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Add IsNonCompressedTarball method to Compressor interface #122

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mdzhigarov wants to merge 3 commits into from
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Add IsNonCompressedTarball method to Compressor interface #122

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bc8f5dd
Add IsNonCompressedTarball method to Compressor interface
mdzhigarov Oct 22, 2025
f54397f
Fixes a failing unit test
mdzhigarov Oct 22, 2025
5f582d4
Implements the IsNonCompressedTarball directly in go instead of relyi…
mdzhigarov Oct 23, 2025
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2 changes: 2 additions & 0 deletions fileutil/compressor_interface.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@ type Compressor interface {

DecompressFileToDir(path string, dir string, options CompressorOptions) (err error)

IsNonCompressedTarball(path string) (bool, error)

// CleanUp cleans up compressed file after it was used
CleanUp(path string) error
}
4 changes: 4 additions & 0 deletions fileutil/fakes/fake_compressor.go
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Expand Up @@ -65,6 +65,10 @@ func (fc *FakeCompressor) DecompressFileToDir(tarballPath string, dir string, op
return fc.DecompressFileToDirErr
}

func (fc *FakeCompressor) IsNonCompressedTarball(path string) (bool, error) {
return false, nil
}

func (fc *FakeCompressor) CleanUp(tarballPath string) error {
fc.CleanUpTarballPath = tarballPath
return fc.CleanUpErr
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11 changes: 11 additions & 0 deletions fileutil/tarball_compressor.go
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Expand Up @@ -3,6 +3,7 @@ package fileutil
import (
"fmt"
"runtime"
"strings"

bosherr "github.com/cloudfoundry/bosh-utils/errors"
boshsys "github.com/cloudfoundry/bosh-utils/system"
Expand Down Expand Up @@ -80,6 +81,16 @@ func (c tarballCompressor) DecompressFileToDir(tarballPath string, dir string, o
return nil
}

func (c tarballCompressor) IsNonCompressedTarball(path string) (bool, error) {
stdout, _, exitStatus, err := c.cmdRunner.RunCommand("file", path)
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@aramprice aramprice Oct 22, 2025

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I think that this will need to be implemented in Golang, rather than using file, or have a separate path for windows.
The agent needs to be able to function on Windows stemcells.

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@mdzhigarov mdzhigarov Oct 22, 2025

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If this is ran on a windows stemcell the file command will not be found and the cmdRunner will simply return an error. That is completely fine - the tar will be treated as compressed so same behavior as today.

This would work even if the tar was originally created with the --no-compression flag. On Windows, we'd compress it again after compilation which is not a big deal.

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@aramprice aramprice Oct 22, 2025

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I agree that this is the likely outcome but I don't want to introduce a(nother) behavior difference between Linux and Windows.
Probably the cleanest option is to use a golang-native way to do this rather than shelling out to file.

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@mdzhigarov mdzhigarov Oct 23, 2025

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Agreed. Updated the PR to detect the tar compression natively.
Tested the with bosh-agent compile on the latest lite stemcell.

if err != nil || exitStatus != 0 {
return false, err
}

fileOutputStr := strings.TrimSpace(stdout)
return strings.Contains(fileOutputStr, "POSIX tar archive"), nil
}

func (c tarballCompressor) CleanUp(tarballPath string) error {
return c.fs.RemoveAll(tarballPath)
}
118 changes: 118 additions & 0 deletions fileutil/tarball_compressor_test.go
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Expand Up @@ -273,6 +273,124 @@ var _ = Describe("tarballCompressor", func() {
})
})

Describe("IsNonCompressedTarball", func() {
It("returns true for non-compressed tarball files", func() {
cmdRunner := fakesys.NewFakeCmdRunner()
compressor := NewTarballCompressor(cmdRunner, fs)

// Mock the file command output for a non-compressed tarball
cmdRunner.AddCmdResult("file /test/file.tar", fakesys.FakeCmdResult{
Stdout: "/test/file.tar: POSIX tar archive\n",
Stderr: "",
ExitStatus: 0,
})

result, err := compressor.IsNonCompressedTarball("/test/file.tar")
Expect(err).ToNot(HaveOccurred())
Expect(result).To(BeTrue())

Expect(1).To(Equal(len(cmdRunner.RunCommands)))
Expect(cmdRunner.RunCommands[0]).To(Equal([]string{"file", "/test/file.tar"}))
})

It("returns false for compressed tarball files", func() {
cmdRunner := fakesys.NewFakeCmdRunner()
compressor := NewTarballCompressor(cmdRunner, fs)

// Mock the file command output for a compressed tarball
cmdRunner.AddCmdResult("file /test/file.tgz", fakesys.FakeCmdResult{
Stdout: "/test/file.tgz: gzip compressed data, from Unix, original size modulo 2^32 1024\n",
Stderr: "",
ExitStatus: 0,
})

result, err := compressor.IsNonCompressedTarball("/test/file.tgz")
Expect(err).ToNot(HaveOccurred())
Expect(result).To(BeFalse())

Expect(1).To(Equal(len(cmdRunner.RunCommands)))
Expect(cmdRunner.RunCommands[0]).To(Equal([]string{"file", "/test/file.tgz"}))
})

It("returns false for non-tarball files", func() {
cmdRunner := fakesys.NewFakeCmdRunner()
compressor := NewTarballCompressor(cmdRunner, fs)

// Mock the file command output for a regular text file
cmdRunner.AddCmdResult("file /test/file.txt", fakesys.FakeCmdResult{
Stdout: "/test/file.txt: ASCII text\n",
Stderr: "",
ExitStatus: 0,
})

result, err := compressor.IsNonCompressedTarball("/test/file.txt")
Expect(err).ToNot(HaveOccurred())
Expect(result).To(BeFalse())

Expect(1).To(Equal(len(cmdRunner.RunCommands)))
Expect(cmdRunner.RunCommands[0]).To(Equal([]string{"file", "/test/file.txt"}))
})

It("returns error when file command fails", func() {
cmdRunner := fakesys.NewFakeCmdRunner()
compressor := NewTarballCompressor(cmdRunner, fs)

// Mock the file command to return an error
cmdRunner.AddCmdResult("file /test/nonexistent.tar", fakesys.FakeCmdResult{
Stdout: "",
Stderr: "file: cannot open `/test/nonexistent.tar' (No such file or directory)\n",
ExitStatus: 1,
})

result, err := compressor.IsNonCompressedTarball("/test/nonexistent.tar")
Expect(err).To(HaveOccurred())
Expect(result).To(BeFalse())

Expect(1).To(Equal(len(cmdRunner.RunCommands)))
Expect(cmdRunner.RunCommands[0]).To(Equal([]string{"file", "/test/nonexistent.tar"}))
})

It("returns error when file command execution fails", func() {
cmdRunner := fakesys.NewFakeCmdRunner()
compressor := NewTarballCompressor(cmdRunner, fs)

// Mock the file command to return an execution error
cmdRunner.AddCmdResult("file /test/file.tar", fakesys.FakeCmdResult{
Stdout: "",
Stderr: "",
ExitStatus: 0,
Error: errors.New("command execution failed"),
})

result, err := compressor.IsNonCompressedTarball("/test/file.tar")
Expect(err).To(HaveOccurred())
Expect(err.Error()).To(ContainSubstring("command execution failed"))
Expect(result).To(BeFalse())

Expect(1).To(Equal(len(cmdRunner.RunCommands)))
Expect(cmdRunner.RunCommands[0]).To(Equal([]string{"file", "/test/file.tar"}))
})

It("handles file command output with extra whitespace", func() {
cmdRunner := fakesys.NewFakeCmdRunner()
compressor := NewTarballCompressor(cmdRunner, fs)

// Mock the file command output with extra whitespace
cmdRunner.AddCmdResult("file /test/file.tar", fakesys.FakeCmdResult{
Stdout: " /test/file.tar: POSIX tar archive \n",
Stderr: "",
ExitStatus: 0,
})

result, err := compressor.IsNonCompressedTarball("/test/file.tar")
Expect(err).ToNot(HaveOccurred())
Expect(result).To(BeTrue())

Expect(1).To(Equal(len(cmdRunner.RunCommands)))
Expect(cmdRunner.RunCommands[0]).To(Equal([]string{"file", "/test/file.tar"}))
})
})

Describe("CleanUp", func() {
It("removes tarball path", func() {
fs := fakesys.NewFakeFileSystem()
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