Avoid collisions on RemoteSocket paths

Add lock files and re-generate the UUID if we
are not a known-unique user of the socket path.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

3 files changed, 27 insertions, 2 deletions

diff --git a/test/e2e/common_test.go b/test/e2e/common_test.go
index 456e2bab1..bd744aa78 100644
--- a/test/e2e/common_test.go
+++ b/test/e2e/common_test.go
@@ -281,8 +281,26 @@ func PodmanTestCreateUtil(tempDir string, remote bool) *PodmanTestIntegration {
 			runtimeDir := os.Getenv("XDG_RUNTIME_DIR")
 			pathPrefix = filepath.Join(runtimeDir, "podman")
 		}
-		uuid := stringid.GenerateNonCryptoID()
-		p.RemoteSocket = fmt.Sprintf("unix:%s-%s.sock", pathPrefix, uuid)
+		// We want to avoid collisions in socket paths, but using the
+		// socket directly for a collision check doesn’t work; bind(2) on AF_UNIX
+		// creates the file, and we need to pass a unique path now before the bind(2)
+		// happens. So, use a podman-%s.sock-lock empty file as a marker.
+		tries := 0
+		for {
+			uuid := stringid.GenerateNonCryptoID()
+			lockPath := fmt.Sprintf("%s-%s.sock-lock", pathPrefix, uuid)
+			lockFile, err := os.OpenFile(lockPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0700)
+			if err == nil {
+				lockFile.Close()
+				p.RemoteSocketLock = lockPath
+				p.RemoteSocket = fmt.Sprintf("unix:%s-%s.sock", pathPrefix, uuid)
+				break
+			}
+			tries++
+			if tries >= 1000 {
+				panic("Too many RemoteSocket collisions")
+			}
+		}
 	}
 
 	// Setup registries.conf ENV variable
diff --git a/test/e2e/libpod_suite_remote_test.go b/test/e2e/libpod_suite_remote_test.go
index d60383029..4644e3748 100644
--- a/test/e2e/libpod_suite_remote_test.go
+++ b/test/e2e/libpod_suite_remote_test.go
@@ -1,3 +1,4 @@
+//go:build remote
 // +build remote
 
 package integration
@@ -143,6 +144,11 @@ func (p *PodmanTestIntegration) StopRemoteService() {
 	if err := os.Remove(socket); err != nil {
 		fmt.Println(err)
 	}
+	if p.RemoteSocketLock != "" {
+		if err := os.Remove(p.RemoteSocketLock); err != nil {
+			fmt.Println(err)
+		}
+	}
 }
 
 //MakeOptions assembles all the podman main options
diff --git a/test/utils/utils.go b/test/utils/utils.go
index f41024072..a73bdb856 100644
--- a/test/utils/utils.go
+++ b/test/utils/utils.go
@@ -41,6 +41,7 @@ type PodmanTest struct {
 	RemotePodmanBinary string
 	RemoteSession      *os.Process
 	RemoteSocket       string
+	RemoteSocketLock   string // If not "", should be removed _after_ RemoteSocket is removed
 	RemoteCommand      *exec.Cmd
 	ImageCacheDir      string
 	ImageCacheFS       string