On 08/08/2012 06:14 PM, Pádraig Brady wrote: > But then it won't fail. It's tricky :)
I thought about that case again, and to me something's still wrong when mtab is missing. When mtab cannot be read, then df cannot determine the file system type. Example (/tmp/mnt is an nfs mount): $ src/df -T /tmp/mnt ; echo $? src/df: Warning: cannot read table of mounted file systems: No such file or directory Filesystem Type 1K-blocks Used Available Use% Mounted on - - 155527168 114567680 33058816 78% /tmp/mnt 0 I think $? == 0 is okay for this case. $ src/df -t hello /tmp/mnt ; echo $? src/df: Warning: cannot read table of mounted file systems: No such file or directory Filesystem 1K-blocks Used Available Use% Mounted on - 155527168 114567680 33058816 78% /tmp/mnt 0 $ src/df -x nfs /tmp/mnt ; echo $? src/df: Warning: cannot read table of mounted file systems: No such file or directory Filesystem 1K-blocks Used Available Use% Mounted on - 155527168 114567680 33058816 78% /tmp/mnt 0 But in the case -t/-x I believe that df should exit(1). The same applies to -a and -l. Here's a proposed patch. Have a nice day, Berny >From 32e3007a8cab32484e4e312ceb1784f6ad1d396f Mon Sep 17 00:00:00 2001 From: Bernhard Voelker <[email protected]> Date: Thu, 9 Aug 2012 13:46:30 +0200 Subject: [PATCH] df: fail when the mount list cannot be read but is needed * src/df.c (main): Add conditions to fail when the mount list cannot be read: this includes the cases when a file name argument is given and either of -a, -l -t or -x is used. * doc/coreutils.texi: Document the additional error conditions. * tests/df/no-mtab-status: Add a new test. * tests/Makefile.am: Reference the new test. * NEWS: Mention the fix. --- NEWS | 5 +++ doc/coreutils.texi | 5 +++ src/df.c | 18 ++++++++-- tests/Makefile.am | 1 + tests/df/no-mtab-status | 81 +++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 106 insertions(+), 4 deletions(-) create mode 100755 tests/df/no-mtab-status diff --git a/NEWS b/NEWS index ca4568a..d0d462c 100644 --- a/NEWS +++ b/NEWS @@ -22,6 +22,11 @@ GNU coreutils NEWS -*- outline -*- file system --type options do not lead to a processed file system. [This bug dates back to when --total was added in coreutils-7.0] + df now fails in cases when the list of mounted file systems (/etc/mtab) + cannot be read but the file system type information is needed to process + certain options like -a, -l, -t and -x. + [This bug was present in "the beginning".] + head --lines=-N (-n-N) now resets the read pointer of a seekable input file. This means that "head -n-3" no longer consumes all of its input, and lines not output by head may be processed by other programs. For example, this diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 516ec73..2fe0dd3 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -10754,6 +10754,11 @@ inspect the exit status of a command like @samp{df -t ext3 -t reiserfs @var{dir}} to test whether @var{dir} is on a file system of type @samp{ext3} or @samp{reiserfs}. +As the list of file systems (@var{mtab}) is needed to determine the +file system type, failure includes the cases when that list cannot +be read and either of the options @option{-a}, @option{-l}, @option{-t} +or @option{-x} is used together with a file name argument. + @node du invocation @section @command{du}: Estimate file space usage diff --git a/src/df.c b/src/df.c index 4f3b56b..a2e6866 100644 --- a/src/df.c +++ b/src/df.c @@ -1100,10 +1100,20 @@ main (int argc, char **argv) if (mount_list == NULL) { /* Couldn't read the table of mounted file systems. - Fail if df was invoked with no file name arguments; - Otherwise, merely give a warning and proceed. */ - int status = (optind < argc ? 0 : EXIT_FAILURE); - const char *warning = (optind < argc ? _("Warning: ") : ""); + Fail if df was invoked with no file name arguments, + or when either of -a, -l, -t or -x is used with file name + arguments. Otherwise, merely give a warning and proceed. */ + int status = 0; + if ( !(optind < argc) + ||(optind < argc + && (show_all_fs + || show_local_fs + || fs_select_list != NULL + || fs_exclude_list != NULL))) + { + status = EXIT_FAILURE; + } + const char *warning = (status == 0 ? _("Warning: ") : ""); error (status, errno, "%s%s", warning, _("cannot read table of mounted file systems")); } diff --git a/tests/Makefile.am b/tests/Makefile.am index edc04b4..273405f 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -376,6 +376,7 @@ TESTS = \ df/df-P \ df/unreadable \ df/total-unprocessed \ + df/no-mtab-status \ dd/direct \ dd/misc \ dd/nocache \ diff --git a/tests/df/no-mtab-status b/tests/df/no-mtab-status new file mode 100755 index 0000000..f568842 --- /dev/null +++ b/tests/df/no-mtab-status @@ -0,0 +1,81 @@ +#!/bin/sh +# Test df's behaviour when the mount list cannot be read. +# This test is skipped on systems that lack LD_PRELOAD support; that's fine. + +# Copyright (C) 2012 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 <http://www.gnu.org/licenses/>. + +. "${srcdir=.}/init.sh"; path_prepend_ ../src +print_ver_ df + +df || skip_ "df fails" + +# Simulate "mtab" failure. +cat > k.c <<'EOF' || framework_failure_ +#include <stdio.h> +#include <errno.h> + +struct mntent *getmntent(FILE *fp) +{ + /* Prove that LD_PRELOAD works. */ + static int done = 0; + if (!done) + { + fclose (fopen ("x", "w")); + ++done; + } + /* Now simulate the failure. */ + errno = ENOENT; + return NULL; +} +EOF + +# Then compile/link it: +$CC -shared -fPIC -ldl -O2 k.c -o k.so \ + || framework_failure_ 'failed to compile with -shared -fPIC' + +cp k.so /tmp + +# Test if LD_PRELOAD works: +LD_PRELOAD=./k.so df +test -f x || skip_ "internal test failure: maybe LD_PRELOAD doesn't work?" + +# These tests are supposed to succeed: +LD_PRELOAD=./k.so df '.' || fail=1 +LD_PRELOAD=./k.so df -i '.' || fail=1 +LD_PRELOAD=./k.so df -T '.' || fail=1 +LD_PRELOAD=./k.so df -Ti '.' || fail=1 +LD_PRELOAD=./k.so df --total '.' || fail=1 + +# These tests are supposed to fail: +LD_PRELOAD=./k.so df && fail=1 +LD_PRELOAD=./k.so df -i && fail=1 +LD_PRELOAD=./k.so df -T && fail=1 +LD_PRELOAD=./k.so df -Ti && fail=1 +LD_PRELOAD=./k.so df --total || fail=1 + +LD_PRELOAD=./k.so df -a && fail=1 +LD_PRELOAD=./k.so df -a '.' && fail=1 + +LD_PRELOAD=./k.so df -l && fail=1 +LD_PRELOAD=./k.so df -l '.' && fail=1 + +LD_PRELOAD=./k.so df -t hello && fail=1 +LD_PRELOAD=./k.so df -t hello '.' && fail=1 + +LD_PRELOAD=./k.so df -x hello && fail=1 +LD_PRELOAD=./k.so df -x hello '.' && fail=1 + +Exit $fail -- 1.7.7
