[Mesa-dev] [PATCH] scons: put the generated git_sha1.h file in top-level src/ directory

[Eric Engestrom]

On Wed, Jun 15, 2016 at 11:58:29AM -0600, Brian Paul wrote:
> To match what's done in the automake build.
> ---
>  src/SConscript      | 43 +++++++++++++++++++++++++++++++++++++++++++
>  src/mesa/SConscript | 43 ++-----------------------------------------
>  2 files changed, 45 insertions(+), 41 deletions(-)
> 
> diff --git a/src/SConscript b/src/SConscript
> index 4ba0a32..719aa69 100644
> --- a/src/SConscript
> +++ b/src/SConscript
> @@ -1,5 +1,6 @@
>  Import('*')
>  
> +import os
>  
>  if env['platform'] == 'windows':
>      SConscript('getopt/SConscript')
> @@ -12,6 +13,48 @@ if env['hostonly']:
>      # compilation
>      Return()
>  
> +
> +def write_git_sha1_h_file(filename):
> +    """Mesa looks for a git_sha1.h file at compile time in order to display
> +    the current git hash id in the GL_VERSION string.  This function tries
> +    to retrieve the git hashid and write the header file.  An empty file
> +    will be created if anything goes wrong."""
> +
> +    args = [ 'git', 'log', '-n', '1', '--oneline' ]

You could take the opportunity to change this to:

	args = [ 'git', 'rev-parse', '--short', 'HEAD' ]

to match what's being done on the make build:
https://patchwork.freedesktop.org/patch/90532/

> +    try:
> +        (commit, foo) = subprocess.Popen(args, stdout=subprocess.PIPE).communicate()
> +    except:
> +        # git log command didn't work
> +        if not os.path.exists(filename):
> +            dirname = os.path.dirname(filename)
> +            if dirname and not os.path.exists(dirname):
> +                os.makedirs(dirname)
> +            # create an empty file if none already exists
> +            f = open(filename, "w")
> +            f.close()
> +        return
> +
> +    commit = '#define MESA_GIT_SHA1 "git-%s"\n' % commit[0:7]

That fixed truncation can give non-unique hashes. Switching to rev-parse
(suggested above) fixes this.
I had a quick grep and found Mesa has already 314 commits that can't be
uniquely described from the first 7 chars of their hashes:

	$ git rev-list --all --abbrev=0 --abbrev-commit | grep -E '.{8,}' | wc -l
	314

(I also tend to dislike overwriting a variable with something
semantically different from what it contained before, but that's
a matter of opinion, and you didn't author that code anyway.)

The rest looks good, but I've never used SCons and my Python experience
is very limited so I won't formally give an r-b on this.

> +    tempfile = "git_sha1.h.tmp"
> +    f = open(tempfile, "w")
> +    f.write(commit)
> +    f.close()
> +    if not os.path.exists(filename) or not filecmp.cmp(tempfile, filename):
> +        # The filename does not exist or it's different from the new file,
> +        # so replace old file with new.
> +        if os.path.exists(filename):
> +            os.remove(filename)
> +        os.rename(tempfile, filename)
> +    return
> +
> +
> +# Create the git_sha1.h header file
> +write_git_sha1_h_file("git_sha1.h")
> +# and update CPPPATH so the git_sha1.h header can be found
> +env.Append(CPPPATH = ["#" + env['build_dir']])
> +
> +
> +
>  if env['platform'] != 'windows':
>      SConscript('loader/SConscript')
>  
> diff --git a/src/mesa/SConscript b/src/mesa/SConscript
> index 434800e..2a340ac 100644
> --- a/src/mesa/SConscript
> +++ b/src/mesa/SConscript
> @@ -4,7 +4,6 @@
>  
>  Import('*')
>  import filecmp
> -import os
>  import subprocess
>  from sys import executable as python_cmd
>  
> @@ -18,10 +17,12 @@ env.Append(CPPPATH = [
>      '#/src/mapi',
>      '#/src/glsl',
>      '#/src/mesa',
> +    '#/src/mesa/main',
>      '#/src/gallium/include',
>      '#/src/gallium/auxiliary',
>      Dir('../mapi'), # src/mapi build path
>      Dir('.'), # src/mesa build path
> +    Dir('main'),  # src/mesa/main/ build path
>  ])
>  
>  if env['platform'] == 'windows':
> @@ -119,46 +120,6 @@ if env['platform'] not in ('cygwin', 'darwin', 'windows', 'haiku'):
>          env.Append(CPPPATH = [matypes[0].dir])
>  
>  
> -def write_git_sha1_h_file(filename):
> -    """Mesa looks for a git_sha1.h file at compile time in order to display
> -    the current git hash id in the GL_VERSION string.  This function tries
> -    to retrieve the git hashid and write the header file.  An empty file
> -    will be created if anything goes wrong."""
> -
> -    args = [ 'git', 'log', '-n', '1', '--oneline' ]
> -    try:
> -        (commit, foo) = subprocess.Popen(args, stdout=subprocess.PIPE).communicate()
> -    except:
> -        # git log command didn't work
> -        if not os.path.exists(filename):
> -            dirname = os.path.dirname(filename)
> -            if not os.path.exists(dirname):
> -                os.makedirs(dirname)
> -            # create an empty file if none already exists
> -            f = open(filename, "w")
> -            f.close()
> -        return
> -
> -    commit = '#define MESA_GIT_SHA1 "git-%s"\n' % commit[0:7]
> -    tempfile = "git_sha1.h.tmp"
> -    f = open(tempfile, "w")
> -    f.write(commit)
> -    f.close()
> -    if not os.path.exists(filename) or not filecmp.cmp(tempfile, filename):
> -        # The filename does not exist or it's different from the new file,
> -        # so replace old file with new.
> -        if os.path.exists(filename):
> -            os.remove(filename)
> -        os.rename(tempfile, filename)
> -    return
> -
> -
> -# Create the git_sha1.h header file
> -write_git_sha1_h_file("main/git_sha1.h")
> -# and update CPPPATH so the git_sha1.h header can be found
> -env.Append(CPPPATH = ["#" + env['build_dir'] + "/mesa/main"])
> -
> -
>  #
>  # Libraries
>  #
> -- 
> 1.9.1
> 
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