From: Crystal Kolipe <kolipe.c@exoticsilicon.com>
Subject: Re: diff(1) -s option can produce erroneous positives
To: "Todd C. Miller" <millert@openbsd.org>
Cc: tech@openbsd.org
Date: Tue, 21 Jul 2026 18:26:31 -0000

On Mon, Jul 20, 2026 at 09:34:39AM -0600, Todd C. Miller wrote:
> This looks reasonable but I would like to see D_INDETERMINATE listed
> in the switch() in print_status() with an empty body, just to make
> it clear that this was not forgotten.

Sure, here is an updated diff with that included:

--- usr.bin/diff/diff.c.dist	Thu Apr 16 19:25:12 2026
+++ usr.bin/diff/diff.c	Tue Jul 21 13:33:46 2026
@@ -386,6 +386,8 @@
 		printf("File %s%s is not a regular file or directory and was skipped\n",
 		    path2, entry);
 		break;
+	case D_INDETERMINATE:
+		break;
 	}
 }
 
--- usr.bin/diff/diff.h
+++ usr.bin/diff/diff.h
@@ -75,6 +75,7 @@
 #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_INDETERMINATE	7	/* One or both files could not be opened */
 
 struct excludes {
 	char *pattern;
--- usr.bin/diff/diffreg.c
+++ usr.bin/diff/diffreg.c
@@ -318,6 +318,7 @@
 			    fstat(fileno(f1), &stb1) == -1) {
 				warn("%s", file1);
 				status |= 2;
+				rval = D_INDETERMINATE;
 				goto closem;
 			}
 		} else if (strcmp(file1, "-") == 0)
@@ -328,6 +329,7 @@
 	if (f1 == NULL) {
 		warn("%s", file1);
 		status |= 2;
+		rval = D_INDETERMINATE;
 		goto closem;
 	}
 
@@ -339,6 +341,7 @@
 			    fstat(fileno(f2), &stb2) == -1) {
 				warn("%s", file2);
 				status |= 2;
+				rval = D_INDETERMINATE;
 				goto closem;
 			}
 		} else if (strcmp(file2, "-") == 0)
@@ -349,6 +352,7 @@
 	if (f2 == NULL) {
 		warn("%s", file2);
 		status |= 2;
+		rval = D_INDETERMINATE;
 		goto closem;
 	}