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WIP: zfs: hacky resume token parsing
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105
zfs/resume_token.go
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105
zfs/resume_token.go
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@ -0,0 +1,105 @@
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package zfs
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import (
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"context"
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"errors"
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"os/exec"
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"regexp"
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"strconv"
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"time"
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)
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type ResumeToken struct {
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HasFromGUID, HasToGUID bool
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FromGUID, ToGUID uint64
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// no support for other fields
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}
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var resumeTokenNVListRE = regexp.MustCompile(`\t(\S+) = (.*)`)
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var resumeTokenContentsRE = regexp.MustCompile(`resume token contents:\nnvlist version: 0`)
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var resumeTokenIsCorruptRE = regexp.MustCompile(`resume token is corrupt`)
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var ResumeTokenCorruptError = errors.New("resume token is corrupt")
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var ResumeTokenDecodingNotSupported = errors.New("zfs binary does not allow decoding resume token or zrepl cannot scrape zfs output")
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var ResumeTokenParsingError = errors.New("zrepl cannot parse resume token values")
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// Abuse 'zfs send' to decode the resume token
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//
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// FIXME: implement nvlist unpacking in Go and read through libzfs_sendrecv.c
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func ParseResumeToken(ctx context.Context, token string) (*ResumeToken, error) {
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// Example resume tokens:
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//
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// From a non-incremental send
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// 1-bf31b879a-b8-789c636064000310a500c4ec50360710e72765a5269740f80cd8e4d3d28a534b18e00024cf86249f5459925acc802a8facbf243fbd3433858161f5ddb9ab1ae7c7466a20c97382e5f312735319180af2f3730cf58166953824c2cc0200cde81651
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// From an incremental send
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// 1-c49b979a2-e0-789c636064000310a501c49c50360710a715e5e7a69766a63040c1eabb735735ce8f8d5400b2d991d4e52765a5269740f82080219f96569c5ac2000720793624f9a4ca92d46206547964fd25f91057f09e37babb88c9bf5503499e132c9f97989bcac050909f9f63a80f34abc421096616007c881d4c
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// Resulting output of zfs send -nvt <token>
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//
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//resume token contents:
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//nvlist version: 0
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// fromguid = 0x595d9f81aa9dddab
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// object = 0x1
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// offset = 0x0
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// bytes = 0x0
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// toguid = 0x854f02a2dd32cf0d
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// toname = pool1/test@b
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//cannot resume send: 'pool1/test@b' used in the initial send no longer exists
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ctx, _ = context.WithTimeout(ctx, 500*time.Millisecond)
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cmd := exec.CommandContext(ctx, ZFS_BINARY, "send", "-nvt", string(token))
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output, err := cmd.CombinedOutput()
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if err != nil {
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if exitErr, ok := err.(*exec.ExitError); ok {
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if !exitErr.Exited() {
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return nil, err
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}
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// we abuse zfs send for decoding, the exit error may be due to
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// a) the token being from a third machine
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// b) it no longer exists on the machine where
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} else {
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return nil, err
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}
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}
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if !resumeTokenContentsRE.Match(output) {
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if resumeTokenIsCorruptRE.Match(output) {
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return nil, ResumeTokenCorruptError
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}
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return nil, ResumeTokenDecodingNotSupported
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}
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matches := resumeTokenNVListRE.FindAllStringSubmatch(string(output), -1)
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if matches == nil {
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return nil, ResumeTokenDecodingNotSupported
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}
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rt := &ResumeToken{}
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for _, m := range matches {
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attr, val := m[1], m[2]
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switch attr {
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case "fromguid":
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rt.FromGUID, err = strconv.ParseUint(val, 0, 64)
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if err != nil {
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return nil, ResumeTokenParsingError
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}
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rt.HasFromGUID = true
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case "toguid":
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rt.ToGUID, err = strconv.ParseUint(val, 0, 64)
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if err != nil {
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return nil, ResumeTokenParsingError
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}
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rt.HasToGUID = true
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}
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}
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if !rt.HasToGUID {
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return nil, ResumeTokenDecodingNotSupported
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}
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return rt, nil
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}
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64
zfs/resume_token_test.go
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64
zfs/resume_token_test.go
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package zfs_test
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import (
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"context"
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"github.com/stretchr/testify/assert"
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"github.com/zrepl/zrepl/zfs"
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"testing"
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)
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type ResumeTokenTest struct {
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Msg string
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Token string
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ExpectToken *zfs.ResumeToken
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ExpectError error
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}
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func (rtt *ResumeTokenTest) Test(t *testing.T) {
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t.Log(rtt.Msg)
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res, err := zfs.ParseResumeToken(context.TODO(), rtt.Token)
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if rtt.ExpectError != nil {
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assert.EqualValues(t, rtt.ExpectError, err)
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return
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}
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if rtt.ExpectToken != nil {
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assert.Nil(t, err)
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assert.EqualValues(t, rtt.ExpectToken, res)
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return
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}
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}
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func TestParseResumeToken(t *testing.T) {
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tbl := []ResumeTokenTest{
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{
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Msg: "normal send (non-incremental)",
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Token: `1-bf31b879a-b8-789c636064000310a500c4ec50360710e72765a5269740f80cd8e4d3d28a534b18e00024cf86249f5459925acc802a8facbf243fbd3433858161f5ddb9ab1ae7c7466a20c97382e5f312735319180af2f3730cf58166953824c2cc0200cde81651`,
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ExpectToken: &zfs.ResumeToken{
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HasToGUID: true,
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ToGUID: 0x595d9f81aa9dddab,
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},
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},
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{
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Msg: "normal send (incremental)",
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Token: `1-c49b979a2-e0-789c636064000310a501c49c50360710a715e5e7a69766a63040c1eabb735735ce8f8d5400b2d991d4e52765a5269740f82080219f96569c5ac2000720793624f9a4ca92d46206547964fd25f91057f09e37babb88c9bf5503499e132c9f97989bcac050909f9f63a80f34abc421096616007c881d4c`,
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ExpectToken: &zfs.ResumeToken{
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HasToGUID: true,
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ToGUID: 0x854f02a2dd32cf0d,
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HasFromGUID: true,
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FromGUID: 0x595d9f81aa9dddab,
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},
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},
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{
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Msg: "corrupted token",
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Token: `1-bf31b879a-b8-789c636064000310a500c4ec50360710e72765a5269740f80cd8e4d3d28a534b18e00024cf86249f5459925acc802a8facbf243fbd3433858161f5ddb9ab1ae7c7466a20c97382e5f312735319180af2f3730cf58166953824c2cc0200cd12345`,
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ExpectError: zfs.ResumeTokenCorruptError,
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},
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}
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for _, test := range tbl {
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test.Test(t)
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}
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}
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