[Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Laszlo Ersek]

When building QEMU from a git working tree (either in-tree or
out-of-tree), it is useful to capture the working tree status in the QEMU
binary, for the "-version" option to report.

Daniel suggested using the "pkgversion" variable (tied to the
"--with-pkgversion" option) of the configure script for this. Downstream
packagers of QEMU already use this option for customizing their builds,
plus libvirtd captures "pkgversion" (with the "-version" option) in
"/var/log/libvirt/qemu/$GUEST.log", whenever a guest is started.

The information we include in "pkgversion" is the output of git-describe,
with a plus sign (+) appended if there are staged or unstaged changes to
tracked files, at the time of "configure" being executed.

The content of "pkgversion" is not changed when "--with-pkgversion" is
used on the command line.

Cc: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Kashyap Chamarthy <kchamart@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 configure | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/configure b/configure
index b5aab7257b33..20a7ec5cc0fd 100755
--- a/configure
+++ b/configure
@@ -4255,6 +4255,44 @@ if have_backend "dtrace"; then
 fi
 
 ##########################################
+# save git working tree information in pkgversion
+
+# If pkgversion has not been set to a non-empty string, fetch the output of
+# "git describe" into it. If the working tree is unclean (there are staged or
+# unstaged changes in tracked files), then append a plus sign.
+#
+# If we're not building from a git working tree, then pkgversion is not
+# changed. Otherwise, git errors are fatal.
+
+if test -z "$pkgversion" && test -d "$source_path/.git"; then
+  pkgversion=$(
+    export GIT_DIR=$source_path/.git
+    export GIT_WORK_TREE=$source_path
+
+    git_desc=$(git describe)
+    git_exit=$?
+    if test $git_exit -ne 0; then
+      exit $git_exit
+    fi
+
+    git_changes=
+    for git_diff_option in "" --staged; do
+      git diff $git_diff_option --quiet
+      git_exit=$?
+      case $git_exit in
+      (0) ;;
+      (1) git_changes=+
+          ;;
+      (*) exit $git_exit
+          ;;
+      esac
+    done
+
+    printf " (%s%s)" "$git_desc" "$git_changes"
+  ) || error_exit "Failed to get git description, working tree or index status"
+fi
+
+##########################################
 # check and set a backend for coroutine
 
 # We prefer ucontext, but it's not always possible. The fallback
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Daniel P. Berrange]

On Tue, May 31, 2016 at 05:04:04PM +0200, Laszlo Ersek wrote:
> When building QEMU from a git working tree (either in-tree or
> out-of-tree), it is useful to capture the working tree status in the QEMU
> binary, for the "-version" option to report.
> 
> Daniel suggested using the "pkgversion" variable (tied to the
> "--with-pkgversion" option) of the configure script for this. Downstream
> packagers of QEMU already use this option for customizing their builds,
> plus libvirtd captures "pkgversion" (with the "-version" option) in
> "/var/log/libvirt/qemu/$GUEST.log", whenever a guest is started.
> 
> The information we include in "pkgversion" is the output of git-describe,
> with a plus sign (+) appended if there are staged or unstaged changes to
> tracked files, at the time of "configure" being executed.
> 
> The content of "pkgversion" is not changed when "--with-pkgversion" is
> used on the command line.
> 
> Cc: "Daniel P. Berrange" <berrange@redhat.com>
> Cc: Kashyap Chamarthy <kchamart@redhat.com>
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>  configure | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/configure b/configure
> index b5aab7257b33..20a7ec5cc0fd 100755
> --- a/configure
> +++ b/configure
> @@ -4255,6 +4255,44 @@ if have_backend "dtrace"; then
>  fi
>  
>  ##########################################
> +# save git working tree information in pkgversion
> +
> +# If pkgversion has not been set to a non-empty string, fetch the output of
> +# "git describe" into it. If the working tree is unclean (there are staged or
> +# unstaged changes in tracked files), then append a plus sign.
> +#
> +# If we're not building from a git working tree, then pkgversion is not
> +# changed. Otherwise, git errors are fatal.
> +
> +if test -z "$pkgversion" && test -d "$source_path/.git"; then
> +  pkgversion=$(
> +    export GIT_DIR=$source_path/.git
> +    export GIT_WORK_TREE=$source_path
> +
> +    git_desc=$(git describe)
> +    git_exit=$?
> +    if test $git_exit -ne 0; then
> +      exit $git_exit
> +    fi
> +
> +    git_changes=
> +    for git_diff_option in "" --staged; do
> +      git diff $git_diff_option --quiet
> +      git_exit=$?
> +      case $git_exit in
> +      (0) ;;
> +      (1) git_changes=+
> +          ;;
> +      (*) exit $git_exit
> +          ;;
> +      esac
> +    done

An alternative to this would be to jus use

 "git describe --dirty"

which appends "--dirty" to its output if working tre has uncommitted
changes.

Not sure if the --dirty flag is a recent option or whether we can just
assume it always exists.

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Laszlo Ersek]

On 05/31/16 17:14, Daniel P. Berrange wrote:
> On Tue, May 31, 2016 at 05:04:04PM +0200, Laszlo Ersek wrote:
>> When building QEMU from a git working tree (either in-tree or
>> out-of-tree), it is useful to capture the working tree status in the QEMU
>> binary, for the "-version" option to report.
>>
>> Daniel suggested using the "pkgversion" variable (tied to the
>> "--with-pkgversion" option) of the configure script for this. Downstream
>> packagers of QEMU already use this option for customizing their builds,
>> plus libvirtd captures "pkgversion" (with the "-version" option) in
>> "/var/log/libvirt/qemu/$GUEST.log", whenever a guest is started.
>>
>> The information we include in "pkgversion" is the output of git-describe,
>> with a plus sign (+) appended if there are staged or unstaged changes to
>> tracked files, at the time of "configure" being executed.
>>
>> The content of "pkgversion" is not changed when "--with-pkgversion" is
>> used on the command line.
>>
>> Cc: "Daniel P. Berrange" <berrange@redhat.com>
>> Cc: Kashyap Chamarthy <kchamart@redhat.com>
>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>> ---
>>  configure | 38 ++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 38 insertions(+)
>>
>> diff --git a/configure b/configure
>> index b5aab7257b33..20a7ec5cc0fd 100755
>> --- a/configure
>> +++ b/configure
>> @@ -4255,6 +4255,44 @@ if have_backend "dtrace"; then
>>  fi
>>  
>>  ##########################################
>> +# save git working tree information in pkgversion
>> +
>> +# If pkgversion has not been set to a non-empty string, fetch the output of
>> +# "git describe" into it. If the working tree is unclean (there are staged or
>> +# unstaged changes in tracked files), then append a plus sign.
>> +#
>> +# If we're not building from a git working tree, then pkgversion is not
>> +# changed. Otherwise, git errors are fatal.
>> +
>> +if test -z "$pkgversion" && test -d "$source_path/.git"; then
>> +  pkgversion=$(
>> +    export GIT_DIR=$source_path/.git
>> +    export GIT_WORK_TREE=$source_path
>> +
>> +    git_desc=$(git describe)
>> +    git_exit=$?
>> +    if test $git_exit -ne 0; then
>> +      exit $git_exit
>> +    fi
>> +
>> +    git_changes=
>> +    for git_diff_option in "" --staged; do
>> +      git diff $git_diff_option --quiet
>> +      git_exit=$?
>> +      case $git_exit in
>> +      (0) ;;
>> +      (1) git_changes=+
>> +          ;;
>> +      (*) exit $git_exit
>> +          ;;
>> +      esac
>> +    done
> 
> An alternative to this would be to jus use
> 
>  "git describe --dirty"
> 
> which appends "--dirty" to its output if working tre has uncommitted
> changes.

Good idea!

> Not sure if the --dirty flag is a recent option or whether we can just
> assume it always exists.

Grepping git's Documentation/RelNotes/ directory, I find:
- in "1.6.6.txt": the introduction of --dirty
- in "1.7.6.4.txt": an apparently important bugfix for --dirty

Version 1.7.6.4 of git was tagged on Sep 23 2011.

Does this information help in deciding if we can use --dirty?

For example, Debian oldstable ("wheezy"), which I tend to use as one
reference point for "ancient but still supported", has 1.7.10.4:

https://packages.debian.org/wheezy/git

Another example: the latest git package in EPEL-5 is 1.8.2.3:

http://koji.fedoraproject.org/koji/buildinfo?buildID=757915

Thanks
Laszlo

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Daniel P. Berrange]

On Tue, May 31, 2016 at 05:40:38PM +0200, Laszlo Ersek wrote:
> On 05/31/16 17:14, Daniel P. Berrange wrote:
> > On Tue, May 31, 2016 at 05:04:04PM +0200, Laszlo Ersek wrote:
> >> When building QEMU from a git working tree (either in-tree or
> >> out-of-tree), it is useful to capture the working tree status in the QEMU
> >> binary, for the "-version" option to report.
> >>
> >> Daniel suggested using the "pkgversion" variable (tied to the
> >> "--with-pkgversion" option) of the configure script for this. Downstream
> >> packagers of QEMU already use this option for customizing their builds,
> >> plus libvirtd captures "pkgversion" (with the "-version" option) in
> >> "/var/log/libvirt/qemu/$GUEST.log", whenever a guest is started.
> >>
> >> The information we include in "pkgversion" is the output of git-describe,
> >> with a plus sign (+) appended if there are staged or unstaged changes to
> >> tracked files, at the time of "configure" being executed.
> >>
> >> The content of "pkgversion" is not changed when "--with-pkgversion" is
> >> used on the command line.
> >>
> >> Cc: "Daniel P. Berrange" <berrange@redhat.com>
> >> Cc: Kashyap Chamarthy <kchamart@redhat.com>
> >> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> >> ---
> >>  configure | 38 ++++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 38 insertions(+)
> >>
> >> diff --git a/configure b/configure
> >> index b5aab7257b33..20a7ec5cc0fd 100755
> >> --- a/configure
> >> +++ b/configure
> >> @@ -4255,6 +4255,44 @@ if have_backend "dtrace"; then
> >>  fi
> >>  
> >>  ##########################################
> >> +# save git working tree information in pkgversion
> >> +
> >> +# If pkgversion has not been set to a non-empty string, fetch the output of
> >> +# "git describe" into it. If the working tree is unclean (there are staged or
> >> +# unstaged changes in tracked files), then append a plus sign.
> >> +#
> >> +# If we're not building from a git working tree, then pkgversion is not
> >> +# changed. Otherwise, git errors are fatal.
> >> +
> >> +if test -z "$pkgversion" && test -d "$source_path/.git"; then
> >> +  pkgversion=$(
> >> +    export GIT_DIR=$source_path/.git
> >> +    export GIT_WORK_TREE=$source_path
> >> +
> >> +    git_desc=$(git describe)
> >> +    git_exit=$?
> >> +    if test $git_exit -ne 0; then
> >> +      exit $git_exit
> >> +    fi
> >> +
> >> +    git_changes=
> >> +    for git_diff_option in "" --staged; do
> >> +      git diff $git_diff_option --quiet
> >> +      git_exit=$?
> >> +      case $git_exit in
> >> +      (0) ;;
> >> +      (1) git_changes=+
> >> +          ;;
> >> +      (*) exit $git_exit
> >> +          ;;
> >> +      esac
> >> +    done
> > 
> > An alternative to this would be to jus use
> > 
> >  "git describe --dirty"
> > 
> > which appends "--dirty" to its output if working tre has uncommitted
> > changes.
> 
> Good idea!
> 
> > Not sure if the --dirty flag is a recent option or whether we can just
> > assume it always exists.
> 
> Grepping git's Documentation/RelNotes/ directory, I find:
> - in "1.6.6.txt": the introduction of --dirty
> - in "1.7.6.4.txt": an apparently important bugfix for --dirty
> 
> Version 1.7.6.4 of git was tagged on Sep 23 2011.
> 
> Does this information help in deciding if we can use --dirty?

5 years old sounds new enough for my liking :-)

I guess we could use --dirty and catch the non-zero exit code and just
re-try without --dirty.

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Laszlo Ersek]

On 05/31/16 17:43, Daniel P. Berrange wrote:
> On Tue, May 31, 2016 at 05:40:38PM +0200, Laszlo Ersek wrote:
>> On 05/31/16 17:14, Daniel P. Berrange wrote:
>>> On Tue, May 31, 2016 at 05:04:04PM +0200, Laszlo Ersek wrote:
>>>> When building QEMU from a git working tree (either in-tree or
>>>> out-of-tree), it is useful to capture the working tree status in the QEMU
>>>> binary, for the "-version" option to report.
>>>>
>>>> Daniel suggested using the "pkgversion" variable (tied to the
>>>> "--with-pkgversion" option) of the configure script for this. Downstream
>>>> packagers of QEMU already use this option for customizing their builds,
>>>> plus libvirtd captures "pkgversion" (with the "-version" option) in
>>>> "/var/log/libvirt/qemu/$GUEST.log", whenever a guest is started.
>>>>
>>>> The information we include in "pkgversion" is the output of git-describe,
>>>> with a plus sign (+) appended if there are staged or unstaged changes to
>>>> tracked files, at the time of "configure" being executed.
>>>>
>>>> The content of "pkgversion" is not changed when "--with-pkgversion" is
>>>> used on the command line.
>>>>
>>>> Cc: "Daniel P. Berrange" <berrange@redhat.com>
>>>> Cc: Kashyap Chamarthy <kchamart@redhat.com>
>>>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>>>> ---
>>>>  configure | 38 ++++++++++++++++++++++++++++++++++++++
>>>>  1 file changed, 38 insertions(+)
>>>>
>>>> diff --git a/configure b/configure
>>>> index b5aab7257b33..20a7ec5cc0fd 100755
>>>> --- a/configure
>>>> +++ b/configure
>>>> @@ -4255,6 +4255,44 @@ if have_backend "dtrace"; then
>>>>  fi
>>>>  
>>>>  ##########################################
>>>> +# save git working tree information in pkgversion
>>>> +
>>>> +# If pkgversion has not been set to a non-empty string, fetch the output of
>>>> +# "git describe" into it. If the working tree is unclean (there are staged or
>>>> +# unstaged changes in tracked files), then append a plus sign.
>>>> +#
>>>> +# If we're not building from a git working tree, then pkgversion is not
>>>> +# changed. Otherwise, git errors are fatal.
>>>> +
>>>> +if test -z "$pkgversion" && test -d "$source_path/.git"; then
>>>> +  pkgversion=$(
>>>> +    export GIT_DIR=$source_path/.git
>>>> +    export GIT_WORK_TREE=$source_path
>>>> +
>>>> +    git_desc=$(git describe)
>>>> +    git_exit=$?
>>>> +    if test $git_exit -ne 0; then
>>>> +      exit $git_exit
>>>> +    fi
>>>> +
>>>> +    git_changes=
>>>> +    for git_diff_option in "" --staged; do
>>>> +      git diff $git_diff_option --quiet
>>>> +      git_exit=$?
>>>> +      case $git_exit in
>>>> +      (0) ;;
>>>> +      (1) git_changes=+
>>>> +          ;;
>>>> +      (*) exit $git_exit
>>>> +          ;;
>>>> +      esac
>>>> +    done
>>>
>>> An alternative to this would be to jus use
>>>
>>>  "git describe --dirty"
>>>
>>> which appends "--dirty" to its output if working tre has uncommitted
>>> changes.
>>
>> Good idea!
>>
>>> Not sure if the --dirty flag is a recent option or whether we can just
>>> assume it always exists.
>>
>> Grepping git's Documentation/RelNotes/ directory, I find:
>> - in "1.6.6.txt": the introduction of --dirty
>> - in "1.7.6.4.txt": an apparently important bugfix for --dirty
>>
>> Version 1.7.6.4 of git was tagged on Sep 23 2011.
>>
>> Does this information help in deciding if we can use --dirty?
> 
> 5 years old sounds new enough for my liking :-)
> 
> I guess we could use --dirty and catch the non-zero exit code and just
> re-try without --dirty.

But, if we can't use --dirty, I should probably use the plus-sign
fallback (we need *something* to mark a dirty state).

In which case however, shouldn't we just go with the current patch,
which doesn't care about --dirty at all? Otherwise, some build hosts
will append "-dirty", and others will append "+".

IMO we should either require --dirty, or go with the current patch.

Thanks
Laszlo

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Eric Blake]

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On 05/31/2016 11:01 AM, Laszlo Ersek wrote:

>>> Grepping git's Documentation/RelNotes/ directory, I find:
>>> - in "1.6.6.txt": the introduction of --dirty
>>> - in "1.7.6.4.txt": an apparently important bugfix for --dirty
>>>
>>> Version 1.7.6.4 of git was tagged on Sep 23 2011.
>>>
>>> Does this information help in deciding if we can use --dirty?
>>
>> 5 years old sounds new enough for my liking :-)
>>
>> I guess we could use --dirty and catch the non-zero exit code and just
>> re-try without --dirty.
> 
> But, if we can't use --dirty, I should probably use the plus-sign
> fallback (we need *something* to mark a dirty state).
> 
> In which case however, shouldn't we just go with the current patch,
> which doesn't care about --dirty at all? Otherwise, some build hosts
> will append "-dirty", and others will append "+".
> 
> IMO we should either require --dirty, or go with the current patch.

Gnulib's build-aux/git-version-gen script doesn't yet use --dirty, but
may be an inspiration for how to generate the same suffix:

# Test whether to append the "-dirty" suffix only if the version
# string we're using came from git.  I.e., skip the test if it's "UNKNOWN"
# or if it came from .tarball-version.
if test "x$v_from_git" != x; then
  # Don't declare a version "dirty" merely because a time stamp has changed.
  git update-index --refresh > /dev/null 2>&1

  dirty=`exec 2>/dev/null;git diff-index --name-only HEAD` || dirty=
  case "$dirty" in
      '') ;;
      *) # Append the suffix only if there isn't one already.
          case $v in
            *-dirty) ;;
            *) v="$v-dirty" ;;
          esac ;;
  esac
fi

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Laszlo Ersek]

On 05/31/16 19:45, Eric Blake wrote:
> On 05/31/2016 11:01 AM, Laszlo Ersek wrote:
> 
>>>> Grepping git's Documentation/RelNotes/ directory, I find:
>>>> - in "1.6.6.txt": the introduction of --dirty
>>>> - in "1.7.6.4.txt": an apparently important bugfix for --dirty

(*)

>>>>
>>>> Version 1.7.6.4 of git was tagged on Sep 23 2011.
>>>>
>>>> Does this information help in deciding if we can use --dirty?
>>>
>>> 5 years old sounds new enough for my liking :-)
>>>
>>> I guess we could use --dirty and catch the non-zero exit code and just
>>> re-try without --dirty.
>>
>> But, if we can't use --dirty, I should probably use the plus-sign
>> fallback (we need *something* to mark a dirty state).
>>
>> In which case however, shouldn't we just go with the current patch,
>> which doesn't care about --dirty at all? Otherwise, some build hosts
>> will append "-dirty", and others will append "+".
>>
>> IMO we should either require --dirty, or go with the current patch.
> 
> Gnulib's build-aux/git-version-gen script doesn't yet use --dirty, but
> may be an inspiration for how to generate the same suffix:
> 
> # Test whether to append the "-dirty" suffix only if the version
> # string we're using came from git.  I.e., skip the test if it's "UNKNOWN"
> # or if it came from .tarball-version.
> if test "x$v_from_git" != x; then
>   # Don't declare a version "dirty" merely because a time stamp has changed.
>   git update-index --refresh > /dev/null 2>&1

(
This is exactly the fix (*) that went into git v1.7.6.4 (and v1.7.7):

$ git log --oneline --reverse v1.7.6.3..v1.7.6.4

0f64bfa9567f ls-files: fix pathspec display on error
e9d4f7405b6a branch.c: use the parsed branch name
13d6ec913330 read_gitfile_gently(): rename misnamed function to read_gitfile()
9b0ebc722cfc clone: allow to clone from .git file
dbc92b072dd7 clone: allow more than one --reference
e6baf4a1ae1b clone: clone from a repository with relative alternates
2f633f41d695 check-ref-format --print: Normalize refnames that start with slashes
f3738c1ce919 Forbid DEL characters in reference names
385ceec1cb46 t3005: do not assume a particular order of stdout and stderr of git-ls-files
dff4b0ef30cd am: format is in $patch_format, not parse_patch
e622f41dcd97 git-mergetool: check return value from read
40ffc4987661 Merge branch 'gb/maint-am-patch-format-error-message' into maint
503359f13abc Merge branch 'mg/branch-set-upstream-previous' into maint
be5acb3b63af Merge branch 'mh/check-ref-format-print-normalize' into maint
406c1c4dd4a8 Merge branch 'nd/maint-clone-gitdir' into maint
84b051462fca Merge branch 'jc/maint-clone-alternates' into maint
85b3c75f4fd3 describe: Refresh the index when run with --dirty
a0b1cb60ab29 Merge branch 'cb/maint-ls-files-error-report' into maint
632052641517 Git 1.7.6.4

--> https://github.com/git/git/commit/85b3c75f4fd3
    "describe: Refresh the index when run with --dirty"
)

> 
>   dirty=`exec 2>/dev/null;git diff-index --name-only HEAD` || dirty=
>   case "$dirty" in
>       '') ;;
>       *) # Append the suffix only if there isn't one already.
>           case $v in
>             *-dirty) ;;
>             *) v="$v-dirty" ;;
>           esac ;;
>   esac
> fi

This seems to do the right thing, yes.

I'll submit a new version later.

Thanks!
Laszlo

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Laszlo Ersek]

On 05/31/16 19:45, Eric Blake wrote:
> On 05/31/2016 11:01 AM, Laszlo Ersek wrote:
> 
>>>> Grepping git's Documentation/RelNotes/ directory, I find:
>>>> - in "1.6.6.txt": the introduction of --dirty
>>>> - in "1.7.6.4.txt": an apparently important bugfix for --dirty
>>>>
>>>> Version 1.7.6.4 of git was tagged on Sep 23 2011.
>>>>
>>>> Does this information help in deciding if we can use --dirty?
>>>
>>> 5 years old sounds new enough for my liking :-)
>>>
>>> I guess we could use --dirty and catch the non-zero exit code and just
>>> re-try without --dirty.
>>
>> But, if we can't use --dirty, I should probably use the plus-sign
>> fallback (we need *something* to mark a dirty state).
>>
>> In which case however, shouldn't we just go with the current patch,
>> which doesn't care about --dirty at all? Otherwise, some build hosts
>> will append "-dirty", and others will append "+".
>>
>> IMO we should either require --dirty, or go with the current patch.
> 
> Gnulib's build-aux/git-version-gen script doesn't yet use --dirty, but
> may be an inspiration for how to generate the same suffix:
> 
> # Test whether to append the "-dirty" suffix only if the version
> # string we're using came from git.  I.e., skip the test if it's "UNKNOWN"
> # or if it came from .tarball-version.
> if test "x$v_from_git" != x; then
>   # Don't declare a version "dirty" merely because a time stamp has changed.
>   git update-index --refresh > /dev/null 2>&1
> 
>   dirty=`exec 2>/dev/null;git diff-index --name-only HEAD` || dirty=
>   case "$dirty" in
>       '') ;;
>       *) # Append the suffix only if there isn't one already.
>           case $v in
>             *-dirty) ;;
>             *) v="$v-dirty" ;;
>           esac ;;
>   esac
> fi
> 

BTW, my patch has a functionality bug. Consider the case when you change
some of the tracked files, then stage all those changes with "git add",
then *undo* the changes in the working tree only. In this case, my patch
will report "dirty" ("+"), because there will be both staged changes
(relative to the HEAD commit) and working tree changes (relative to the
index). But that's incorrect -- the working tree actually matches the
HEAD commit, so the build qualifies as "clean".

On the other hand, git-diff-index will do the right thing, namely:

       git-diff-index <tree-ish>
           compares the <tree-ish> and the files on the filesystem.

which is exactly right. The index (= the staged changes) are irrelevant
for a build; only the working tree matters.

(Anyway, this is moot now; I'll happily leave it to Fam! :))

Thanks
Laszlo

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Fam Zheng]

On Wed, 06/01 10:55, Laszlo Ersek wrote:
> (Anyway, this is moot now; I'll happily leave it to Fam! :))

Thanks, I wrote the code before you sent this, so I posted it today anyway.  :)

Also note that we shouldn't do this at configure time, because between
./configure and make, the tree can be modified. That's why my patch is in
Makefile, and always checks the "dirtiness".

Fam

Re: [Qemu-devel] [PATCH] configure: save git working tree information in "pkgversion"

[Kashyap Chamarthy]

On Tue, May 31, 2016 at 05:04:04PM +0200, Laszlo Ersek wrote:
> When building QEMU from a git working tree (either in-tree or
> out-of-tree), it is useful to capture the working tree status in the QEMU
> binary, for the "-version" option to report.
> 
> Daniel suggested using the "pkgversion" variable (tied to the
> "--with-pkgversion" option) of the configure script for this. Downstream
> packagers of QEMU already use this option for customizing their builds,
> plus libvirtd captures "pkgversion" (with the "-version" option) in
> "/var/log/libvirt/qemu/$GUEST.log", whenever a guest is started.
> 
> The information we include in "pkgversion" is the output of git-describe,
> with a plus sign (+) appended if there are staged or unstaged changes to
> tracked files, at the time of "configure" being executed.
> 
> The content of "pkgversion" is not changed when "--with-pkgversion" is
> used on the command line.
> 
> Cc: "Daniel P. Berrange" <berrange@redhat.com>
> Cc: Kashyap Chamarthy <kchamart@redhat.com>
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>  configure | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)

[...]

Thanks, this is quite handy as I often have multiple QEMU binaries, and
it'd be useful to associate the binary with a Git tree.

Just tested on a clean tree.

Before:

    $ ./x86_64-softmmu/qemu-system-x86_64 -version
    QEMU emulator version 2.5.50, Copyright (c) 2003-2008 Fabrice Bellard

After applying the patch:

    $ ./x86_64-softmmu/qemu-system-x86_64 -version
    QEMU emulator version 2.6.50 (v2.6.0-602-g0132639), Copyright (c) 2003-2008 Fabrice Bellard

- - -

I see there's an in-progress discussion of "git describe --dirty" vs. the
plus-sign fallback.  For the current version:

Tested-by: Kashyap Chamarthy <kchamart@redhat.com>

-- 
/kashyap