pkg/osutil: provide better Rename

os.Rename fails for cross-device renaming (e.g. to/from tmpfs).
This is quite unpleasant. Provide own version that falls back to copying.

10 files changed, 22 insertions, 9 deletions

diff --git a/pkg/build/akaros.go b/pkg/build/akaros.go
index 6ee3d774b..60750028f 100644
--- a/pkg/build/akaros.go
+++ b/pkg/build/akaros.go
@@ -52,7 +52,7 @@ func (ctx akaros) build(targetArch, vmType, kernelDir, outputDir, compiler, user
 		return err
 	}
 	targetKey := filepath.Join(kernelDir, "kern", "kfs", ".ssh", "authorized_keys")
-	if err := os.Rename(sshkeyPub, targetKey); err != nil {
+	if err := osutil.Rename(sshkeyPub, targetKey); err != nil {
 		return err
 	}
 	const init = `#!/bin/bash
diff --git a/pkg/build/linux.go b/pkg/build/linux.go
index f2bc4e0fe..dbe9cfbb7 100644
--- a/pkg/build/linux.go
+++ b/pkg/build/linux.go
@@ -71,7 +71,7 @@ func (linux) buildKernel(kernelDir, outputDir, compiler string, config []byte) e
 	}
 	vmlinux := filepath.Join(kernelDir, "vmlinux")
 	outputVmlinux := filepath.Join(outputDir, "obj", "vmlinux")
-	if err := os.Rename(vmlinux, outputVmlinux); err != nil {
+	if err := osutil.Rename(vmlinux, outputVmlinux); err != nil {
 		return fmt.Errorf("failed to rename vmlinux: %v", err)
 	}
 	return nil
diff --git a/pkg/db/db.go b/pkg/db/db.go
index fde371d90..e3492031b 100644
--- a/pkg/db/db.go
+++ b/pkg/db/db.go
@@ -118,7 +118,7 @@ func (db *DB) compact() error {
 		return err
 	}
 	f.Close()
-	if err := os.Rename(f.Name(), db.filename); err != nil {
+	if err := osutil.Rename(f.Name(), db.filename); err != nil {
 		return err
 	}
 	db.uncompacted = len(db.Records)
diff --git a/pkg/osutil/fileutil.go b/pkg/osutil/fileutil.go
index 3e107828f..0b09ff0b4 100644
--- a/pkg/osutil/fileutil.go
+++ b/pkg/osutil/fileutil.go
@@ -40,6 +40,16 @@ func CopyFile(oldFile, newFile string) error {
 	return os.Rename(tmpFile, newFile)
 }
 
+// Rename is similar to os.Rename but handles cross-device renaming (by copying).
+func Rename(oldFile, newFile string) error {
+	err := os.Rename(oldFile, newFile)
+	if err != nil {
+		// Can't use syscall.EXDEV because this is used in appengine app.
+		return CopyFile(oldFile, newFile)
+	}
+	return err
+}
+
 // WriteTempFile writes data to a temp file and returns its name.
 func WriteTempFile(data []byte) (string, error) {
 	// Note: pkg/report knows about "syzkaller" prefix as it appears in crashes as process name.
diff --git a/pkg/vcs/fuchsia.go b/pkg/vcs/fuchsia.go
index 354be6c8d..f9a027f67 100644
--- a/pkg/vcs/fuchsia.go
+++ b/pkg/vcs/fuchsia.go
@@ -56,7 +56,7 @@ func (ctx *fuchsia) initRepo() error {
 	if _, err := runSandboxed(tmpDir, "bash", "-c", cmd); err != nil {
 		return err
 	}
-	return os.Rename(filepath.Join(tmpDir, "fuchsia"), ctx.dir)
+	return osutil.Rename(filepath.Join(tmpDir, "fuchsia"), ctx.dir)
 }
 
 func (ctx *fuchsia) CheckoutBranch(repo, branch string) (*Commit, error) {
diff --git a/syz-ci/manager.go b/syz-ci/manager.go
index 3401daa4b..a227acd28 100644
--- a/syz-ci/manager.go
+++ b/syz-ci/manager.go
@@ -331,7 +331,7 @@ func (mgr *Manager) build(kernelCommit *vcs.Commit) error {
 	if err := os.RemoveAll(mgr.latestDir); err != nil {
 		return fmt.Errorf("failed to remove latest dir: %v", err)
 	}
-	return os.Rename(tmpDir, mgr.latestDir)
+	return osutil.Rename(tmpDir, mgr.latestDir)
 }
 
 func (mgr *Manager) restartManager() {
diff --git a/syz-ci/managercmd.go b/syz-ci/managercmd.go
index 74f99307f..eee09d151 100644
--- a/syz-ci/managercmd.go
+++ b/syz-ci/managercmd.go
@@ -74,7 +74,7 @@ func (mc *ManagerCmd) loop() {
 			// don't restart too frequently (in case it instantly exits with an error)
 			if time.Since(started) > restartPeriod {
 				started = time.Now()
-				os.Rename(mc.log, mc.log+".old")
+				osutil.Rename(mc.log, mc.log+".old")
 				logfile, err := os.Create(mc.log)
 				if err != nil {
 					mc.errorf("failed to create manager log: %v", err)
diff --git a/tools/syz-benchcmp/benchcmp.go b/tools/syz-benchcmp/benchcmp.go
index b34acafd7..387feb485 100644
--- a/tools/syz-benchcmp/benchcmp.go
+++ b/tools/syz-benchcmp/benchcmp.go
@@ -18,6 +18,8 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sort"
+
+	"github.com/google/syzkaller/pkg/osutil"
 )
 
 var (
@@ -190,7 +192,7 @@ func display(graphs []*Graph) {
 	}
 	outf.Close()
 	name := outf.Name() + ".html"
-	if err := os.Rename(outf.Name(), name); err != nil {
+	if err := osutil.Rename(outf.Name(), name); err != nil {
 		failf("failed to rename file: %v", err)
 	}
 	if err := exec.Command("xdg-open", name).Start(); err != nil {
diff --git a/tools/syz-fmt/syz-fmt.go b/tools/syz-fmt/syz-fmt.go
index 3367a4344..76d6a8eae 100644
--- a/tools/syz-fmt/syz-fmt.go
+++ b/tools/syz-fmt/syz-fmt.go
@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/google/syzkaller/pkg/ast"
+	"github.com/google/syzkaller/pkg/osutil"
 	"github.com/google/syzkaller/sys/targets"
 )
 
@@ -67,7 +68,7 @@ func processFile(file string, mode os.FileMode) {
 		return
 	}
 	fmt.Printf("reformatting %v\n", file)
-	if err := os.Rename(file, file+"~"); err != nil {
+	if err := osutil.Rename(file, file+"~"); err != nil {
 		fmt.Fprintf(os.Stderr, "%v\n", err)
 		os.Exit(1)
 	}
diff --git a/vm/kvm/kvm.go b/vm/kvm/kvm.go
index a12db5bf8..e7948ab02 100644
--- a/vm/kvm/kvm.go
+++ b/vm/kvm/kvm.go
@@ -241,7 +241,7 @@ func (inst *instance) Run(timeout time.Duration, stop <-chan bool, command strin
 	if err := osutil.WriteExecFile(tmpFile, []byte(command)); err != nil {
 		return nil, nil, err
 	}
-	if err := os.Rename(tmpFile, cmdFile); err != nil {
+	if err := osutil.Rename(tmpFile, cmdFile); err != nil {
 		return nil, nil, err
 	}