[parted-devel] [PATCH]: Diagnose "ext2 FS too small" rather than triggering an assertion

[Jim Meyering]

Here's another ext2-related fix.
I stumbled upon it when accidentally trying to create a second partition
in exactly the same location as the first one.  It triggered the
PED_ASSERT that I recently added to protect against a buffer overrun
that would otherwise happen when ext2_mkfs got "numblocks == 0".

	Diagnose "ext2 FS too small" rather than triggering an assertion.
	* libparted/fs/ext2/ext2_mkfs.c (ext2_mkfs): An overlapping ext2
	partition request could still lead to a bug: constraint-resolution
	code would produce a single-sector candidate "range", and that
	would cause the ext2 fs-creation code to misbehave.  Now, it
	properly detects and reports the FS as being too small.
	* tests/t3000-constraints.sh: New test for the above.
	* tests/Makefile.am (TESTS): Add t3000-constraints.sh.

diff --git a/libparted/fs/ext2/ext2_mkfs.c b/libparted/fs/ext2/ext2_mkfs.c
index 8f74a45..92261f6 100644
--- a/libparted/fs/ext2/ext2_mkfs.c
+++ b/libparted/fs/ext2/ext2_mkfs.c
@@ -542,7 +542,8 @@ struct ext2_fs *ext2_mkfs(struct ext2_dev_handle *handle,

 	if (numblocks == 0)
 		numblocks = handle->ops->get_size(handle->cookie);
-        PED_ASSERT(numblocks != 0, return NULL);
+        if (numblocks == 0)
+                goto diagnose_fs_too_small;

 	if (blocks_per_group == (unsigned int) 0)
 		blocks_per_group = 8 << log_block_size;
@@ -589,6 +590,7 @@ struct ext2_fs *ext2_mkfs(struct ext2_dev_handle *handle,
           fs_too_small = 1;

 	if (fs_too_small) {
+	diagnose_fs_too_small:
 		ped_exception_throw (
 			PED_EXCEPTION_ERROR,
 			PED_EXCEPTION_CANCEL,
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 59d38e5..27689c9 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -3,7 +3,8 @@ TESTS = \
   t1000-mkpartfs.sh \
   t1100-busy-label.sh \
   t1500-small-ext2.sh \
-  t2000-mkfs.sh
+  t2000-mkfs.sh \
+  t3000-constraints.sh

 EXTRA_DIST = \
   $(TESTS) test-lib.sh mkdtemp
diff --git a/tests/t3000-constraints.sh b/tests/t3000-constraints.sh
new file mode 100755
index 0000000..07fe1b3
--- /dev/null
+++ b/tests/t3000-constraints.sh
@@ -0,0 +1,61 @@
+#!/bin/sh
+
+# Copyright (C) 2007 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.
+
+test_description="exercise Parted's constraint-management code"
+
+. ./init.sh
+
+# FIXME: move this to test-lib.sh, and use it in t0000*.sh
+emit_superuser_warning()
+{
+  uid=`id -u` || uid=1
+  test "$uid" != 0 &&
+    echo 'WARNING: You are not superuser.  Watch out for permissions.'
+}
+
+dev=loop-file
+N=2
+t=ext2
+
+test_expect_success \
+    "setup: label and create a small $t partition" \
+    'dd if=/dev/zero of=$dev bs=${N}M count=1 2>/dev/null &&
+     { echo y; echo c; } > in &&
+     { emit_superuser_warning
+       echo "Warning: You requested a partition from 1000kB to 2000kB."
+       echo "The closest location we can manage is 15.9kB to 15.9kB." \
+	    " Is this still acceptable to you?"
+       echo "Yes/No? y"
+       echo "Error: File system too small for ext2."; } > exp &&
+     parted -s $dev mklabel msdos &&
+     parted -s $dev mkpartfs primary $t 1 $N'
+
+# Before parted-1.9, this would fail with a buffer overrun
+# leading to a segfault.
+test_expect_failure \
+    'try to create another partition in the same place' \
+    'parted ---pretend-input-tty $dev mkpartfs primary $t 1 $N <in >out 2>&1'
+
+test_expect_success \
+    'normalize the actual output' \
+    'sed "s,
   *
,,;s, $,," out > o2 && mv -f o2 out'
+
+test_expect_success 'check for expected output' '$compare out exp'
+
+test_done