pkg/architecture: Define core architecture types and constants

Introduce the architecture package that represents the core of the
Toolbx cross-architecture support, which is based on user-mode emulation
using QEMU and binfmt_misc.

The Architecture struct collects all per-architecture data (ELF
magic/mask, OCI and binfmt naming, aliases, binfmt registration
parameters) into a single map. Architectures present in the
supportedArchitectures map represent the set of supported
architectures within Toolbx.

Define architecture ID constants NotSpecified, Aarch64, Ppc64le, and
X86_64, along with their supportedArchitectures entries.

Add core query functions:
- ParseArgArchValue() for resolving user-supplied architecture strings

- GetArchNameBinfmt() and GetArchNameOCI() for name
  lookups (one architecture can have multiple valid names [1])

- HasContainerNativeArch() for comparing against the host

- ImageReferenceGetArchFromTag() for extracting architecture
  from image tag suffixes like "42-aarch64" for architecture detection

Expose the HostArchID package variable, which is set in the init()
function, so the variable can be accessed in the early init() state
from every inheritor that utilizes the architecture package (HostArchID
serves as a default value for initContainer --arch flag), and the Config
struct for preserving the architecture ID and the QEMU emulator path,
through the call chain.

[1] https://itsfoss.com/arm-aarch64-x86_64/

containers#1782

Signed-off-by: Dalibor Kricka <dalidalk@seznam.cz>

Author: DaliborKr

src/pkg/architecture/architecture.go

@@ -0,0 +1,165 @@
+/*
+ * Copyright © 2019 – 2026 Red Hat Inc.
+ *
+ * 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.
+ */
+
+package architecture
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+
+	"github.com/containers/toolbox/pkg/utils"
+	"github.com/sirupsen/logrus"
+)
+
+type Architecture struct {
+	ID         int
+	NameBinfmt string
+	NameOCI    string
+	Aliases    []string
+	ELFMagic   []byte
+	ELFMask    []byte
+
+	BinfmtFlags     string
+	BinfmtName      string
+	BinfmtMagicType string
+	BinfmtOffset    string
+}
+
+type Config struct {
+	ID               int
+	QemuEmulatorPath string
+}
+
+const (
+	NotSpecified = iota
+	Aarch64
+	Ppc64le
+	X86_64
+)
+
+var supportedArchitectures = map[int]Architecture{
+	Aarch64: {
+		ID:         Aarch64,
+		NameBinfmt: "aarch64",
+		NameOCI:    "arm64",
+		Aliases:    []string{"aarch64", "arm64"},
+		ELFMagic:   []byte{0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xb7, 0x00},
+		ELFMask:    []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xff},
+	},
+	Ppc64le: {
+		ID:         Ppc64le,
+		NameBinfmt: "ppc64le",
+		NameOCI:    "ppc64le",
+		Aliases:    []string{"ppc64le"},
+		ELFMagic:   []byte{0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x15, 0x00},
+		ELFMask:    []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0x00},
+	},
+	X86_64: {
+		ID:         X86_64,
+		NameBinfmt: "x86_64",
+		NameOCI:    "amd64",
+		Aliases:    []string{"x86_64", "amd64"},
+		ELFMagic:   []byte{0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x3e, 0x00},
+		ELFMask:    []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xff},
+	},
+}
+
+var (
+	HostArchID             int
+	supportedArgArchValues map[string]int
+)
+
+func init() {
+	HostArchID, _ = ParseArgArchValue(runtime.GOARCH)
+
+	supportedArgArchValues = make(map[string]int)
+	for archID, arch := range supportedArchitectures {
+		for _, alias := range arch.Aliases {
+			supportedArgArchValues[alias] = archID
+		}
+	}
+}
+
+func GetArchConfigDefault() Config {
+	return Config{
+		ID:               HostArchID,
+		QemuEmulatorPath: "",
+	}
+}
+
+func getArchitecture(archID int) (Architecture, bool) {
+	arch, exists := supportedArchitectures[archID]
+	return arch, exists
+}
+
+func getArchNameBinfmt(arch int) string {
+	if arch == NotSpecified {
+		logrus.Warnf("Getting arch name for not specified architecture")
+		return "arch_not_specified"
+	}
+	if archObj, exists := supportedArchitectures[arch]; exists {
+		return archObj.NameBinfmt
+	}
+	return ""
+}
+
+func GetArchNameOCI(arch int) string {
+	if arch == NotSpecified {
+		logrus.Warnf("Getting arch name for not specified architecture")
+		return "arch_not_specified"
+	}
+	if archObj, exists := supportedArchitectures[arch]; exists {
+		return archObj.NameOCI
+	}
+	return ""
+}
+
+func HasContainerNativeArch(archID int) bool {
+	return archID == HostArchID
+}
+
+func ImageReferenceGetArchFromTag(image string) int {
+	tag := utils.ImageReferenceGetTag(image)
+
+	if tag == "" {
+		return NotSpecified
+	}
+
+	i := strings.LastIndexByte(tag, '-')
+	if i == -1 {
+		return NotSpecified
+	}
+
+	archInTag := tag[i+1:]
+
+	for archID, arch := range supportedArchitectures {
+		if arch.NameBinfmt == archInTag || arch.NameOCI == archInTag {
+			return archID
+		}
+	}
+
+	return NotSpecified
+}
+
+func ParseArgArchValue(value string) (int, error) {
+	archID, exists := supportedArgArchValues[value]
+	if !exists {
+		return NotSpecified, fmt.Errorf("architecture '%s' is not supported by Toolbx", value)
+	}
+
+	return archID, nil
+}