[Qemu-devel] [PATCH 0/2] block: Fix backing paths for filenames with colons

[Qemu-devel] [PATCH 0/2] block: Fix backing paths for filenames with colons

[Max Reitz]

See here:
$ ./qemu-img create -f qcow2 backing.qcow2 64M
Formatting 'backing.qcow2', fmt=qcow2 size=67108864 encryption=off
    cluster_size=65536 lazy_refcounts=off refcount_bits=16
$ ./qemu-img create -f qcow2 -b backing.qcow2 ./top:image.qcow2
qemu-img: ./top:image.qcow2: Could not open './top:backing.qcow2':
    No such file or directory

:-(

(See also: https://bugzilla.redhat.com/show_bug.cgi?id=1212715)


Max Reitz (2):
  block: Fix backing paths for filenames with colons
  iotests: Add test for colon handling

 block.c                    | 15 ++++++---
 tests/qemu-iotests/126     | 76 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/126.out | 16 ++++++++++
 tests/qemu-iotests/group   |  1 +
 4 files changed, 103 insertions(+), 5 deletions(-)
 create mode 100755 tests/qemu-iotests/126
 create mode 100644 tests/qemu-iotests/126.out

-- 
2.9.4

[Qemu-devel] [PATCH 1/2] block: Fix backing paths for filenames with colons

[Max Reitz]

path_combine() naturally tries to preserve a protocol prefix. However,
it recognizes such a prefix by scanning for the first colon; which is
different from what path_has_protocol() does: There only is a protocol
prefix if there is a colon before the first slash.

A protocol prefix that is not recognized by path_has_protocol() is none,
and should thus not be taken as one.

Case in point, before this patch:
$ ./qemu-img create -f qcow2 -b backing.qcow2 ./top:image.qcow2
qemu-img: ./top:image.qcow2: Could not open './top:backing.qcow2':
    No such file or directory

Afterwards:
$ ./qemu-img create -f qcow2 -b backing.qcow2 ./top:image.qcow2
qemu-img: ./top:image.qcow2: Could not open './backing.qcow2':
    No such file or directory

Reported-by: yangyang <yangyang@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/block.c b/block.c
index 50ba264..b72b872 100644
--- a/block.c
+++ b/block.c
@@ -163,11 +163,16 @@ void path_combine(char *dest, int dest_size,
     if (path_is_absolute(filename)) {
         pstrcpy(dest, dest_size, filename);
     } else {
-        p = strchr(base_path, ':');
-        if (p)
-            p++;
-        else
-            p = base_path;
+        const char *protocol_stripped = NULL;
+
+        if (path_has_protocol(base_path)) {
+            protocol_stripped = strchr(base_path, ':');
+            if (protocol_stripped) {
+                protocol_stripped++;
+            }
+        }
+        p = protocol_stripped ?: base_path;
+
         p1 = strrchr(base_path, '/');
 #ifdef _WIN32
         {
-- 
2.9.4

[Qemu-devel] [PATCH 2/2] iotests: Add test for colon handling

[Max Reitz]

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
I apologize for the patch title for sounding a bit squishy. But I like
it so I won't change it.
---
 tests/qemu-iotests/126     | 76 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/126.out | 16 ++++++++++
 tests/qemu-iotests/group   |  1 +
 3 files changed, 93 insertions(+)
 create mode 100755 tests/qemu-iotests/126
 create mode 100644 tests/qemu-iotests/126.out

diff --git a/tests/qemu-iotests/126 b/tests/qemu-iotests/126
new file mode 100755
index 0000000..1445a81
--- /dev/null
+++ b/tests/qemu-iotests/126
@@ -0,0 +1,76 @@
+#!/bin/bash
+#
+# Tests handling of colons in filenames (which may be confused with protocol
+# prefixes)
+#
+# Copyright (C) 2017 Red Hat, 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, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=mreitz@redhat.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+here="$PWD"
+status=1	# failure is the default!
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+# Needs backing file support
+_supported_fmt qcow qcow2 qed vmdk
+# This is the default protocol (and we want to test the difference between
+# colons which separate a protocol prefix from the rest and colons which are
+# just part of the filename, so we cannot test protocols which require a prefix)
+_supported_proto file
+_supported_os Linux
+
+echo
+echo '=== Testing plain files ==='
+echo
+
+# A colon after a slash is not a protocol prefix separator
+TEST_IMG="$TEST_DIR/a:b.$IMGFMT" _make_test_img 64M
+_rm_test_img "$TEST_DIR/a:b.$IMGFMT"
+
+# But if you want to be really sure, you can do this
+TEST_IMG="file:$TEST_DIR/a:b.$IMGFMT" _make_test_img 64M
+_rm_test_img "$TEST_DIR/a:b.$IMGFMT"
+
+
+echo
+echo '=== Testing relative backing filename resolution ==='
+echo
+
+BASE_IMG="$TEST_DIR/image:base.$IMGFMT"
+TOP_IMG="$TEST_DIR/image:top.$IMGFMT"
+
+TEST_IMG=$BASE_IMG _make_test_img 64M
+TEST_IMG=$TOP_IMG _make_test_img -b ./image:base.$IMGFMT
+
+# The default cluster size depends on the image format
+TEST_IMG=$TOP_IMG _img_info | grep -v 'cluster_size'
+
+_rm_test_img "$BASE_IMG"
+_rm_test_img "$TOP_IMG"
+
+
+# success, all done
+echo '*** done'
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/126.out b/tests/qemu-iotests/126.out
new file mode 100644
index 0000000..52991bb
--- /dev/null
+++ b/tests/qemu-iotests/126.out
@@ -0,0 +1,16 @@
+QA output created by 126
+
+=== Testing plain files ===
+
+Formatting 'TEST_DIR/a:b.IMGFMT', fmt=IMGFMT size=67108864
+Formatting 'TEST_DIR/a:b.IMGFMT', fmt=IMGFMT size=67108864
+
+=== Testing relative backing filename resolution ===
+
+Formatting 'TEST_DIR/image:base.IMGFMT', fmt=IMGFMT size=67108864
+Formatting 'TEST_DIR/image:top.IMGFMT', fmt=IMGFMT size=67108864 backing_file=./image:base.IMGFMT
+image: TEST_DIR/image:top.IMGFMT
+file format: IMGFMT
+virtual size: 64M (67108864 bytes)
+backing file: ./image:base.IMGFMT (actual path: TEST_DIR/./image:base.IMGFMT)
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 5c8ea0f..30717cb 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -130,6 +130,7 @@
 122 rw auto
 123 rw auto quick
 124 rw auto backing
+126 rw auto backing
 128 rw auto quick
 129 rw auto quick
 130 rw auto quick
-- 
2.9.4

Re: [Qemu-devel] [PATCH 2/2] iotests: Add test for colon handling

[Eric Blake]

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On 05/22/2017 01:07 PM, Max Reitz wrote:
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
> I apologize for the patch title for sounding a bit squishy. But I like
> it so I won't change it.

That was a mental image I did not need. ;)

> ---
>  tests/qemu-iotests/126     | 76 ++++++++++++++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/126.out | 16 ++++++++++
>  tests/qemu-iotests/group   |  1 +

What - we really have never used 126?  And as a nice bonus - you won't
have to rebase your patch based on collisions with other new tests.  Sly.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH 1/2] block: Fix backing paths for filenames with colons

[Eric Blake]

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On 05/22/2017 01:07 PM, Max Reitz wrote:
> path_combine() naturally tries to preserve a protocol prefix. However,
> it recognizes such a prefix by scanning for the first colon; which is
> different from what path_has_protocol() does: There only is a protocol
> prefix if there is a colon before the first slash.
> 
> A protocol prefix that is not recognized by path_has_protocol() is none,
> and should thus not be taken as one.
> 
> Case in point, before this patch:
> $ ./qemu-img create -f qcow2 -b backing.qcow2 ./top:image.qcow2
> qemu-img: ./top:image.qcow2: Could not open './top:backing.qcow2':
>     No such file or directory
> 
> Afterwards:
> $ ./qemu-img create -f qcow2 -b backing.qcow2 ./top:image.qcow2
> qemu-img: ./top:image.qcow2: Could not open './backing.qcow2':
>     No such file or directory
> 
> Reported-by: yangyang <yangyang@redhat.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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