Add arbitrary symlinks to archive

Signed-off-by: Chris Koch <[email protected]>

uimage/uimage.go

@@ -176,6 +176,11 @@ type Opts struct {
  // - "/home/foo" is equivalent to "/home/foo:home/foo".
  ExtraFiles []string
 
+ // Symlinks to create in the archive. File path in archive -> target
+ //
+ // Target can be the name of a command. If not, it will be created as given.
+ Symlinks map[string]string
+
  // If true, do not use ldd to pick up dependencies from local machine for
  // ExtraFiles. Useful if you have all deps revision controlled and wish to
  // ensure builds are repeatable, and/or if the local machine's binaries use
@@ -293,6 +298,22 @@ func WithEnv(gopts ...golang.Opt) Modifier {
  }
 }
 
+// WithSymlink adds a symlink to the archive.
+//
+// Target can be the name of a command. If not, it will be created as given.
+func WithSymlink(file string, target string) Modifier {
+ return func(o *Opts) error {
+ if o.Symlinks == nil {
+ o.Symlinks = make(map[string]string)
+ }
+ if other, ok := o.Symlinks[file]; ok {
+ return fmt.Errorf("%w: cannot add symlink for %q as %q, already points to %q", os.ErrExist, file, target, other)
+ }
+ o.Symlinks[file] = target
+ return nil
+ }
+}
+
 // WithFiles adds files to the archive.
 //
 // Shared library dependencies will automatically also be added to the archive
@@ -563,6 +584,15 @@ func CreateInitramfs(l *llog.Logger, opts Opts) error {
  if err := opts.addSymlinkTo(l, archive, opts.DefaultShell, "bin/defaultsh"); err != nil {
  return fmt.Errorf("%w: %w", err, errDefaultshSymlink)
  }
+ for p, target := range opts.Symlinks {
+ p = path.Clean(p)
+ if len(p) >= 1 && p[0] == '/' {
+ p = p[1:]
+ }
+ if err := opts.addSymlinkTo(l, archive, target, p); err != nil {
+ return fmt.Errorf("%w: could not add additional symlink", err)
+ }
+ }
 
  // Finally, write the archive.
  if err := initramfs.Write(archive); err != nil {

uimage/uimage_test.go

@@ -459,6 +459,52 @@ func TestCreateInitramfs(t *testing.T) {
  },
  errs: []error{initramfs.ErrNoPath},
  },
+ {
+ name: "symlinks",
+ opts: Opts{
+ Env: golang.Default(golang.DisableCGO()),
+ TempDir: dir,
+ InitCmd: "init",
+ DefaultShell: "ls",
+ Symlinks: map[string]string{
+ "ubin/foo": "ls",
+ "ubin/fooa": "/bin/systemd",
+ },
+ Commands: BusyboxCmds(
+ "github.com/u-root/u-root/cmds/core/init",
+ "github.com/u-root/u-root/cmds/core/ls",
+ ),
+ },
+ validators: []itest.ArchiveValidator{
+ itest.HasFile{Path: "bbin/bb"},
+ itest.HasRecord{R: cpio.Symlink("bbin/init", "bb")},
+ itest.HasRecord{R: cpio.Symlink("bbin/ls", "bb")},
+ itest.HasRecord{R: cpio.Symlink("bin/defaultsh", "../bbin/ls")},
+ itest.HasRecord{R: cpio.Symlink("bin/sh", "../bbin/ls")},
+ itest.HasRecord{R: cpio.Symlink("ubin/foo", "../bbin/ls")},
+ itest.HasRecord{R: cpio.Symlink("ubin/fooa", "../bin/systemd")},
+ },
+ },
+ {
+ name: "dup symlinks",
+ opts: Opts{
+ Env: golang.Default(golang.DisableCGO()),
+ TempDir: dir,
+ InitCmd: "init",
+ DefaultShell: "ls",
+ Symlinks: map[string]string{
+ "/bbin/ls": "init",
+ },
+ Commands: BusyboxCmds(
+ "github.com/u-root/u-root/cmds/core/init",
+ "github.com/u-root/u-root/cmds/core/ls",
+ ),
+ },
+ errs: []error{os.ErrExist},
+ validators: []itest.ArchiveValidator{
+ itest.IsEmpty{},
+ },
+ },
  } {
  t.Run(fmt.Sprintf("Test %d [%s]", i, tt.name), func(t *testing.T) {
  archive := cpio.InMemArchive()
@@ -892,6 +938,60 @@ func TestCreateInitramfsWithAPI(t *testing.T) {
  itest.HasContent{Path: "etc/foo", Content: "bar"},
  },
  },
+ {
+ name: "symlinks",
+ opts: []Modifier{
+ WithTempDir(dir),
+ WithEnv(golang.DisableCGO()),
+ WithInit("init"),
+ WithShell("ls"),
+ WithBusyboxCommands(
+ "github.com/u-root/u-root/cmds/core/init",
+ "github.com/u-root/u-root/cmds/core/ls",
+ ),
+ WithSymlink("ubin/foo", "ls"),
+ WithSymlink("ubin/fooa", "/bin/systemd"),
+ },
+ validators: []itest.ArchiveValidator{
+ itest.HasFile{Path: "bbin/bb"},
+ itest.HasRecord{R: cpio.Symlink("bbin/init", "bb")},
+ itest.HasRecord{R: cpio.Symlink("bbin/ls", "bb")},
+ itest.HasRecord{R: cpio.Symlink("bin/defaultsh", "../bbin/ls")},
+ itest.HasRecord{R: cpio.Symlink("bin/sh", "../bbin/ls")},
+ itest.HasRecord{R: cpio.Symlink("ubin/foo", "../bbin/ls")},
+ itest.HasRecord{R: cpio.Symlink("ubin/fooa", "../bin/systemd")},
+ },
+ },
+ {
+ name: "dup symlinks",
+ opts: []Modifier{
+ WithTempDir(dir),
+ WithEnv(golang.DisableCGO()),
+ WithInit("init"),
+ WithShell("ls"),
+ WithBusyboxCommands(
+ "github.com/u-root/u-root/cmds/core/init",
+ "github.com/u-root/u-root/cmds/core/ls",
+ ),
+ WithSymlink("/bbin/ls", "init"),
+ },
+ errs: []error{os.ErrExist},
+ validators: []itest.ArchiveValidator{
+ itest.IsEmpty{},
+ },
+ },
+ {
+ name: "dup with symlinks",
+ opts: []Modifier{
+ WithTempDir(dir),
+ WithSymlink("ubin/ls", "/bin/foo"),
+ WithSymlink("ubin/ls", "../bbin/ls"),
+ },
+ errs: []error{os.ErrExist},
+ validators: []itest.ArchiveValidator{
+ itest.IsEmpty{},
+ },
+ },
  } {
  t.Run(fmt.Sprintf("Test %d [%s]", i, tt.name), func(t *testing.T) {
  archive := cpio.InMemArchive()