Commit Graph

236 Commits

Author SHA1 Message Date
Michal Privoznik
63857eb4a0 tests: Introduce qemucapabilitiestest
This test is there to ensure that our capabilities detection code isn't
broken somehow.

How to gather test data:

Firstly, the data is split into two separate files. The former (with
suffix .replies) contains all the qemu replies. This is very fragile as
introducing a new device can mean yet another monitor command and hence
edit of this file in the future. But there's no better way of doing
this. To get this data simply turn on debug logs and copy all the
QEMU_MONITOR_IO_PROCESS lines. But be careful to not copy incomplete
ones (yeah, we report some incomplete lines too). Long story short, at
the libvirtd startup, a dummy qemu is spawn to get all the capabilities.

The latter (with suffix .caps) contains capabilities XML. Just start a
domain and copy the corresponding part from its state XML file.
Including <qemuCaps> tag.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2013-10-01 11:13:36 +02:00
Michal Privoznik
4679e9422a fchosttest: Run the test only under linux
Currently, we have functions to handle fc_host implemented just
for linux. On all other platforms an error is thrown. It makes no
sense to run the test on those platforms then.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2013-09-27 18:32:43 +02:00
Eric Blake
9940392c2f build: fix testsuite building under cygwin
Similar to commit 8f34f19.

* tests/Makefile.am (virnetserverclienttest_CFLAGS): Add XDR_CFLAGS.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-09-27 07:26:09 -06:00
Daniel P. Berrange
6fdafe278d Add test case for virNetServerClient object identity code
Start a test case for the virNetServerClient object, which
initially checks the creation of a virIdentityPtr object.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-09-24 09:37:26 +01:00
Doug Goldstein
7457cbe871 VMware: Make version parsing testable and add tests
This splits up the version parsing code into a callable API like QEMU
help/version string parsing so that we can test it as we need to add
additional patterns for newer versions/products.
2013-09-20 08:23:31 -05:00
Peter Krempa
2e23c77b00 tests: Add metadata tests
This test exercises the virDomain[Get|Set]Metadata API and tests it for
regressions
2013-09-17 09:53:30 +02:00
Eric Blake
012c25e88c build: use library rather than cross-directory compilation
If we use subdir-objects with automake, any reference to a
cross-directory .c file will result in automake creating
rules that track dependency in the cross directory.  But this
presents a problem during 'make distclean' - if the cross
directory is cleaned up first, then the daemon directory will
be left with dangling references to .Po dependency files that
no longer exist.

Meanwhile, referring to the cross-directory .c file means
that we are compiling the file twice - once in src, and once
in daemon.  Better is to compile just once in src into a
convenience library, and then use that library from daemon.

The tests directory had a similar situation of a cross-directory
.c file; to solve that, we actually need a convenience library.

* daemon/Makefile.am (DAEMON_SOURCES): Drop .c files...
(libvirtd_LDADD): ...and instead use library.
(libvirtd_conf_la_SOURCES): Declare a new convenience library.
(libvirtd_LDFLAGS): Drop duplicate flag.
* tests/Makefile.am (libvirtdconftest_SOURCES): Drop .c file...
(libvirtdconftest_LDADD): ..and instead use library.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-09-09 12:04:03 -06:00
Eric Blake
adf335f066 build: only run fdstreamtest when libvirtd is built
An rpm build with client_only set to 1 (for example, RHEL 5 on
s390, or by modifying libvirt.spec.in) failed with

TEST: fdstreamtest
 1) Stream read blocking                                              ... OK
 2) Stream read non-blocking                                          ... Unexpected EOF block 0 want 128
FAILED
 3) Stream write blocking                                             ... OK
 4) Stream write non-blocking                                         ... Failed to finish stream: internal error: libvirt:  error : cannot execute binary /home/eblake/rpmbuild/BUILD/libvirt-1.1.1/tests/../src/libvirt_iohelper: No such file or directory

Since the test depends on something that was only built for
WITH_LIBVIRTD (see src/Makefile.am), we must do the same for
the test.

* tests/Makefile.am (test_programs): Make fdstreamtest conditional.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-09-04 12:44:41 -06:00
Eric Blake
ec81852f46 build: enforce makefile conditional style
Automake has builtin support to prevent botched conditional nesting,
but only if you use:
if FOO
else !FOO
endif !FOO

An example error message when using the wrong name:

daemon/Makefile.am:378: error: else reminder (LIBVIRT_INIT_SCRIPT_SYSTEMD_TRUE) incompatible with current conditional: LIBVIRT_INIT_SCRIPT_SYSTEMD_FALSE
daemon/Makefile.am:381: error: endif reminder (LIBVIRT_INIT_SCRIPT_SYSTEMD_TRUE) incompatible with current conditional: LIBVIRT_INIT_SCRIPT_SYSTEMD_FALSE

As our makefiles tend to have quite a bit of nested conditionals,
it's better to take advantage of the benefits of the build system
double-checking that our conditionals are well-nested, but that
requires a syntax check to enforce our usage style.

Alas, unlike C preprocessor and spec files, we can't use indentation
to make it easier to see how deeply nesting goes.

* cfg.mk (sc_makefile_conditionals): New rule.
* daemon/Makefile.am: Enforce the style.
* gnulib/tests/Makefile.am: Likewise.
* python/Makefile.am: Likewise.
* src/Makefile.am: Likewise.
* tests/Makefile.am: Likewise.
* tools/Makefile.am: Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-09-04 09:40:20 -06:00
Ján Tomko
2d9185a9f3 Test network update XML parsing
Add checks for updating sections of network definition via
virNetworkDefUpdateSection.

https://bugzilla.redhat.com/show_bug.cgi?id=989569
2013-08-28 08:05:46 +02:00
Guido Günther
3e2799add2 Check for --no-copy-dt-needed linker flag
and use it when available
2013-08-22 16:17:36 +02:00
Martin Kletzander
398de14734 tests: Add URI precedence checking
Commit a0b6a36f is fixing what commit abfff210 broke, so to avoid having
to deal with this issue again, herec comes "virsh-uriprecedence".
2013-08-22 15:03:38 +02:00
Claudio Bley
d7c4e00367 tests: fix building without xattr support
Only compile securityselinuxhelper.c if xattr support was detected to
avoid this error:

securityselinuxhelper.c:34:24: fatal error: attr/xattr.h: No such file
or directory compilation terminated.

Since all SELinux tests depend upon the securityselinuxhelper library,
these test programs are now only build when xattr support is
available.
2013-08-21 15:17:12 +02:00
Guido Günther
f790457172 Directly link against needed libraries
The Linux build revealed another missing direct link target, this time
against selinux libs:

    http://honk.sigxcpu.org:8001/view/libvirt/job/libvirt-build-debian-sid-amd64/9/console
2013-08-13 17:42:12 +02:00
Guido Günther
6ba0b7d2b4 Directly link against needed libraries
otherwise having a strict --no-copy-dt-needed-entries fails in several
places like:

    CCLD     virdbustest
    /usr/bin/ld: virdbustest-virdbustest.o: undefined reference to symbol 'dbus_message_unref'
    /lib/x86_64-linux-gnu/libdbus-1.so.3: error adding symbols: DSO missing from command line
    collect2: error: ld returned 1 exit status
2013-08-12 22:53:44 +02:00
Eric Blake
70363ea9ff build: add configure option to disable gnulib tests
The gnulib testsuite is relatively stable - the only times it is
likely to have a test change from pass to fail is on a gnulib
submodule update or a major system change (such as moving from
Fedora 18 to 19, or other large change to libc).  While it is an
important test for end users on arbitrary machines (to make sure
that the portability glue works for their machine), it mostly
wastes time for development testing (as most developers aren't
making any of the major changes that would cause gnulib tests
to alter behavior).  Thus, it pays to make the tests optional
at configure time, defaulting to off for development, on for
tarballs, with autobuilders requesting it to be on.  It also
helps to allow a make-time override, via VIR_TEST_EXPENSIVE=[01]
(much the way automake sets up V=[01] for overriding the configure
time default of how verbose to be).

Automake has some pretty hard-coded magic with regards to the
TESTS variable; I had quite a job figuring out how to keep
'make distcheck' passing regardless of the configure option
setting in use, while still disabling the tests at runtime
when I did not configure them on and did not use the override
variable.  Thankfully, we require GNU make, which lets me
hide some information from Automake's magic handling of TESTS.

* bootstrap.conf (bootstrap_epilogue): Munge gnulib test variable.
* configure.ac (--enable-expensive-tests): Add new enable switch.
(VIR_TEST_EXPENSIVE_DEFAULT, WITH_EXPENSIVE_TESTS): Set new
witnesses.
* gnulib/tests/Makefile.am (TESTS): Make tests conditional on
configure settings and the VIR_TEST_EXPENSIVE variable.
* tests/Makefile.am (TESTS_ENVIRONMENT): Expose VIR_TEST_EXPENSIVE
to all tests.
* autobuild.sh: Enable all tests during autobuilds.
* libvirt.spec.in (%configure): Likewise.
* mingw-libvirt.spec.in (%mingw_configure): Likewise.
* docs/hacking.html.in: Document the option.
* HACKING: Regenerate.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-08-12 10:02:38 -06:00
Daniel P. Berrange
236da82dae Split TLS test into two separate tests
The virnettlscontexttest.c tests both virNetTLSContext
and virNetTLSSession functionality. Split into two
separate tests, to make the code size more manageable

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-08-08 10:00:42 +01:00
Jincheng Miao
a320730a88 build: fix qemuagenttest build with -O0 in fedora 19.
When building libvirt with -O0 flag in fedora 19, it will fail to
generate qemuagenttest, a link error occurs like:

./.libs/libqemumonitortestutils.a(qemumonitortestutils.o): In function `qemuMonitorTestFree':
libvirt/tests/qemumonitortestutils.c:346: undefined reference to `qemuMonitorClose'
./.libs/libqemumonitortestutils.a(qemumonitortestutils.o): In function `qemuMonitorTestNew':
libvirt/tests/qemumonitortestutils.c:870: undefined reference to `qemuMonitorOpen'
collect2: error: ld returned 1 exit status

Fix it by listing libraries in the correct order to avoid lazy linkage.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-08-01 14:07:03 -06:00
Peter Krempa
5c94dfdd76 tests: Add qemuagenttest
Add a basic test framework with two simple tests to test guest agent
interaction.
2013-07-31 14:25:43 +02:00
Daniel P. Berrange
dff93f8cab Add API for calling systemd-machined's DBus API
To register virtual machines and containers with systemd-machined,
and thus have cgroups auto-created, we need to talk over DBus.
This is somewhat tedious code, so introduce a dedicated function
to isolate the DBus call in one place.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-07-22 13:09:58 +01:00
Daniel P. Berrange
834c9c9459 Introduce virDBusCallMethod & virDBusMessageRead methods
Doing DBus method calls using libdbus.so is tedious in the
extreme. systemd developers came up with a nice high level
API for DBus method calls (sd_bus_call_method). While
systemd doesn't use libdbus.so, their API design can easily
be ported to libdbus.so.

This patch thus introduces methods virDBusCallMethod &
virDBusMessageRead, which are based on the code used for
sd_bus_call_method and sd_bus_message_read. This code in
systemd is under the LGPLv2+, so we're license compatible.

This code is probably pretty unintelligible unless you are
familiar with the DBus type system. So I added some API
docs trying to explain how to use them, as well as test
cases to validate that I didn't screw up the adaptation
from the original systemd code.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-07-22 13:09:58 +01:00
Eric Blake
d21d40bf0c maint: split long lines in Makefiles
Makefiles are another easy file to enforce line limits.

Mostly straightforward; interesting tricks worth noting:
src/Makefile.am: $(confdir) was already defined, use it in more places
tests/Makefile.am: path_add and VG required some interesting compression

* cfg.mk (sc_prohibit_long_lines): Add another test.
* Makefile.am: Fix offenders.
* daemon/Makefile.am: Likewise.
* docs/Makefile.am: Likewise.
* python/Makefile.am: Likewise.
* src/Makefile.am: Likewise.
* tests/Makefile.am: Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-07-19 05:25:35 -06:00
Laine Stump
ec30f0f7bf test: include qemuhotplugtest data files in source rpm
commit 0fc12bca added a new test called qemuhotplugtest which has
several data files in tests/qemuhotplugtestdata, but didn't add that
directory to EXTRA_DIST in the tests Makefile.am, so the make check
done during a make rpm was failing due to missing data files.
2013-06-26 01:48:01 -04:00
Michal Privoznik
0fc12bca08 tests: Introduce qemuhotplugtest
As my punishment for the break in 7f15ebc7 (fixed in 752596b5dd) I'm
introducing this test to make sure it won't happen again. Currently,
only test for <graphics/> is supported.
2013-06-25 17:00:56 +02:00
Eric Blake
d7f53c7b97 maint: use LGPL correctly
Several files called out COPYING or COPYING.LIB instead of using
the normal boilerplate.  It's especially important that we don't
call out COPYING from an LGPL file, since COPYING is traditionally
used for the GPL.  A few files were lacking copyright altogether.

* src/rpc/gendispatch.pl: Add missing copyright.
* Makefile.nonreentrant: Likewise.
* src/check-symfile.pl: Likewise.
* src/check-symsorting.pl: Likewise.
* src/driver.h: Likewise.
* src/internal.h: Likewise.
* tools/libvirt-guests.sh.in: Likewise.
* tools/virt-pki-validate.in: Mention copyright in comment, not just code.
* tools/virt-sanlock-cleanup.in: Likewise.
* src/rpc/genprotocol.pl: Spell out license terms.
* src/xen/xend_internal.h: Likewise.
* src/xen/xend_internal.c: Likewise.
* Makefile.am: Likewise.
* daemon/Makefile.am: Likewise.
* docs/Makefile.am: Likewise.
* docs/schemas/Makefile.am: Likewise.
* examples/apparmor/Makefile.am: Likewise.
* examples/domain-events/events-c/Makefile.am: Likewise.
* examples/dominfo/Makefile.am: Likewise.
* examples/domsuspend/Makefile.am: Likewise.
* examples/hellolibvirt/Makefile.am: Likewise.
* examples/openauth/Makefile.am: Likewise.
* examples/python/Makefile.am: Likewise.
* examples/systemtap/Makefile.am: Likewise.
* examples/xml/nwfilter/Makefile.am: Likewise.
* gnulib/lib/Makefile.am: Likewise.
* gnulib/tests/Makefile.am: Likewise.
* include/Makefile.am: Likewise.
* include/libvirt/Makefile.am: Likewise.
* python/Makefile.am: Likewise.
* python/tests/Makefile.am: Likewise.
* src/Makefile.am: Likewise.
* tests/Makefile.am: Likewise.
* tools/Makefile.am: Likewise.
* configure.ac: Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>
2013-05-20 14:03:48 -06:00
Ján Tomko
25b98d31ec schema: make source optional in volume XML
We don't parse it anyway.

https://bugzilla.redhat.com/show_bug.cgi?id=893273
2013-05-17 08:35:08 +02:00
Ján Tomko
a07b88ee03 schema: require target path in storage pool xml
Make target path mandatory for pool types that require target,
since we refuse to parse a target without a path.

https://bugzilla.redhat.com/show_bug.cgi?id=893273
2013-05-17 08:33:22 +02:00
Osier Yang
5606c7a867 tests: Sort the EXTRA_DIST list
Commit 1cc8259bfe fixes the build failure, but forgot to keep the
list alphanumeric sorted.
2013-05-15 11:34:27 +08:00
Osier Yang
1cc8259bfe tests: Add fchostdata in EXTRA_DIST
Pushed under build-breaker rule.
2013-05-15 01:18:26 +08:00
Osier Yang
9706d85fe9 tests: Add tests for fc_host
Since the NPIV machine is not easy to get, it's very likely to
introduce regressions when doing changes on the existing code.
This patch dumps part of the sysfs files (the necessary ones)
of fc_host as test input data, to test the related util functions.
It could be extended for more fc_host related testing in future.
2013-05-13 17:24:18 +08:00
Daniel P. Berrange
31989e66c6 Add a test case for the fdstream file read/write code
Add a test case which exercises the virFDStreamOpenFile
and virFDStreamCreateFile methods. Ensure that both the
synchronous and non-blocking iohelper code paths work.
This validates the regression recently fixed which
broke reading in non-blocking mode

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-05-10 19:57:18 +01:00
Daniel P. Berrange
d14524701a Add a test suite for cgroups functionality
Some aspects of the cgroups setup / detection code are quite subtle
and easy to break. It would greatly benefit from unit testing, but
this is difficult because the test suite won't have privileges to
play around with cgroups. The solution is to use monkey patching
via LD_PRELOAD to override the fopen, open, mkdir, access functions
to redirect access of cgroups files to some magic stubs in the
test suite.

Using this we provide custom content for the /proc/cgroup and
/proc/self/mounts files which report a fixed cgroup setup. We
then override open/mkdir/access so that access to the cgroups
filesystem gets redirected into files in a temporary directory
tree in the test suite build dir.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-04-15 17:35:31 +01:00
Daniel P. Berrange
b7f1d218d8 Conditionally compile storagevolxml2argvtest
Only compile storagevolxml2argvtest if WITH_STORAGE is
set, because it links to that driver

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-04-15 17:35:31 +01:00
Daniel P. Berrange
15d8511b41 Add a test suite for keycode mapping functions
Validate that translations between different keycode sets
are functioning.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-04-08 10:03:20 +01:00
Gene Czarcinski
1cd2078c88 rename tests/conftest.c
To prevent confusion with configure's popular name
for a file, rename conftest.c to test_conf.c which
is consistent with the invoking test_conf.sh
Signed-off-by: Gene Czarcinski <gene@czarc.net>
2013-03-19 13:13:28 -06:00
Daniel P. Berrange
3aabe27247 Define internal APIs for managing identities
Introduce a local object virIdentity for managing security
attributes used to form a client application's identity.
Instances of this object are intended to be used as if they
were immutable, once created & populated with attributes

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-03-19 13:37:37 +00:00
Eric Blake
b6176e5226 tests: old automake lacks abs_builddir
On RHEL 5, 'make check' included failures such as:

TEST: virstoragetest
unable to create directory /virstoragedata/sub
unable to return to correct directory, refusing to clean up /virstoragedata

It turns out that with automake 1.9.x, $(abs_builddir) is not
automatically provided.  We have previously worked around this
by using `pwd` before, but because we did not do it everywhere,
we had a number of broken tests.

This patch brings RHEL 5 from 8 failed tests down to 5 (the
remaining failures may be due to bugs in the older libxml2 and
RNG schema validation available in RHEL 5, so I'm not sure if
they can be fixed in libvirt, but I'm still investigating).

* tests/Makefile.am (AM_CFLAGS): Reliably set abs_builddir.
(*_la_CFLAGS): Factor out common settings; delete when nothing
remains to be added.
2013-02-26 10:37:50 -07:00
Ján Tomko
56e1b4c30f storage: add test for qemu-img command line generation 2013-02-24 18:11:40 +01:00
Eric Blake
a18452d0d2 storage: test backing chain traversal
Testing our backing chain handling will make it much easier to
ensure that we avoid issues in the future.  If only I had written
this test before I first caused several regressions...

* tests/virstoragetest.c: New test.
* tests/Makefile.am (test_programs): Build it.
* .gitignore: Ignore new files.
2013-02-15 16:07:01 -07:00
Eric Blake
c6f1060ca7 util: add virendian.h macros
We have several cases where we need to read endian-dependent
data regardless of host endianness; rather than open-coding
these call sites, it will be nicer to funnel things through
a macro.

The virendian.h file can be expanded to add writer functions,
and/or 16-bit access patterns, if needed.  Also, if we need
to turn things into a function to avoid multiple evaluations
of buf, that can be done later.  But for now, a macro worked.

* src/util/virendian.h: New file.
* src/Makefile.am (UTIL_SOURCES): Ship it.
* tests/virendiantest.c: New test.
* tests/Makefile.am (test_programs, virendiantest_SOURCES): Run
the test.
* .gitignore: Ignore built file.
2013-02-12 09:00:15 -07:00
Jiri Denemark
d6c8597046 tests: Don't build securityselinuxlabeltest without qemu
Sources for securityselinuxlabeltest are only defined if qemu driver is
enabled so we should not try to build the test if qemu driver is
disabled.
2013-01-31 10:32:43 +01:00
Daniel P. Berrange
9c9d4d32d3 Add a port allocator class
Introduce a virPortAllocator for managing TCP port allocations.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-01-16 11:02:58 +00:00
Daniel P. Berrange
907a39e735 Add a test suite for validating SELinux labelling
There are many aspects of the guest XML which result in the
SELinux driver applying file labelling. With the increasing
configuration options it is desirable to test this behaviour.
It is not possible to assume that the test suite has the
ability to set SELinux labels. Most filesystems though will
support extended attributes. Thus for the purpose of testing,
it is possible to extend the existing LD_PRELOAD hack to
override setfilecon() and getfilecon() to simply use the
'user.libvirt.selinux' attribute for the sake of testing.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-01-14 13:40:04 +00:00
Daniel P. Berrange
bccd4a8cbc Rename HAVE_GNUTLS to WITH_GNUTLS 2013-01-14 13:26:47 +00:00
Daniel P. Berrange
49a1c16027 Convert HAVE_YAJL into WITH_YAJL
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-01-11 11:03:22 +00:00
Daniel P. Berrange
f587c27768 Make TLS support conditional
Add checks for existence of GNUTLS and automatically disable
it if not found.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2013-01-08 20:57:31 +00:00
Viktor Mihajlovski
347a712ab1 tests: Add tests for sysinfo
Test cases for virSysinfoRead. Initially, there are tests for
x86 (DMI based) and s390 (/proc/... based).
In lack of PPC data, I have stubbed out the test for it, but it
can be added with a minimal effort.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
2012-12-17 17:37:17 +00:00
Gene Czarcinski
8b32c80df0 network: put dnsmasq parameters in conf-file instead of command line
This patch changes how parameters are passed to dnsmasq.  Instead of
being on the command line, the parameters are put into a file (one
parameter per line) and a commandline --conf-file= specifies the
location of the file.  The file is located in the same directory as
the leases file.

Putting the dnsmasq parameters into a configuration file
allows them to be examined and more easily understood than
examining the command lines displayed by "ps ax".  This is
especially true when a number of networks have been started.

When the use of dnsmasq was originally done, the required command line
was simple, but it has gotten more complicated over time and will
likely become even more complicated in the future.

Note: The test conf files have all been renamed .conf instead of
.argv, and tests/networkxml2xmlargvdata was moved to
tests/networkxml2xmlconfdata.
2012-12-11 05:49:45 -05:00
Daniel P. Berrange
76c1fd33c8 Introduce APIs for splitting/joining strings
This introduces a few new APIs for dealing with strings.
One to split a char * into a char **, another to join a
char ** into a char *, and finally one to free a char **

There is a simple test suite to validate the edge cases
too. No more need to use the horrible strtok_r() API,
or hand-written code for splitting strings.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2012-11-30 20:05:43 +00:00
Daniel P. Berrange
eca72d4759 Introduce an internal API for handling file based lockspaces
The previously introduced virFile{Lock,Unlock} APIs provide a
way to acquire/release fcntl() locks on individual files. For
unknown reason though, the POSIX spec says that fcntl() locks
are released when *any* file handle referring to the same path
is closed. In the following sequence

  threadA: fd1 = open("foo")
  threadB: fd2 = open("foo")
  threadA: virFileLock(fd1)
  threadB: virFileLock(fd2)
  threadB: close(fd2)

you'd expect threadA to come out holding a lock on 'foo', and
indeed it does hold a lock for a very short time. Unfortunately
when threadB does close(fd2) this releases the lock associated
with fd1. For the current libvirt use case for virFileLock -
pidfiles - this doesn't matter since the lock is acquired
at startup while single threaded an never released until
exit.

To provide a more generally useful API though, it is necessary
to introduce a slightly higher level abstraction, which is to
be referred to as a "lockspace".  This is to be provided by
a virLockSpacePtr object in src/util/virlockspace.{c,h}. The
core idea is that the lockspace keeps track of what files are
already open+locked. This means that when a 2nd thread comes
along and tries to acquire a lock, it doesn't end up opening
and closing a new FD. The lockspace just checks the current
list of held locks and immediately returns VIR_ERR_RESOURCE_BUSY.

NB, the API as it stands is designed on the basis that the
files being locked are not being otherwise opened and used
by the application code. One approach to using this API is to
acquire locks based on a hash of the filepath.

eg to lock /var/lib/libvirt/images/foo.img the application
might do

   virLockSpacePtr lockspace = virLockSpaceNew("/var/lib/libvirt/imagelocks");
   lockname = md5sum("/var/lib/libvirt/images/foo.img");
   virLockSpaceAcquireLock(lockspace, lockname);

NB, in this example, the caller should ensure that the path
is canonicalized before calculating the checksum.

It is also possible to do locks directly on resources by
using a NULL lockspace directory and then using the file
path as the lock name eg

   virLockSpacePtr lockspace = virLockSpaceNew(NULL);
   virLockSpaceAcquireLock(lockspace, "/var/lib/libvirt/images/foo.img");

This is only safe to do though if no other part of the process
will be opening the files. This will be the case when this
code is used inside the soon-to-be-reposted virlockd daemon

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2012-10-16 15:45:55 +01:00