Phase 7: Port BBS archive downloaders (SSH + SMB)

Add SSH (SFTP) and SMB archive download capabilities to the BBS package.
These downloaders are used by bbs2gh migrate-repo to download Bitbucket
Server export archives before uploading them for GitHub import.

SSH downloader:
- Uses golang.org/x/crypto/ssh + github.com/pkg/sftp
- sftpClient interface (Stat/Open/Close) for testability
- Progress logging with rate-limited output
- UserError with --bbs-shared-home hint when using default Linux path

SMB downloader:
- Uses github.com/hirochachacha/go-smb2
- smbConnector + smbShare interfaces for testability
- Connect → Login → Mount → Read loop with cleanup
- UserError with --bbs-shared-home hint when using default Windows path

Shared infrastructure (archive.go):
- Constants: ExportArchiveSourceDirectory, DefaultTargetDirectory,
  DefaultBbsSharedHomeDirectory{Linux,Windows}
- Path helpers: ExportArchiveFileName, SourceExportArchiveAbsolutePath
- fileSystem interface + osFileSystem for testable file operations
- progressLogger with mutex-protected rate limiting
- copyWithProgress shared copy loop
- logFriendlySize and percentage formatters

New files: archive.go, ssh_downloader.go, sftp_client.go,
ssh_downloader_test.go, smb_downloader.go, smb_client.go,
smb_downloader_test.go

15 new tests (6 SSH + 9 SMB), all passing. 0 lint issues.

Author: offbyone

go.mod

@@ -10,8 +10,11 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/s3 v1.97.3
 	github.com/google/go-github/v68 v68.0.0
 	github.com/google/uuid v1.6.0
+	github.com/hirochachacha/go-smb2 v1.1.0
+	github.com/pkg/sftp v1.13.10
 	github.com/spf13/cobra v1.10.2
 	github.com/stretchr/testify v1.11.1
+	golang.org/x/crypto v0.45.0
 )
 
 require (
@@ -27,11 +30,14 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.21 // indirect
 	github.com/aws/smithy-go v1.24.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/geoffgarside/ber v1.1.0 // indirect
 	github.com/google/go-querystring v1.1.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/kr/fs v0.1.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/spf13/pflag v1.0.9 // indirect
 	golang.org/x/net v0.47.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
 	golang.org/x/text v0.31.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -39,6 +39,8 @@ github.com/aws/smithy-go v1.24.2/go.mod h1:YE2RhdIuDbA5E5bTdciG9KrW3+TiEONeUWCqx
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/geoffgarside/ber v1.1.0 h1:qTmFG4jJbwiSzSXoNJeHcOprVzZ8Ulde2Rrrifu5U9w=
+github.com/geoffgarside/ber v1.1.0/go.mod h1:jVPKeCbj6MvQZhwLYsGwaGI52oUorHoHKNecGT85ZCc=
 github.com/golang-jwt/jwt/v5 v5.3.0 h1:pv4AsKCKKZuqlgs5sUmn4x8UlGa0kEVt/puTpKx9vvo=
 github.com/golang-jwt/jwt/v5 v5.3.0/go.mod h1:fxCRLWMO43lRc8nhHWY6LGqRcf+1gQWArsqaEUEa5bE=
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
@@ -50,8 +52,12 @@ github.com/google/go-querystring v1.1.0 h1:AnCroh3fv4ZBgVIf1Iwtovgjaw/GiKJo8M8yD
 github.com/google/go-querystring v1.1.0/go.mod h1:Kcdr2DB4koayq7X8pmAG4sNG59So17icRSOU623lUBU=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/hirochachacha/go-smb2 v1.1.0 h1:b6hs9qKIql9eVXAiN0M2wSFY5xnhbHAQoCwRKbaRTZI=
+github.com/hirochachacha/go-smb2 v1.1.0/go.mod h1:8F1A4d5EZzrGu5R7PU163UcMRDJQl4FtcxjBfsY8TZE=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/kr/fs v0.1.0 h1:Jskdu9ieNAYnjxsi0LbQp1ulIKZV1LAFgK1tWhpZgl8=
+github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -60,6 +66,8 @@ github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c h1:+mdjkGKdHQG3305AYmdv1U2eRNDiU2ErMBj1gwrq8eQ=
 github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
+github.com/pkg/sftp v1.13.10 h1:+5FbKNTe5Z9aspU88DPIKJ9z2KZoaGCu6Sr6kKR/5mU=
+github.com/pkg/sftp v1.13.10/go.mod h1:bJ1a7uDhrX/4OII+agvy28lzRvQrmIQuaHrcI1HbeGA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/go-internal v1.12.0 h1:exVL4IDcn6na9z1rAb56Vxr+CgyK3nn3O+epU5NdKM8=
@@ -72,12 +80,20 @@ github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200728195943-123391ffb6de/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.45.0 h1:jMBrvKuj23MTlT0bQEOBcAE0mjg8mK9RXFhRH6nyF3Q=
 golang.org/x/crypto v0.45.0/go.mod h1:XTGrrkGJve7CYK7J8PEww4aY7gM3qMCElcJQ8n8JdX4=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.47.0 h1:Mx+4dIFzqraBXUugkia1OOvlD6LemFo1ALMHjrXDOhY=
 golang.org/x/net v0.47.0/go.mod h1:/jNxtkgq5yWUGYkaZGqo27cfGZ1c5Nen03aYrrKpVRU=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
 golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/term v0.37.0 h1:8EGAD0qCmHYZg6J17DvsMy9/wJ7/D/4pV/wfnld5lTU=
+golang.org/x/term v0.37.0/go.mod h1:5pB4lxRNYYVZuTLmy8oR2BH8dflOR+IbTYFD8fi3254=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=
 golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

pkg/bbs/archive.go

@@ -0,0 +1,135 @@
+package bbs
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/github/gh-gei/pkg/logger"
+)
+
+// Archive download constants matching C# IBbsArchiveDownloader and BbsSettings.
+const (
+	ExportArchiveSourceDirectory         = "data/migration/export"
+	DefaultTargetDirectory               = "bbs_archive_downloads"
+	DefaultBbsSharedHomeDirectoryLinux   = "/var/atlassian/application-data/bitbucket/shared"
+	DefaultBbsSharedHomeDirectoryWindows = `c$\atlassian\applicationdata\bitbucket\shared`
+	downloadProgressReportInterval       = 10 * time.Second
+)
+
+// ExportArchiveFileName returns the archive filename for an export job.
+func ExportArchiveFileName(exportJobID int64) string {
+	return fmt.Sprintf("Bitbucket_export_%d.tar", exportJobID)
+}
+
+// SourceExportArchiveAbsolutePath returns the full path to the export archive on the BBS server.
+func SourceExportArchiveAbsolutePath(bbsSharedHome string, exportJobID int64) string {
+	return filepath.ToSlash(filepath.Join(bbsSharedHome, ExportArchiveSourceDirectory, ExportArchiveFileName(exportJobID)))
+}
+
+// fileSystem abstracts filesystem operations for testability.
+type fileSystem interface {
+	MkdirAll(path string, perm os.FileMode) error
+	Create(path string) (io.WriteCloser, error)
+}
+
+// osFileSystem is the default fileSystem implementation using the real OS.
+type osFileSystem struct{}
+
+func (osFileSystem) MkdirAll(path string, perm os.FileMode) error {
+	return os.MkdirAll(path, perm)
+}
+
+func (osFileSystem) Create(path string) (io.WriteCloser, error) {
+	return os.Create(path)
+}
+
+// progressLogger tracks download progress with rate-limited log output.
+type progressLogger struct {
+	log              *logger.Logger
+	mu               sync.Mutex
+	nextProgressTime time.Time
+}
+
+func newProgressLogger(log *logger.Logger) *progressLogger {
+	return &progressLogger{
+		log:              log,
+		nextProgressTime: time.Now(),
+	}
+}
+
+func (p *progressLogger) logProgress(downloadedBytes, totalBytes int64) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if time.Now().Before(p.nextProgressTime) {
+		return
+	}
+
+	if totalBytes > 0 {
+		p.log.Info(
+			"Archive download in progress, %s out of %s (%s) completed...",
+			logFriendlySize(downloadedBytes),
+			logFriendlySize(totalBytes),
+			percentage(downloadedBytes, totalBytes),
+		)
+	} else {
+		p.log.Info("Archive download in progress, %s completed...", logFriendlySize(downloadedBytes))
+	}
+
+	p.nextProgressTime = p.nextProgressTime.Add(downloadProgressReportInterval)
+}
+
+func percentage(downloaded, total int64) string {
+	if total == 0 {
+		return "unknown%"
+	}
+	pct := int(float64(downloaded) * 100.0 / float64(total))
+	return fmt.Sprintf("%d%%", pct)
+}
+
+func logFriendlySize(size int64) string {
+	const (
+		kilobyte = 1024
+		megabyte = 1024 * kilobyte
+		gigabyte = 1024 * megabyte
+	)
+
+	switch {
+	case size < kilobyte:
+		return fmt.Sprintf("%d bytes", size)
+	case size < megabyte:
+		return fmt.Sprintf("%.0f KB", float64(size)/float64(kilobyte))
+	case size < gigabyte:
+		return fmt.Sprintf("%.0f MB", float64(size)/float64(megabyte))
+	default:
+		return fmt.Sprintf("%.2f GB", float64(size)/float64(gigabyte))
+	}
+}
+
+// copyWithProgress copies from src to dst, reporting download progress.
+func copyWithProgress(src io.Reader, dst io.Writer, totalSize int64, log *logger.Logger) error {
+	progress := newProgressLogger(log)
+	buf := make([]byte, 64*1024)
+	var downloaded int64
+	for {
+		n, readErr := src.Read(buf)
+		if n > 0 {
+			if _, writeErr := dst.Write(buf[:n]); writeErr != nil {
+				return fmt.Errorf("write to local file: %w", writeErr)
+			}
+			downloaded += int64(n)
+			progress.logProgress(downloaded, totalSize)
+		}
+		if readErr == io.EOF {
+			break
+		}
+		if readErr != nil {
+			return fmt.Errorf("read from remote: %w", readErr)
+		}
+	}
+	return nil
+}