Allow a 'tmp' directory during dolt init

go/cmd/dolt/system_checks.go

@@ -19,6 +19,7 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/dolthub/dolt/go/libraries/doltcore/env"
 	"github.com/dolthub/dolt/go/libraries/utils/file"
 	"github.com/dolthub/dolt/go/libraries/utils/filesys"
 	"github.com/dolthub/dolt/go/store/util/tempfiles"
@@ -47,7 +48,7 @@ func reconfigIfTempFileMoveFails(dataDir filesys.Filesys) error {
 		dotDoltCreated = true
 	}
 
-	doltTmpDir := filepath.Join(doltDir, "tmp")
+	doltTmpDir := filepath.Join(doltDir, env.TmpDirName)
 	stat, err = os.Stat(doltTmpDir)
 	if err != nil {
 		err := os.MkdirAll(doltTmpDir, os.ModePerm)
@@ -76,7 +77,7 @@ func reconfigIfTempFileMoveFails(dataDir filesys.Filesys) error {
 
 	err = file.Rename(name, movedName)
 	if err == nil {
-		// tmp file system is the same as the data dir, so no need to change it.
+		// If rename was successful, then the tmp dir is fine, so no need to change it. Clean up the things we created.
 		_ = file.Remove(movedName)
 
 		if tmpDirCreated {
@@ -89,7 +90,7 @@ func reconfigIfTempFileMoveFails(dataDir filesys.Filesys) error {
 
 		return nil
 	}
-	_ = file.Remove(movedName)
+	_ = file.Remove(name)
 
 	// Rename failed. So we force the tmp dir to be the data dir.
 	tempfiles.MovableTempFileProvider = tempfiles.NewTempFileProviderAt(doltTmpDir)

go/libraries/doltcore/env/environment.go

@@ -51,6 +51,8 @@ const (
 	DefaultRemotesApiPort = "443"
 
 	tempTablesDir = "temptf"
+
+	TmpDirName = "tmp"
 )
 
 var zeroHashStr = (hash.Hash{}).String()
@@ -450,13 +452,21 @@ func (dEnv *DoltEnv) createDirectories(dir string) (string, error) {
 	}
 
 	if dEnv.hasDoltDir(dir) {
-		// Special case a completely empty directory. We can allow that.
+		// Special case a completely empty directory, or one which has a "tmp" directory but nothing else.
+		// The `.dolt/tmp` directory is created while verifying that we can rename table files which is early
+		// in the startup process. It will only exist if we need it because the TMPDIR environment variable is set to
+		// a path which is on a different partition than the .dolt directory.
 		dotDolt := mustAbs(dEnv, dbfactory.DoltDir)
 		entries, err := os.ReadDir(dotDolt)
 		if err != nil {
 			return "", err
 		}
-		if len(entries) != 0 {
+
+		if len(entries) == 1 {
+			if !entries[0].IsDir() || entries[0].Name() != TmpDirName {
+				return "", fmt.Errorf(".dolt directory already exists at '%s'", dir)
+			}
+		} else if len(entries) != 0 {
 			return "", fmt.Errorf(".dolt directory already exists at '%s'", dir)
 		}
 	}