From c7599d323b369df6dd25b93955f62f8674e6cac6 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Sat, 6 Jun 2020 22:13:48 -0700
Subject: [PATCH] fix: throw error if symmetry cannot be obtained (#9780)

For example `{1...17}/{1...52}` symmetrical
distribution of drives cannot be obtained

- Because 17 is a prime number
- Is not divisible by any pre-defined setCounts i.e
  from 1 to 16
---
 cmd/endpoint-ellipses.go      |  5 +++++
 cmd/endpoint-ellipses_test.go | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/cmd/endpoint-ellipses.go b/cmd/endpoint-ellipses.go
index b7a9f2486..92e8b224b 100644
--- a/cmd/endpoint-ellipses.go
+++ b/cmd/endpoint-ellipses.go
@@ -181,6 +181,11 @@ func getSetIndexes(args []string, totalSizes []uint64, customSetDriveCount uint6
 		// Returns possible set counts with symmetry.
 		setCounts = possibleSetCountsWithSymmetry(setCounts, argPatterns)
 
+		if len(setCounts) == 0 {
+			msg := fmt.Sprintf("No symmetric distribution detected with input endpoints provided %s, disks %d cannot be spread symmetrically by any supported erasure set sizes %d", args, commonSize, setSizes)
+			return nil, config.ErrInvalidNumberOfErasureEndpoints(nil).Msg(msg)
+		}
+
 		// Final set size with all the symmetry accounted for.
 		setSize = commonSetDriveCount(commonSize, setCounts)
 	}
diff --git a/cmd/endpoint-ellipses_test.go b/cmd/endpoint-ellipses_test.go
index f73d776a4..14cf07f71 100644
--- a/cmd/endpoint-ellipses_test.go
+++ b/cmd/endpoint-ellipses_test.go
@@ -211,6 +211,12 @@ func TestGetSetIndexes(t *testing.T) {
 			nil,
 			false,
 		},
+		{
+			[]string{"data{1...17}/export{1...52}"},
+			[]uint64{14144},
+			nil,
+			false,
+		},
 		// Valid inputs.
 		{
 			[]string{"data{1...27}"},
@@ -272,6 +278,12 @@ func TestGetSetIndexes(t *testing.T) {
 			[][]uint64{{10}, {10}, {10}},
 			true,
 		},
+		{
+			[]string{"data{1...16}/export{1...52}"},
+			[]uint64{832},
+			[][]uint64{{16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16}},
+			true,
+		},
 	}
 
 	for _, testCase := range testCases {