cksum: validate options more consistently

pixelb · pixelb · commit 9200747f65e3 · 2026-01-08T16:14:57.000Z
We disallow `cksum --tag --check` which is fine, but the error should be consistent with md5sum, and less confusing, as it currently mentions "--binary" and "--text" which weren't specified. We disallow `cksum --tag --text` which is fine, but we should also disallow `cksum --text --tag`. We should honor an explicit --binary (output *) with this combination of options: cksum --binary --tag --untagged -a md5 /dev/null Note this also makes both of `cksum -a md5` and `cksum --tag -a md5` consistently use binary mode when reading from a tty on systems like MinGW where O_BINARY is set. * src/cksum.c (main): Adjust --text,--binary and --tag,--untagged option processing. * tests/cksum/cksum-a.sh: Add test cases. * tests/cksum/cksum-c.sh: Likewise. * NEWS: Mention the improvement. Fixes #163
diff --git a/NEWS b/NEWS
@@ -70,6 +70,9 @@ GNU coreutils NEWS                                    -*- outline -*-
   is reduced in size by 3.2% through the more efficient reuse of the cksum
   utility by the md5sum and sha*sum utilities.
 
+  'cksum' now validates its options more consistently.
+  E.g., `cksum --text --tag` now fails like `cksum --tag --text` already did.
+
   csplit, ls, and sort, now handle a more complete set of terminating signals.
 
   'du' now processes directories with 10,000 or more entries up to 9 times
diff --git a/src/cksum.c b/src/cksum.c
@@ -1623,14 +1623,11 @@ main (int argc, char **argv)
         raw_digest = true;
         break;
       case UNTAG_OPTION:
-        if (prefix_tag == 1)
-          binary = -1;
         prefix_tag = 0;
         break;
 # endif
       case TAG_OPTION:
         prefix_tag = 1;
-        binary = 1;
         break;
       case 'z':
         digest_delim = '\0';
@@ -1735,38 +1732,20 @@ main (int argc, char **argv)
    }
 #endif
 
-  if (prefix_tag == -1)
-    prefix_tag = HASH_ALGO_CKSUM;
-
-  if (prefix_tag && !binary)
-   {
-     /* This could be supported in a backwards compatible way
-        by prefixing the output line with a space in text mode.
-        However that's invasive enough that it was agreed to
-        not support this mode with --tag, as --text use cases
-        are adequately supported by the default output format.  */
-#if !HASH_ALGO_CKSUM
-     error (0, 0, _("--tag does not support --text mode"));
-#else
-     error (0, 0, _("--text mode is only supported with --untagged"));
-#endif
-     usage (EXIT_FAILURE);
-   }
-
   if (digest_delim != '\n' && do_check)
     {
       error (0, 0, _("the --zero option is not supported when "
                      "verifying checksums"));
       usage (EXIT_FAILURE);
     }
-#if !HASH_ALGO_CKSUM
-  if (prefix_tag && do_check)
+  if (1 <= prefix_tag && do_check)
     {
+      /* Note we allow --untagged with --check to more
+         seamlessly support --untagged in an emulation wrapper.  */
       error (0, 0, _("the --tag option is meaningless when "
                      "verifying checksums"));
       usage (EXIT_FAILURE);
     }
-#endif
 
   if (0 <= binary && do_check)
     {
@@ -1811,8 +1790,28 @@ main (int argc, char **argv)
      usage (EXIT_FAILURE);
    }
 
+  if (prefix_tag == -1)
+    prefix_tag = HASH_ALGO_CKSUM;
+
+  if (prefix_tag && !binary)
+   {
+     /* This could be supported in a backwards compatible way
+        by prefixing the output line with a space in text mode.
+        However that's invasive enough that it was agreed to
+        not support this mode with --tag, as --text use cases
+        are adequately supported by the default output format.  */
+#if !HASH_ALGO_CKSUM
+     error (0, 0, _("--tag does not support --text mode"));
+#else
+     error (0, 0, _("--text mode is only supported with --untagged"));
+#endif
+     usage (EXIT_FAILURE);
+   }
+
   if (!O_BINARY && binary < 0)
     binary = 0;
+  else if (prefix_tag)
+    binary = 1;
 
   char **operand_lim = argv + argc;
   if (optind == argc)
diff --git a/tests/cksum/cksum-a.sh b/tests/cksum/cksum-a.sh
@@ -68,20 +68,23 @@ returns_ 1 cksum -a bsd --check </dev/null || fail=1
 # Ensure abbreviations not supported for algorithm selection
 returns_ 1 cksum -a sha22 </dev/null || fail=1
 
+# Ensure --text and --tag combo is disallowed
+returns_ 1 cksum --text --tag -a md5 </dev/null || fail=1
+returns_ 1 cksum --tag --text -a md5 </dev/null || fail=1
+
 # Ensure --tag -> --untagged transition resets binary indicator
 cksum --tag --untagged -a md5 /dev/null >out-1 || fail=1
-# --binary ignored in this edge case
-cksum --binary --tag --untagged -a md5 /dev/null >out-2 || fail=1
 # base case for comparison
 cksum --untagged -a md5 /dev/null >out || fail=1
 compare out out-1 || fail=1
-compare out out-2 || fail=1
 
 # check that the '*' is present
 cksum --tag --untagged --binary -a md5 /dev/null >out || fail=1
 grep " *" out >/dev/null || { fail=1; cat out; }
 # Verify that the order does not reset binary indicator
 cksum --binary --untagged -a md5 /dev/null >out-1 || fail=1
 compare out out-1 || fail=1
+cksum --binary --tag --untagged -a md5 /dev/null >out-2 || fail=1
+compare out out-2 || fail=1
 
 Exit $fail
diff --git a/tests/cksum/cksum-c.sh b/tests/cksum/cksum-c.sh
@@ -192,4 +192,13 @@ touch empty-1 empty-2 || framework_failure_
 cksum --check empty-1 empty-2 > out 2>&1 && fail=1
 grep 'empty-1: no properly formatted checksum lines found' out || fail=1
 grep 'empty-2: no properly formatted checksum lines found' out || fail=1
+
+
+# Disallow --tag --check, with appropriate error
+returns_ 1 cksum --tag --check /dev/null 2> err
+grep 'the --tag option is meaningless when verifying checksums' err || fail=1
+# Allow --untagged --check, to better support
+# an emulation wrapper for legacy *sum utils.
+cksum -a md5 /dev/null | cksum --untagged --check || fail=1
+
 Exit $fail
