feat: add tooling for creating snapshots programmatically

build/Dockerfile

@@ -103,58 +103,6 @@ RUN <<EOF
     rm -rf /var/lib/apt/lists/*
 EOF
 
-# =============================================================================
-# STAGE: emulator-devel
-#
-# - Install libarchive13 (setup -- required by xgenext2fs).
-# - Install libcmt.
-# - Install xgenext2fs.
-# =============================================================================
-
-FROM emulator AS emulator-devel
-
-ARG MACHINE_TOOLS_VERSION
-ARG MACHINE_XGENEXT2FS_VERSION
-ARG DEBIAN_FRONTEND=noninteractive
-
-# Install libarchive13 (setup -- required by xgenext2fs).
-RUN <<EOF
-    set -e
-    apt-get update
-    apt-get install -y --no-install-recommends libarchive13
-EOF
-
-# Install libcmt (cartesi/machine-emulator-tools).
-RUN <<EOF
-    set -e
-    URL=https://github.com/cartesi/machine-emulator-tools/releases/download
-    VERSION=v${MACHINE_TOOLS_VERSION}
-    ARTIFACT=libcmt-${VERSION}-dev.deb
-    curl -fsSL ${URL}/${VERSION}/${ARTIFACT} -o ./libcmt.deb
-    apt-get install -y ./libcmt.deb
-    rm ./libcmt.deb
-    mv /usr/riscv64-linux-gnu/include/libcmt /usr/include/
-    mv /usr/riscv64-linux-gnu/lib/libcmt.a /usr/lib/
-    rm -rf /usr/riscv64-linux-gnu
-EOF
-
-# Install xgenext2fs (cartesi/genext2fs).
-RUN <<EOF
-    set -e
-    URL=https://github.com/cartesi/genext2fs/releases/download
-    VERSION=v${MACHINE_XGENEXT2FS_VERSION}
-    ARCH=$(dpkg --print-architecture)
-    ARTIFACT=xgenext2fs_${ARCH}.deb
-    curl -fsSL ${URL}/${VERSION}/${ARTIFACT} -o ./xgenext2fs.deb
-    apt-get install -y ./xgenext2fs.deb
-    rm ./xgenext2fs.deb
-EOF
-
-# Clean up.
-RUN <<EOF
-    rm -rf /var/lib/apt/lists/*
-EOF
-
 # =============================================================================
 # STAGE: rollups-node-ci
 #
@@ -165,7 +113,7 @@ EOF
 # - Install docker.
 # =============================================================================
 
-FROM emulator-devel AS rollups-node-ci
+FROM emulator AS rollups-node-ci
 
 # Install git and build-essential (setup).
 RUN <<EOF

test/snapshot/snapshot.go

@@ -0,0 +1,114 @@
+// (c) Cartesi and individual authors (see AUTHORS)
+// SPDX-License-Identifier: Apache-2.0 (see LICENSE)
+
+// Package snapshot implements dynamic snapshot instantiation.
+// It defines the Snapshot type, which manages the lifecycle of a snapshot.
+package snapshot
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"math/rand"
+	"os"
+	"strings"
+
+	"github.com/cartesi/rollups-node/pkg/emulator"
+)
+
+const ramLength = 64 << 20
+
+// ImagesPath is the path to the folder containing the linux.bin and rootfs.ext2 files.
+// It can be redefined in case the files are not in the default folder.
+var ImagesPath = "/usr/share/cartesi-machine/images/"
+
+type Snapshot struct {
+	id   string // an unique id used to avoid name clashing
+	temp string // path to the temporary directory containing snapshot relevant files
+	path string // path to the snapshot directory
+
+	// Reason why the snapshot stopped running before being stored.
+	BreakReason emulator.BreakReason
+}
+
+// FromScript creates a snapshot given an script command.
+func FromScript(command string, cycles uint64) (*Snapshot, error) {
+	snapshot := &Snapshot{id: fmt.Sprintf("fromscript%d", rand.Int())}
+
+	err := snapshot.createTempDir()
+	if err != nil {
+		return nil, err
+	}
+
+	config := defaultMachineConfig()
+	config.Dtb.Entrypoint = command
+
+	err = snapshot.createRunAndStore(config, cycles)
+	return snapshot, err
+}
+
+// Path returns the path to the directory where the snapshot is stored.
+func (snapshot *Snapshot) Path() string {
+	return snapshot.path
+}
+
+// Close deletes the temporary directory created to hold the snapshot files.
+func (snapshot *Snapshot) Close() error {
+	return os.RemoveAll(snapshot.temp)
+}
+
+// ------------------------------------------------------------------------------------------------
+
+func defaultMachineConfig() *emulator.MachineConfig {
+	config := emulator.NewDefaultMachineConfig()
+	config.Ram.Length = ramLength
+	config.Ram.ImageFilename = ImagesPath + "linux.bin"
+	config.Dtb.Bootargs = strings.Join([]string{"quiet",
+		"no4lvl",
+		"quiet",
+		"earlycon=sbi",
+		"console=hvc0",
+		"rootfstype=ext2",
+		"root=/dev/pmem0",
+		"rw",
+		"init=/usr/sbin/cartesi-init"}, " ")
+	config.FlashDrive = []emulator.MemoryRangeConfig{{
+		Start:         0x80000000000000, //nolint:mnd
+		Length:        math.MaxUint64,
+		ImageFilename: ImagesPath + "rootfs.ext2",
+	}}
+	return config
+}
+
+func (snapshot *Snapshot) createTempDir() error {
+	temp, err := os.MkdirTemp("", snapshot.id+"-*")
+	if err != nil {
+		return err
+	}
+	snapshot.temp = temp
+	snapshot.path = snapshot.temp + "/snapshot"
+	return nil
+}
+
+func (snapshot *Snapshot) createRunAndStore(config *emulator.MachineConfig, cycles uint64) error {
+	// Creates the (local) machine.
+	machine, err := emulator.NewMachine(config, &emulator.MachineRuntimeConfig{})
+	if err != nil {
+		return errors.Join(err, snapshot.Close())
+	}
+	defer machine.Delete()
+
+	// Runs the machine.
+	snapshot.BreakReason, err = machine.Run(cycles)
+	if err != nil {
+		return errors.Join(err, snapshot.Close())
+	}
+
+	// Stores the machine.
+	err = machine.Store(snapshot.path)
+	if err != nil {
+		return errors.Join(err, snapshot.Close())
+	}
+
+	return nil
+}