snap-bootstrap: add scan-disk subcommand

build-aux/snap/snapcraft.yaml

@@ -96,6 +96,7 @@ parts:
   runtime:
     plugin: nil
     stage-packages:
+      - libblkid1
       - libbrotli1
       - libc6
       - libcap2
@@ -231,6 +232,7 @@ parts:
       - autoconf-archive
       - automake
       - xfslibs-dev
+      - libblkid-dev
       - libudev-dev
       - libcap-dev
       - libseccomp-dev

cmd/snap-bootstrap/blkid/blkid.go

@@ -0,0 +1,186 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * 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 blkid
+
+//#cgo CFLAGS: -D_FILE_OFFSET_BITS=64
+//#cgo pkg-config: blkid
+//#cgo LDFLAGS:
+//
+//#include <stdlib.h>
+//#include <blkid.h>
+import "C"
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+const (
+	BLKID_PARTS_ENTRY_DETAILS int = C.BLKID_PARTS_ENTRY_DETAILS
+)
+
+// AbstractBlkidProbe is wrapper for blkid_probe
+// See "Low-level" section of libblkid documentation
+type AbstractBlkidProbe interface {
+	// LookupValue is a wrapper for blkid_probe_lookup_value
+	LookupValue(entryName string) (string, error)
+	// Close is a wrapper for blkid_free_probe
+	Close()
+	// EnablePartitions is a wrapper for blkid_probe_enable_partitions
+	EnablePartitions(value bool)
+	// EnableSuperblocks is a wrapper for blkid_probe_enable_superblocks
+	EnableSuperblocks(value bool)
+	// SetPartitionsFlags is a wrapper for blkid_probe_set_partitions_flags
+	SetPartitionsFlags(flags int)
+	// DoSafeprobe is a wrapper for blkid_do_safeprobe
+	DoSafeprobe() error
+	// GetPartitions is a wrapper for blkid_probe_get_partitions
+	GetPartitions() (AbstractBlkidPartlist, error)
+}
+
+// AbstractBlkidPartlist is a wrapper for blkid_partlist
+type AbstractBlkidPartlist interface {
+	// GetPartitions is a wrapper for blkid_partlist_get_partition
+	// and blkid_partlist_numof_partitions.
+	GetPartitions() []AbstractBlkidPartition
+}
+
+// AbstractBlkidPartition is a wrapper for blkid_partition
+type AbstractBlkidPartition interface {
+	// GetName is a wrapper for blkid_partition_get_name
+	GetName() string
+	// GetUUID is a wrapper for blkid_partition_get_uuid
+	GetUUID() string
+}
+
+type blkidProbe struct {
+	probeHandle C.blkid_probe
+}
+
+func newProbeFromFilenameImpl(node string) (AbstractBlkidProbe, error) {
+	cnode := C.CString(node)
+	defer C.free(unsafe.Pointer(cnode))
+	probe, err := C.blkid_new_probe_from_filename(cnode)
+	if probe == nil {
+		if err == nil {
+			return nil, fmt.Errorf("blkid_new_probe_from_filename failed but no error was returned")
+		}
+		return nil, err
+	}
+	return &blkidProbe{probe}, nil
+}
+
+var NewProbeFromFilename = newProbeFromFilenameImpl
+
+func (p *blkidProbe) checkProbe() {
+	if p.probeHandle == nil {
+		panic("used blkid probe after Close")
+	}
+}
+
+func (p *blkidProbe) LookupValue(entryName string) (string, error) {
+	p.checkProbe()
+	var value *C.char
+	var value_len C.size_t
+	cname := C.CString(entryName)
+	defer C.free(unsafe.Pointer(cname))
+	res := C.blkid_probe_lookup_value(p.probeHandle, cname, &value, &value_len)
+	if res < 0 {
+		return "", fmt.Errorf("probe value was not found: %s", entryName)
+	}
+	if value_len > 0 {
+		return C.GoStringN(value, C.int(value_len-1)), nil
+	} else {
+		return "", fmt.Errorf("probe value has unexpected size")
+	}
+}
+
+func (p *blkidProbe) Close() {
+	p.checkProbe()
+	C.blkid_free_probe(p.probeHandle)
+	p.probeHandle = C.blkid_probe(nil)
+}
+
+func (p *blkidProbe) EnablePartitions(value bool) {
+	p.checkProbe()
+	v := 0
+	if value {
+		v = 1
+	}
+	C.blkid_probe_enable_partitions(p.probeHandle, C.int(v))
+}
+
+func (p *blkidProbe) EnableSuperblocks(value bool) {
+	p.checkProbe()
+	v := 0
+	if value {
+		v = 1
+	}
+	C.blkid_probe_enable_superblocks(p.probeHandle, C.int(v))
+}
+
+func (p *blkidProbe) SetPartitionsFlags(flags int) {
+	p.checkProbe()
+	C.blkid_probe_set_partitions_flags(p.probeHandle, C.int(flags))
+}
+
+func (p *blkidProbe) DoSafeprobe() error {
+	p.checkProbe()
+	res, err := C.blkid_do_safeprobe(p.probeHandle)
+	if res < 0 {
+		return err
+	}
+	return nil
+}
+
+type blkidPartlist struct {
+	partlistHandle C.blkid_partlist
+}
+
+func (p *blkidProbe) GetPartitions() (AbstractBlkidPartlist, error) {
+	p.checkProbe()
+	partitions, err := C.blkid_probe_get_partitions(p.probeHandle)
+	if partitions == nil {
+		return nil, err
+	}
+	return &blkidPartlist{partitions}, nil
+}
+
+type blkidPartition struct {
+	partitionHandle C.blkid_partition
+}
+
+func (p *blkidPartlist) GetPartitions() []AbstractBlkidPartition {
+	npartitions := C.blkid_partlist_numof_partitions(p.partlistHandle)
+	ret := make([]AbstractBlkidPartition, npartitions)
+	for i := 0; i < int(npartitions); i++ {
+		partition := C.blkid_partlist_get_partition(p.partlistHandle, C.int(i))
+		ret[i] = &blkidPartition{partition}
+	}
+	return ret
+}
+
+func (p *blkidPartition) GetName() string {
+	return C.GoString(C.blkid_partition_get_name(p.partitionHandle))
+}
+
+func (p *blkidPartition) GetUUID() string {
+	return C.GoString(C.blkid_partition_get_uuid(p.partitionHandle))
+}

cmd/snap-bootstrap/blkid/blkid_test.go

@@ -0,0 +1,90 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * 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 blkid_test
+
+import (
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	. "gopkg.in/check.v1"
+
+	"github.com/snapcore/snapd/cmd/snap-bootstrap/blkid"
+
+	"github.com/snapcore/snapd/testutil"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type blkidSuite struct {
+	testutil.BaseTest
+
+	image string
+}
+
+var _ = Suite(&blkidSuite{})
+
+func (s *blkidSuite) SetUpTest(c *C) {
+	systemdRepart, err := exec.LookPath("systemd-repart")
+	if err != nil {
+		c.Skip("systemd-repart is not available")
+	}
+
+	s.BaseTest.SetUpTest(c)
+
+	tmp := c.MkDir()
+	image := filepath.Join(tmp, "image")
+
+	cmd := exec.Command(systemdRepart, "--offline=yes", "--size=64M", "--empty=create", "--definitions=test-data/repart.d", image)
+	err = cmd.Run()
+	if err != nil {
+		c.Skip("systemd-repart is not working")
+	}
+
+	s.image = image
+}
+
+func (s *blkidSuite) TestScanPartitionTable(c *C) {
+	probe, err := blkid.NewProbeFromFilename(s.image)
+	c.Assert(err, IsNil)
+	defer probe.Close()
+
+	probe.EnablePartitions(true)
+
+	err = probe.DoSafeprobe()
+	c.Assert(err, IsNil)
+
+	pttype, err := probe.LookupValue("PTTYPE")
+	c.Assert(err, IsNil)
+	c.Check(pttype, Equals, "gpt")
+
+	partlist, err := probe.GetPartitions()
+	c.Assert(err, IsNil)
+
+	partitions := 0
+	for _, p := range partlist.GetPartitions() {
+		partitions++
+		label := p.GetName()
+		c.Check(label, Equals, "thelabel")
+		uuid := p.GetUUID()
+		c.Check(uuid, Equals, "93fd7d8f-a662-4451-a03f-c065f2c2e1ab")
+	}
+	c.Check(partitions, Equals, 1)
+}