[PATCH 5/8] gpt_probe: don't attempt to read beyond end of a very small disk

[Jim Meyering]

* libparted/labels/gpt.c (gpt_probe): Don't try to read the
2nd sector if that's beyond the end of the disk.
* tests/t0001-tiny.sh: New test, to expose the above boundary-case bug.
Part of the msdos-partition-creation process involves probing for
other types of partition tables.  Probing for gpt would evoke a
nonsensical diagnostic.
* tests/Makefile.am (TESTS): Add t0001-tiny.sh.
---
 libparted/labels/gpt.c |    3 ++
 tests/Makefile.am      |    1 +
 tests/t0001-tiny.sh    |   51 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 0 deletions(-)
 create mode 100755 tests/t0001-tiny.sh

diff --git a/libparted/labels/gpt.c b/libparted/labels/gpt.c
index 5037d9b..aca555a 100644
--- a/libparted/labels/gpt.c
+++ b/libparted/labels/gpt.c
@@ -444,6 +444,9 @@ gpt_probe (const PedDevice *dev)

   PED_ASSERT (dev != NULL, return 0);

+  if (dev->length <= 1)
+    return 0;
+
   if (ped_device_read (dev, pth_raw, 1, GPT_HEADER_SECTORS)
       || ped_device_read (dev, pth_raw, dev->length - 1, GPT_HEADER_SECTORS))
     {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 79c01b3..ece3f64 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,5 +1,6 @@
 TESTS = \
   t0000-basic.sh \
+  t0001-tiny.sh \
   t0010-script-no-ctrl-chars.sh \
   t0100-print.sh \
   t0200-gpt.sh \
diff --git a/tests/t0001-tiny.sh b/tests/t0001-tiny.sh
new file mode 100755
index 0000000..373a68d
--- /dev/null
+++ b/tests/t0001-tiny.sh
@@ -0,0 +1,51 @@
+#!/bin/sh
+# operate on a very small (1-sector) "disk"
+
+# Copyright (C) 2009 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/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  parted --version
+fi
+
+: ${srcdir=.}
+. $srcdir/t-lib.sh
+
+ss=$sector_size_
+dev=loop-file
+
+fail=0
+
+for opt in '' -s; do
+
+  dd if=/dev/null of=$dev bs=1 seek=$ss || framework_failure
+
+  # create an msdos partition table:
+  # Before parted-2.1, without -s, this would fail with a bogus diagnostic:
+  # Error: Success during read on .../tests/loop-file
+  # Retry/Ignore/Cancel? ^C
+  parted $opt $dev mklabel msdos ---pretend-input-tty </dev/null > out 2>&1 \
+      || fail=1
+  # expect no output
+  sed 's/.*WARNING: You are not superuser.*//;/^$/d' out > k && mv k out || fail=1
+  compare out /dev/null || fail=1
+
+  parted -s $dev p || fail=1
+  rm -f $dev
+
+done
+
+Exit $fail
--
1.6.5.2.372.gc0502