Extract version from .git_archival.txt

Repairs #25.

The stgit version may now be extracted from the .git_archival.txt file. The
version is still sought first from builtin_version.py, then `git describe`,
but now if those fail, the .git_archival.txt file is parsed.

At setup time, it is now required that a valid version be found with either
`git describe` or in the .git_archival.txt file.

At runtime, stg will still run even if none of the version sources succeed,
in which case 'unknown-version' will be reported.

N.B. the .git_archival.txt file is only valid/usable for archives from a
tag. For an archive from a non-tagged commit/tree, no version information
will be extracted from .git_archival.txt. So, in practice, this new
.git_archival.txt version mechanism is specifically meant to support tagged
releases.

The stgit.version.write_builtin_version() capability is moved into setup.py
since writing builtin_version.py is a setup-time only concern.

The VersionUnavailable exception is modified to inherit Exception instead
of StgException. This is done because VersionUnavailable is local to the
stgit.version module. It is helpful to limit the dependencies of the stgit
modules imported at setup time.

Finally, the stgit.version.version variable is removed. Instead,
stgit.version.get_version() is called explicitly at the few sites that need
to reference stgit's version. It is perhaps a bit easier to reason about
the version when importing stgit.version does not have side effects.

Signed-off-by: Peter Grayson <[email protected]>

Author: jpgrayson

setup.py

@@ -7,8 +7,7 @@
 import os
 import sys
 
-from stgit import version
-from stgit import commands, completion
+from stgit import commands, completion, version
 
 
 def __version_to_list(version):
@@ -60,7 +59,17 @@ def __check_git_version():
 # ensure readable template files
 old_mask = os.umask(0o022)
 
-version.write_builtin_version()
+try:
+    ver = version.git_describe_version()
+except version.VersionUnavailable:
+    ver = version.git_archival_version()
+with open('stgit/builtin_version.py', 'w') as f:
+    print(
+        '# This file is automatically generated. Do not edit.',
+        'version = {ver!r}'.format(ver=ver),
+        sep='\n',
+        file=f,
+    )
 
 # generate the python command list
 with open('stgit/commands/cmdlist.py', 'w') as f:
@@ -72,7 +81,7 @@ def __check_git_version():
 
 setup(
     name='stgit',
-    version=version.version,
+    version=ver,
     license='GPLv2',
     author='Catalin Marinas',
     author_email='[email protected]',

stgit/commands/mail.py

@@ -427,7 +427,7 @@ def __build_extra_headers(msg, msg_id, ref_id = None):
         ref_id = '<%s>' % ref_id.strip(' \t\n<>')
         msg['In-Reply-To'] = ref_id
         msg['References'] = ref_id
-    msg['User-Agent'] = 'StGit/%s' % version.version
+    msg['User-Agent'] = 'StGit/%s' % version.get_version()
 
     # update other address headers
     __update_header(msg, 'Reply-To')

stgit/main.py

@@ -138,8 +138,8 @@ def _main():
             print_help()
         sys.exit(utils.STGIT_SUCCESS)
     if cmd in ['-v', '--version', 'version']:
-        from stgit.version import version
-        print('Stacked GIT %s' % version)
+        from stgit.version import get_version
+        print('Stacked GIT %s' % get_version())
         os.system('git --version')
         print('Python version %s' % sys.version)
         sys.exit(utils.STGIT_SUCCESS)

stgit/version.py

@@ -5,62 +5,67 @@
 import re
 import sys
 
-from stgit import run, utils
-from stgit.exception import StgException
 from stgit.run import Run, RunException
 
 
-class VersionUnavailable(StgException):
+class VersionUnavailable(Exception):
     pass
 
+
 def git_describe_version():
-    path = sys.path[0]
+    root = sys.path[0]
     try:
-        v = Run('git', 'describe', '--tags', '--abbrev=4'
-                ).cwd(path).output_one_line()
+        v = Run(
+            'git', 'describe', '--tags', '--abbrev=4'
+        ).cwd(root).output_one_line()
     except RunException as e:
         raise VersionUnavailable(str(e))
-    if not re.match(r'^v[0-9]', v):
-        raise VersionUnavailable('%s: bad version' % v)
+    m = re.match(r'^v([0-9].*)', v)
+    if m:
+        v = m.group()
+    else:
+        raise VersionUnavailable('bad version: %s' % v)
     try:
-        dirty = Run('git', 'diff-index', '--name-only', 'HEAD'
-                    ).cwd(path).raw_output()
+        dirty = Run(
+            'git', 'diff-index', '--name-only', 'HEAD'
+        ).cwd(root).raw_output()
     except RunException as e:
         raise VersionUnavailable(str(e))
     if dirty:
         v += '-dirty'
-    return utils.strip_prefix('v', v)
+    return v
+
+
+def git_archival_version():
+    tag_re = re.compile(r'(?<=\btag: )([^,]+)\b')
+    archival_path = os.path.join(sys.path[0], '.git_archival.txt')
+    with open(archival_path) as f:
+        for line in f:
+            if line.startswith('ref-names:'):
+                tags = tag_re.findall(line)
+                if tags:
+                    return tags[0]
+        else:
+            raise VersionUnavailable('no tags found in %s' % archival_path)
+
 
 def builtin_version():
     try:
-        import stgit.builtin_version as bv
+        import stgit.builtin_version
     except ImportError:
-        raise VersionUnavailable()
+        raise VersionUnavailable('could not import stgit.builtin_version')
     else:
-        return bv.version
-
-def _builtin_version_file(ext = 'py'):
-    return os.path.join(sys.path[0], 'stgit', 'builtin_version.%s' % ext)
+        return stgit.builtin_version.version
 
-def write_builtin_version():
-    try:
-        v = git_describe_version()
-    except VersionUnavailable:
-        return
-    with open(_builtin_version_file(), 'w') as f:
-        f.write(
-            '# This file was generated automatically. Do not edit by hand.\n'
-            'version = %r\n' % v)
 
 def get_version():
-    for v in [builtin_version, git_describe_version]:
+    for v in [builtin_version, git_describe_version, git_archival_version]:
         try:
             return v()
         except VersionUnavailable:
             pass
     return 'unknown-version'
 
-version = get_version()
 
 # minimum version requirements
 git_min_ver = '1.5.2'