PBM-1058: fix phys backups on datadirs with tailing / (#802)

Phys backup while trimming datadir from the file path always added
a slash to the trim prefix. In case datadir was set with a tailing
slash it led to a double slash and datadir wasn't trimmed at all
(`Trimprefix("/data/db/file1", "/data/db//")`). Therefore in the
backup's meta such files contain datadir and the restore would put them
in a subdirectory inside datadir, "/data/db/data/db/file1" instead of
"/data/db/file1".

This change fixes it.

pbm/backup/physical.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path"
 	"strings"
 	"time"
 
@@ -276,15 +277,15 @@ func (b *Backup) doPhysical(ctx context.Context, bcp *pbm.BackupCmd, opid pbm.OP
 	}
 
 	l.Info("uploading data")
-	rsMeta.Files, err = uploadFiles(ctx, bcur.Data, bcp.Name+"/"+rsMeta.Name, bcur.Meta.DBpath+"/",
+	rsMeta.Files, err = uploadFiles(ctx, bcur.Data, bcp.Name+"/"+rsMeta.Name, bcur.Meta.DBpath,
 		b.typ == pbm.IncrementalBackup, stg, bcp.Compression, bcp.CompressionLevel, l)
 	if err != nil {
 		return err
 	}
 	l.Info("uploading data done")
 
 	l.Info("uploading journals")
-	ju, err := uploadFiles(ctx, jrnls, bcp.Name+"/"+rsMeta.Name, bcur.Meta.DBpath+"/",
+	ju, err := uploadFiles(ctx, jrnls, bcp.Name+"/"+rsMeta.Name, bcur.Meta.DBpath,
 		false, stg, bcp.Compression, bcp.CompressionLevel, l)
 	if err != nil {
 		return err
@@ -339,8 +340,6 @@ func (id *UUID) IsZero() bool {
 	return bytes.Equal(id.UUID[:], uuid.Nil[:])
 }
 
-const journalPrefix = "journal/WiredTigerLog."
-
 // Uploads given files to the storage. files may come as 16Mb (by default)
 // blocks in that case it will concat consecutive blocks in one bigger file.
 // For example: f1[0-16], f1[16-24], f1[64-16] becomes f1[0-24], f1[50-16].
@@ -353,6 +352,12 @@ func uploadFiles(ctx context.Context, files []pbm.File, subdir, trimPrefix strin
 		return data, err
 	}
 
+	trim := func(fname string) string {
+		// path.Clean to get rid of `/` at the beginning in case it's
+		// left after TrimPrefix. Just for consistent file names in metadata
+		return path.Clean("./" + strings.TrimPrefix(fname, trimPrefix))
+	}
+
 	wfile := files[0]
 	for _, file := range files[1:] {
 		select {
@@ -369,7 +374,7 @@ func uploadFiles(ctx context.Context, files []pbm.File, subdir, trimPrefix strin
 		if incr && (file.Len == 0 || file.Off >= file.Size) {
 			file.Off = -1
 			file.Len = -1
-			file.Name = strings.TrimPrefix(file.Name, trimPrefix)
+			file.Name = trim(file.Name)
 
 			data = append(data, file)
 			continue
@@ -382,11 +387,11 @@ func uploadFiles(ctx context.Context, files []pbm.File, subdir, trimPrefix strin
 			continue
 		}
 
-		fw, err := writeFile(ctx, wfile, subdir+"/"+strings.TrimPrefix(wfile.Name, trimPrefix), stg, comprT, comprL, l)
+		fw, err := writeFile(ctx, wfile, path.Join(subdir, trim(wfile.Name)), stg, comprT, comprL, l)
 		if err != nil {
 			return data, errors.Wrapf(err, "upload file `%s`", wfile.Name)
 		}
-		fw.Name = strings.TrimPrefix(wfile.Name, trimPrefix)
+		fw.Name = trim(wfile.Name)
 
 		data = append(data, *fw)
 
@@ -397,11 +402,11 @@ func uploadFiles(ctx context.Context, files []pbm.File, subdir, trimPrefix strin
 		return data, nil
 	}
 
-	f, err := writeFile(ctx, wfile, subdir+"/"+strings.TrimPrefix(wfile.Name, trimPrefix), stg, comprT, comprL, l)
+	f, err := writeFile(ctx, wfile, path.Join(subdir, trim(wfile.Name)), stg, comprT, comprL, l)
 	if err != nil {
 		return data, errors.Wrapf(err, "upload file `%s`", wfile.Name)
 	}
-	f.Name = strings.TrimPrefix(wfile.Name, trimPrefix)
+	f.Name = trim(wfile.Name)
 
 	data = append(data, *f)