Unix sockets generally have a maximum path length.  Depending on your
$TEST_DIR, it may be exceeded and then all tests that create and use
Unix sockets there may fail.

Circumvent this by adding a new scratch directory specifically for
Unix socket files.  It defaults to a temporary directory (mktemp -d)
that is completely removed after the iotests are done.

(By default, mktemp -d creates a /tmp/tmp.XXXXXXXXXX directory, which
should be short enough for our use cases.)

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 tests/qemu-iotests/check | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
index 588c453a94..a257215448 100755
--- a/tests/qemu-iotests/check
+++ b/tests/qemu-iotests/check
@@ -97,6 +97,7 @@ IMGFMT        -- $FULL_IMGFMT_DETAILS
 IMGPROTO      -- $IMGPROTO
 PLATFORM      -- $FULL_HOST_DETAILS
 TEST_DIR      -- $TEST_DIR
+SOCK_DIR      -- $SOCK_DIR
 SOCKET_SCM_HELPER -- $SOCKET_SCM_HELPER
 
 EOF
@@ -121,6 +122,16 @@ if [ ! -e "$TEST_DIR" ]; then
         mkdir "$TEST_DIR"
 fi
 
+tmp_sock_dir=false
+if [ -z "$SOCK_DIR" ]; then
+    SOCK_DIR=$(mktemp -d)
+    tmp_sock_dir=true
+fi
+
+if [ ! -d "$SOCK_DIR" ]; then
+    mkdir "$SOCK_DIR"
+fi
+
 diff="diff -u"
 verbose=false
 debug=false
@@ -534,6 +545,7 @@ if [ -z "$SAMPLE_IMG_DIR" ]; then
 fi
 
 export TEST_DIR
+export SOCK_DIR
 export SAMPLE_IMG_DIR
 
 if [ -s $tmp.list ]
@@ -716,6 +728,11 @@ END        { if (NR > 0) {
     rm -f "${TEST_DIR}"/*.out "${TEST_DIR}"/*.err "${TEST_DIR}"/*.time
     rm -f "${TEST_DIR}"/check.pid "${TEST_DIR}"/check.sts
     rm -f $tmp.*
+
+    if $tmp_sock_dir
+    then
+        rm -rf "$SOCK_DIR"
+    fi
 }
 
 trap "_wrapup; exit \$status" 0 1 2 3 15
-- 
2.21.0

On 10/10/19 10:24 AM, Max Reitz wrote:
> Unix sockets generally have a maximum path length.  Depending on your
> $TEST_DIR, it may be exceeded and then all tests that create and use
> Unix sockets there may fail.
> 
> Circumvent this by adding a new scratch directory specifically for
> Unix socket files.  It defaults to a temporary directory (mktemp -d)
> that is completely removed after the iotests are done.
> 
> (By default, mktemp -d creates a /tmp/tmp.XXXXXXXXXX directory, which
> should be short enough for our use cases.)
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   tests/qemu-iotests/check | 17 +++++++++++++++++

> +tmp_sock_dir=false
> +if [ -z "$SOCK_DIR" ]; then
> +    SOCK_DIR=$(mktemp -d)
> +    tmp_sock_dir=true
> +fi
> +
> +if [ ! -d "$SOCK_DIR" ]; then
> +    mkdir "$SOCK_DIR"
> +fi

Should this use mkdir -p, in case two parallel processes compete with 
the same SOCK_DIR?

What if SOCK_DIR is set to something that is not a directory (say a 
file), at which point mkdir fails, but you don't seem to be catching 
that failure.

Otherwise looks good.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

On 10.10.19 20:18, Eric Blake wrote:
> On 10/10/19 10:24 AM, Max Reitz wrote:
>> Unix sockets generally have a maximum path length.  Depending on your
>> $TEST_DIR, it may be exceeded and then all tests that create and use
>> Unix sockets there may fail.
>>
>> Circumvent this by adding a new scratch directory specifically for
>> Unix socket files.  It defaults to a temporary directory (mktemp -d)
>> that is completely removed after the iotests are done.
>>
>> (By default, mktemp -d creates a /tmp/tmp.XXXXXXXXXX directory, which
>> should be short enough for our use cases.)
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   tests/qemu-iotests/check | 17 +++++++++++++++++
> 
>> +tmp_sock_dir=false
>> +if [ -z "$SOCK_DIR" ]; then
>> +    SOCK_DIR=$(mktemp -d)
>> +    tmp_sock_dir=true
>> +fi
>> +
>> +if [ ! -d "$SOCK_DIR" ]; then
>> +    mkdir "$SOCK_DIR"
>> +fi
> 
> Should this use mkdir -p, in case two parallel processes compete with
> the same SOCK_DIR?

I would have used mkdir -p, but I saw we used this construct for
TEST_DIR, so I thought I‘d just go for the same.

> What if SOCK_DIR is set to something that is not a directory (say a
> file), at which point mkdir fails, but you don't seem to be catching
> that failure.

Well, the same applies to TEST_DIR.  And technically, as long as we
don’t use mkdir -p for either, not catching the error at least helps
circumvent the potential race. O:-)

(I’ll convert both to mkdir -p with error handling.)

Max

> Otherwise looks good.