ipc: Check that service and client are the same git revision

src/xrt/ipc/client/ipc_client_instance.c

@@ -16,6 +16,7 @@
 #include "util/u_misc.h"
 #include "util/u_var.h"
 #include "util/u_debug.h"
+#include "util/u_git_tag.h"
 
 #include "shared/ipc_protocol.h"
 #include "client/ipc_client.h"
@@ -305,6 +306,13 @@ ipc_instance_create(struct xrt_instance_info *i_info, struct xrt_instance **out_
 		return -1;
 	}
 
+	if (strncmp(u_git_tag, ii->ipc_c.ism->u_git_tag, IPC_VERSION_NAME_LEN) != 0) {
+		IPC_ERROR((&ii->ipc_c), "Monado client library version %s does not match service version %s", u_git_tag,
+		          ii->ipc_c.ism->u_git_tag);
+		free(ii);
+		return -1;
+	}
+
 	uint32_t count = 0;
 	struct xrt_tracking_origin *xtrack = NULL;
 	struct ipc_shared_memory *ism = ii->ipc_c.ism;

src/xrt/ipc/server/ipc_server_process.c

@@ -23,6 +23,8 @@
 #include "util/u_verify.h"
 #include "util/u_process.h"
 
+#include "util/u_git_tag.h"
+
 #include "shared/ipc_shmem.h"
 #include "server/ipc_server.h"
 
@@ -320,6 +322,8 @@ init_shm(struct ipc_server *s)
 	// Finally tell the client how many devices we have.
 	s->ism->num_isdevs = count;
 
+	snprintf(s->ism->u_git_tag, IPC_VERSION_NAME_LEN, "%s", u_git_tag);
+
 	return 0;
 }
 

src/xrt/ipc/shared/ipc_protocol.h

@@ -37,6 +37,8 @@
 #define IPC_SHARED_MAX_OUTPUTS 128
 #define IPC_SHARED_MAX_BINDINGS 64
 
+// example: v21.0.0-560-g586d33b5
+#define IPC_VERSION_NAME_LEN 64
 
 /*
  *
@@ -174,6 +176,11 @@ struct ipc_layer_slot
  */
 struct ipc_shared_memory
 {
+	/*!
+	 * The git revision of the service, used by clients to detect version mismatches.
+	 */
+	char u_git_tag[IPC_VERSION_NAME_LEN];
+
 	/*!
 	 * Number of elements in @ref itracks that are populated/valid.
 	 */