feat: Added CopyFile from PR 12508

util/argo/argo.go

@@ -8,6 +8,8 @@ import (
 	"sort"
 	"strings"
 	"time"
+	"os"
+	goio "io"
 
 	"github.com/argoproj/gitops-engine/pkg/cache"
 	"github.com/argoproj/gitops-engine/pkg/utils/kube"
@@ -1003,3 +1005,29 @@ func IsValidContainerName(name string) bool {
 	validationErrors := apimachineryvalidation.NameIsDNSLabel(name, false)
 	return len(validationErrors) == 0
 }
+
+// CopyFile has os.filemode, because despite currently (PR12508) we only need to
+// copy files from appsrc repo to repo, being restricted to non-exec files,
+// later it could be used to replace copying the cmp server with /bin/cp,
+// therefore removing the dependency on one of the cli tools (going distroless)
+func CopyFile(srcFile string, dstFile string, perm os.FileMode) error {
+	log.WithFields(log.Fields{
+		"srcFile": srcFile,
+		"dstFile": dstFile,
+		"perm": perm,
+	}).Debugf("CopyFile called")
+	src, err := os.OpenFile(srcFile, os.O_RDONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer src.Close()
+
+	dst, err := os.OpenFile(dstFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
+	if err != nil {
+		return err
+	}
+	defer dst.Close()
+
+	_, err = goio.Copy(dst, src)
+	return err
+}

util/argo/argo_test.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"path/filepath"
 	"testing"
+	"os"
+	"hash/fnv"
 
 	"github.com/argoproj/gitops-engine/pkg/utils/kube"
 	"github.com/argoproj/gitops-engine/pkg/utils/kube/kubetest"
@@ -1328,3 +1330,48 @@ func TestValidatePermissionsMultipleSources(t *testing.T) {
 		assert.Len(t, conditions, 0)
 	})
 }
+
+func TestCopyFile(t *testing.T) {
+
+	// check the testdir first
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("Unable to get cwd: %v", err)
+	}
+
+	testdir := filepath.Join(cwd, "testdata")
+	_, err = os.Lstat(testdir)
+	if err != nil {
+		t.Fatalf("Unable to stat testdir: %v", err)
+	}
+
+	srcFile := filepath.Join(testdir, "copyfile.src")
+	// calculate the src file's checksum
+	srcdata, err := os.ReadFile(srcFile)
+	if err != nil {
+		t.Fatalf("Unable to read testfile: %v", err)
+	}
+	srch := fnv.New32a()
+	_, _ = srch.Write(srcdata)
+	srchash := srch.Sum32()
+
+	// copy it over
+	dstFile := fmt.Sprintf("%s-dstcheck", srcFile)
+	err = CopyFile(srcFile, dstFile, 0644)
+	defer os.Remove(dstFile)
+	if err != nil {
+		t.Fatalf("CopyFile failed: %v", err)
+	}
+
+	// calculate the dst checksum
+	// calculate the src file's checksum
+	dstdata, err := os.ReadFile(dstFile)
+	if err != nil {
+		t.Fatalf("Unable to read testfile dest: %v", err)
+	}
+	dsth := fnv.New32a()
+	_, _ = dsth.Write(dstdata)
+	dsthash := dsth.Sum32()
+
+	assert.Equal(t, srchash, dsthash)
+}