Initial commit

pkg/build/build.go

@@ -0,0 +1,838 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package build
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"slices"
+	"strconv"
+	"strings"
+	"time"
+
+	_ "github.com/goreleaser/nfpm/v2/apk"
+	_ "github.com/goreleaser/nfpm/v2/arch"
+	_ "github.com/goreleaser/nfpm/v2/deb"
+	_ "github.com/goreleaser/nfpm/v2/rpm"
+
+	"github.com/goreleaser/nfpm/v2"
+	"github.com/goreleaser/nfpm/v2/files"
+	"lure.sh/lure/internal/cliutils"
+	"lure.sh/lure/internal/config"
+	"lure.sh/lure/internal/cpu"
+	"lure.sh/lure/internal/db"
+	"lure.sh/lure/internal/dl"
+	"lure.sh/lure/internal/shutils/decoder"
+	"lure.sh/lure/internal/shutils/handlers"
+	"lure.sh/lure/internal/shutils/helpers"
+	"lure.sh/lure/internal/types"
+	"lure.sh/lure/pkg/distro"
+	"lure.sh/lure/pkg/loggerctx"
+	"lure.sh/lure/pkg/manager"
+	"lure.sh/lure/pkg/repos"
+	"mvdan.cc/sh/v3/expand"
+	"mvdan.cc/sh/v3/interp"
+	"mvdan.cc/sh/v3/syntax"
+)
+
+// BuildPackage builds the script at the given path. It returns two slices. One contains the paths
+// to the built package(s), the other contains the names of the built package(s).
+func BuildPackage(ctx context.Context, opts types.BuildOpts) ([]string, []string, error) {
+	log := loggerctx.From(ctx)
+
+	info, err := distro.ParseOSRelease(ctx)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	fl, err := parseScript(info, opts.Script)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// The first pass is just used to get variable values and runs before
+	// the script is displayed, so it's restricted so as to prevent malicious
+	// code from executing.
+	vars, err := executeFirstPass(ctx, info, fl, opts.Script)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	dirs := getDirs(ctx, vars, opts.Script)
+
+	// If opts.Clean isn't set and we find the package already built,
+	// just return it rather than rebuilding
+	if !opts.Clean {
+		builtPkgPath, ok, err := checkForBuiltPackage(opts.Manager, vars, getPkgFormat(opts.Manager), dirs.BaseDir)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		if ok {
+			return []string{builtPkgPath}, nil, err
+		}
+	}
+
+	// Ask the user if they'd like to see the build script
+	err = cliutils.PromptViewScript(ctx, opts.Script, vars.Name, config.Config(ctx).PagerStyle, opts.Interactive)
+	if err != nil {
+		log.Fatal("Failed to prompt user to view build script").Err(err).Send()
+	}
+
+	log.Info("Building package").Str("name", vars.Name).Str("version", vars.Version).Send()
+
+	// The second pass will be used to execute the actual code,
+	// so it's unrestricted. The script has already been displayed
+	// to the user by this point, so it should be safe
+	dec, err := executeSecondPass(ctx, info, fl, dirs)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Get the installed packages on the system
+	installed, err := opts.Manager.ListInstalled(nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	cont, err := performChecks(ctx, vars, opts.Interactive, installed)
+	if err != nil {
+		return nil, nil, err
+	} else if !cont {
+		os.Exit(1)
+	}
+
+	// Prepare the directories for building
+	err = prepareDirs(dirs)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	buildDeps, err := installBuildDeps(ctx, vars, opts, installed)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	err = installOptDeps(ctx, vars, opts, installed)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	builtPaths, builtNames, repoDeps, err := buildLUREDeps(ctx, opts, vars)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	log.Info("Downloading sources").Send()
+
+	err = getSources(ctx, dirs, vars)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	err = executeFunctions(ctx, dec, dirs, vars)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	log.Info("Building package metadata").Str("name", vars.Name).Send()
+
+	pkgFormat := getPkgFormat(opts.Manager)
+
+	pkgInfo, err := buildPkgMetadata(vars, dirs, pkgFormat, append(repoDeps, builtNames...))
+	if err != nil {
+		return nil, nil, err
+	}
+
+	packager, err := nfpm.Get(pkgFormat)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	pkgName := packager.ConventionalFileName(pkgInfo)
+	pkgPath := filepath.Join(dirs.BaseDir, pkgName)
+
+	pkgFile, err := os.Create(pkgPath)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	log.Info("Compressing package").Str("name", pkgName).Send()
+
+	err = packager.Package(pkgInfo, pkgFile)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	err = removeBuildDeps(ctx, buildDeps, opts)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Add the path and name of the package we just built to the
+	// appropriate slices
+	pkgPaths := append(builtPaths, pkgPath)
+	pkgNames := append(builtNames, vars.Name)
+
+	// Remove any duplicates from the pkgPaths and pkgNames.
+	// Duplicates can be introduced if several of the dependencies
+	// depend on the same packages.
+	pkgPaths = removeDuplicates(pkgPaths)
+	pkgNames = removeDuplicates(pkgNames)
+
+	return pkgPaths, pkgNames, nil
+}
+
+// parseScript parses the build script using the built-in bash implementation
+func parseScript(info *distro.OSRelease, script string) (*syntax.File, error) {
+	fl, err := os.Open(script)
+	if err != nil {
+		return nil, err
+	}
+	defer fl.Close()
+
+	file, err := syntax.NewParser().Parse(fl, "lure.sh")
+	if err != nil {
+		return nil, err
+	}
+
+	return file, nil
+}
+
+// executeFirstPass executes the parsed script in a restricted environment
+// to extract the build variables without executing any actual code.
+func executeFirstPass(ctx context.Context, info *distro.OSRelease, fl *syntax.File, script string) (*types.BuildVars, error) {
+	scriptDir := filepath.Dir(script)
+	env := createBuildEnvVars(info, types.Directories{ScriptDir: scriptDir})
+
+	runner, err := interp.New(
+		interp.Env(expand.ListEnviron(env...)),
+		interp.StdIO(os.Stdin, os.Stdout, os.Stderr),
+		interp.ExecHandler(helpers.Restricted.ExecHandler(handlers.NopExec)),
+		interp.ReadDirHandler(handlers.RestrictedReadDir(scriptDir)),
+		interp.StatHandler(handlers.RestrictedStat(scriptDir)),
+		interp.OpenHandler(handlers.RestrictedOpen(scriptDir)),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		return nil, err
+	}
+
+	dec := decoder.New(info, runner)
+
+	var vars types.BuildVars
+	err = dec.DecodeVars(&vars)
+	if err != nil {
+		return nil, err
+	}
+
+	return &vars, nil
+}
+
+// getDirs returns the appropriate directories for the script
+func getDirs(ctx context.Context, vars *types.BuildVars, script string) types.Directories {
+	baseDir := filepath.Join(config.GetPaths(ctx).PkgsDir, vars.Name)
+	return types.Directories{
+		BaseDir:   baseDir,
+		SrcDir:    filepath.Join(baseDir, "src"),
+		PkgDir:    filepath.Join(baseDir, "pkg"),
+		ScriptDir: filepath.Dir(script),
+	}
+}
+
+// executeSecondPass executes the build script for the second time, this time without any restrictions.
+// It returns a decoder that can be used to retrieve functions and variables from the script.
+func executeSecondPass(ctx context.Context, info *distro.OSRelease, fl *syntax.File, dirs types.Directories) (*decoder.Decoder, error) {
+	env := createBuildEnvVars(info, dirs)
+
+	fakeroot := handlers.FakerootExecHandler(2 * time.Second)
+	runner, err := interp.New(
+		interp.Env(expand.ListEnviron(env...)),
+		interp.StdIO(os.Stdin, os.Stdout, os.Stderr),
+		interp.ExecHandler(helpers.Helpers.ExecHandler(fakeroot)),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		return nil, err
+	}
+
+	return decoder.New(info, runner), nil
+}
+
+// prepareDirs prepares the directories for building.
+func prepareDirs(dirs types.Directories) error {
+	err := os.RemoveAll(dirs.BaseDir)
+	if err != nil {
+		return err
+	}
+	err = os.MkdirAll(dirs.SrcDir, 0o755)
+	if err != nil {
+		return err
+	}
+	return os.MkdirAll(dirs.PkgDir, 0o755)
+}
+
+// performChecks checks various things on the system to ensure that the package can be installed.
+func performChecks(ctx context.Context, vars *types.BuildVars, interactive bool, installed map[string]string) (bool, error) {
+	log := loggerctx.From(ctx)
+	if !cpu.IsCompatibleWith(cpu.Arch(), vars.Architectures) {
+		cont, err := cliutils.YesNoPrompt(ctx, "Your system's CPU architecture doesn't match this package. Do you want to build anyway?", interactive, true)
+		if err != nil {
+			return false, err
+		}
+
+		if !cont {
+			return false, nil
+		}
+	}
+
+	if instVer, ok := installed[vars.Name]; ok {
+		log.Warn("This package is already installed").
+			Str("name", vars.Name).
+			Str("version", instVer).
+			Send()
+	}
+
+	return true, nil
+}
+
+// installBuildDeps installs any build dependencies that aren't already installed and returns
+// a slice containing the names of all the packages it installed.
+func installBuildDeps(ctx context.Context, vars *types.BuildVars, opts types.BuildOpts, installed map[string]string) ([]string, error) {
+	log := loggerctx.From(ctx)
+	var buildDeps []string
+	if len(vars.BuildDepends) > 0 {
+		found, notFound, err := repos.FindPkgs(ctx, vars.BuildDepends)
+		if err != nil {
+			return nil, err
+		}
+
+		found = removeAlreadyInstalled(found, installed)
+
+		log.Info("Installing build dependencies").Send()
+
+		flattened := cliutils.FlattenPkgs(ctx, found, "install", opts.Interactive)
+		buildDeps = packageNames(flattened)
+		InstallPkgs(ctx, flattened, notFound, opts)
+	}
+	return buildDeps, nil
+}
+
+// installOptDeps asks the user which, if any, optional dependencies they want to install.
+// If the user chooses to install any optional dependencies, it performs the installation.
+func installOptDeps(ctx context.Context, vars *types.BuildVars, opts types.BuildOpts, installed map[string]string) error {
+	if len(vars.OptDepends) > 0 {
+		optDeps, err := cliutils.ChooseOptDepends(ctx, vars.OptDepends, "install", opts.Interactive)
+		if err != nil {
+			return err
+		}
+
+		if len(optDeps) == 0 {
+			return nil
+		}
+
+		found, notFound, err := repos.FindPkgs(ctx, optDeps)
+		if err != nil {
+			return err
+		}
+
+		found = removeAlreadyInstalled(found, installed)
+		flattened := cliutils.FlattenPkgs(ctx, found, "install", opts.Interactive)
+		InstallPkgs(ctx, flattened, notFound, opts)
+	}
+	return nil
+}
+
+// buildLUREDeps builds all the LURE dependencies of the package. It returns the paths and names
+// of the packages it built, as well as all the dependencies it didn't find in the LURE repo so
+// they can be installed from the system repos.
+func buildLUREDeps(ctx context.Context, opts types.BuildOpts, vars *types.BuildVars) (builtPaths, builtNames, repoDeps []string, err error) {
+	log := loggerctx.From(ctx)
+	if len(vars.Depends) > 0 {
+		log.Info("Installing dependencies").Send()
+
+		found, notFound, err := repos.FindPkgs(ctx, vars.Depends)
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		repoDeps = notFound
+
+		// If there are multiple options for some packages, flatten them all into a single slice
+		pkgs := cliutils.FlattenPkgs(ctx, found, "install", opts.Interactive)
+		scripts := GetScriptPaths(ctx, pkgs)
+		for _, script := range scripts {
+			newOpts := opts
+			newOpts.Script = script
+
+			// Build the dependency
+			pkgPaths, pkgNames, err := BuildPackage(ctx, newOpts)
+			if err != nil {
+				return nil, nil, nil, err
+			}
+
+			// Append the paths of all the built packages to builtPaths
+			builtPaths = append(builtPaths, pkgPaths...)
+			// Append the names of all the built packages to builtNames
+			builtNames = append(builtNames, pkgNames...)
+			// Append the name of the current package to builtNames
+			builtNames = append(builtNames, filepath.Base(filepath.Dir(script)))
+		}
+	}
+
+	// Remove any potential duplicates, which can be introduced if
+	// several of the dependencies depend on the same packages.
+	repoDeps = removeDuplicates(repoDeps)
+	builtPaths = removeDuplicates(builtPaths)
+	builtNames = removeDuplicates(builtNames)
+	return builtPaths, builtNames, repoDeps, nil
+}
+
+// executeFunctions executes the special LURE functions, such as version(), prepare(), etc.
+func executeFunctions(ctx context.Context, dec *decoder.Decoder, dirs types.Directories, vars *types.BuildVars) (err error) {
+	log := loggerctx.From(ctx)
+	version, ok := dec.GetFunc("version")
+	if ok {
+		log.Info("Executing version()").Send()
+
+		buf := &bytes.Buffer{}
+
+		err = version(
+			ctx,
+			interp.Dir(dirs.SrcDir),
+			interp.StdIO(os.Stdin, buf, os.Stderr),
+		)
+		if err != nil {
+			return err
+		}
+
+		newVer := strings.TrimSpace(buf.String())
+		err = setVersion(ctx, dec.Runner, newVer)
+		if err != nil {
+			return err
+		}
+		vars.Version = newVer
+
+		log.Info("Updating version").Str("new", newVer).Send()
+	}
+
+	prepare, ok := dec.GetFunc("prepare")
+	if ok {
+		log.Info("Executing prepare()").Send()
+
+		err = prepare(ctx, interp.Dir(dirs.SrcDir))
+		if err != nil {
+			return err
+		}
+	}
+
+	build, ok := dec.GetFunc("build")
+	if ok {
+		log.Info("Executing build()").Send()
+
+		err = build(ctx, interp.Dir(dirs.SrcDir))
+		if err != nil {
+			return err
+		}
+	}
+
+	packageFn, ok := dec.GetFunc("package")
+	if ok {
+		log.Info("Executing package()").Send()
+
+		err = packageFn(ctx, interp.Dir(dirs.SrcDir))
+		if err != nil {
+			return err
+		}
+	} else {
+		log.Fatal("The package() function is required").Send()
+	}
+
+	return nil
+}
+
+// buildPkgMetadata builds the metadata for the package that's going to be built.
+func buildPkgMetadata(vars *types.BuildVars, dirs types.Directories, pkgFormat string, deps []string) (*nfpm.Info, error) {
+	pkgInfo := &nfpm.Info{
+		Name:        vars.Name,
+		Description: vars.Description,
+		Arch:        cpu.Arch(),
+		Platform:    "linux",
+		Version:     vars.Version,
+		Release:     strconv.Itoa(vars.Release),
+		Homepage:    vars.Homepage,
+		License:     strings.Join(vars.Licenses, ", "),
+		Maintainer:  vars.Maintainer,
+		Overridables: nfpm.Overridables{
+			Conflicts: vars.Conflicts,
+			Replaces:  vars.Replaces,
+			Provides:  vars.Provides,
+			Depends:   deps,
+		},
+	}
+
+	if pkgFormat == "apk" {
+		// Alpine refuses to install packages that provide themselves, so remove any such provides
+		pkgInfo.Overridables.Provides = slices.DeleteFunc(pkgInfo.Overridables.Provides, func(s string) bool {
+			return s == pkgInfo.Name
+		})
+	}
+
+	if vars.Epoch != 0 {
+		pkgInfo.Epoch = strconv.FormatUint(uint64(vars.Epoch), 10)
+	}
+
+	setScripts(vars, pkgInfo, dirs.ScriptDir)
+
+	if slices.Contains(vars.Architectures, "all") {
+		pkgInfo.Arch = "all"
+	}
+
+	contents, err := buildContents(vars, dirs)
+	if err != nil {
+		return nil, err
+	}
+	pkgInfo.Overridables.Contents = contents
+
+	return pkgInfo, nil
+}
+
+// buildContents builds the contents section of the package, which contains the files
+// that will be placed into the final package.
+func buildContents(vars *types.BuildVars, dirs types.Directories) ([]*files.Content, error) {
+	contents := []*files.Content{}
+	err := filepath.Walk(dirs.PkgDir, func(path string, fi os.FileInfo, err error) error {
+		trimmed := strings.TrimPrefix(path, dirs.PkgDir)
+
+		if fi.IsDir() {
+			f, err := os.Open(path)
+			if err != nil {
+				return err
+			}
+
+			// If the directory is empty, skip it
+			_, err = f.Readdirnames(1)
+			if err != io.EOF {
+				return nil
+			}
+
+			contents = append(contents, &files.Content{
+				Source:      path,
+				Destination: trimmed,
+				Type:        "dir",
+				FileInfo: &files.ContentFileInfo{
+					MTime: fi.ModTime(),
+				},
+			})
+
+			return f.Close()
+		}
+
+		if fi.Mode()&os.ModeSymlink != 0 {
+			link, err := os.Readlink(path)
+			if err != nil {
+				return err
+			}
+			// Remove pkgdir from the symlink's path
+			link = strings.TrimPrefix(link, dirs.PkgDir)
+
+			contents = append(contents, &files.Content{
+				Source:      link,
+				Destination: trimmed,
+				Type:        "symlink",
+				FileInfo: &files.ContentFileInfo{
+					MTime: fi.ModTime(),
+					Mode:  fi.Mode(),
+				},
+			})
+
+			return nil
+		}
+
+		fileContent := &files.Content{
+			Source:      path,
+			Destination: trimmed,
+			FileInfo: &files.ContentFileInfo{
+				MTime: fi.ModTime(),
+				Mode:  fi.Mode(),
+				Size:  fi.Size(),
+			},
+		}
+
+		// If the file is supposed to be backed up, set its type to config|noreplace
+		if slices.Contains(vars.Backup, trimmed) {
+			fileContent.Type = "config|noreplace"
+		}
+
+		contents = append(contents, fileContent)
+
+		return nil
+	})
+	return contents, err
+}
+
+// removeBuildDeps asks the user if they'd like to remove the build dependencies that were
+// installed by installBuildDeps. If so, it uses the package manager to do that.
+func removeBuildDeps(ctx context.Context, buildDeps []string, opts types.BuildOpts) error {
+	if len(buildDeps) > 0 {
+		remove, err := cliutils.YesNoPrompt(ctx, "Would you like to remove the build dependencies?", opts.Interactive, false)
+		if err != nil {
+			return err
+		}
+
+		if remove {
+			err = opts.Manager.Remove(
+				&manager.Opts{
+					AsRoot:    true,
+					NoConfirm: true,
+				},
+				buildDeps...,
+			)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// checkForBuiltPackage tries to detect a previously-built package and returns its path
+// and true if it finds one. If it doesn't find it, it returns "", false, nil.
+func checkForBuiltPackage(mgr manager.Manager, vars *types.BuildVars, pkgFormat, baseDir string) (string, bool, error) {
+	filename, err := pkgFileName(vars, pkgFormat)
+	if err != nil {
+		return "", false, err
+	}
+
+	pkgPath := filepath.Join(baseDir, filename)
+
+	_, err = os.Stat(pkgPath)
+	if err != nil {
+		return "", false, nil
+	}
+
+	return pkgPath, true, nil
+}
+
+// pkgFileName returns the filename of the package if it were to be built.
+// This is used to check if the package has already been built.
+func pkgFileName(vars *types.BuildVars, pkgFormat string) (string, error) {
+	pkgInfo := &nfpm.Info{
+		Name:    vars.Name,
+		Arch:    cpu.Arch(),
+		Version: vars.Version,
+		Release: strconv.Itoa(vars.Release),
+		Epoch:   strconv.FormatUint(uint64(vars.Epoch), 10),
+	}
+
+	packager, err := nfpm.Get(pkgFormat)
+	if err != nil {
+		return "", err
+	}
+
+	return packager.ConventionalFileName(pkgInfo), nil
+}
+
+// getPkgFormat returns the package format of the package manager,
+// or LURE_PKG_FORMAT if that's set.
+func getPkgFormat(mgr manager.Manager) string {
+	pkgFormat := mgr.Format()
+	if format, ok := os.LookupEnv("LURE_PKG_FORMAT"); ok {
+		pkgFormat = format
+	}
+	return pkgFormat
+}
+
+// createBuildEnvVars creates the environment variables that will be set in the
+// build script when it's executed.
+func createBuildEnvVars(info *distro.OSRelease, dirs types.Directories) []string {
+	env := os.Environ()
+
+	env = append(
+		env,
+		"DISTRO_NAME="+info.Name,
+		"DISTRO_PRETTY_NAME="+info.PrettyName,
+		"DISTRO_ID="+info.ID,
+		"DISTRO_VERSION_ID="+info.VersionID,
+		"DISTRO_ID_LIKE="+strings.Join(info.Like, " "),
+		"ARCH="+cpu.Arch(),
+		"NCPU="+strconv.Itoa(runtime.NumCPU()),
+	)
+
+	if dirs.ScriptDir != "" {
+		env = append(env, "scriptdir="+dirs.ScriptDir)
+	}
+
+	if dirs.PkgDir != "" {
+		env = append(env, "pkgdir="+dirs.PkgDir)
+	}
+
+	if dirs.SrcDir != "" {
+		env = append(env, "srcdir="+dirs.SrcDir)
+	}
+
+	return env
+}
+
+// getSources downloads the sources from the script.
+func getSources(ctx context.Context, dirs types.Directories, bv *types.BuildVars) error {
+	log := loggerctx.From(ctx)
+	if len(bv.Sources) != len(bv.Checksums) {
+		log.Fatal("The checksums array must be the same length as sources").Send()
+	}
+
+	for i, src := range bv.Sources {
+		opts := dl.Options{
+			Name:        fmt.Sprintf("%s[%d]", bv.Name, i),
+			URL:         src,
+			Destination: dirs.SrcDir,
+			Progress:    os.Stderr,
+			LocalDir:    dirs.ScriptDir,
+		}
+
+		if !strings.EqualFold(bv.Checksums[i], "SKIP") {
+			// If the checksum contains a colon, use the part before the colon
+			// as the algorithm and the part after as the actual checksum.
+			// Otherwise, use the default sha256 with the whole string as the checksum.
+			algo, hashData, ok := strings.Cut(bv.Checksums[i], ":")
+			if ok {
+				checksum, err := hex.DecodeString(hashData)
+				if err != nil {
+					return err
+				}
+				opts.Hash = checksum
+				opts.HashAlgorithm = algo
+			} else {
+				checksum, err := hex.DecodeString(bv.Checksums[i])
+				if err != nil {
+					return err
+				}
+				opts.Hash = checksum
+			}
+		}
+
+		err := dl.Download(ctx, opts)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// setScripts adds any hook scripts to the package metadata.
+func setScripts(vars *types.BuildVars, info *nfpm.Info, scriptDir string) {
+	if vars.Scripts.PreInstall != "" {
+		info.Scripts.PreInstall = filepath.Join(scriptDir, vars.Scripts.PreInstall)
+	}
+
+	if vars.Scripts.PostInstall != "" {
+		info.Scripts.PostInstall = filepath.Join(scriptDir, vars.Scripts.PostInstall)
+	}
+
+	if vars.Scripts.PreRemove != "" {
+		info.Scripts.PreRemove = filepath.Join(scriptDir, vars.Scripts.PreRemove)
+	}
+
+	if vars.Scripts.PostRemove != "" {
+		info.Scripts.PostRemove = filepath.Join(scriptDir, vars.Scripts.PostRemove)
+	}
+
+	if vars.Scripts.PreUpgrade != "" {
+		info.ArchLinux.Scripts.PreUpgrade = filepath.Join(scriptDir, vars.Scripts.PreUpgrade)
+		info.APK.Scripts.PreUpgrade = filepath.Join(scriptDir, vars.Scripts.PreUpgrade)
+	}
+
+	if vars.Scripts.PostUpgrade != "" {
+		info.ArchLinux.Scripts.PostUpgrade = filepath.Join(scriptDir, vars.Scripts.PostUpgrade)
+		info.APK.Scripts.PostUpgrade = filepath.Join(scriptDir, vars.Scripts.PostUpgrade)
+	}
+
+	if vars.Scripts.PreTrans != "" {
+		info.RPM.Scripts.PreTrans = filepath.Join(scriptDir, vars.Scripts.PreTrans)
+	}
+
+	if vars.Scripts.PostTrans != "" {
+		info.RPM.Scripts.PostTrans = filepath.Join(scriptDir, vars.Scripts.PostTrans)
+	}
+}
+
+// setVersion changes the version variable in the script runner.
+// It's used to set the version to the output of the version() function.
+func setVersion(ctx context.Context, r *interp.Runner, to string) error {
+	fl, err := syntax.NewParser().Parse(strings.NewReader("version='"+to+"'"), "")
+	if err != nil {
+		return err
+	}
+	return r.Run(ctx, fl)
+}
+
+// removeAlreadyInstalled returns a map without any dependencies that are already installed
+func removeAlreadyInstalled(found map[string][]db.Package, installed map[string]string) map[string][]db.Package {
+	filteredPackages := make(map[string][]db.Package)
+
+	for name, pkgList := range found {
+		filteredPkgList := []db.Package{}
+		for _, pkg := range pkgList {
+			if _, isInstalled := installed[pkg.Name]; !isInstalled {
+				filteredPkgList = append(filteredPkgList, pkg)
+			}
+		}
+		filteredPackages[name] = filteredPkgList
+	}
+
+	return filteredPackages
+}
+
+// packageNames returns the names of all the given packages
+func packageNames(pkgs []db.Package) []string {
+	names := make([]string, len(pkgs))
+	for i, p := range pkgs {
+		names[i] = p.Name
+	}
+	return names
+}
+
+// removeDuplicates removes any duplicates from the given slice
+func removeDuplicates(slice []string) []string {
+	seen := map[string]struct{}{}
+	result := []string{}
+
+	for _, s := range slice {
+		if _, ok := seen[s]; !ok {
+			seen[s] = struct{}{}
+			result = append(result, s)
+		}
+	}
+
+	return result
+}