find: fix error diagnostics of options with mandatory, numeric arguments

The error diagnostic for wrong invocations with option that require
numeric arguments (-inum, -links, -gid, -uid) was wrong and not helpful:
  $ find -gid
  find: invalid argument `-gid' to `-gid'

* find/parser.c (parse_gid): Remove changing back of the ARG_PTR in
the error case; thus simplify.
(parse_inum,parse_links,parse_uid): Likewise.
(get_num): While at it, mention -gid and -uid in the comment as well.
(insert_num): Also improve the error diagnostic in the case the user
has provided a non-numeric argument.  Previously, it was just "invalid
argument".
* tests/find/opt-numeric-arg.sh: Add test.
* tests/local.mk: Reference it.
* NEWS (Bug Fixes): Mention the fix.

Reported by Andreas Schwab <schwab@linux-m68k.org> in
<https://lists.gnu.org/r/bug-findutils/2023-01/msg00001.html>

4 files changed, 55 insertions, 21 deletions

diff --git a/NEWS b/NEWS
index c43297c6..e9a2dae9 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,11 @@ GNU findutils NEWS - User visible changes.      -*- outline -*- (allout)
   to match the root directory "/".  Previously, a diagnostic falsely claimed
   that this pattern would not match anything. [#62227]
 
+  'find -gid' (without the mandatory argument) now outputs a correct error
+  diagnostic.  Previously it output: "find: invalid argument `-gid' to `-gid'".
+  The error diagnostic for non-numeric arguments has been improved as well.
+  Likewise for -inum, -links and -uid.
+
 ** Changes to the build process
 
   findutils now builds again on systems with musl-libc.
diff --git a/find/parser.c b/find/parser.c
index f1fe7408..78c3f969 100644
--- a/find/parser.c
+++ b/find/parser.c
@@ -1127,11 +1127,7 @@ parse_gid (const struct parser_table* entry, char **argv, int *arg_ptr)
       p->est_success_rate = (p->args.numinfo.l_val < 100) ? 0.99 : 0.2;
       return true;
     }
-  else
-    {
-      --*arg_ptr;		/* don't consume the invalid argument. */
-      return false;
-    }
+  return false;
 }
 
 
@@ -1319,11 +1315,7 @@ parse_inum (const struct parser_table* entry, char **argv, int *arg_ptr)
       p->need_type = false;
       return true;
     }
-  else
-    {
-      --*arg_ptr;		/* don't consume the invalid argument. */
-      return false;
-    }
+  return false;
 }
 
 static bool
@@ -1346,11 +1338,7 @@ parse_links (const struct parser_table* entry, char **argv, int *arg_ptr)
 	p->est_success_rate = 1e-3;
       return true;
     }
-  else
-    {
-      --*arg_ptr;		/* don't consume the invalid argument. */
-      return false;
-    }
+  return false;
 }
 
 static bool
@@ -2415,11 +2403,7 @@ parse_uid (const struct parser_table* entry, char **argv, int *arg_ptr)
       p->est_success_rate = (p->args.numinfo.l_val < 100) ? 0.99 : 0.2;
       return true;
     }
-  else
-    {
-      --*arg_ptr;		/* don't consume the invalid argument. */
-      return false;
-    }
+  return false;
 }
 
 static bool
@@ -3334,7 +3318,7 @@ get_num (const char *str,
    A new predicate node is assigned, along with an argument node
    obtained with malloc.
 
-   Used by -inum and -links parsers. */
+   Used by -inum, -uid, -gid and -links parsers. */
 
 static struct predicate *
 insert_num (char **argv, int *arg_ptr, const struct parser_table *entry)
@@ -3364,6 +3348,16 @@ insert_num (char **argv, int *arg_ptr, const struct parser_table *entry)
 	  }
 	return our_pred;
       }
+    else
+      {
+	const char *predicate = argv[(*arg_ptr)-2];
+	die (EXIT_FAILURE, 0,
+	     _("non-numeric argument to %s: %s"),
+	     predicate,
+	     quotearg_n_style (0, options.err_quoting_style, numstr));
+	/*NOTREACHED*/
+	return NULL;
+      }
   }
   return NULL;
 }
diff --git a/tests/find/opt-numeric-arg.sh b/tests/find/opt-numeric-arg.sh
new file mode 100755
index 00000000..bbf0dd8c
--- /dev/null
+++ b/tests/find/opt-numeric-arg.sh
@@ -0,0 +1,34 @@
+#!/bin/sh
+# Exercise error diagnostics for options with mandatory numeric arguments.
+
+# Copyright (C) 2023 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; fu_path_prepend_
+print_ver_ find
+
+for o in -inum -links -uid -gid; do
+  # Check error diagnosic for missing argument.
+  returns_ 1 find $o >out 2>err || fail=1
+  compare /dev/null out || fail=1
+  grep -F 'missing argument to' err || { fail=1; cat err; }
+
+  # Check error diagnosic for non-numeric argument.
+  returns_ 1 find $o foo >out 2>err || fail=1
+  compare /dev/null out || fail=1
+  grep -F 'non-numeric argument to' err || { fail=1; cat err; }
+done
+
+Exit $fail
diff --git a/tests/local.mk b/tests/local.mk
index 45a1cc73..ff4dd909 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -121,6 +121,7 @@ all_tests = \
   tests/find/debug-missing-arg.sh \
   tests/find/used.sh \
   tests/find/newer.sh \
+  tests/find/opt-numeric-arg.sh \
   tests/xargs/conflicting_opts.sh \
   tests/xargs/verbose-quote.sh \
   $(all_root_tests)