From 187d5bbba52d6233cd132af68d35a57ca0459f55 Mon Sep 17 00:00:00 2001
From: Gustavo Lima <gustcol@gmail.com>
Date: Sun, 12 Apr 2026 15:36:34 +0200
Subject: [PATCH] fix(cp): apply --destination-region in shouldOverride for
 --no-clobber

Fixes #839

shouldOverride performs a HEAD request on the destination object to
decide whether to skip the copy.  doUpload and doCopy both called
c.storageOpts.SetRegion(c.dstRegion) before creating the destination
client, but shouldOverride did not.  When --destination-region is set
and the bucket lives in a non-default region, the HEAD was signed for
the wrong region, producing HTTP 400 AuthorizationHeaderMalformed.

Fix: derive a local dstOpts copy inside shouldOverride and set the
region on it before constructing the destination client, matching the
pattern already used in doUpload and doCopy.

Reproducer:
  s5cmd cp --no-clobber --destination-region eu-central-1 \
    local.txt s3://eu-bucket/object.txt
  # Fails: AWS Error: AuthorizationHeaderMalformed (400)

After this change:
  HEAD request is signed for eu-central-1; --no-clobber works correctly.
---
 command/cp.go      |  9 ++++++++-
 command/cp_test.go | 31 +++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/command/cp.go b/command/cp.go
index 7ed06bfee..99b2f474a 100644
--- a/command/cp.go
+++ b/command/cp.go
@@ -864,7 +864,14 @@ func (c Copy) shouldOverride(ctx context.Context, srcurl *url.URL, dsturl *url.U
 		return err
 	}
 
-	dstClient, err := storage.NewClient(ctx, dsturl, c.storageOpts)
+	// Apply destination-region override so the HEAD request is signed for the
+	// correct region. Without this, --no-clobber with --destination-region
+	// sends a mis-signed HEAD that returns HTTP 400 AuthorizationHeaderMalformed.
+	dstOpts := c.storageOpts
+	if c.dstRegion != "" {
+		dstOpts.SetRegion(c.dstRegion)
+	}
+	dstClient, err := storage.NewClient(ctx, dsturl, dstOpts)
 	if err != nil {
 		return err
 	}
diff --git a/command/cp_test.go b/command/cp_test.go
index ccac38ff3..8039a9041 100644
--- a/command/cp_test.go
+++ b/command/cp_test.go
@@ -1,13 +1,44 @@
 package command
 
 import (
+	"context"
 	"io"
 	"os"
 	"testing"
 
 	"gotest.tools/v3/assert"
+
+	"github.com/peak/s5cmd/v2/storage"
+	"github.com/peak/s5cmd/v2/storage/url"
 )
 
+// TestShouldOverride_NoFlagsIsNoop verifies that shouldOverride returns nil
+// immediately when none of the override-gating flags are set. This confirms
+// the fast-path remains intact and also serves as a compile-time check that
+// the Copy struct fields referenced by shouldOverride (including dstRegion)
+// are spelled correctly.
+func TestShouldOverride_NoFlagsIsNoop(t *testing.T) {
+	t.Parallel()
+
+	srcURL, _ := url.New("s3://bucket/src.txt")
+	dstURL, _ := url.New("s3://bucket/dst.txt")
+
+	c := Copy{
+		noClobber:     false,
+		ifSizeDiffer:  false,
+		ifSourceNewer: false,
+		// dstRegion is set; the fix ensures it would be forwarded to dstOpts
+		// when the function proceeds past the early return.
+		dstRegion:   "us-west-2",
+		storageOpts: storage.Options{},
+	}
+
+	// shouldOverride must return nil (no-op) when no override flag is set.
+	if err := c.shouldOverride(context.Background(), srcURL, dstURL); err != nil {
+		t.Errorf("expected nil when no override flags set, got %v", err)
+	}
+}
+
 func TestGuessContentType(t *testing.T) {
 	t.Parallel()