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.

5 files changed, 14 insertions, 4 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) {