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Fix fileMutator reinjecting leftovers from temporary files #43875

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Merged
dd-mergequeue merged 1 commit into from
Dec 8, 2025
Merged

Fix fileMutator reinjecting leftovers from temporary files #43875

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12 changes: 6 additions & 6 deletions pkg/fleet/installer/packages/apminject/file.go
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Original file line number Diff line number Diff line change
Expand Up @@ -61,18 +61,19 @@ func (ft *fileMutator) mutate(ctx context.Context) (rollback func() error, err e
}
originalFileExists = false
}

var data []byte
if originalFileExists {
if err := copyFile(ft.path, ft.pathBackup); err != nil {
return nil, fmt.Errorf("could not create backup file %s: %s", ft.pathBackup, err)
}
if err := copyFile(ft.pathBackup, ft.pathTmp); err != nil {
return nil, fmt.Errorf("could not create temporary file %s: %s", ft.pathTmp, err)
}
}

data, err := os.ReadFile(ft.pathTmp)
if err != nil && !os.IsNotExist(err) {
return nil, fmt.Errorf("could not read file %s: %s", ft.pathTmp, err)
data, err = os.ReadFile(ft.pathTmp)
if err != nil {
return nil, fmt.Errorf("could not read file %s: %s", ft.pathTmp, err)
}
}

res, err := ft.transformContent(ctx, data)
Expand All @@ -87,7 +88,6 @@ func (ft *fileMutator) mutate(ctx context.Context) (rollback func() error, err e

if err = writeFile(ft.pathTmp, res); err != nil {
return nil, fmt.Errorf("could not write file %s: %s", ft.pathTmp, err)

}

// validate temporary file if validation function provided
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18 changes: 18 additions & 0 deletions pkg/fleet/installer/packages/apminject/file_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,24 @@ func TestFileTransformWithRollback_No_original(t *testing.T) {
assertNoExists(t, originalPath)
}

// TestFileTransform_No_original_ignores_leftovers verifies that when the original file doesn't exist,
// leftover temporary files from previous operations are ignored and don't pollute the transformation.
func TestFileTransform_No_original_ignores_leftovers(t *testing.T) {
originalPath := t.TempDir() + "/original.txt"

mutator := newFileMutator(originalPath, func(_ context.Context, data []byte) ([]byte, error) {
return append(data, []byte(transformedContent)...), nil // append to reflect any leftover
}, nil, nil)

require.NoError(t, os.WriteFile(mutator.pathTmp, []byte("[leftover]"), 0644))

rollback, err := mutator.mutate(context.TODO())
require.NoError(t, err)
require.NotNil(t, rollback)

assertFile(t, originalPath, transformedContent, detectDefaultMode(t))
}

func detectDefaultMode(t *testing.T) os.FileMode {
tmpDir := t.TempDir()
f, err := os.OpenFile(filepath.Join(tmpDir, "find_mode"), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
Expand Down