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/$GUEST.log", whenever a guest is started.
> 
> The information we include in "pkgversion" is the output of git-describe,
> with a plus sign (+) appended if there are staged or unstaged changes to
> tracked files, at the time of "configure" being executed.
> 
> The content of "pkgversion" is not changed when "--with-pkgversion" is
> used on the command line.
> 
> Cc: "Daniel P. Berrange" <address@hidden>
> Cc: Kashyap Chamarthy <address@hidden>
> Signed-off-by: Laszlo Ersek <address@hidden>
> ---
>  configure | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/configure b/configure
> index b5aab7257b33..20a7ec5cc0fd 100755
> --- a/configure
> +++ b/configure
> @@ -4255,6 +4255,44 @@ if have_backend "dtrace"; then
>  fi
>  
>  ##########################################
> +# save git working tree information in pkgversion
> +
> +# If pkgversion has not been set to a non-empty string, fetch the output of
> +# "git describe" into it. If the working tree is unclean (there are staged or
> +# unstaged changes in tracked files), then append a plus sign.
> +#
> +# If we're not building from a git working tree, then pkgversion is not
> +# changed. Otherwise, git errors are fatal.
> +
> +if test -z "$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
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