Merge lp:~mvo/snappy/snappy-tar-unpack-mknod into lp:~snappy-dev/snappy/snappy-moved-to-github

[Michael Vogt]

Add support for unpacking device files in a tar.

This branch adds support for unpack tars that contains device files.

[John Lenton (chipaca)]

Silly things, inline.

review: Needs Fixing

[Michael Vogt (mvo)]

Thanks a lot for the review! I commented inline and I hope I addressed the comments in r447.

[John Lenton (chipaca)]

Yes, thank you.

review: Approve

[Snappy Tarmac (snappydevtarmac)]

The attempt to merge lp:~mvo/snappy/snappy-tar-unpack-mknod into lp:snappy failed. Below is the output from the failed tests.

Checking formatting
Installing godeps
Install golint
Obtaining dependencies
update code.google.com/p/go.crypto failed; trying to fetch newer version
update github.com/blakesmith/ar failed; trying to fetch newer version
code.google.com/p/go.crypto now at 69e2a90ed92d03812364aeb947b7068dc42e561e
update github.com/cheggaaa/pb failed; trying to fetch newer version
github.com/blakesmith/ar now at c9a977dd0cc1392b023382c7bfa5a22af8d3b730
update github.com/jessevdk/go-flags failed; trying to fetch newer version
github.com/cheggaaa/pb now at e8c7cc515bfde3e267957a3b110080ceed51354e
update github.com/juju/loggo failed; trying to fetch newer version
github.com/jessevdk/go-flags now at 15347ef417a300349807983f15af9e65cd2e1b3a
update github.com/mvo5/goconfigparser failed; trying to fetch newer version
github.com/juju/loggo now at 4c7cbce140ca070eeb59a28f4bf9507e511711f9
update gopkg.in/yaml.v2 failed; trying to fetch newer version
github.com/mvo5/goconfigparser now at 26426272dda20cc76aa1fa44286dc743d2972fe8
update launchpad.net/gocheck failed; trying to fetch newer version
gopkg.in/yaml.v2 now at 49c95bdc21843256fb6c4e0d370a05f24a0bf213
launchpad.net/gocheck now at <email address hidden>
Building

# we always run in a fresh dir in tarmac
export GOPATH=$(mktemp -d)
trap 'rm -rf "$GOPATH"' EXIT

# this is a hack, but not sure tarmac is golang friendly
mkdir -p $GOPATH/src/launchpad.net/snappy
cp -a . $GOPATH/src/launchpad.net/snappy/
cd $GOPATH/src/launchpad.net/snappy

./run-checks

if which goctest >/dev/null; then
    goctest="goctest"
else
    goctest="go test"
fi

echo Checking formatting
fmt=$(gofmt -l .)

if [ -n "$fmt" ]; then
    echo "Formatting wrong in following files"
    echo $fmt
    exit 1
fi

echo Installing godeps
go get launchpad.net/godeps
export PATH=$PATH:$GOPATH/bin

echo Install golint
go get github.com/golang/lint/golint
export PATH=$PATH:$GOPATH/bin

echo Obtaining dependencies
godeps -u dependencies.tsv

echo Building
go build -v launchpad.net/snappy/...
github.com/blakesmith/ar
launchpad.net/snappy/helpers
launchpad.net/snappy/clickdeb
code.google.com/p/go.crypto/ssh/terminal
github.com/jessevdk/go-flags
github.com/juju/loggo
launchpad.net/snappy/logger
launchpad.net/snappy/priv
github.com/cheggaaa/pb
launchpad.net/snappy/progress
github.com/mvo5/goconfigparser
gopkg.in/yaml.v2
launchpad.net/snappy/coreconfig
launchpad.net/snappy/partition
launchpad.net/snappy/policy
launchpad.net/snappy/release
launchpad.net/snappy/systemd
launchpad.net/snappy/snappy
# launchpad.net/snappy/snappy
snappy/build.go:398: undefined: syscall
snappy/build.go:399: undefined: syscall

[lp:~mvo/snappy/snappy-tar-unpack-mknod]

448. By Michael Vogt on 2015-05-07

merged lp:snappy

449. By Michael Vogt on 2015-05-07

snappy/build.go: fix test failure

[Michael Vogt (mvo)]

review: Approve

=== modified file 'helpers/helpers.go'
--- helpers/helpers.go	2015-04-29 09:10:08 +0000
+++ helpers/helpers.go	2015-05-07 16:27:49 +0000
@@ -95,10 +95,17 @@
 	return (mode & os.ModeSymlink) == os.ModeSymlink
 }
 
+// IsDevice checks if the given os.FileMode coresponds to a device (char/block)
+func IsDevice(mode os.FileMode) bool {
+	return (mode & (os.ModeDevice | os.ModeCharDevice)) != 0
+}
+
 // UnpackTarTransformFunc can be used to change the names during unpack
 // or to return a error for files that are not acceptable
 type UnpackTarTransformFunc func(path string) (newPath string, err error)
 
+var mknod = syscall.Mknod
+
 // UnpackTar unpacks the given tar file into the target directory
 func UnpackTar(r io.Reader, targetDir string, fn UnpackTarTransformFunc) error {
 	return TarIterate(r, func(tr *tar.Reader, hdr *tar.Header) (err error) {
@@ -127,6 +134,18 @@
 			if err := os.Symlink(hdr.Linkname, path); err != nil {
 				return err
 			}
+		case IsDevice(mode):
+			switch {
+			case (mode & os.ModeCharDevice) != 0:
+				mode |= syscall.S_IFCHR
+			case (mode & os.ModeDevice) != 0:
+				mode |= syscall.S_IFBLK
+			}
+			devNum := Makedev(uint32(hdr.Devmajor), uint32(hdr.Devminor))
+			err = mknod(path, uint32(mode), int(devNum))
+			if err != nil {
+				return err
+			}
 		case mode.IsRegular():
 			out, err := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, mode)
 			if err != nil {
@@ -317,3 +336,27 @@
 	return syscall.Getuid() == 0 || syscall.Getgid() == 0
 
 }
+
+// MajorMinor returns the major/minor number of the given os.FileInfo
+func MajorMinor(info os.FileInfo) (uint32, uint32, error) {
+	if !IsDevice(info.Mode()) {
+		return 0, 0, fmt.Errorf("No device %s", info.Name())
+	}
+
+	unixStat, ok := info.Sys().(*syscall.Stat_t)
+	if ok {
+		// see glibc: sysdeps/unix/sysv/linux/makedev.c
+		dev := uint32(unixStat.Rdev)
+		major := ((dev >> 8) & 0xfff) | ((dev >> 32) & ^uint32(0xfff))
+		minor := (dev & 0xff) | ((dev >> 12) & ^uint32(0xff))
+
+		return major, minor, nil
+	}
+
+	return 0, 0, fmt.Errorf("failed to get syscall.stat_t for %v", info.Name())
+}
+
+// Makedev implements makedev(3)
+func Makedev(major, minor uint32) uint32 {
+	return uint32((minor & 0xff) | ((major & 0xfff) << 8))
+}

=== modified file 'helpers/helpers_test.go'
--- helpers/helpers_test.go	2015-04-23 11:12:32 +0000
+++ helpers/helpers_test.go	2015-05-07 16:27:49 +0000
@@ -268,3 +268,55 @@
 	c.Assert(err, IsNil)
 	c.Assert(home, Equals, oldHome)
 }
+
+func (ts *HTestSuite) TestMajorMinorSimple(c *C) {
+	stat, err := os.Stat("/dev/kmsg")
+	if err != nil {
+		c.Skip("Can not stat /dev/kmsg")
+	}
+
+	major, minor, err := MajorMinor(stat)
+	c.Assert(err, IsNil)
+	c.Assert(major, Equals, uint32(1))
+	c.Assert(minor, Equals, uint32(11))
+}
+
+func (ts *HTestSuite) TestMajorMinorNoDevice(c *C) {
+	stat, err := os.Stat(c.MkDir())
+	c.Assert(err, IsNil)
+
+	_, _, err = MajorMinor(stat)
+	c.Assert(err, NotNil)
+}
+
+func (ts *HTestSuite) TestMakedev(c *C) {
+	// $ python -c 'import os;print(os.makedev(1,11))'
+	// 267
+	c.Assert(Makedev(1, 11), Equals, uint32(267))
+}
+
+func (ts *HTestSuite) TestUnpacksMknod(c *C) {
+
+	// mknod mock
+	mknodWasCalled := false
+	mknod = func(path string, mode uint32, dev int) error {
+		mknodWasCalled = true
+		return nil
+	}
+
+	// setup tmpdir
+	tmpdir := c.MkDir()
+	tmpfile := filepath.Join(tmpdir, "device.tar")
+
+	cmd := exec.Command("tar", "cf", tmpfile, "/dev/kmsg")
+	err := cmd.Run()
+	c.Assert(err, IsNil)
+
+	f, err := os.Open(tmpfile)
+	c.Assert(err, IsNil)
+
+	err = UnpackTar(f, c.MkDir(), nil)
+	c.Assert(err, IsNil)
+	c.Assert(mknodWasCalled, Equals, true)
+
+}

=== modified file 'snappy/build.go'
--- snappy/build.go	2015-05-07 10:34:05 +0000
+++ snappy/build.go	2015-05-07 16:27:49 +0000
@@ -233,14 +233,9 @@
 
 	// major/minor handling
 	device := ""
-	if (info.Mode()&os.ModeDevice) != 0 || (info.Mode()&os.ModeCharDevice) != 0 {
-		unixStat, ok := info.Sys().(*syscall.Stat_t)
-		if ok {
-			// see  /usr/include/linux/kdev_t.h
-			major := int64(unixStat.Rdev >> 8)
-			minor := int64(unixStat.Rdev & 0xff)
-			device = fmt.Sprintf("%v,%v", major, minor)
-		}
+	major, minor, err := helpers.MajorMinor(info)
+	if err == nil {
+		device = fmt.Sprintf("%v,%v", major, minor)
 	}
 
 	if buildDir != "" {