Fix/separate migration bins

cmd/ipfs/daemon.go

@@ -26,7 +26,7 @@ import (
 	libp2p "github.com/ipfs/go-ipfs/core/node/libp2p"
 	nodeMount "github.com/ipfs/go-ipfs/fuse/node"
 	fsrepo "github.com/ipfs/go-ipfs/repo/fsrepo"
-	migrate "github.com/ipfs/go-ipfs/repo/fsrepo/migrations"
+	"github.com/ipfs/go-ipfs/repo/fsrepo/migrations"
 	sockets "github.com/libp2p/go-socket-activation"
 
 	cmds "github.com/ipfs/go-ipfs-cmds"
@@ -288,7 +288,9 @@ func daemonFunc(req *cmds.Request, re cmds.ResponseEmitter, env cmds.Environment
 			return fmt.Errorf("fs-repo requires migration")
 		}
 
-		err = migrate.RunMigration(fsrepo.RepoVersion)
+		// Fetch migrations from current distribution, or location from environ
+		fetcher := migrations.NewHttpFetcher(migrations.GetDistPathEnv(migrations.CurrentIpfsDist), "", "go-ipfs", 0)
+		err = migrations.RunMigration(cctx.Context(), fetcher, fsrepo.RepoVersion, "", false)
 		if err != nil {
 			fmt.Println("The migrations of fs-repo failed:")
 			fmt.Printf("  %s\n", err)

go.mod

@@ -4,9 +4,10 @@ require (
 	bazil.org/fuse v0.0.0-20200117225306-7b5117fecadc
 	contrib.go.opencensus.io/exporter/prometheus v0.2.0
 	github.com/blang/semver v3.5.1+incompatible
+	github.com/blang/semver/v4 v4.0.0
 	github.com/bren2010/proquint v0.0.0-20160323162903-38337c27106d
 	github.com/cheggaaa/pb v1.0.29
-	github.com/coreos/go-systemd/v22 v22.1.0
+	github.com/coreos/go-systemd/v22 v22.3.0
 	github.com/dustin/go-humanize v1.0.0
 	github.com/elgris/jsondiff v0.0.0-20160530203242-765b5c24c302
 	github.com/fsnotify/fsnotify v1.4.9

go.sum

@@ -59,6 +59,8 @@ github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/blang/semver v3.5.1+incompatible h1:cQNTCjp13qL8KC3Nbxr/y2Bqb63oX6wdnnjpJbkM4JQ=
 github.com/blang/semver v3.5.1+incompatible/go.mod h1:kRBLl5iJ+tD4TcOOxsy/0fnwebNt5EWlYSAyrTnjyyk=
+github.com/blang/semver/v4 v4.0.0 h1:1PFHFE6yCCTv8C1TeyNNarDzntLi7wMI5i/pzqYIsAM=
+github.com/blang/semver/v4 v4.0.0/go.mod h1:IbckMUScFkM3pff0VJDNKRiT6TG/YpiHIM2yvyW5YoQ=
 github.com/bradfitz/go-smtpd v0.0.0-20170404230938-deb6d6237625/go.mod h1:HYsPBTaaSFSlLx/70C2HPIMNZpVV8+vt/A+FMnYP11g=
 github.com/bren2010/proquint v0.0.0-20160323162903-38337c27106d h1:QgeLLoPD3kRVmeu/1al9iIpIANMi9O1zXFm8BnYGCJg=
 github.com/bren2010/proquint v0.0.0-20160323162903-38337c27106d/go.mod h1:Jbj8eKecMNwf0KFI75skSUZqMB4UCRcndUScVBTWyUI=
@@ -103,8 +105,8 @@ github.com/coreos/go-semver v0.3.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3Ee
 github.com/coreos/go-systemd v0.0.0-20181012123002-c6f51f82210d h1:t5Wuyh53qYyg9eqn4BbnlIT+vmhyww0TatL+zT3uWgI=
 github.com/coreos/go-systemd v0.0.0-20181012123002-c6f51f82210d/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
 github.com/coreos/go-systemd/v22 v22.0.0/go.mod h1:xO0FLkIi5MaZafQlIrOotqXZ90ih+1atmu1JpKERPPk=
-github.com/coreos/go-systemd/v22 v22.1.0 h1:kq/SbG2BCKLkDKkjQf5OWwKWUKj1lgs3lFI4PxnR5lg=
-github.com/coreos/go-systemd/v22 v22.1.0/go.mod h1:xO0FLkIi5MaZafQlIrOotqXZ90ih+1atmu1JpKERPPk=
+github.com/coreos/go-systemd/v22 v22.3.0 h1:C8u/Ljj8G8O6rqWJh2J8cDyeEFBMWvXlvJ/ccMyzcqw=
+github.com/coreos/go-systemd/v22 v22.3.0/go.mod h1:xO0FLkIi5MaZafQlIrOotqXZ90ih+1atmu1JpKERPPk=
 github.com/cpuguy83/go-md2man v1.0.10/go.mod h1:SmD6nW6nTyfqj6ABTjUi3V3JVMnlJmwcJI5acqYI6dE=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/crackcomm/go-gitignore v0.0.0-20170627025303-887ab5e44cc3 h1:HVTnpeuvF6Owjd5mniCL8DEXo7uYXdQEmOP4FJbV5tg=
@@ -167,7 +169,6 @@ github.com/godbus/dbus/v5 v5.0.3/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5x
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
 github.com/gogo/protobuf v1.3.0/go.mod h1:SlYgWuQ5SjCEi6WLHjHCa1yvBfUnHcTbrrZtXPKa29o=
-github.com/gogo/protobuf v1.3.1 h1:DqDEcV5aeaTmdFBePNpYsp3FlcVH/2ISVVM9Qf8PSls=
 github.com/gogo/protobuf v1.3.1/go.mod h1:SlYgWuQ5SjCEi6WLHjHCa1yvBfUnHcTbrrZtXPKa29o=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
@@ -457,7 +458,6 @@ github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfV
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
 github.com/kami-zh/go-capturer v0.0.0-20171211120116-e492ea43421d/go.mod h1:P2viExyCEfeWGU259JnaQ34Inuec4R38JCyBx2edgD0=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
-github.com/kisielk/errcheck v1.2.0 h1:reN85Pxc5larApoH1keMBiu2GWtPqXQ1nc9gx+jOU+E=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=
 github.com/kisielk/errcheck v1.5.0 h1:e8esj/e4R+SAOwFwN+n3zr0nYeCyeweozKfO23MvHzY=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
@@ -619,7 +619,6 @@ github.com/libp2p/go-libp2p-pnet v0.2.0 h1:J6htxttBipJujEjz1y0a5+eYoiPcFHhSYHH6n
 github.com/libp2p/go-libp2p-pnet v0.2.0/go.mod h1:Qqvq6JH/oMZGwqs3N1Fqhv8NVhrdYcO0BW4wssv21LA=
 github.com/libp2p/go-libp2p-protocol v0.0.1/go.mod h1:Af9n4PiruirSDjHycM1QuiMi/1VZNHYcK8cLgFJLZ4s=
 github.com/libp2p/go-libp2p-protocol v0.1.0/go.mod h1:KQPHpAabB57XQxGrXCNvbL6UEXfQqUgC/1adR2Xtflk=
-github.com/libp2p/go-libp2p-pubsub v0.4.0 h1:YNVRyXqBgv9i4RG88jzoTtkSOaSB45CqHkL29NNBZb4=
 github.com/libp2p/go-libp2p-pubsub v0.4.0/go.mod h1:izkeMLvz6Ht8yAISXjx60XUQZMq9ZMe5h2ih4dLIBIQ=
 github.com/libp2p/go-libp2p-pubsub v0.4.1 h1:j4umIg5nyus+sqNfU+FWvb9aeYFQH/A+nDFhWj+8yy8=
 github.com/libp2p/go-libp2p-pubsub v0.4.1/go.mod h1:izkeMLvz6Ht8yAISXjx60XUQZMq9ZMe5h2ih4dLIBIQ=
@@ -990,7 +989,6 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
-github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
@@ -1156,7 +1154,6 @@ golang.org/x/net v0.0.0-20200222125558-5a598a2470a0/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200520004742-59133d7f0dd7/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
 golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
-golang.org/x/net v0.0.0-20200707034311-ab3426394381 h1:VXak5I6aEWmAXeQjA+QSZzlgNrpq9mjcfDemuexIKsU=
 golang.org/x/net v0.0.0-20200707034311-ab3426394381/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974 h1:IX6qOQeG5uLjB/hjjwjedwfjND0hgjPMMyO1RoIXQNI=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
@@ -1176,7 +1173,6 @@ golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208 h1:qwRHBd0NqMbJxfbotnDhm2ByMI1Shq4Y6oRJo21SGJA=
 golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9 h1:SQFwaSi55rU7vdNs9Yr0Z324VNlrF+0wMqRXT4St8ck=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -1223,7 +1219,6 @@ golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200519105757-fe76b779f299/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1 h1:ogLJMz+qpzav7lGMh10LMvAkM/fAoGlaiiHYiFYdm80=
 golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f h1:+Nyd8tzPX9R7BWHguqsrbFdRx3WQ/1ib8I44HXV5yTA=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -1273,13 +1268,11 @@ golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapK
 golang.org/x/tools v0.0.0-20200207183749-b753a1ba74fa/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/tools v0.0.0-20200212150539-ea181f53ac56/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/tools v0.0.0-20200619180055-7c47624df98f/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
-golang.org/x/tools v0.0.0-20200827010519-17fd2f27a9e3 h1:r3P/5xOq/dK1991B65Oy6E1fRF/2d/fSYZJ/fXGVfJc=
 golang.org/x/tools v0.0.0-20200827010519-17fd2f27a9e3/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20210106214847-113979e3529a h1:CB3a9Nez8M13wwlr/E2YtwoU+qYHKfC+JrDa45RXXoQ=
 golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

repo/fsrepo/fsrepo.go

@@ -14,7 +14,7 @@ import (
 	keystore "github.com/ipfs/go-ipfs/keystore"
 	repo "github.com/ipfs/go-ipfs/repo"
 	"github.com/ipfs/go-ipfs/repo/common"
-	mfsr "github.com/ipfs/go-ipfs/repo/fsrepo/migrations"
+	"github.com/ipfs/go-ipfs/repo/fsrepo/migrations"
 	dir "github.com/ipfs/go-ipfs/thirdparty/dir"
 
 	ds "github.com/ipfs/go-datastore"
@@ -142,7 +142,7 @@ func open(repoPath string) (repo.Repo, error) {
 	}()
 
 	// Check version, and error out if not matching
-	ver, err := mfsr.RepoPath(r.path).Version()
+	ver, err := migrations.RepoVersion(r.path)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return nil, ErrNoVersion
@@ -291,7 +291,7 @@ func Init(repoPath string, conf *config.Config) error {
 		return err
 	}
 
-	if err := mfsr.RepoPath(repoPath).WriteVersion(RepoVersion); err != nil {
+	if err := migrations.WriteRepoVersion(repoPath, RepoVersion); err != nil {
 		return err
 	}
 

repo/fsrepo/migrations/fetch.go

@@ -0,0 +1,172 @@
+package migrations
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+// FetchBinary downloads an archive from the distribution site and unpacks it.
+//
+// The base name of the binary inside the archive may differ from the base
+// archive name.  If it does, then specify binName.  For example, the following
+// is needed because the archive "go-ipfs_v0.7.0_linux-amd64.tar.gz" contains a
+// binary named "ipfs"
+//
+//     FetchBinary(ctx, fetcher, "go-ipfs", "v0.7.0", "ipfs", tmpDir)
+//
+// If out is a directory, then the binary is written to that directory with the
+// same name it has inside the archive.  Otherwise, the binary file is written
+// to the file named by out.
+func FetchBinary(ctx context.Context, fetcher Fetcher, dist, ver, binName, out string) (string, error) {
+	// The archive file name is the base of dist. This is to support a possible subdir in
+	// dist, for example: "ipfs-repo-migrations/fs-repo-11-to-12"
+	arcName := filepath.Base(dist)
+	// If binary base name is not specified, then it is same as archive base name.
+	if binName == "" {
+		binName = arcName
+	}
+
+	// Name of binary that exists inside archive
+	binName = ExeName(binName)
+
+	// Return error if file exists or stat fails for reason other than not
+	// exists.  If out is a directory, then write extracted binary to that dir.
+	fi, err := os.Stat(out)
+	if !os.IsNotExist(err) {
+		if err != nil {
+			return "", err
+		}
+		if !fi.IsDir() {
+			return "", &os.PathError{
+				Op:   "FetchBinary",
+				Path: out,
+				Err:  os.ErrExist,
+			}
+		}
+		// out exists and is a directory, so compose final name
+		out = filepath.Join(out, binName)
+		// Check if the binary already exists in the directory
+		_, err = os.Stat(out)
+		if !os.IsNotExist(err) {
+			if err != nil {
+				return "", err
+			}
+			return "", &os.PathError{
+				Op:   "FetchBinary",
+				Path: out,
+				Err:  os.ErrExist,
+			}
+		}
+	}
+
+	// Create temp directory to store download
+	tmpDir, err := ioutil.TempDir("", arcName)
+	if err != nil {
+		return "", err
+	}
+	defer os.RemoveAll(tmpDir)
+
+	atype := "tar.gz"
+	if runtime.GOOS == "windows" {
+		atype = "zip"
+	}
+
+	arcDistPath, arcFullName := makeArchivePath(dist, arcName, ver, atype)
+
+	// Create a file to write the archive data to
+	arcPath := filepath.Join(tmpDir, arcFullName)
+	arcFile, err := os.Create(arcPath)
+	if err != nil {
+		return "", err
+	}
+	defer arcFile.Close()
+
+	// Open connection to download archive from ipfs path
+	rc, err := fetcher.Fetch(ctx, arcDistPath)
+	if err != nil {
+		return "", err
+	}
+	defer rc.Close()
+
+	// Write download data
+	_, err = io.Copy(arcFile, rc)
+	if err != nil {
+		return "", err
+	}
+	arcFile.Close()
+
+	// Unpack the archive and write binary to out
+	err = unpackArchive(arcPath, atype, dist, binName, out)
+	if err != nil {
+		return "", err
+	}
+
+	// Set mode of binary to executable
+	err = os.Chmod(out, 0755)
+	if err != nil {
+		return "", err
+	}
+
+	return out, nil
+}
+
+// osWithVariant returns the OS name with optional variant.
+// Currently returns either runtime.GOOS, or "linux-musl".
+func osWithVariant() (string, error) {
+	if runtime.GOOS != "linux" {
+		return runtime.GOOS, nil
+	}
+
+	// ldd outputs the system's kind of libc.
+	// - on standard ubuntu: ldd (Ubuntu GLIBC 2.23-0ubuntu5) 2.23
+	// - on alpine: musl libc (x86_64)
+	//
+	// we use the combined stdout+stderr,
+	// because ldd --version prints differently on different OSes.
+	// - on standard ubuntu: stdout
+	// - on alpine: stderr (it probably doesn't know the --version flag)
+	//
+	// we suppress non-zero exit codes (see last point about alpine).
+	out, err := exec.Command("sh", "-c", "ldd --version || true").CombinedOutput()
+	if err != nil {
+		return "", err
+	}
+
+	// now just see if we can find "musl" somewhere in the output
+	scan := bufio.NewScanner(bytes.NewBuffer(out))
+	for scan.Scan() {
+		if strings.Contains(scan.Text(), "musl") {
+			return "linux-musl", nil
+		}
+	}
+
+	return "linux", nil
+}
+
+// makeArchivePath composes the path, relative to the distribution site, from which to
+// download a binary.  The path returned does not contain the distribution site path,
+// e.g. "/ipns/dist.ipfs.io/", since that is know to the fetcher.
+//
+// Returns the archive path and the base name.
+//
+// The ipfs path format is: distribution/version/archiveName
+// - distribution is the name of a distribution, such as "go-ipfs"
+// - version is the version to fetch, such as "v0.8.0-rc2"
+// - archiveName is formatted as name_version_osv-GOARCH.atype, such as
+//     "go-ipfs_v0.8.0-rc2_linux-amd64.tar.gz"
+//
+// This would form the path:
+// go-ipfs/v0.8.0/go-ipfs_v0.8.0_linux-amd64.tar.gz
+func makeArchivePath(dist, name, ver, atype string) (string, string) {
+	arcName := fmt.Sprintf("%s_%s_%s-%s.%s", name, ver, runtime.GOOS, runtime.GOARCH, atype)
+	return fmt.Sprintf("%s/%s/%s", dist, ver, arcName), arcName
+}