Support in-place upgrades of new minio binary and releases. (#4961)

This PR allows 'minio update' to not only shows update banner
but also allows for in-place upgrades.

Updates are done safely by validating the downloaded
sha256 of the binary.

Fixes #4781

vendor/github.com/inconshreveable/go-update/internal/binarydist/License

@@ -0,0 +1,22 @@
+Copyright 2012 Keith Rarick
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/inconshreveable/go-update/internal/binarydist/Readme.md

@@ -0,0 +1,7 @@
+# binarydist
+
+Package binarydist implements binary diff and patch as described on
+<http://www.daemonology.net/bsdiff/>. It reads and writes files
+compatible with the tools there.
+
+Documentation at <http://go.pkgdoc.org/github.com/kr/binarydist>.

vendor/github.com/inconshreveable/go-update/internal/binarydist/bzip2.go

@@ -0,0 +1,40 @@
+package binarydist
+
+import (
+	"io"
+	"os/exec"
+)
+
+type bzip2Writer struct {
+	c *exec.Cmd
+	w io.WriteCloser
+}
+
+func (w bzip2Writer) Write(b []byte) (int, error) {
+	return w.w.Write(b)
+}
+
+func (w bzip2Writer) Close() error {
+	if err := w.w.Close(); err != nil {
+		return err
+	}
+	return w.c.Wait()
+}
+
+// Package compress/bzip2 implements only decompression,
+// so we'll fake it by running bzip2 in another process.
+func newBzip2Writer(w io.Writer) (wc io.WriteCloser, err error) {
+	var bw bzip2Writer
+	bw.c = exec.Command("bzip2", "-c")
+	bw.c.Stdout = w
+
+	if bw.w, err = bw.c.StdinPipe(); err != nil {
+		return nil, err
+	}
+
+	if err = bw.c.Start(); err != nil {
+		return nil, err
+	}
+
+	return bw, nil
+}

vendor/github.com/inconshreveable/go-update/internal/binarydist/diff.go

@@ -0,0 +1,408 @@
+package binarydist
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+	"io/ioutil"
+)
+
+func swap(a []int, i, j int) { a[i], a[j] = a[j], a[i] }
+
+func split(I, V []int, start, length, h int) {
+	var i, j, k, x, jj, kk int
+
+	if length < 16 {
+		for k = start; k < start+length; k += j {
+			j = 1
+			x = V[I[k]+h]
+			for i = 1; k+i < start+length; i++ {
+				if V[I[k+i]+h] < x {
+					x = V[I[k+i]+h]
+					j = 0
+				}
+				if V[I[k+i]+h] == x {
+					swap(I, k+i, k+j)
+					j++
+				}
+			}
+			for i = 0; i < j; i++ {
+				V[I[k+i]] = k + j - 1
+			}
+			if j == 1 {
+				I[k] = -1
+			}
+		}
+		return
+	}
+
+	x = V[I[start+length/2]+h]
+	jj = 0
+	kk = 0
+	for i = start; i < start+length; i++ {
+		if V[I[i]+h] < x {
+			jj++
+		}
+		if V[I[i]+h] == x {
+			kk++
+		}
+	}
+	jj += start
+	kk += jj
+
+	i = start
+	j = 0
+	k = 0
+	for i < jj {
+		if V[I[i]+h] < x {
+			i++
+		} else if V[I[i]+h] == x {
+			swap(I, i, jj+j)
+			j++
+		} else {
+			swap(I, i, kk+k)
+			k++
+		}
+	}
+
+	for jj+j < kk {
+		if V[I[jj+j]+h] == x {
+			j++
+		} else {
+			swap(I, jj+j, kk+k)
+			k++
+		}
+	}
+
+	if jj > start {
+		split(I, V, start, jj-start, h)
+	}
+
+	for i = 0; i < kk-jj; i++ {
+		V[I[jj+i]] = kk - 1
+	}
+	if jj == kk-1 {
+		I[jj] = -1
+	}
+
+	if start+length > kk {
+		split(I, V, kk, start+length-kk, h)
+	}
+}
+
+func qsufsort(obuf []byte) []int {
+	var buckets [256]int
+	var i, h int
+	I := make([]int, len(obuf)+1)
+	V := make([]int, len(obuf)+1)
+
+	for _, c := range obuf {
+		buckets[c]++
+	}
+	for i = 1; i < 256; i++ {
+		buckets[i] += buckets[i-1]
+	}
+	copy(buckets[1:], buckets[:])
+	buckets[0] = 0
+
+	for i, c := range obuf {
+		buckets[c]++
+		I[buckets[c]] = i
+	}
+
+	I[0] = len(obuf)
+	for i, c := range obuf {
+		V[i] = buckets[c]
+	}
+
+	V[len(obuf)] = 0
+	for i = 1; i < 256; i++ {
+		if buckets[i] == buckets[i-1]+1 {
+			I[buckets[i]] = -1
+		}
+	}
+	I[0] = -1
+
+	for h = 1; I[0] != -(len(obuf) + 1); h += h {
+		var n int
+		for i = 0; i < len(obuf)+1; {
+			if I[i] < 0 {
+				n -= I[i]
+				i -= I[i]
+			} else {
+				if n != 0 {
+					I[i-n] = -n
+				}
+				n = V[I[i]] + 1 - i
+				split(I, V, i, n, h)
+				i += n
+				n = 0
+			}
+		}
+		if n != 0 {
+			I[i-n] = -n
+		}
+	}
+
+	for i = 0; i < len(obuf)+1; i++ {
+		I[V[i]] = i
+	}
+	return I
+}
+
+func matchlen(a, b []byte) (i int) {
+	for i < len(a) && i < len(b) && a[i] == b[i] {
+		i++
+	}
+	return i
+}
+
+func search(I []int, obuf, nbuf []byte, st, en int) (pos, n int) {
+	if en-st < 2 {
+		x := matchlen(obuf[I[st]:], nbuf)
+		y := matchlen(obuf[I[en]:], nbuf)
+
+		if x > y {
+			return I[st], x
+		} else {
+			return I[en], y
+		}
+	}
+
+	x := st + (en-st)/2
+	if bytes.Compare(obuf[I[x]:], nbuf) < 0 {
+		return search(I, obuf, nbuf, x, en)
+	} else {
+		return search(I, obuf, nbuf, st, x)
+	}
+	panic("unreached")
+}
+
+// Diff computes the difference between old and new, according to the bsdiff
+// algorithm, and writes the result to patch.
+func Diff(old, new io.Reader, patch io.Writer) error {
+	obuf, err := ioutil.ReadAll(old)
+	if err != nil {
+		return err
+	}
+
+	nbuf, err := ioutil.ReadAll(new)
+	if err != nil {
+		return err
+	}
+
+	pbuf, err := diffBytes(obuf, nbuf)
+	if err != nil {
+		return err
+	}
+
+	_, err = patch.Write(pbuf)
+	return err
+}
+
+func diffBytes(obuf, nbuf []byte) ([]byte, error) {
+	var patch seekBuffer
+	err := diff(obuf, nbuf, &patch)
+	if err != nil {
+		return nil, err
+	}
+	return patch.buf, nil
+}
+
+func diff(obuf, nbuf []byte, patch io.WriteSeeker) error {
+	var lenf int
+	I := qsufsort(obuf)
+	db := make([]byte, len(nbuf))
+	eb := make([]byte, len(nbuf))
+	var dblen, eblen int
+
+	var hdr header
+	hdr.Magic = magic
+	hdr.NewSize = int64(len(nbuf))
+	err := binary.Write(patch, signMagLittleEndian{}, &hdr)
+	if err != nil {
+		return err
+	}
+
+	// Compute the differences, writing ctrl as we go
+	pfbz2, err := newBzip2Writer(patch)
+	if err != nil {
+		return err
+	}
+	var scan, pos, length int
+	var lastscan, lastpos, lastoffset int
+	for scan < len(nbuf) {
+		var oldscore int
+		scan += length
+		for scsc := scan; scan < len(nbuf); scan++ {
+			pos, length = search(I, obuf, nbuf[scan:], 0, len(obuf))
+
+			for ; scsc < scan+length; scsc++ {
+				if scsc+lastoffset < len(obuf) &&
+					obuf[scsc+lastoffset] == nbuf[scsc] {
+					oldscore++
+				}
+			}
+
+			if (length == oldscore && length != 0) || length > oldscore+8 {
+				break
+			}
+
+			if scan+lastoffset < len(obuf) && obuf[scan+lastoffset] == nbuf[scan] {
+				oldscore--
+			}
+		}
+
+		if length != oldscore || scan == len(nbuf) {
+			var s, Sf int
+			lenf = 0
+			for i := 0; lastscan+i < scan && lastpos+i < len(obuf); {
+				if obuf[lastpos+i] == nbuf[lastscan+i] {
+					s++
+				}
+				i++
+				if s*2-i > Sf*2-lenf {
+					Sf = s
+					lenf = i
+				}
+			}
+
+			lenb := 0
+			if scan < len(nbuf) {
+				var s, Sb int
+				for i := 1; (scan >= lastscan+i) && (pos >= i); i++ {
+					if obuf[pos-i] == nbuf[scan-i] {
+						s++
+					}
+					if s*2-i > Sb*2-lenb {
+						Sb = s
+						lenb = i
+					}
+				}
+			}
+
+			if lastscan+lenf > scan-lenb {
+				overlap := (lastscan + lenf) - (scan - lenb)
+				s := 0
+				Ss := 0
+				lens := 0
+				for i := 0; i < overlap; i++ {
+					if nbuf[lastscan+lenf-overlap+i] == obuf[lastpos+lenf-overlap+i] {
+						s++
+					}
+					if nbuf[scan-lenb+i] == obuf[pos-lenb+i] {
+						s--
+					}
+					if s > Ss {
+						Ss = s
+						lens = i + 1
+					}
+				}
+
+				lenf += lens - overlap
+				lenb -= lens
+			}
+
+			for i := 0; i < lenf; i++ {
+				db[dblen+i] = nbuf[lastscan+i] - obuf[lastpos+i]
+			}
+			for i := 0; i < (scan-lenb)-(lastscan+lenf); i++ {
+				eb[eblen+i] = nbuf[lastscan+lenf+i]
+			}
+
+			dblen += lenf
+			eblen += (scan - lenb) - (lastscan + lenf)
+
+			err = binary.Write(pfbz2, signMagLittleEndian{}, int64(lenf))
+			if err != nil {
+				pfbz2.Close()
+				return err
+			}
+
+			val := (scan - lenb) - (lastscan + lenf)
+			err = binary.Write(pfbz2, signMagLittleEndian{}, int64(val))
+			if err != nil {
+				pfbz2.Close()
+				return err
+			}
+
+			val = (pos - lenb) - (lastpos + lenf)
+			err = binary.Write(pfbz2, signMagLittleEndian{}, int64(val))
+			if err != nil {
+				pfbz2.Close()
+				return err
+			}
+
+			lastscan = scan - lenb
+			lastpos = pos - lenb
+			lastoffset = pos - scan
+		}
+	}
+	err = pfbz2.Close()
+	if err != nil {
+		return err
+	}
+
+	// Compute size of compressed ctrl data
+	l64, err := patch.Seek(0, 1)
+	if err != nil {
+		return err
+	}
+	hdr.CtrlLen = int64(l64 - 32)
+
+	// Write compressed diff data
+	pfbz2, err = newBzip2Writer(patch)
+	if err != nil {
+		return err
+	}
+	n, err := pfbz2.Write(db[:dblen])
+	if err != nil {
+		pfbz2.Close()
+		return err
+	}
+	if n != dblen {
+		pfbz2.Close()
+		return io.ErrShortWrite
+	}
+	err = pfbz2.Close()
+	if err != nil {
+		return err
+	}
+
+	// Compute size of compressed diff data
+	n64, err := patch.Seek(0, 1)
+	if err != nil {
+		return err
+	}
+	hdr.DiffLen = n64 - l64
+
+	// Write compressed extra data
+	pfbz2, err = newBzip2Writer(patch)
+	if err != nil {
+		return err
+	}
+	n, err = pfbz2.Write(eb[:eblen])
+	if err != nil {
+		pfbz2.Close()
+		return err
+	}
+	if n != eblen {
+		pfbz2.Close()
+		return io.ErrShortWrite
+	}
+	err = pfbz2.Close()
+	if err != nil {
+		return err
+	}
+
+	// Seek to the beginning, write the header, and close the file
+	_, err = patch.Seek(0, 0)
+	if err != nil {
+		return err
+	}
+	err = binary.Write(patch, signMagLittleEndian{}, &hdr)
+	if err != nil {
+		return err
+	}
+	return nil
+}

vendor/github.com/inconshreveable/go-update/internal/binarydist/doc.go

@@ -0,0 +1,24 @@
+// Package binarydist implements binary diff and patch as described on
+// http://www.daemonology.net/bsdiff/. It reads and writes files
+// compatible with the tools there.
+package binarydist
+
+var magic = [8]byte{'B', 'S', 'D', 'I', 'F', 'F', '4', '0'}
+
+// File format:
+//   0       8    "BSDIFF40"
+//   8       8    X
+//   16      8    Y
+//   24      8    sizeof(newfile)
+//   32      X    bzip2(control block)
+//   32+X    Y    bzip2(diff block)
+//   32+X+Y  ???  bzip2(extra block)
+// with control block a set of triples (x,y,z) meaning "add x bytes
+// from oldfile to x bytes from the diff block; copy y bytes from the
+// extra block; seek forwards in oldfile by z bytes".
+type header struct {
+	Magic   [8]byte
+	CtrlLen int64
+	DiffLen int64
+	NewSize int64
+}

vendor/github.com/inconshreveable/go-update/internal/binarydist/encoding.go

@@ -0,0 +1,53 @@
+package binarydist
+
+// SignMagLittleEndian is the numeric encoding used by the bsdiff tools.
+// It implements binary.ByteOrder using a sign-magnitude format
+// and little-endian byte order. Only methods Uint64 and String
+// have been written; the rest panic.
+type signMagLittleEndian struct{}
+
+func (signMagLittleEndian) Uint16(b []byte) uint16 { panic("unimplemented") }
+
+func (signMagLittleEndian) PutUint16(b []byte, v uint16) { panic("unimplemented") }
+
+func (signMagLittleEndian) Uint32(b []byte) uint32 { panic("unimplemented") }
+
+func (signMagLittleEndian) PutUint32(b []byte, v uint32) { panic("unimplemented") }
+
+func (signMagLittleEndian) Uint64(b []byte) uint64 {
+	y := int64(b[0]) |
+		int64(b[1])<<8 |
+		int64(b[2])<<16 |
+		int64(b[3])<<24 |
+		int64(b[4])<<32 |
+		int64(b[5])<<40 |
+		int64(b[6])<<48 |
+		int64(b[7]&0x7f)<<56
+
+	if b[7]&0x80 != 0 {
+		y = -y
+	}
+	return uint64(y)
+}
+
+func (signMagLittleEndian) PutUint64(b []byte, v uint64) {
+	x := int64(v)
+	neg := x < 0
+	if neg {
+		x = -x
+	}
+
+	b[0] = byte(x)
+	b[1] = byte(x >> 8)
+	b[2] = byte(x >> 16)
+	b[3] = byte(x >> 24)
+	b[4] = byte(x >> 32)
+	b[5] = byte(x >> 40)
+	b[6] = byte(x >> 48)
+	b[7] = byte(x >> 56)
+	if neg {
+		b[7] |= 0x80
+	}
+}
+
+func (signMagLittleEndian) String() string { return "signMagLittleEndian" }

vendor/github.com/inconshreveable/go-update/internal/binarydist/patch.go

@@ -0,0 +1,109 @@
+package binarydist
+
+import (
+	"bytes"
+	"compress/bzip2"
+	"encoding/binary"
+	"errors"
+	"io"
+	"io/ioutil"
+)
+
+var ErrCorrupt = errors.New("corrupt patch")
+
+// Patch applies patch to old, according to the bspatch algorithm,
+// and writes the result to new.
+func Patch(old io.Reader, new io.Writer, patch io.Reader) error {
+	var hdr header
+	err := binary.Read(patch, signMagLittleEndian{}, &hdr)
+	if err != nil {
+		return err
+	}
+	if hdr.Magic != magic {
+		return ErrCorrupt
+	}
+	if hdr.CtrlLen < 0 || hdr.DiffLen < 0 || hdr.NewSize < 0 {
+		return ErrCorrupt
+	}
+
+	ctrlbuf := make([]byte, hdr.CtrlLen)
+	_, err = io.ReadFull(patch, ctrlbuf)
+	if err != nil {
+		return err
+	}
+	cpfbz2 := bzip2.NewReader(bytes.NewReader(ctrlbuf))
+
+	diffbuf := make([]byte, hdr.DiffLen)
+	_, err = io.ReadFull(patch, diffbuf)
+	if err != nil {
+		return err
+	}
+	dpfbz2 := bzip2.NewReader(bytes.NewReader(diffbuf))
+
+	// The entire rest of the file is the extra block.
+	epfbz2 := bzip2.NewReader(patch)
+
+	obuf, err := ioutil.ReadAll(old)
+	if err != nil {
+		return err
+	}
+
+	nbuf := make([]byte, hdr.NewSize)
+
+	var oldpos, newpos int64
+	for newpos < hdr.NewSize {
+		var ctrl struct{ Add, Copy, Seek int64 }
+		err = binary.Read(cpfbz2, signMagLittleEndian{}, &ctrl)
+		if err != nil {
+			return err
+		}
+
+		// Sanity-check
+		if newpos+ctrl.Add > hdr.NewSize {
+			return ErrCorrupt
+		}
+
+		// Read diff string
+		_, err = io.ReadFull(dpfbz2, nbuf[newpos:newpos+ctrl.Add])
+		if err != nil {
+			return ErrCorrupt
+		}
+
+		// Add old data to diff string
+		for i := int64(0); i < ctrl.Add; i++ {
+			if oldpos+i >= 0 && oldpos+i < int64(len(obuf)) {
+				nbuf[newpos+i] += obuf[oldpos+i]
+			}
+		}
+
+		// Adjust pointers
+		newpos += ctrl.Add
+		oldpos += ctrl.Add
+
+		// Sanity-check
+		if newpos+ctrl.Copy > hdr.NewSize {
+			return ErrCorrupt
+		}
+
+		// Read extra string
+		_, err = io.ReadFull(epfbz2, nbuf[newpos:newpos+ctrl.Copy])
+		if err != nil {
+			return ErrCorrupt
+		}
+
+		// Adjust pointers
+		newpos += ctrl.Copy
+		oldpos += ctrl.Seek
+	}
+
+	// Write the new file
+	for len(nbuf) > 0 {
+		n, err := new.Write(nbuf)
+		if err != nil {
+			return err
+		}
+		nbuf = nbuf[n:]
+	}
+
+	return nil
+}

vendor/github.com/inconshreveable/go-update/internal/binarydist/seek.go

@@ -0,0 +1,43 @@
+package binarydist
+
+import (
+	"errors"
+)
+
+type seekBuffer struct {
+	buf []byte
+	pos int
+}
+
+func (b *seekBuffer) Write(p []byte) (n int, err error) {
+	n = copy(b.buf[b.pos:], p)
+	if n == len(p) {
+		b.pos += n
+		return n, nil
+	}
+	b.buf = append(b.buf, p[n:]...)
+	b.pos += len(p)
+	return len(p), nil
+}
+
+func (b *seekBuffer) Seek(offset int64, whence int) (ret int64, err error) {
+	var abs int64
+	switch whence {
+	case 0:
+		abs = offset
+	case 1:
+		abs = int64(b.pos) + offset
+	case 2:
+		abs = int64(len(b.buf)) + offset
+	default:
+		return 0, errors.New("binarydist: invalid whence")
+	}
+	if abs < 0 {
+		return 0, errors.New("binarydist: negative position")
+	}
+	if abs >= 1<<31 {
+		return 0, errors.New("binarydist: position out of range")
+	}
+	b.pos = int(abs)
+	return abs, nil
+}

vendor/github.com/inconshreveable/go-update/internal/osext/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/github.com/inconshreveable/go-update/internal/osext/README.md

@@ -0,0 +1,16 @@
+### Extensions to the "os" package.
+
+## Find the current Executable and ExecutableFolder.
+
+There is sometimes utility in finding the current executable file
+that is running. This can be used for upgrading the current executable
+or finding resources located relative to the executable file. Both
+working directory and the os.Args[0] value are arbitrary and cannot
+be relied on; os.Args[0] can be "faked".
+
+Multi-platform and supports:
+ * Linux
+ * OS X
+ * Windows
+ * Plan 9
+ * BSDs.

vendor/github.com/inconshreveable/go-update/internal/osext/osext.go

@@ -0,0 +1,27 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Extensions to the standard "os" package.
+package osext
+
+import "path/filepath"
+
+// Executable returns an absolute path that can be used to
+// re-invoke the current program.
+// It may not be valid after the current program exits.
+func Executable() (string, error) {
+	p, err := executable()
+	return filepath.Clean(p), err
+}
+
+// Returns same path as Executable, returns just the folder
+// path. Excludes the executable name and any trailing slash.
+func ExecutableFolder() (string, error) {
+	p, err := Executable()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Dir(p), nil
+}

vendor/github.com/inconshreveable/go-update/internal/osext/osext_plan9.go

@@ -0,0 +1,20 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package osext
+
+import (
+	"os"
+	"strconv"
+	"syscall"
+)
+
+func executable() (string, error) {
+	f, err := os.Open("/proc/" + strconv.Itoa(os.Getpid()) + "/text")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	return syscall.Fd2path(int(f.Fd()))
+}

vendor/github.com/inconshreveable/go-update/internal/osext/osext_procfs.go

@@ -0,0 +1,36 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux netbsd openbsd solaris dragonfly
+
+package osext
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+)
+
+func executable() (string, error) {
+	switch runtime.GOOS {
+	case "linux":
+		const deletedTag = " (deleted)"
+		execpath, err := os.Readlink("/proc/self/exe")
+		if err != nil {
+			return execpath, err
+		}
+		execpath = strings.TrimSuffix(execpath, deletedTag)
+		execpath = strings.TrimPrefix(execpath, deletedTag)
+		return execpath, nil
+	case "netbsd":
+		return os.Readlink("/proc/curproc/exe")
+	case "openbsd", "dragonfly":
+		return os.Readlink("/proc/curproc/file")
+	case "solaris":
+		return os.Readlink(fmt.Sprintf("/proc/%d/path/a.out", os.Getpid()))
+	}
+	return "", errors.New("ExecPath not implemented for " + runtime.GOOS)
+}

vendor/github.com/inconshreveable/go-update/internal/osext/osext_sysctl.go

@@ -0,0 +1,79 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin freebsd
+
+package osext
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+var initCwd, initCwdErr = os.Getwd()
+
+func executable() (string, error) {
+	var mib [4]int32
+	switch runtime.GOOS {
+	case "freebsd":
+		mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
+	case "darwin":
+		mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
+	}
+
+	n := uintptr(0)
+	// Get length.
+	_, _, errNum := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
+	if errNum != 0 {
+		return "", errNum
+	}
+	if n == 0 { // This shouldn't happen.
+		return "", nil
+	}
+	buf := make([]byte, n)
+	_, _, errNum = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
+	if errNum != 0 {
+		return "", errNum
+	}
+	if n == 0 { // This shouldn't happen.
+		return "", nil
+	}
+	for i, v := range buf {
+		if v == 0 {
+			buf = buf[:i]
+			break
+		}
+	}
+	var err error
+	execPath := string(buf)
+	// execPath will not be empty due to above checks.
+	// Try to get the absolute path if the execPath is not rooted.
+	if execPath[0] != '/' {
+		execPath, err = getAbs(execPath)
+		if err != nil {
+			return execPath, err
+		}
+	}
+	// For darwin KERN_PROCARGS may return the path to a symlink rather than the
+	// actual executable.
+	if runtime.GOOS == "darwin" {
+		if execPath, err = filepath.EvalSymlinks(execPath); err != nil {
+			return execPath, err
+		}
+	}
+	return execPath, nil
+}
+
+func getAbs(execPath string) (string, error) {
+	if initCwdErr != nil {
+		return execPath, initCwdErr
+	}
+	// The execPath may begin with a "../" or a "./" so clean it first.
+	// Join the two paths, trailing and starting slashes undetermined, so use
+	// the generic Join function.
+	return filepath.Join(initCwd, filepath.Clean(execPath)), nil
+}

vendor/github.com/inconshreveable/go-update/internal/osext/osext_windows.go

@@ -0,0 +1,34 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package osext
+
+import (
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+)
+
+var (
+	kernel                = syscall.MustLoadDLL("kernel32.dll")
+	getModuleFileNameProc = kernel.MustFindProc("GetModuleFileNameW")
+)
+
+// GetModuleFileName() with hModule = NULL
+func executable() (exePath string, err error) {
+	return getModuleFileName()
+}
+
+func getModuleFileName() (string, error) {
+	var n uint32
+	b := make([]uint16, syscall.MAX_PATH)
+	size := uint32(len(b))
+
+	r0, _, e1 := getModuleFileNameProc.Call(0, uintptr(unsafe.Pointer(&b[0])), uintptr(size))
+	n = uint32(r0)
+	if n == 0 {
+		return "", e1
+	}
+	return string(utf16.Decode(b[0:n])), nil
+}