The 2nd and 3rd hunk show the only double-closed file descriptor code part that I found while trying to clean up close(). The first hunk seems a harmless cleanup in that same file.

* src/storage/storage_backend.c (virStorageBackendCreateQemuImg)
(virStorageBackendCreateQcowCreate): Use virAsprintf instead.
* src/storage/storage_backend_disk.c
(virStorageBackendDiskCreateVol, virStorageBackendDiskPartFormat):
Likewise.

* src/storage/storage_backend_disk.c
(virStorageBackendDiskPartFormat): Fix spacing.

- a pure typo error and a wrong command referenced in an error message.

Found by clang.  Clang complained that virStorageBackendProbeTarget
could dereference NULL if backingStoreFormat was NULL, but since all
callers passed a valid pointer, I added attributes instead of null
checks.

* src/storage/storage_backend.c
(virStorageBackendQEMUImgBackingFormat): Kill dead store.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Likewise.  Skip null checks, by adding attributes.

One error exit in virStorageBackendCreateBlockFrom was setting the
return value to errno. The convention for volume build functions is to
return 0 on success or -1 on failure. Not only was it not necessary to
set the return value (it defaults to -1, and is set to 0 when
everything has been successfully completed), in the case that some
caller were checking for < 0 rather than != 0, they would incorrectly
believe that it completed successfully.

virDirCreate also previously returned 0 on success and errno on
failure. This makes it fit the recommended convention of returning 0
on success, -errno (ie a negative number) on failure.

Previously virStorageBackendCopyToFD would simply return -1 on
error. This made the error return from one of its callers inconsistent
(createRawFileOpHook is supposed to return -errno, but if
virStorageBackendCopyToFD failed, createRawFileOpHook would just
return -1). Since there is a useful errno in every case of error
return from virStorageBackendCopyToFD, and since the other uses of
that function ignore the return code (beyond simply checking to see if
it is < 0), this is a safe change.

virFileOperation previously returned 0 on success, or the value of
errno on failure. Although there are other functions in libvirt that
use this convention, the preferred (and more common) convention is to
return 0 on success and -errno (or simply -1 in some cases) on
failure. This way the check for failure is always (ret < 0).

* src/util/util.c - change virFileOperation and virFileOperationNoFork to
                    return -errno on failure.

* src/storage/storage_backend.c, src/qemu/qemu_driver.c
  - change the hook functions passed to virFileOperation to return
    -errno on failure.

Originally the storage volume files were opened with O_DSYNC to make
sure they were flushed to disk immediately. It turned out that this
was extremely slow in some cases, so the O_DSYNC was removed in favor
of just calling fsync() after all the data had been written. However,
this call to fsync was inside the block that is executed to zero-fill
the end of the volume file. In cases where the new volume is copied
from an old volume, and they are the same length, this fsync would
never take place.

Now the fsync is *always* done, unless there is an error (in which
case it isn't important, and is most likely inappropriate.

A missing set of braces around an error condition caused us to skip
zero'ing out the remainder of a new volume file if the new volume was
longer than the original (the goto was supposed to be taken only in
the case of error, but was always being taken).

The storage volume lookup code was probing for the backing store
format, instead of using the format extracted from the file
itself. This meant it could report in accurate information. If
a format is included in the file, then use that in preference,
with probing as a fallback.

* src/storage/storage_backend_fs.c: Use extracted backing store
  format

When creating qcow2 files with a backing store, it is important
to set an explicit format to prevent QEMU probing. The storage
backend was only doing this if it found a 'kvm-img' binary. This
is wrong because plenty of kvm-img binaries don't support an
explicit format, and plenty of 'qemu-img' binaries do support
a format. The result was that most qcow2 files were not getting
a backing store format.

This patch runs 'qemu-img -h' to check for the two support
argument formats

  '-o backing_format=raw'
  '-F raw'

and use whichever option it finds

* src/storage/storage_backend.c: Query binary to determine
  how to set the backing store format

Require the disk image to be passed into virStorageFileGetMetadata.
If this is set to VIR_STORAGE_FILE_AUTO, then the format will be
resolved using probing. This makes it easier to control when
probing will be used

* src/qemu/qemu_driver.c, src/qemu/qemu_security_dac.c,
  src/security/security_selinux.c, src/security/virt-aa-helper.c:
  Set VIR_STORAGE_FILE_AUTO when calling virStorageFileGetMetadata.
* src/storage/storage_backend_fs.c: Probe for disk format before
  calling virStorageFileGetMetadata.
* src/util/storage_file.h, src/util/storage_file.c: Remove format
  from virStorageFileMeta struct & require it to be passed into
  method.

There are many naming conventions for partitions associated with a
block device.  Some of the major ones are:

/dev/foo -> /dev/foo1
/dev/foo1 -> /dev/foo1p1
/dev/mapper/foo -> /dev/mapper/foop1
/dev/disk/by-path/foo -> /dev/disk/by-path/foo-part1

The universe of possible conventions isn't clear.  Rather than trying
to understand all possible conventions, this patch divides devices
into two groups, device mapper devices and everything else.  Device
mapper devices seem always to follow the convention of device ->
devicep1; everything else is canonicalized.

Daniel's patch works with gcc and CFLAGS containing -O (the
autoconf default), but fails with non-gcc or with other
CFLAGS (such as -g), since c-ctype.h declares c_isdigit as
a macro only for certain compilation settings.

* src/Makefile.am (libvirt_parthelper_LDFLAGS): Add gnulib
library, for when c_isdigit is not a macro.
* src/storage/parthelper.c (main): Avoid out-of-bounds
dereference, noticed by Jim Meyering.

Disks with a trailing digit in their path (eg /dev/loop0 or
/dev/dm0) have an extra 'p' appended before the partition
number (eg, to form /dev/loop0p1 not /dev/loop01). Fix the
partition lookup to append this extra 'p' when required

* src/storage/parthelper.c: Add a 'p' before partition
  number if required

The storage pool driver is mistakenly using the error code
VIR_ERR_INVALID_STORAGE_POOL which is for diagnosing invalid
pointers. This patch switches it to use VIR_ERR_NO_STORAGE_POOL
which is the correct code for cases where the storage pool does
not exist

* src/storage/storage_driver.c: Replace VIR_ERR_INVALID_STORAGE_POOL
  with VIR_ERR_NO_STORAGE_POOL

The storage pool driver is not doing correct checking for
duplicate UUID/name values. This introduces a new method
virStoragePoolObjIsDuplicate, based on the previously
written virDomainObjIsDuplicate.

* src/conf/storage_conf.c, src/conf/storage_conf.c,
  src/libvirt_private.syms: Add virStoragePoolObjIsDuplicate,
* src/storage/storage_driver.c: Call virStoragePoolObjIsDuplicate
  for checking uniqueness of uuid/names

* src/storage/storage_backend.h (VIR_STORAGE_VOL_OPEN_DEFAULT):
Adjust s/#define/# define/, and align continued lines.

If a directory pool contains pipes or sockets, a pool start can fail or hang:

https://bugzilla.redhat.com/show_bug.cgi?id=589577

We already try to avoid these special files, but only attempt after
opening the path, which is where the problems lie. Unify volume opening
into helper functions, which use the proper open() flags to avoid error,
followed by fstat to validate storage mode.

Previously, virStorageBackendUpdateVolTargetInfoFD attempted to enforce the
storage mode check, but allowed callers to detect this case and silently
continue. In practice, only the FS backend was using this feature, the rest
were treating unknown mode as an error condition. Unfortunately the InfoFD
function wasn't raising an error message here, so error reporting was
busted.

This patch adds 2 functions: virStorageBackendVolOpen, and
virStorageBackendVolOpenModeSkip. The latter retains the original opt out
semantics, the former now throws an explicit error.

This patch maintains the previous volume mode checks: allowing specific
modes for specific pool types requires a bit of surgery, since VolOpen
is called through several different helper functions.

v2: Use ATTRIBUTE_NONNULL. Drop stat check, just open with
    O_NONBLOCK|O_NOCTTY.

v3: Move mode check logic back to VolOpen. Use 2 VolOpen functions with
    different error semantics.

v4: Make second VolOpen function more extensible. Didn't opt to change
    FS backend defaults, this can just be to fix the original bug.

v5: Prefix default flags with VIR_, use ATTRIBUTE_RETURN_CHECK

Spurious / in a pool target path makes life difficult for apps using the
GetVolByPath, and doing other path based comparisons with pools. This
has caused a few issues for virt-manager users:

https://bugzilla.redhat.com/show_bug.cgi?id=494005
https://bugzilla.redhat.com/show_bug.cgi?id=593565

Add a new util API which removes spurious /, virFileSanitizePath. Sanitize
target paths when parsing pool XML, and for paths passed to GetVolByPath.

v2: Leading // must be preserved, properly sanitize path=/, sanitize
    away /./ -> /

v3: Properly handle starting ./ and ending /.

v4: Drop all '.' handling, just sanitize / for now.

Volume detection in the scsi backend was duplicating code already
present in storage_backend.c. Let's drop the duplicate code.

Also, change the shared function name to be less generic, and remove
some error squashing in the other call site.

We were squashing error messages in a few cases. Recode to follow common
ret = -1 convention.

v2: Handle more error squashing issues further up in MakeNewVol and
    CreateVols. Use ret = -1 convention in MakeVols.

Run this command:
  git grep -l VIR_DEBUG|xargs perl -pi -e \
    's/(VIR_DEBUG0?)\s*\(_\((".*?")\)/$1($2/'

Run this:
  git grep -l 'VIR_ERROR\s*("'|xargs perl -pi -e \
    's/(VIR_ERROR)\s*\((".*?"),/$1(_($2),/'

virFileResolveLink was returning a positive value on error,
thus confusing callers that assumed failure was < 0.  The
confusion is further evidenced by callers that would have
ended up calling virReportSystemError with a negative value
instead of a valid errno.

Fixes Red Hat BZ #591363.

* src/util/util.c (virFileResolveLink): Live up to documentation.
* src/qemu/qemu_security_dac.c
(qemuSecurityDACRestoreSecurityFileLabel): Adjust callers.
* src/security/security_selinux.c
(SELinuxRestoreSecurityFileLabel): Likewise.
* src/storage/storage_backend_disk.c
(virStorageBackendDiskDeleteVol): Likewise.

* configure.ac: Drop sys/wait.h check.
* src/libvirt.c (includes): Use header unconditionally.
* src/remote/remote_driver.c (includes): Likewise.
* src/storage/storage_backend.c (includes): Likewise.
* src/util/ebtables.c (includes): Likewise.
* src/util/hooks.c (includes): Likewise.
* src/util/iptables.c (includes): Likewise.
* src/util/util.c (includes): Likewise.

WIN32 is always defined when __MINGW32__ is defined, but the
converse is not true.  WIN32 is more generic, if someone were
to ever attempt porting to a microsoft compiler.  This does
not affect Cygwin, which intentionally does not define WIN32.

* src/qemu/qemu_driver.c (qemuDomainGetBlockInfo): Use more
generic flag macro.
* src/storage/storage_backend.c
(virStorageBackendUpdateVolTargetInfoFD)
(virStorageBackendRunProgRegex): Likewise.
* tools/console.h (vshRunConsole): Likewise.

* src/qemu/qemu_driver.c: Implementation of virDomainGetBlockInfo
* src/util/storage_file.h: Add DEV_BSIZE
* src/storage/storage_backend.c: Remove DEV_BSIZE

* src/storage/storage_backend_fs.c (virStorageBackendFileSystemMount):
Use virAsprintf only when needed.  In this case, strdup works fine.

* src/storage/storage_backend_fs.c (virStorageBackendFileSystemMount):
Clang was not smart enough, and mistakenly reported that "options"
could be used uninitialized.  Initialize it.

* src/storage/storage_backend.c (createRawFileOpHook): Remove dead
stores and declaration of each stored-to variable.

Instead of opening storage file with O_DSYNC, make sure data are written
to a disk only before we claim allocation has finished.

* global: patch created by running:
for f in $(git ls-files '*.[ch]') ; do
    cppi $f > $f.t && mv $f.t $f
done

This allows the config to have a setting that means "leave it alone",
eg when building a pool where the directory already exists the user
may want the current uid/gid of the directory left intact. This
actually gets us back to older behavior - before recent changes to the
pool building code, we weren't as insistent about honoring the uid/gid
settings in the XML, and virt-manager was taking advantage of this
behavior.

As a side benefit, removing calls to getuid/getgid from the XML
parsing functions also seems like a good idea. And having a default
that is different from a common/useful value (0 == root) is a good
thing in general, as it removes ambiguity from decisions (at least one
place in the code was checking for (perms.uid == 0) to see if a
special uid was requested).

Note that this will only affect newly created pools and volumes. Due
to the way that the XML is parsed, then formatted for newly created
volumes, all existing pools/volumes already have an explicit uid and
gid set.

src/conf/storage_conf.c: Remove calls to setuid/setgid for default values
                         of uid/gid, and set them to -1 instead

src/storage/storage_backend.c:
src/storage/storage_backend_fs.c:
        Make account for the new default values of perms.uid
        and perms.gid.