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1 /*
2 goredo -- djb's redo implementation on pure Go
3 Copyright (C) 2020-2022 Sergey Matveev <stargrave@stargrave.org>
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, version 3 of the License.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
16 */
17
18 // Targets runner
19
20 package main
21
22 import (
23         "bufio"
24         "crypto/rand"
25         "encoding/hex"
26         "errors"
27         "flag"
28         "fmt"
29         "io"
30         "log"
31         "os"
32         "os/exec"
33         "path"
34         "path/filepath"
35         "strconv"
36         "strings"
37         "sync"
38         "syscall"
39         "time"
40
41         "go.cypherpunks.ru/recfile"
42         "go.cypherpunks.ru/tai64n/v2"
43         "golang.org/x/sys/unix"
44 )
45
46 const (
47         EnvDepFd        = "REDO_DEP_FD"
48         EnvDirPrefix    = "REDO_DIRPREFIX"
49         EnvDepCwd       = "REDO_DEP_CWD"
50         EnvBuildUUID    = "REDO_BUILD_UUID"
51         EnvStderrPrefix = "REDO_STDERR_PREFIX"
52         EnvTrace        = "REDO_TRACE"
53         EnvStderrKeep   = "REDO_LOGS"
54         EnvStderrSilent = "REDO_SILENT"
55         EnvNoSync       = "REDO_NO_SYNC"
56         EnvStopIfMod    = "REDO_STOP_IF_MODIFIED"
57
58         RedoDir      = ".redo"
59         LockSuffix   = ".lock"
60         DepSuffix    = ".rec"
61         TmpPrefix    = ".redo."
62         LogSuffix    = ".log"
63         LogRecSuffix = ".log-rec"
64 )
65
66 var (
67         NoSync       = false
68         StderrKeep   = false
69         StderrSilent = false
70         StderrPrefix string
71         StopIfMod    = false
72         Jobs         sync.WaitGroup
73
74         flagTrace          *bool
75         flagTraceAll       *bool
76         flagStderrKeep     *bool
77         flagStderrSilent   *bool
78         flagForcedIfchange *bool
79
80         TracedAll bool
81
82         RunningProcs  = map[int]*os.Process{}
83         RunningProcsM sync.Mutex
84
85         Err1WasTouched = errors.New("$1 was explicitly touched")
86 )
87
88 func init() {
89         cmdName := CmdName()
90         if !(cmdName == CmdNameRedo || cmdName == CmdNameRedoIfchange) {
91                 return
92         }
93         flagTrace = flag.Bool("x", false, "trace (sh -x) current targets")
94         flagTraceAll = flag.Bool("xx", false,
95                 fmt.Sprintf("trace (sh -x) all targets (%s=1)", EnvTrace))
96         flagStderrKeep = flag.Bool("k", false,
97                 fmt.Sprintf("keep job's stderr (%s=1)", EnvStderrKeep))
98         flagStderrSilent = flag.Bool("s", false,
99                 fmt.Sprintf("silent, do not print job's stderr (%s=1)", EnvStderrSilent))
100         flagForcedIfchange = flag.Bool("f", false, "forced redo-ifchange")
101 }
102
103 type RunError struct {
104         Tgt      string
105         DoFile   string
106         Started  *time.Time
107         Finished *time.Time
108         Err      error
109 }
110
111 func (e *RunError) Name() string {
112         var name string
113         if e.DoFile == "" {
114                 name = e.Tgt
115         } else {
116                 name = fmt.Sprintf("%s (%s)", e.Tgt, e.DoFile)
117         }
118         if e.Finished == nil {
119                 return name
120         }
121         return fmt.Sprintf("%s (%.3fs)", name, e.Finished.Sub(*e.Started).Seconds())
122 }
123
124 func (e RunError) Error() string {
125         return fmt.Sprintf("%s: %s", e.Name(), e.Err)
126 }
127
128 func mkdirs(pth string) error {
129         if FileExists(pth) {
130                 return nil
131         }
132         return os.MkdirAll(pth, os.FileMode(0777))
133 }
134
135 func isModified(cwd, redoDir, tgt string) (bool, *Inode, string, error) {
136         fdDep, err := os.Open(path.Join(redoDir, tgt+DepSuffix))
137         if err != nil {
138                 if os.IsNotExist(err) {
139                         return false, nil, "", nil
140                 }
141                 return false, nil, "", err
142         }
143         defer fdDep.Close()
144         r := recfile.NewReader(fdDep)
145         var modified bool
146         var ourInode *Inode
147         var hshPrev string
148         for {
149                 m, err := r.NextMap()
150                 if err != nil {
151                         if errors.Is(err, io.EOF) {
152                                 break
153                         }
154                         return false, nil, "", err
155                 }
156                 if m["Type"] != DepTypeIfchange || m["Target"] != tgt {
157                         continue
158                 }
159                 ourInode, err = inodeFromFileByPath(path.Join(cwd, tgt))
160                 if err != nil {
161                         if os.IsNotExist(err) {
162                                 return false, nil, "", nil
163                         }
164                         return false, nil, "", err
165                 }
166                 theirInode, err := inodeFromRec(m)
167                 if err != nil {
168                         return false, nil, "", err
169                 }
170                 hshPrev = m["Hash"]
171                 modified = !ourInode.Equals(theirInode)
172                 break
173         }
174         return modified, ourInode, hshPrev, nil
175 }
176
177 func syncDir(dir string) error {
178         fd, err := os.Open(dir)
179         if err != nil {
180                 return err
181         }
182         err = fd.Sync()
183         fd.Close()
184         return err
185 }
186
187 func runScript(tgtOrig string, errs chan error, traced bool) error {
188         cwd, tgt := cwdAndTgt(tgtOrig)
189         redoDir := path.Join(cwd, RedoDir)
190         if err := mkdirs(redoDir); err != nil {
191                 return TgtError{tgtOrig, err}
192         }
193
194         shCtx := fmt.Sprintf("sh: %s: cwd:%s", tgtOrig, cwd)
195         jsToken := jsAcquire(shCtx)
196         jsNeedsRelease := true
197         defer func() {
198                 if jsNeedsRelease {
199                         jsRelease(shCtx, jsToken)
200                 }
201         }()
202
203         // Acquire lock
204         fdLock, err := os.OpenFile(
205                 path.Join(redoDir, tgt+LockSuffix),
206                 os.O_WRONLY|os.O_TRUNC|os.O_CREATE,
207                 os.FileMode(0666),
208         )
209         if err != nil {
210                 return TgtError{tgtOrig, err}
211         }
212         flock := unix.Flock_t{
213                 Type:   unix.F_WRLCK,
214                 Whence: io.SeekStart,
215         }
216         lockRelease := func() {
217                 tracef(CLock, "LOCK_UN: %s", fdLock.Name())
218                 flock.Type = unix.F_UNLCK
219                 if err := unix.FcntlFlock(fdLock.Fd(), unix.F_SETLK, &flock); err != nil {
220                         log.Fatalln(err)
221                 }
222                 fdLock.Close()
223         }
224         tracef(CLock, "LOCK_NB: %s", fdLock.Name())
225
226         // Waiting for job completion, already taken by someone else
227         if err = unix.FcntlFlock(fdLock.Fd(), unix.F_SETLK, &flock); err != nil {
228                 if uintptr(err.(syscall.Errno)) != uintptr(unix.EAGAIN) {
229                         fdLock.Close()
230                         return TgtError{tgtOrig, err}
231                 }
232                 Jobs.Add(1)
233                 if err = unix.FcntlFlock(fdLock.Fd(), unix.F_GETLK, &flock); err != nil {
234                         log.Fatalln(err)
235                 }
236                 tracef(CDebug, "waiting: %s (pid=%d)", tgtOrig, flock.Pid)
237                 if FdStatus != nil {
238                         if _, err = FdStatus.Write([]byte{StatusWait}); err != nil {
239                                 log.Fatalln(err)
240                         }
241                 }
242                 go func() {
243                         defer Jobs.Done()
244                         tracef(CLock, "LOCK_EX: %s", fdLock.Name())
245                         if err := unix.FcntlFlock(fdLock.Fd(), unix.F_SETLKW, &flock); err != nil {
246                                 log.Fatalln(err)
247                         }
248                         lockRelease()
249                         tracef(CDebug, "waiting done: %s", tgtOrig)
250                         if FdStatus != nil {
251                                 if _, err = FdStatus.Write([]byte{StatusWaited}); err != nil {
252                                         log.Fatalln(err)
253                                 }
254                         }
255                         var depInfo *DepInfo
256                         fdDep, err := os.Open(path.Join(redoDir, tgt+DepSuffix))
257                         if err != nil {
258                                 if os.IsNotExist(err) {
259                                         err = errors.New("was not built: no .rec")
260                                 }
261                                 goto Finish
262                         }
263                         defer fdDep.Close()
264                         depInfo, err = depRead(fdDep)
265                         if err != nil {
266                                 goto Finish
267                         }
268                         if depInfo.build != BuildUUID {
269                                 err = errors.New("was not built: build differs")
270                         }
271                 Finish:
272                         if err != nil {
273                                 err = TgtError{tgtOrig, err}
274                                 fdLock.Close()
275                         }
276                         errs <- err
277                 }()
278                 return nil
279         }
280
281         // Check if target is not modified externally
282         modified, inodePrev, hshPrev, err := isModified(cwd, redoDir, tgt)
283         if err != nil {
284                 lockRelease()
285                 return TgtError{tgtOrig, err}
286         }
287         if modified {
288                 lockRelease()
289                 if StopIfMod {
290                         return fmt.Errorf("%s externally modified", tgtOrig)
291                 }
292                 tracef(CWarn, "%s externally modified: not redoing", tgtOrig)
293                 go func() {
294                         errs <- nil
295                 }()
296                 return nil
297         }
298
299         // Start preparing .rec
300         fdDep, err := tempfile(redoDir, tgt+DepSuffix)
301         if err != nil {
302                 lockRelease()
303                 return TgtError{tgtOrig, err}
304         }
305         fdDepPath := fdDep.Name()
306         cleanup := func() {
307                 lockRelease()
308                 fdDep.Close()
309                 os.Remove(fdDep.Name())
310         }
311         if _, err = recfile.NewWriter(fdDep).WriteFields(
312                 recfile.Field{Name: "Build", Value: BuildUUID},
313         ); err != nil {
314                 cleanup()
315                 return TgtError{tgtOrig, err}
316         }
317
318         // Find .do
319         doFile, upLevels, err := findDo(fdDep, cwd, tgt)
320         if err != nil {
321                 cleanup()
322                 return TgtError{tgtOrig, err}
323         }
324         if doFile == "" {
325                 cleanup()
326                 return TgtError{tgtOrig, errors.New("no .do found")}
327         }
328
329         // Determine basename and DIRPREFIX
330         doFileRelPath := doFile
331         ents := strings.Split(cwd, "/")
332         ents = ents[len(ents)-upLevels:]
333         dirPrefix := path.Join(ents...)
334         cwdOrig := cwd
335         for i := 0; i < upLevels; i++ {
336                 cwd = path.Join(cwd, "..")
337                 doFileRelPath = path.Join("..", doFileRelPath)
338         }
339         cwd = path.Clean(cwd)
340         doFilePath := path.Join(cwd, doFile)
341         basename := tgt
342         runErr := RunError{Tgt: tgtOrig}
343         if strings.HasPrefix(doFile, "default.") {
344                 basename = tgt[:len(tgt)-(len(doFile)-len("default.")-len(".do"))-1]
345                 runErr.DoFile = doFileRelPath
346         }
347
348         if err = depWrite(fdDep, cwdOrig, doFileRelPath, ""); err != nil {
349                 cleanup()
350                 return TgtError{tgtOrig, err}
351         }
352         fdDep.Close()
353         tracef(CWait, "%s", runErr.Name())
354
355         // Prepare command line
356         var cmdName string
357         var args []string
358         if err = unix.Access(doFilePath, unix.X_OK); err == nil {
359                 cmdName = doFilePath
360                 args = make([]string, 0, 3)
361         } else {
362                 cmdName = "/bin/sh"
363                 if traced || TracedAll {
364                         args = append(args, "-ex")
365                 } else {
366                         args = append(args, "-e")
367                 }
368                 args = append(args, doFile)
369         }
370
371         // Temporary file for stdout
372         fdStdout, err := tempfile(cwdOrig, tgt)
373         if err != nil {
374                 cleanup()
375                 return TgtError{tgtOrig, err}
376         }
377         stdoutPath := fdStdout.Name()
378         fdStdout.Close()
379         tmpPath := stdoutPath + ".3" // and for $3
380         tmpPathRel, err := filepath.Rel(cwd, tmpPath)
381         if err != nil {
382                 panic(err)
383         }
384         args = append(
385                 args,
386                 path.Join(dirPrefix, tgt),
387                 path.Join(dirPrefix, basename),
388                 tmpPathRel,
389         )
390         shCtx = fmt.Sprintf(
391                 "sh: %s: %s %s cwd:%s dirprefix:%s",
392                 tgtOrig, cmdName, args, cwd, dirPrefix,
393         )
394
395         cmd := exec.Command(cmdName, args...)
396         cmd.Dir = cwd
397         // cmd.Stdin reads from /dev/null by default
398         cmd.Env = append(os.Environ(), fmt.Sprintf("%s=%d", EnvLevel, Level+1))
399         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", EnvDirPrefix, dirPrefix))
400         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", EnvBuildUUID, BuildUUID))
401
402         childStderrPrefixRaw := make([]byte, 8)
403         if _, err = io.ReadFull(rand.Reader, childStderrPrefixRaw); err != nil {
404                 panic(err)
405         }
406         childStderrPrefix := hex.EncodeToString(childStderrPrefixRaw)
407         cmd.Env = append(cmd.Env, fmt.Sprintf(
408                 "%s=%s", EnvStderrPrefix, childStderrPrefix,
409         ))
410
411         fdNum := 0
412         cmd.ExtraFiles = append(cmd.ExtraFiles, FdOODTgts)
413         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", EnvOODTgtsFd, 3+fdNum))
414         fdNum++
415         cmd.ExtraFiles = append(cmd.ExtraFiles, FdOODTgtsLock)
416         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", EnvOODTgtsLockFd, 3+fdNum))
417         fdNum++
418
419         if FdStatus == nil {
420                 cmd.Env = append(cmd.Env, fmt.Sprintf("%s=NO", EnvStatusFd))
421         } else {
422                 cmd.ExtraFiles = append(cmd.ExtraFiles, FdStatus)
423                 cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", EnvStatusFd, 3+fdNum))
424                 fdNum++
425         }
426
427         // Preparing stderr
428         var fdStderr *os.File
429         if StderrKeep {
430                 fdStderr, err = os.OpenFile(
431                         path.Join(redoDir, tgt+LogSuffix),
432                         os.O_WRONLY|os.O_CREATE|os.O_TRUNC,
433                         os.FileMode(0666),
434                 )
435                 if err != nil {
436                         cleanup()
437                         return TgtError{tgtOrig, err}
438                 }
439         }
440         tracef(CDebug, "%s", shCtx)
441
442         jsNeedsRelease = false
443         Jobs.Add(1)
444         go func() {
445                 if JSR == nil {
446                         // infinite jobs
447                         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=NO", EnvJobs))
448                 } else {
449                         cmd.ExtraFiles = append(cmd.ExtraFiles, JSR)
450                         cmd.ExtraFiles = append(cmd.ExtraFiles, JSW)
451                         makeFlags := fmt.Sprintf(
452                                 "%s %s%d,%d", MakeFlags, MakeJSArg, 3+fdNum+0, 3+fdNum+1,
453                         )
454                         makeFlags = strings.Trim(makeFlags, " ")
455                         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", MakeFlagsName, makeFlags))
456                         fdNum += 2
457                         cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", EnvJSToken, jsToken))
458                 }
459
460                 if FdStatus != nil {
461                         if _, err = FdStatus.Write([]byte{StatusRun}); err != nil {
462                                 log.Fatalln(err)
463                         }
464                 }
465
466                 defer jsRelease(shCtx, jsToken)
467
468                 var finished time.Time
469                 var exitErr *exec.ExitError
470                 started := time.Now()
471                 runErr.Started = &started
472                 fdStdout, err = os.OpenFile(stdoutPath, os.O_RDWR, os.FileMode(0666))
473                 if err != nil {
474                         if fdStderr != nil {
475                                 fdStderr.Close()
476                         }
477                         runErr.Err = err
478                         errs <- runErr
479                         return
480                 }
481                 cmd.Stdout = fdStdout
482                 fdDep, err = os.OpenFile(fdDepPath, os.O_WRONLY|os.O_APPEND, os.FileMode(0666))
483                 if err != nil {
484                         if fdStderr != nil {
485                                 fdStderr.Close()
486                         }
487                         fdStdout.Close()
488                         runErr.Err = err
489                         errs <- runErr
490                         return
491                 }
492                 cmd.ExtraFiles = append(cmd.ExtraFiles, fdDep)
493                 cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", EnvDepFd, 3+fdNum))
494                 fdNum++
495                 cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", EnvDepCwd, cwd))
496
497                 defer func() {
498                         fdDep.Close()
499                         fdStdout.Close()
500                         if fdStderr != nil {
501                                 fdStderr.Close()
502                                 logRecPath := path.Join(redoDir, tgt+LogRecSuffix)
503                                 if fdStderr, err = os.OpenFile(
504                                         logRecPath,
505                                         os.O_WRONLY|os.O_CREATE|os.O_TRUNC,
506                                         os.FileMode(0666),
507                                 ); err == nil {
508                                         fields := []recfile.Field{
509                                                 {Name: "Build", Value: BuildUUID},
510                                                 {Name: "PPID", Value: strconv.Itoa(os.Getpid())},
511                                                 {Name: "Cwd", Value: cwd},
512                                         }
513                                         if cmd.Process != nil {
514                                                 fields = append(fields, recfile.Field{
515                                                         Name: "PID", Value: strconv.Itoa(cmd.Process.Pid),
516                                                 })
517                                         }
518                                         ts := new(tai64n.TAI64N)
519                                         ts.FromTime(started)
520                                         fields = append(fields,
521                                                 recfile.Field{Name: "Started", Value: tai64n.Encode(ts[:])},
522                                         )
523                                         ts.FromTime(finished)
524                                         fields = append(fields,
525                                                 recfile.Field{Name: "Finished", Value: tai64n.Encode(ts[:])})
526                                         fields = append(fields, recfile.Field{
527                                                 Name:  "Duration",
528                                                 Value: strconv.FormatInt(finished.Sub(started).Nanoseconds(), 10),
529                                         })
530                                         fields = append(fields, recfile.Field{Name: "Cmd", Value: cmdName})
531                                         for _, arg := range args {
532                                                 fields = append(fields, recfile.Field{Name: "Arg", Value: arg})
533                                         }
534                                         for _, env := range cmd.Env {
535                                                 fields = append(fields, recfile.Field{Name: "Env", Value: env})
536                                         }
537                                         if exitErr != nil {
538                                                 fields = append(fields, recfile.Field{
539                                                         Name:  "ExitCode",
540                                                         Value: strconv.Itoa(exitErr.ProcessState.ExitCode()),
541                                                 })
542                                         }
543                                         w := bufio.NewWriter(fdStderr)
544
545                                         var depInfo *DepInfo
546                                         fdDep, err := os.Open(fdDepPath)
547                                         if err != nil {
548                                                 goto Err
549                                         }
550                                         depInfo, err = depRead(fdDep)
551                                         fdDep.Close()
552                                         if err != nil {
553                                                 goto Err
554                                         }
555                                         for _, dep := range depInfo.ifchanges {
556                                                 fields = append(fields, recfile.Field{
557                                                         Name:  "Ifchange",
558                                                         Value: dep["Target"],
559                                                 })
560                                         }
561                                         _, err = recfile.NewWriter(w).WriteFields(fields...)
562                                         if err != nil {
563                                                 goto Err
564                                         }
565                                         err = w.Flush()
566                                 Err:
567                                         if err != nil {
568                                                 log.Println(err)
569                                                 os.Remove(logRecPath)
570                                         }
571                                         fdStderr.Close()
572                                 } else {
573                                         log.Println("can not open", logRecPath, ":", err)
574                                 }
575                         }
576                         lockRelease()
577                         os.Remove(fdDep.Name())
578                         os.Remove(fdStdout.Name())
579                         os.Remove(tmpPath)
580                         if FdStatus != nil {
581                                 if _, err = FdStatus.Write([]byte{StatusDone}); err != nil {
582                                         log.Fatalln(err)
583                                 }
584                         }
585                         Jobs.Done()
586                 }()
587                 stderr, err := cmd.StderrPipe()
588                 if err != nil {
589                         runErr.Err = err
590                         errs <- runErr
591                         return
592                 }
593                 started = time.Now()
594                 err = cmd.Start()
595                 if err != nil {
596                         runErr.Err = err
597                         errs <- runErr
598                         return
599                 }
600                 RunningProcsM.Lock()
601                 RunningProcs[cmd.Process.Pid] = cmd.Process
602                 RunningProcsM.Unlock()
603                 pid := fmt.Sprintf("[%d]", cmd.Process.Pid)
604                 tracef(CDebug, "%s runs %s", tgtOrig, pid)
605
606                 stderrTerm := make(chan struct{})
607                 go func() {
608                         scanner := bufio.NewScanner(stderr)
609                         var line string
610                         ts := new(tai64n.TAI64N)
611                         for scanner.Scan() {
612                                 line = scanner.Text()
613                                 if strings.HasPrefix(line, childStderrPrefix) {
614                                         line = line[len(childStderrPrefix):]
615                                         os.Stderr.WriteString(StderrPrefix + line + "\n")
616                                         continue
617                                 }
618                                 if fdStderr != nil {
619                                         ts.FromTime(time.Now())
620                                         LogMutex.Lock()
621                                         fmt.Fprintln(fdStderr, tai64n.Encode(ts[:]), line)
622                                         LogMutex.Unlock()
623                                 }
624                                 if StderrSilent {
625                                         continue
626                                 }
627                                 if MyPid == 0 {
628                                         tracef(CNone, "%s", line)
629                                 } else {
630                                         tracef(CNone, "%s %s", pid, line)
631                                 }
632                         }
633                         close(stderrTerm)
634                 }()
635
636                 // Wait for job completion
637                 <-stderrTerm
638                 err = cmd.Wait()
639                 RunningProcsM.Lock()
640                 delete(RunningProcs, cmd.Process.Pid)
641                 RunningProcsM.Unlock()
642                 finished = time.Now()
643                 runErr.Finished = &finished
644                 if err != nil {
645                         exitErr = err.(*exec.ExitError)
646                         runErr.Err = err
647                         errs <- runErr
648                         return
649                 }
650
651                 // Was $1 touched?
652                 if inode, err := inodeFromFileByPath(path.Join(cwdOrig, tgt)); err == nil {
653                         if inodePrev == nil {
654                                 runErr.Err = Err1WasTouched
655                                 errs <- runErr
656                                 return
657                         }
658                         if err != nil {
659                                 runErr.Err = err
660                                 errs <- runErr
661                                 return
662                         }
663                         if !inode.Equals(inodePrev) {
664                                 runErr.Err = Err1WasTouched
665                                 errs <- runErr
666                                 return
667                         }
668                 }
669
670                 if inodePrev != nil {
671                         if inode, err := inodeFromFileByPath(path.Join(cwdOrig, tgt)); err == nil {
672                                 if !inode.Equals(inodePrev) {
673                                         runErr.Err = Err1WasTouched
674                                         errs <- runErr
675                                         return
676                                 }
677                         }
678                 }
679
680                 // Does it produce both stdout and tmp?
681                 fiStdout, err := os.Stat(fdStdout.Name())
682                 if err != nil {
683                         runErr.Err = err
684                         errs <- runErr
685                         return
686                 }
687                 tmpExists := false
688                 _, err = os.Stat(tmpPath)
689                 if err == nil {
690                         if fiStdout.Size() > 0 {
691                                 runErr.Err = errors.New("created both tmp and stdout")
692                                 errs <- runErr
693                                 return
694                         }
695                         tmpExists = true
696                 } else if !os.IsNotExist(err) {
697                         runErr.Err = err
698                         errs <- runErr
699                         return
700                 }
701
702                 // Determine what file we must process at last
703                 var fd *os.File
704                 if tmpExists {
705                         fd, err = os.Open(tmpPath)
706                         if err != nil {
707                                 goto Finish
708                         }
709                         defer fd.Close()
710                 } else if fiStdout.Size() > 0 {
711                         fd = fdStdout
712                 }
713
714                 // Do we need to ifcreate it, or ifchange with renaming?
715                 if fd == nil {
716                         os.Remove(path.Join(cwdOrig, tgt))
717                         err = ifcreate(fdDep, tgt)
718                         if err != nil {
719                                 goto Finish
720                         }
721                 } else {
722                         var hsh string
723                         if hshPrev != "" {
724                                 _, err = fd.Seek(0, io.SeekStart)
725                                 if err != nil {
726                                         goto Finish
727                                 }
728                                 hsh, err = fileHash(fd)
729                                 if err != nil {
730                                         goto Finish
731                                 }
732                                 if hsh == hshPrev {
733                                         tracef(CDebug, "%s has same hash, not renaming", tgtOrig)
734                                         err = os.Remove(fd.Name())
735                                         if err != nil {
736                                                 goto Finish
737                                         }
738                                         err = os.Chtimes(path.Join(cwdOrig, tgt), finished, finished)
739                                         if err != nil {
740                                                 goto Finish
741                                         }
742                                         if !NoSync {
743                                                 err = syncDir(cwdOrig)
744                                                 if err != nil {
745                                                         goto Finish
746                                                 }
747                                         }
748                                         err = depWrite(fdDep, cwdOrig, tgt, hshPrev)
749                                         if err != nil {
750                                                 goto Finish
751                                         }
752                                         goto RecCommit
753                                 }
754                         }
755                         if !NoSync {
756                                 err = fd.Sync()
757                                 if err != nil {
758                                         goto Finish
759                                 }
760                         }
761                         err = os.Rename(fd.Name(), path.Join(cwdOrig, tgt))
762                         if err != nil {
763                                 goto Finish
764                         }
765                         if !NoSync {
766                                 err = syncDir(cwdOrig)
767                                 if err != nil {
768                                         goto Finish
769                                 }
770                         }
771                         err = depWrite(fdDep, cwdOrig, tgt, hsh)
772                         if err != nil {
773                                 goto Finish
774                         }
775                 }
776
777         RecCommit:
778                 // Commit .rec
779                 if !NoSync {
780                         err = fdDep.Sync()
781                         if err != nil {
782                                 goto Finish
783                         }
784                 }
785                 fdDepPath = path.Join(redoDir, tgt+DepSuffix)
786                 err = os.Rename(fdDep.Name(), fdDepPath)
787                 if err != nil {
788                         goto Finish
789                 }
790                 if !NoSync {
791                         err = syncDir(redoDir)
792                         if err != nil {
793                                 goto Finish
794                         }
795                 }
796
797                 // Post-commit .rec sanitizing
798                 fdDep.Close()
799                 if fdDepR, err := os.Open(fdDepPath); err == nil {
800                         depInfo, err := depRead(fdDepR)
801                         fdDepR.Close()
802                         if err != nil {
803                                 goto Finish
804                         }
805                         ifchangeSeen := make(map[string]struct{}, len(depInfo.ifchanges))
806                         for _, dep := range depInfo.ifchanges {
807                                 ifchangeSeen[dep["Target"]] = struct{}{}
808                         }
809                         for _, dep := range depInfo.ifcreates {
810                                 if _, exists := ifchangeSeen[dep]; exists {
811                                         tracef(CWarn, "simultaneous ifcreate and ifchange records: %s", tgt)
812                                 }
813                         }
814                 }
815
816         Finish:
817                 runErr.Err = err
818                 errs <- runErr
819         }()
820         return nil
821 }
822
823 func isOkRun(err error) bool {
824         if err == nil {
825                 return true
826         }
827         var runErr RunError
828         if errors.As(err, &runErr) && runErr.Err == nil {
829                 tracef(CRedo, "%s", runErr.Name())
830                 return true
831         }
832         tracef(CErr, "%s", err)
833         return false
834 }