fix: ListObjectsV2 for SSE S3 Gateway when maxKeys is 0

Makefile

@@ -10,33 +10,35 @@ TAG ?= "minio/minio:$(VERSION)"
 
 all: build
 
-checks:
+checks: ## check dependencies
 	@echo "Checking dependencies"
 	@(env bash $(PWD)/buildscripts/checkdeps.sh)
 
-getdeps:
+help: ## print this help
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' Makefile | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
+
+getdeps: ## fetch necessary dependencies
 	@mkdir -p ${GOPATH}/bin
 	@echo "Installing golangci-lint" && curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(GOPATH)/bin v1.40.1
 	@which msgp 1>/dev/null || (echo "Installing msgp" && go install -v github.com/tinylib/msgp@v1.1.3)
 	@which stringer 1>/dev/null || (echo "Installing stringer" && go install -v golang.org/x/tools/cmd/stringer)
 
-crosscompile:
+crosscompile: ## cross compile minio
 	@(env bash $(PWD)/buildscripts/cross-compile.sh)
 
 verifiers: getdeps lint check-gen
 
-check-gen:
+check-gen: ## check for updated autogenerated files
 	@go generate ./... >/dev/null
 	@(! git diff --name-only | grep '_gen.go$$') || (echo "Non-committed changes in auto-generated code is detected, please commit them to proceed." && false)
 
-lint:
+lint: ## runs golangci-lint suite of linters
 	@echo "Running $@ check"
 	@GO111MODULE=on ${GOPATH}/bin/golangci-lint cache clean
 	@GO111MODULE=on ${GOPATH}/bin/golangci-lint run --build-tags kqueue --timeout=10m --config ./.golangci.yml
 
-# Builds minio, runs the verifiers then runs the tests.
 check: test
-test: verifiers build
+test: verifiers build ## builds minio, runs linters, tests
 	@echo "Running unit tests"
 	@GOGC=25 GO111MODULE=on CGO_ENABLED=0 go test -tags kqueue ./... 1>/dev/null
 
@@ -44,20 +46,17 @@ test-race: verifiers build
 	@echo "Running unit tests under -race"
 	@(env bash $(PWD)/buildscripts/race.sh)
 
-# Verify minio binary
-verify:
+verify: ## verify minio various setups
 	@echo "Verifying build with race"
 	@GO111MODULE=on CGO_ENABLED=1 go build -race -tags kqueue -trimpath --ldflags "$(LDFLAGS)" -o $(PWD)/minio 1>/dev/null
 	@(env bash $(PWD)/buildscripts/verify-build.sh)
 
-# Verify healing of disks with minio binary
-verify-healing:
+verify-healing: ## verify healing and replacing disks with minio binary
 	@echo "Verify healing build with race"
 	@GO111MODULE=on CGO_ENABLED=1 go build -race -tags kqueue -trimpath --ldflags "$(LDFLAGS)" -o $(PWD)/minio 1>/dev/null
 	@(env bash $(PWD)/buildscripts/verify-healing.sh)
 
-# Builds minio locally.
-build: checks
+build: checks ## builds minio to $(PWD)
 	@echo "Building minio binary to './minio'"
 	@GO111MODULE=on CGO_ENABLED=0 go build -tags kqueue -trimpath --ldflags "$(LDFLAGS)" -o $(PWD)/minio 1>/dev/null
 
@@ -65,23 +64,22 @@ hotfix-vars:
 	$(eval LDFLAGS := $(shell MINIO_RELEASE="RELEASE" MINIO_HOTFIX="hotfix.$(shell git rev-parse --short HEAD)" go run buildscripts/gen-ldflags.go $(shell git describe --tags --abbrev=0 | \
     sed 's#RELEASE\.\([0-9]\+\)-\([0-9]\+\)-\([0-9]\+\)T\([0-9]\+\)-\([0-9]\+\)-\([0-9]\+\)Z#\1-\2-\3T\4:\5:\6Z#')))
 	$(eval TAG := "minio/minio:$(shell git describe --tags --abbrev=0).hotfix.$(shell git rev-parse --short HEAD)")
-hotfix: hotfix-vars install
+hotfix: hotfix-vars install ## builds minio binary with hotfix tags
 
-docker-hotfix: hotfix checks
+docker-hotfix: hotfix checks ## builds minio docker container with hotfix tags
 	@echo "Building minio docker image '$(TAG)'"
 	@docker build -t $(TAG) . -f Dockerfile.dev
 
-docker: build checks
+docker: build checks ## builds minio docker container
 	@echo "Building minio docker image '$(TAG)'"
 	@docker build -t $(TAG) . -f Dockerfile.dev
 
-# Builds minio and installs it to $GOPATH/bin.
-install: build
+install: build ## builds minio and installs it to $GOPATH/bin.
 	@echo "Installing minio binary to '$(GOPATH)/bin/minio'"
 	@mkdir -p $(GOPATH)/bin && cp -f $(PWD)/minio $(GOPATH)/bin/minio
 	@echo "Installation successful. To learn more, try \"minio --help\"."
 
-clean:
+clean: ## cleanup all generated assets
 	@echo "Cleaning up all the generated files"
 	@find . -name '*.test' | xargs rm -fv
 	@find . -name '*~' | xargs rm -fv

cmd/gateway/s3/gateway-s3-sse.go

@@ -113,7 +113,7 @@ func (l *s3EncObjects) ListObjectsV2(ctx context.Context, bucket, prefix, contin
 			} else {
 				objects = append(objects, obj)
 			}
-			if len(objects) > maxKeys {
+			if maxKeys > 0 && len(objects) > maxKeys {
 				break
 			}
 		}
@@ -130,7 +130,7 @@ func (l *s3EncObjects) ListObjectsV2(ctx context.Context, bucket, prefix, contin
 				prefixes = append(prefixes, p)
 			}
 		}
-		if (len(objects) > maxKeys) || !loi.IsTruncated {
+		if (maxKeys > 0 && len(objects) > maxKeys) || !loi.IsTruncated {
 			break
 		}
 	}