to be used as a storage backend for OCI-compliant container registries and image management systems.
+
+## Features
+
+- **OCI Manifest Support**: Store and manage OCI image manifests
+- **OCI Config Support**: Store and manage OCI image configurations
+- **OCI Layer Support**: Store and manage OCI image layers
+- **OCI Index Support**: Store and manage OCI image indexes
+- **Validation**: Validate OCI manifests and configs
+- **Extraction**: Extract BFC containers to OCI format
+
+## API Reference
+
+### OCI Manifest Functions
+
+```c
+// Create BFC container from OCI image manifest
+int bfc_create_from_oci_manifest(bfc_t* bfc, const bfc_oci_manifest_t* manifest, const char* config_json);
+
+// Get OCI manifest from BFC container
+int bfc_get_oci_manifest(bfc_t* bfc, bfc_oci_manifest_t* manifest);
+
+// Validate OCI manifest
+int bfc_validate_oci_manifest(const bfc_oci_manifest_t* manifest);
+```
+
+### OCI Layer Functions
+
+```c
+// Add OCI layer to BFC container
+int bfc_add_oci_layer(bfc_t* bfc, const bfc_oci_layer_t* layer, FILE* layer_data);
+
+// List OCI layers in BFC container
+int bfc_list_oci_layers(bfc_t* bfc, bfc_oci_layer_t** layers, size_t* layer_count);
+```
+
+### OCI Index Functions
+
+```c
+// Create BFC container from OCI image index
+int bfc_create_from_oci_index(bfc_t* bfc, const bfc_oci_index_t* index);
+```
+
+### Utility Functions
+
+```c
+// Extract BFC container to OCI format
+int bfc_extract_to_oci(bfc_t* bfc, const char* output_dir);
+
+// Free OCI structures
+void bfc_free_oci_manifest(bfc_oci_manifest_t* manifest);
+void bfc_free_oci_config(bfc_oci_config_t* config);
+void bfc_free_oci_layer(bfc_oci_layer_t* layer);
+void bfc_free_oci_index(bfc_oci_index_t* index);
+void bfc_free_oci_layers(bfc_oci_layer_t** layers, size_t layer_count);
+```
+
+## Data Structures
+
+### OCI Manifest
+
+```c
+typedef struct {
+    char* schema_version;        // OCI schema version (e.g., "2.0.1")
+    char* media_type;            // Media type (e.g., "application/vnd.oci.image.manifest.v1+json")
+    char* config_digest;         // SHA256 digest of config
+    size_t config_size;          // Size of config in bytes
+    char** layer_digests;        // Array of layer digests
+    size_t layer_count;          // Number of layers
+    char* annotations;           // JSON annotations
+} bfc_oci_manifest_t;
+```
+
+### OCI Config
+
+```c
+typedef struct {
+    char* architecture;          // Target architecture (e.g., "amd64")
+    char* os;                    // Target OS (e.g., "linux")
+    char* created;               // Creation timestamp
+    char* author;                // Image author
+    char* config;                // Container configuration
+    char* rootfs;                // Root filesystem configuration
+    char* history;               // Image history
+} bfc_oci_config_t;
+```
+
+### OCI Layer
+
+```c
+typedef struct {
+    char* digest;                // Layer digest (e.g., "sha256:abc123...")
+    char* media_type;            // Layer media type
+    size_t size;                 // Layer size in bytes
+    char** urls;                 // Optional URLs for layer
+    size_t url_count;            // Number of URLs
+    char* annotations;           // Layer annotations
+} bfc_oci_layer_t;
+```
+
+## Usage Example
+
+```c
+#include "bfc_oci.h"
+
+int main() {
+    // Create BFC container
+    bfc_t* bfc = NULL;
+    bfc_create("image.bfc", 4096, 0, &bfc);
+
+    // Create OCI manifest
+    bfc_oci_manifest_t* manifest = calloc(1, sizeof(bfc_oci_manifest_t));
+    manifest->schema_version = strdup("2.0.1");
+    manifest->media_type = strdup("application/vnd.oci.image.manifest.v1+json");
+    manifest->config_digest = strdup("sha256:abc123...");
+    manifest->config_size = 1024;
+    manifest->layer_count = 1;
+    manifest->layer_digests = calloc(1, sizeof(char*));
+    manifest->layer_digests[0] = strdup("sha256:def456...");
+
+    // Add manifest to BFC
+    bfc_create_from_oci_manifest(bfc, manifest, "{\"architecture\":\"amd64\"}");
+
+    // Add layer
+    bfc_oci_layer_t* layer = calloc(1, sizeof(bfc_oci_layer_t));
+    layer->digest = strdup("sha256:def456...");
+    layer->media_type = strdup("application/vnd.oci.image.layer.v1.tar+gzip");
+    layer->size = 1024 * 1024;
+
+    FILE* layer_data = fopen("layer.tar.gz", "rb");
+    bfc_add_oci_layer(bfc, layer, layer_data);
+    fclose(layer_data);
+
+    // Finish container
+    bfc_finish(bfc);
+    bfc_close(bfc);
+
+    // Cleanup
+    bfc_free_oci_manifest(manifest);
+    bfc_free_oci_layer(layer);
+
+    return 0;
+}
+```
+
+## Building with OCI Support
+
+To build BFC with OCI support, include the OCI source file:
+
+```bash
+gcc -o bfc_oci_example examples/oci_example.c src/bfc_oci.c src/bfc.c -Iinclude
+```
+
+## Integration with Container Runtimes
+
+BFC with OCI support can be integrated with:
+
+- **Docker**: Use BFC as a storage backend for Docker images
+- **Podman**: Use BFC as a storage backend for Podman images
+- **containerd**: Use BFC as a storage backend for containerd
+- **CRI-O**: Use BFC as a storage backend for CRI-O
+- **Custom Runtimes**: Use BFC as a storage backend for custom container runtimes
+
+## Benefits
+
+1. **Efficiency**: Single file storage for entire OCI images
+2. **Compression**: Built-in zstd compression support
+3. **Encryption**: Built-in ChaCha20-Poly1305 encryption support
+4. **Integrity**: Built-in CRC32c checksums
+5. **Portability**: Easy to copy and transfer OCI images
+6. **ZFS Integration**: Works well with ZFS snapshots and clones
+
+## Future Enhancements
+
+- **Registry Integration**: Direct integration with OCI registries
+- **Layer Deduplication**: Automatic deduplication of identical layers
+- **Compression Optimization**: Automatic compression level selection
+- **Encryption Key Management**: Advanced encryption key management
+- **Metadata Indexing**: Fast metadata search and indexing
+
+## Contributing
+
+Contributions to OCI support are welcome! Please see the main BFC repository for contribution guidelines.
+
+## License
+
+This OCI support code is licensed under the Apache License 2.0, same as the main BFC project.