--- usr.bin/diff/diff.h.orig	2021-01-06 05:22:41.672124000 +0000
+++ usr.bin/diff/diff.h	2021-01-06 05:34:02.134227000 +0000
@@ -83,6 +83,7 @@
 #define	D_MISMATCH2	4	/* path1 was a file, path2 a dir */
 #define	D_SKIPPED1	5	/* path1 was a special file */
 #define	D_SKIPPED2	6	/* path2 was a special file */
+#define	D_ERROR		7	/* A file access error occurred */
 
 struct excludes {
 	char *pattern;
--- usr.bin/diff/diff.c.orig	2021-01-06 05:22:41.672067000 +0000
+++ usr.bin/diff/diff.c	2021-01-06 05:35:11.308546000 +0000
@@ -511,6 +511,8 @@
 		printf("File %s%s is not a regular file or directory and was skipped\n",
 		    path2, entry);
 		break;
+	case D_ERROR:
+		break;
 	}
 }
 
--- usr.bin/diff/diffreg.c.orig	2021-01-06 05:22:41.672285000 +0000
+++ usr.bin/diff/diffreg.c	2021-01-06 05:38:33.991406000 +0000
@@ -299,6 +299,7 @@
 			if ((f1 = opentemp(file1)) == NULL ||
 			    fstat(fileno(f1), &stb1) == -1) {
 				warn("%s", file1);
+				rval = D_ERROR;
 				status |= 2;
 				goto closem;
 			}
@@ -309,6 +310,7 @@
 	}
 	if (f1 == NULL) {
 		warn("%s", file1);
+		rval = D_ERROR;
 		status |= 2;
 		goto closem;
 	}
@@ -320,6 +322,7 @@
 			if ((f2 = opentemp(file2)) == NULL ||
 			    fstat(fileno(f2), &stb2) == -1) {
 				warn("%s", file2);
+				rval = D_ERROR;
 				status |= 2;
 				goto closem;
 			}
@@ -330,6 +333,7 @@
 	}
 	if (f2 == NULL) {
 		warn("%s", file2);
+		rval = D_ERROR;
 		status |= 2;
 		goto closem;
 	}
@@ -365,6 +369,7 @@
 		break;
 	default:
 		/* error */
+		rval = D_ERROR;
 		status |= 2;
 		goto closem;
 	}