Create an AndroidBuild class

Implementations of this class represent android build artifacts from
various different sources.

Bug: b/469219913

Author: Databean

base/cvd/cuttlefish/host/commands/assemble_cvd/android_build/BUILD.bazel

@@ -0,0 +1,18 @@
+load("//cuttlefish/bazel:rules.bzl", "cf_cc_library")
+
+package(
+    default_visibility = ["//:android_cuttlefish"],
+)
+
+exports_files([".clang-tidy"])
+
+cf_cc_library(
+    name = "android_build",
+    srcs = ["android_build.cc"],
+    hdrs = ["android_build.h"],
+    deps = [
+        "//cuttlefish/common/libs/utils:result",
+        "@abseil-cpp//absl/strings:str_format",
+        "@fmt",
+    ],
+)

base/cvd/cuttlefish/host/commands/assemble_cvd/android_build/android_build.cc

@@ -0,0 +1,67 @@
+//
+// Copyright (C) 2025 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cuttlefish/host/commands/assemble_cvd/android_build/android_build.h"
+
+#include <functional>
+#include <optional>
+#include <ostream>
+#include <set>
+#include <string>
+#include <string_view>
+
+#include "cuttlefish/common/libs/utils/result.h"
+
+namespace cuttlefish {
+
+Result<std::set<std::string, std::less<void>>> AndroidBuild::Images() {
+  return CF_ERRF("Unimplemented for '{}'", *this);
+}
+
+Result<std::string> AndroidBuild::ImageFile(
+    std::string_view name, std::optional<std::string_view> extract_dir) {
+  return CF_ERRF("Unimplemented for '{}': (name = '{}', extract_dir = '{}'",
+                 *this, name, extract_dir.value_or("(empty)"));
+}
+
+Result<std::set<std::string, std::less<void>>> AndroidBuild::AbPartitions() {
+  return CF_ERRF("Unimplemented for '{}'", *this);
+}
+
+Result<std::set<std::string, std::less<void>>>
+AndroidBuild::SystemPartitions() {
+  return CF_ERRF("Unimplemented for '{}'", *this);
+}
+
+Result<std::set<std::string, std::less<void>>>
+AndroidBuild::VendorPartitions() {
+  return CF_ERRF("Unimplemented for '{}'", *this);
+}
+
+Result<std::set<std::string, std::less<void>>>
+AndroidBuild::LogicalPartitions() {
+  return CF_ERRF("Unimplemented for '{}'", *this);
+}
+
+Result<std::set<std::string, std::less<void>>>
+AndroidBuild::PhysicalPartitions() {
+  return CF_ERRF("Unimplemented for '{}'", *this);
+}
+
+std::ostream& operator<<(std::ostream& out, const AndroidBuild& build) {
+  return build.Format(out);
+}
+
+}  // namespace cuttlefish

base/cvd/cuttlefish/host/commands/assemble_cvd/android_build/android_build.h

@@ -0,0 +1,111 @@
+//
+// Copyright (C) 2025 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include <functional>
+#include <optional>
+#include <ostream>
+#include <set>
+#include <string_view>
+
+#include "absl/strings/str_format.h"
+#include "fmt/ostream.h"
+
+#include "cuttlefish/common/libs/utils/result.h"
+
+namespace cuttlefish {
+
+/**
+ * Represents an Android build, as defined by image files and some of the
+ * metadata text files produced by the build system.
+ *
+ * The build system produces a subset of these files with faster `m` builds, and
+ * does the complete set and packages them up into zip files in slower `m dist`
+ * builds. The zip files are uploaded to the Android Build server, and the `cvd
+ * fetch` tool can download subsets of them to the local filesystem.
+ *
+ * Image files also contain some duplication: the 'super' image contains logical
+ * partitions that may also be present as standalone image files, depending on
+ * the file subset available.
+ *
+ * Note the distinction between "images" and "partitions" in methods. Image
+ * files may contain zero or more partitions.
+ *
+ * Instances of this class present a subset of the files produced by the build
+ * system. This may be complete or incomplete subset.
+ */
+class AndroidBuild {
+ public:
+  virtual ~AndroidBuild() = default;
+
+  /**
+   * Image information, as reported by the Android build system.
+   *
+   * An image may be one of three different categories:
+   * - A partition in the top-level GPT, such as the the `super` partition.
+   * - A logical partition stored inside the GPT `super` partition.
+   * - A `super_empty` pseudo-partition file that reports what should be in the
+   *   `super` partition, but without the logical partition contents.
+   */
+  virtual Result<std::set<std::string, std::less<void>>> Images();
+  /*
+   * A file on the host that represents an image. If the file is not already
+   * stored in a distinct file on the host, it is first saved to `extract_dir`
+   * and returned from there. If the file needs to be extracted and
+   * `extract_dir` is not provided, returns an error.
+   *
+   * It's possible for there to be an image file in `Images()` that cannot be
+   * extracted to the filesystem, if a metadata file reports that an image or
+   * partition should exist, but it's not actually present anywhere.
+   */
+  virtual Result<std::string> ImageFile(
+      std::string_view name, std::optional<std::string_view> extract_dir = {});
+
+  virtual Result<std::set<std::string, std::less<void>>> AbPartitions();
+
+  /**
+   * If this build is combined with another build by mixing system and vendor
+   * from different places, reports which partitions this build expects to
+   * contribute to a particular side of the mix. System and vendor partition
+   * sets should be disjoint.
+   */
+  virtual Result<std::set<std::string, std::less<void>>> SystemPartitions();
+  virtual Result<std::set<std::string, std::less<void>>> VendorPartitions();
+
+  /** Partitions in the super image. Disjoint from GPT entries. */
+  virtual Result<std::set<std::string, std::less<void>>> LogicalPartitions();
+  /** Entries in the GPT. Disjoint from logical partitions. */
+  virtual Result<std::set<std::string, std::less<void>>> PhysicalPartitions();
+
+ private:
+  virtual std::ostream& Format(std::ostream&) const = 0;
+
+  template <typename Sink>
+  friend void AbslStringify(Sink& sink, const AndroidBuild& provider) {
+    sink.Append(absl::FormatStreamed(provider));
+  }
+
+  friend std::ostream& operator<<(std::ostream&, const AndroidBuild&);
+};
+
+}  // namespace cuttlefish
+
+namespace fmt {
+
+template <>
+struct formatter<::cuttlefish::AndroidBuild> : ostream_formatter {};
+
+}  // namespace fmt