find: fix visiting of files with inode number Zero

On GNU/Hurd, the value 0 is a valid inode number, and is e.g. used
for /dev/console and /dev/tty.  The find(1) program aborted on this
platform when the user specified the -inum test and when the search
visited such a file.

  $ find /dev/null /dev/tty -inum 40799 -printf '%i:%p\n'
  40799:/dev/null
  find: util.c:330: get_info: Assertion `p->st_ino' failed.
  Aborted

Likewise, 'find -printf %i' aborted when hitting such a file.

* find/defs.h (get_info): Remove declaration.
* find/pred.c (pred_inum): Remove the redundant assert for ST_INO
as parse_inum sets need_inum=true which ensures that the inode number
is known.
* find/util.c (get_info): Declare static, and simplify: remove the
assertions for the inode number and file type.
While at it, add condition !state.have_stat in the need_stat case
for consistency.
* tests/find/inode-zero.sh: Add test.
* tests/local.mk (all_tests): Reference it.

Problem introduced by the inum optimisation in commit 2bf001636e6.

Reported by Andrea Monaco <andrea.monaco@autistici.org> in
https://lists.gnu.org/r/bug-findutils/2021-12/msg00008.html

1 files changed, 54 insertions, 0 deletions

diff --git a/tests/find/inode-zero.sh b/tests/find/inode-zero.sh
new file mode 100755
index 00000000..7bfc2698
--- /dev/null
+++ b/tests/find/inode-zero.sh
@@ -0,0 +1,54 @@
+#!/bin/sh
+# Ensure find(1) treats inode number 0 correctly.
+
+# Copyright (C) 2021 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/>.
+
+. "${srcdir=.}/tests/init.sh"; fu_path_prepend_
+print_ver_ find
+
+# Skip test unless we find a file with inode number 0.
+# GNU/Hurd uses inode 0 for /dev/console.
+f='/dev/console'
+test -e "${f}" \
+  && ino=$( stat -c '%i' "${f}" ) \
+  && test "${ino}" = '0' \
+  || skip_ "no file with inode number 0 here"
+
+echo "${f}" > exp || framework_failure_
+
+# Ensure -inum works.
+# Find by exact inode number 0.
+find "${f}" -inum 0 >out 2>err || fail=1
+compare exp out || fail=1
+compare /dev/null err || fail=1
+
+# Find by inode number <1.
+find "${f}" -inum -1 >out 2>err || fail=1
+compare exp out || fail=1
+compare /dev/null err || fail=1
+
+# No match with unrelated inode number.
+find "${f}" -inum 12345 >out 2>err || fail=1
+compare /dev/null out || fail=1
+compare /dev/null err || fail=1
+
+# Ensure '-printf "%i"' works.
+echo 0 > exp || framework_failure_
+find "${f}" -printf '%i\n' >out 2>err || fail=1
+compare exp out || fail=1
+compare /dev/null err || fail=1
+
+Exit $fail