[coreutils] [PATCH] du: don't print junk when diagnosing out-of-range time stamps

[Paul Eggert]

While looking into the inttostr issues circulated recently on
bug-gnulib, I was experimenting with an inttostr variant that I hope
will be nicer.  In the process, I discovered a bug in du, where du
uses uninitialized storage.  Here's a patch.

The tabs in the new file tests/du/bigtime should not be replaced by
spaces: hope that's OK.

There are a lot of file systems that do reeeeally flaky things
with time stamps.  For example, NetApp silently replaces out-of-range
time stamps with the nearest representable time stamp: it uses
32-bit unsigned time stamps so the year range is from 1970 to 2106.
tests/du/bigtime attempts to detect any such shortcomings, and to
apply the test to du only on hosts where file systems work correctly
on big time stamps, but localtime does not.

Conversely, it's conceivable that the file system and localtime
both support big timestamps, in which case du should not report
an error when converting.  The test also tries to detect hosts where
that is true, and to skip the test if so.  I don't know of any such
hosts, so I haven't tested that part of the script.

I haven't pushed this patch, because I don't know whether it's
safe to get back into the water after the recent coreutils release.

>From afb834402d639936977bed7db35cda48b609e46f Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Sat, 23 Oct 2010 11:54:55 -0700
Subject: [PATCH] du: don't print junk when diagnosing out-of-range time stamps

* src/du.c (show_date): Fix call to fputs with a buffer that
contains some uninitialized data.  While we're at it, print
the nanosecond part of the time stamp, too, if the file system
supports that.
* tests/Makefile.am (TESTS): Add du/big-timestamp.
* tests/du/bigtime: New file, which checks for the bug.
---
 src/du.c          |   27 ++++++++++++++++++++++++---
 tests/Makefile.am |    1 +
 tests/du/bigtime  |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 3 deletions(-)
 create mode 100755 tests/du/bigtime

diff --git a/src/du.c b/src/du.c
index 3d92579..33f2656 100644
--- a/src/du.c
+++ b/src/du.c
@@ -350,9 +350,30 @@ show_date (const char *format, struct timespec when)
   struct tm *tm = localtime (&when.tv_sec);
   if (! tm)
     {
-      char buf[INT_BUFSIZE_BOUND (intmax_t)];
-      error (0, 0, _("time %s is out of range"), timetostr (when.tv_sec, buf));
-      fputs (buf, stdout);
+      char buf[INT_BUFSIZE_BOUND (intmax_t) + 10];
+      char *when_str = timetostr (when.tv_sec, buf);
+      int nsec = when.tv_nsec;
+
+      /* Display the fraction, omitting trailing zeros.  */
+      if (nsec)
+        {
+          char *p = when_str + strlen (when_str);
+          int power_of_ten = 100000000;
+          *p++ = '.';
+
+          do
+            {
+              *p++ = '0' + nsec / power_of_ten;
+              nsec %= power_of_ten;
+              power_of_ten /= 10;
+            }
+          while (nsec);
+
+          *p = '\0';
+        }
+
+      error (0, 0, _("time %s is out of range"), when_str);
+      fputs (when_str, stdout);
       return;
     }
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 41e0cbc..84db367 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -346,6 +346,7 @@ TESTS =                                             \
   du/2g                                                \
   du/8gb                                       \
   du/basic                                     \
+  du/bigtime                                   \
   du/deref                                     \
   du/deref-args                                        \
   du/exclude                                   \
diff --git a/tests/du/bigtime b/tests/du/bigtime
new file mode 100755
index 0000000..1a78d52
--- /dev/null
+++ b/tests/du/bigtime
@@ -0,0 +1,48 @@
+#!/bin/sh
+# Exercise du on a file with a big time stamp.
+
+# Copyright (C) 2010 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/>.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+
+export LC_ALL=C
+export TZ=UTC0
+
+# 2**63 - 1
+bignum=9223372036854775807
+
+touch -d @$bignum future 2>/dev/null &&
+future_time=$(ls -l future) &&
+case "$future_time" in
+*" $bignum "*)
+  : ;;
+*' Dec  4  300627798676 '*)
+  skip_ "file system and localtime both handle big timestamps" ;;
+*)
+  skip_ "file system or localtime mishandles big time stamps: $future_time" ;;
+esac || skip_ "file system cannot represent big time stamps"
+
+cat >exp <<EOF
+0      $bignum future
+EOF
+cat >err_ok <<EOF
+du: time $bignum is out of range
+EOF
+du --time future >out 2>err || fail=1
+compare out exp || fail=1
+compare err err_ok || fail=1
+
+Exit $fail
-- 
1.7.2