gst-env.py

   1 #!/usr/bin/env python3
   2
   3 import argparse
   4 import glob
   5 import json
   6 import os
   7 import platform
   8 import re
   9 import shlex
  10 import shutil
  11 import subprocess
  12 import tempfile
  13 import pathlib
  14 import signal
  15 from functools import lru_cache
  16 from pathlib import PurePath, Path
  17 from sys import exit
  18
  19 from typing import Any
  20
  21 from scripts.common import get_meson
  22 from scripts.common import git
  23 from scripts.common import win32_get_short_path_name
  24 from scripts.common import get_wine_shortpath
  25
  26 SCRIPTDIR = os.path.dirname(os.path.realpath(__file__))
  27 PREFIX_DIR = os.path.join(SCRIPTDIR, 'prefix')
  28 # Look for the following build dirs: `build` `_build` `builddir`
  29 DEFAULT_BUILDDIR = os.path.join(SCRIPTDIR, 'build')
  30 if not os.path.exists(DEFAULT_BUILDDIR):
  31     DEFAULT_BUILDDIR = os.path.join(SCRIPTDIR, '_build')
  32 if not os.path.exists(DEFAULT_BUILDDIR):
  33     DEFAULT_BUILDDIR = os.path.join(SCRIPTDIR, 'builddir')
  34
  35 TYPELIB_REG = re.compile(r'.*\.typelib$')
  36 SHAREDLIB_REG = re.compile(r'\.so|\.dylib|\.dll')
  37
  38 # libdir is expanded from option of the same name listed in the `meson
  39 # introspect --buildoptions` output.
  40 GSTPLUGIN_FILEPATH_REG_TEMPLATE = r'.*/{libdir}/gstreamer-1.0/[^/]+$'
  41 GSTPLUGIN_FILEPATH_REG = None
  42
  43 BC_RC = '''
  44 BASH_COMPLETION_SCRIPTS="{bash_completions}"
  45 BASH_COMPLETION_PATHS="{bash_completions_paths}"
  46 for p in $BASH_COMPLETION_PATHS; do
  47 for f in $BASH_COMPLETION_SCRIPTS; do
  48   [ -f "$p/$f" ] && . "$p/$f"
  49 done
  50 done
  51 '''
  52 BASH_COMPLETION_PATHS = [SCRIPTDIR + '/subprojects/gstreamer/data/bash-completion/completions']
  53 BASH_COMPLETION_PATHS += [SCRIPTDIR + '/subprojects/gst-devtools/validate/data/bash-completion/completions']
  54
  55
  56 def str_to_bool(value: Any) -> bool:
  57     """Return whether the provided string (or any value really) represents true. Otherwise false.
  58     Just like plugin server stringToBoolean.
  59     """
  60     if not value:
  61         return False
  62     return str(value).lower() in ("y", "yes", "t", "true", "on", "1")
  63
  64
  65 def listify(o):
  66     if isinstance(o, str):
  67         return [o]
  68     if isinstance(o, list):
  69         return o
  70     raise AssertionError('Object {!r} must be a string or a list'.format(o))
  71
  72
  73 def stringify(o):
  74     if isinstance(o, str):
  75         return o
  76     if isinstance(o, list):
  77         if len(o) == 1:
  78             return o[0]
  79         raise AssertionError('Did not expect object {!r} to have more than one element'.format(o))
  80     raise AssertionError('Object {!r} must be a string or a list'.format(o))
  81
  82
  83 def prepend_env_var(env, var, value, sysroot):
  84     if var is None:
  85         return
  86     if value.startswith(sysroot):
  87         value = value[len(sysroot):]
  88     # Try not to exceed maximum length limits for env vars on Windows
  89     if os.name == 'nt':
  90         value = win32_get_short_path_name(value)
  91     env_val = env.get(var, '')
  92     val = os.pathsep + value + os.pathsep
  93     # Don't add the same value twice
  94     if val in env_val or env_val.startswith(value + os.pathsep):
  95         return
  96     env[var] = val + env_val
  97     env[var] = env[var].replace(os.pathsep + os.pathsep, os.pathsep).strip(os.pathsep)
  98
  99
 100 def get_target_install_filename(target, filename):
 101     '''
 102     Checks whether this file is one of the files installed by the target
 103     '''
 104     basename = os.path.basename(filename)
 105     for install_filename in listify(target['install_filename']):
 106         if install_filename.endswith(basename):
 107             return install_filename
 108     return None
 109
 110
 111 def get_pkgconfig_variable_from_pcfile(pcfile, varname):
 112     variables = {}
 113     substre = re.compile('\$\{[^${}]+\}')
 114     with pcfile.open('r', encoding='utf-8') as f:
 115         for line in f:
 116             if '=' not in line:
 117                 continue
 118             key, value = line[:-1].split('=', 1)
 119             subst = {}
 120             for each in substre.findall(value):
 121                 substkey = each[2:-1]
 122                 subst[each] = variables.get(substkey, '')
 123             for k, v in subst.items():
 124                 value = value.replace(k, v)
 125             variables[key] = value
 126     return variables.get(varname, '')
 127
 128
 129 @lru_cache()
 130 def get_pkgconfig_variable(builddir, pcname, varname):
 131     '''
 132     Parsing isn't perfect, but it's good enough.
 133     '''
 134     pcfile = Path(builddir) / 'meson-private' / (pcname + '.pc')
 135     if pcfile.is_file():
 136         return get_pkgconfig_variable_from_pcfile(pcfile, varname)
 137     return subprocess.check_output(['pkg-config', pcname, '--variable=' + varname],
 138                                    universal_newlines=True, encoding='utf-8')
 139
 140
 141 def is_gio_module(target, filename, builddir):
 142     if target['type'] != 'shared module':
 143         return False
 144     install_filename = get_target_install_filename(target, filename)
 145     if not install_filename:
 146         return False
 147     giomoduledir = PurePath(get_pkgconfig_variable(builddir, 'gio-2.0', 'giomoduledir'))
 148     fpath = PurePath(install_filename)
 149     if fpath.parent != giomoduledir:
 150         return False
 151     return True
 152
 153
 154 def is_library_target_and_not_plugin(target, filename):
 155     '''
 156     Don't add plugins to PATH/LD_LIBRARY_PATH because:
 157     1. We don't need to
 158     2. It causes us to exceed the PATH length limit on Windows and Wine
 159     '''
 160     if target['type'] != 'shared library':
 161         return False
 162     # Check if this output of that target is a shared library
 163     if not SHAREDLIB_REG.search(filename):
 164         return False
 165     # Check if it's installed to the gstreamer plugin location
 166     install_filename = get_target_install_filename(target, filename)
 167     if not install_filename:
 168         return False
 169     global GSTPLUGIN_FILEPATH_REG
 170     if GSTPLUGIN_FILEPATH_REG is None:
 171         GSTPLUGIN_FILEPATH_REG = re.compile(GSTPLUGIN_FILEPATH_REG_TEMPLATE)
 172     if GSTPLUGIN_FILEPATH_REG.search(install_filename.replace('\\', '/')):
 173         return False
 174     return True
 175
 176
 177 def is_binary_target_and_in_path(target, filename, bindir):
 178     if target['type'] != 'executable':
 179         return False
 180     # Check if this file installed by this target is installed to bindir
 181     install_filename = get_target_install_filename(target, filename)
 182     if not install_filename:
 183         return False
 184     fpath = PurePath(install_filename)
 185     if fpath.parent != bindir:
 186         return False
 187     return True
 188
 189
 190 def get_wine_subprocess_env(options, env):
 191     with open(os.path.join(options.builddir, 'meson-info', 'intro-buildoptions.json')) as f:
 192         buildoptions = json.load(f)
 193
 194     prefix, = [o for o in buildoptions if o['name'] == 'prefix']
 195     path = os.path.normpath(os.path.join(prefix['value'], 'bin'))
 196     prepend_env_var(env, "PATH", path, options.sysroot)
 197     wine_path = get_wine_shortpath(
 198         options.wine.split(' '),
 199         [path] + env.get('WINEPATH', '').split(';')
 200     )
 201     if options.winepath:
 202         wine_path += ';' + options.winepath
 203     env['WINEPATH'] = wine_path
 204     env['WINEDEBUG'] = 'fixme-all'
 205
 206     return env
 207
 208
 209 def setup_gdb(options):
 210     python_paths = set()
 211
 212     if not shutil.which('gdb'):
 213         return python_paths
 214
 215     bdir = pathlib.Path(options.builddir).resolve()
 216     for libpath, gdb_path in [
 217             (os.path.join("subprojects", "gstreamer", "gst"),
 218              os.path.join("subprojects", "gstreamer", "libs", "gst", "helpers")),
 219             (os.path.join("subprojects", "glib", "gobject"), None),
 220             (os.path.join("subprojects", "glib", "glib"), None)]:
 221
 222         if not gdb_path:
 223             gdb_path = libpath
 224
 225         autoload_path = (pathlib.Path(bdir) / 'gdb-auto-load').joinpath(*bdir.parts[1:]) / libpath
 226         autoload_path.mkdir(parents=True, exist_ok=True)
 227         for gdb_helper in glob.glob(str(bdir / gdb_path / "*-gdb.py")):
 228             python_paths.add(str(bdir / gdb_path))
 229             python_paths.add(os.path.join(options.srcdir, gdb_path))
 230             try:
 231                 if os.name == 'nt':
 232                     shutil.copy(gdb_helper, str(autoload_path / os.path.basename(gdb_helper)))
 233                 else:
 234                     os.symlink(gdb_helper, str(autoload_path / os.path.basename(gdb_helper)))
 235             except (FileExistsError, shutil.SameFileError):
 236                 pass
 237
 238     gdbinit_line = 'add-auto-load-scripts-directory {}\n'.format(bdir / 'gdb-auto-load')
 239     try:
 240         with open(os.path.join(options.srcdir, '.gdbinit'), 'r') as f:
 241             if gdbinit_line in f.readlines():
 242                 return python_paths
 243     except FileNotFoundError:
 244         pass
 245
 246     with open(os.path.join(options.srcdir, '.gdbinit'), 'a') as f:
 247         f.write(gdbinit_line)
 248
 249     return python_paths
 250
 251
 252 def is_bash_completion_available(options):
 253     return os.path.exists(os.path.join(options.builddir, 'subprojects/gstreamer/data/bash-completion/helpers/gst'))
 254
 255
 256 def get_subprocess_env(options, gst_version):
 257     env = os.environ.copy()
 258
 259     env["CURRENT_GST"] = os.path.normpath(SCRIPTDIR)
 260     env["GST_VERSION"] = gst_version
 261     prepend_env_var(env, "GST_VALIDATE_SCENARIOS_PATH", os.path.normpath(
 262         "%s/subprojects/gst-devtools/validate/data/scenarios" % SCRIPTDIR),
 263         options.sysroot)
 264     env["GST_VALIDATE_PLUGIN_PATH"] = os.path.normpath(
 265         "%s/subprojects/gst-devtools/validate/plugins" % options.builddir)
 266     prepend_env_var(env, "GST_VALIDATE_APPS_DIR", os.path.normpath(
 267         "%s/subprojects/gst-editing-services/tests/validate" % SCRIPTDIR),
 268         options.sysroot)
 269     env["GST_ENV"] = gst_version
 270     env["GST_REGISTRY"] = os.path.normpath(options.builddir + "/registry.dat")
 271     prepend_env_var(env, "PATH", os.path.normpath(
 272         "%s/subprojects/gst-devtools/validate/tools" % options.builddir),
 273         options.sysroot)
 274
 275     prepend_env_var(env, "GST_VALIDATE_SCENARIOS_PATH", os.path.normpath(
 276         "%s/subprojects/gst-examples/webrtc/check/validate/scenarios" %
 277         SCRIPTDIR), options.sysroot)
 278     prepend_env_var(env, "GST_VALIDATE_APPS_DIR", os.path.normpath(
 279         "%s/subprojects/gst-examples/webrtc/check/validate/apps" %
 280         SCRIPTDIR), options.sysroot)
 281
 282     if options.wine:
 283         return get_wine_subprocess_env(options, env)
 284
 285     prepend_env_var(env, "PATH", os.path.join(SCRIPTDIR, 'meson'),
 286         options.sysroot)
 287
 288     env["GST_PLUGIN_SYSTEM_PATH"] = ""
 289     env["GST_PLUGIN_SCANNER"] = os.path.normpath(
 290         "%s/subprojects/gstreamer/libs/gst/helpers/gst-plugin-scanner" % options.builddir)
 291     env["GST_PTP_HELPER"] = os.path.normpath(
 292         "%s/subprojects/gstreamer/libs/gst/helpers/gst-ptp-helper" % options.builddir)
 293
 294     if os.name == 'nt':
 295         lib_path_envvar = 'PATH'
 296     elif platform.system() == 'Darwin':
 297         # RPATH is sufficient on macOS, and DYLD_LIBRARY_PATH can cause issues with dynamic linker path priority
 298         lib_path_envvar = None
 299     else:
 300         lib_path_envvar = 'LD_LIBRARY_PATH'
 301
 302     prepend_env_var(env, "GST_PLUGIN_PATH", os.path.join(SCRIPTDIR, 'subprojects',
 303                                                         'gst-python', 'plugin'),
 304                     options.sysroot)
 305     prepend_env_var(env, "GST_PLUGIN_PATH", os.path.join(PREFIX_DIR, 'lib',
 306                                                         'gstreamer-1.0'),
 307                     options.sysroot)
 308     prepend_env_var(env, "GST_PLUGIN_PATH", os.path.join(options.builddir, 'subprojects',
 309                                                          'libnice', 'gst'),
 310                     options.sysroot)
 311     prepend_env_var(env, "GST_VALIDATE_SCENARIOS_PATH",
 312                     os.path.join(PREFIX_DIR, 'share', 'gstreamer-1.0',
 313                                  'validate', 'scenarios'),
 314                     options.sysroot)
 315     prepend_env_var(env, "GI_TYPELIB_PATH", os.path.join(PREFIX_DIR, 'lib',
 316                                                          'lib', 'girepository-1.0'),
 317                     options.sysroot)
 318     prepend_env_var(env, "PKG_CONFIG_PATH", os.path.join(PREFIX_DIR, 'lib', 'pkgconfig'),
 319                     options.sysroot)
 320
 321     # gst-indent
 322     prepend_env_var(env, "PATH", os.path.join(SCRIPTDIR, 'scripts'),
 323                     options.sysroot)
 324
 325     # tools: gst-launch-1.0, gst-inspect-1.0
 326     prepend_env_var(env, "PATH", os.path.join(options.builddir, 'subprojects',
 327                                               'gstreamer', 'tools'),
 328                     options.sysroot)
 329     # plugin scanner and generator
 330     prepend_env_var(env, "PATH", os.path.join(options.builddir, 'subprojects',
 331                                               'gstreamer', 'docs'),
 332                     options.sysroot)
 333     prepend_env_var(env, "PATH", os.path.join(options.builddir, 'subprojects',
 334                                               'gst-plugins-base', 'tools'),
 335                     options.sysroot)
 336
 337     # Library and binary search paths
 338     prepend_env_var(env, "PATH", os.path.join(PREFIX_DIR, 'bin'),
 339                     options.sysroot)
 340     if lib_path_envvar != 'PATH':
 341         prepend_env_var(env, lib_path_envvar, os.path.join(PREFIX_DIR, 'lib'),
 342                         options.sysroot)
 343         prepend_env_var(env, lib_path_envvar, os.path.join(PREFIX_DIR, 'lib64'),
 344                         options.sysroot)
 345     elif 'QMAKE' in os.environ:
 346         # There's no RPATH on Windows, so we need to set PATH for the qt5 DLLs
 347         prepend_env_var(env, 'PATH', os.path.dirname(os.environ['QMAKE']),
 348                         options.sysroot)
 349
 350     meson = get_meson()
 351     targets_s = subprocess.check_output(meson + ['introspect', options.builddir, '--targets'])
 352     targets = json.loads(targets_s.decode())
 353     paths = set()
 354     mono_paths = set()
 355     srcdir_path = pathlib.Path(options.srcdir)
 356
 357     build_options_s = subprocess.check_output(meson + ['introspect', options.builddir, '--buildoptions'])
 358     build_options = json.loads(build_options_s.decode())
 359     libdir, = [o['value'] for o in build_options if o['name'] == 'libdir']
 360     libdir = PurePath(libdir)
 361     prefix, = [o['value'] for o in build_options if o['name'] == 'prefix']
 362     bindir, = [o['value'] for o in build_options if o['name'] == 'bindir']
 363     prefix = PurePath(prefix)
 364     bindir = prefix / bindir
 365
 366     global GSTPLUGIN_FILEPATH_REG_TEMPLATE
 367     GSTPLUGIN_FILEPATH_REG_TEMPLATE = GSTPLUGIN_FILEPATH_REG_TEMPLATE.format(libdir=libdir.as_posix())
 368
 369     for target in targets:
 370         filenames = listify(target['filename'])
 371         if not target['installed']:
 372             continue
 373         for filename in filenames:
 374             root = os.path.dirname(filename)
 375             if srcdir_path / "subprojects/gst-devtools/validate/plugins" in (srcdir_path / root).parents:
 376                 continue
 377             if filename.endswith('.dll'):
 378                 mono_paths.add(os.path.join(options.builddir, root))
 379             if TYPELIB_REG.search(filename):
 380                 prepend_env_var(env, "GI_TYPELIB_PATH",
 381                                 os.path.join(options.builddir, root),
 382                                 options.sysroot)
 383             elif is_library_target_and_not_plugin(target, filename):
 384                 prepend_env_var(env, lib_path_envvar,
 385                                 os.path.join(options.builddir, root),
 386                                 options.sysroot)
 387             elif is_binary_target_and_in_path(target, filename, bindir):
 388                 paths.add(os.path.join(options.builddir, root))
 389             elif is_gio_module(target, filename, options.builddir):
 390                 prepend_env_var(env, 'GIO_EXTRA_MODULES',
 391                                 os.path.join(options.builddir, root),
 392                                 options.sysroot)
 393
 394     # Search for the Plugin paths file either in the build directory root
 395     # or check if gstreamer is a subproject of another project
 396     for sub_directories in [[], ['subprojects', 'gstreamer']]:
 397         plugin_paths = os.path.join(options.builddir, *sub_directories, 'GstPluginsPath.json')
 398         if os.path.exists(plugin_paths):
 399             with open(plugin_paths) as f:
 400                 for plugin_path in json.load(f):
 401                     prepend_env_var(env, 'GST_PLUGIN_PATH', plugin_path,
 402                                     options.sysroot)
 403             break
 404
 405     # Sort to iterate in a consistent order (`set`s and `hash`es are randomized)
 406     for p in sorted(paths):
 407         prepend_env_var(env, 'PATH', p, options.sysroot)
 408
 409     if os.name != 'nt':
 410         for p in sorted(mono_paths):
 411             prepend_env_var(env, "MONO_PATH", p, options.sysroot)
 412
 413     presets = set()
 414     encoding_targets = set()
 415     python_dirs = setup_gdb(options)
 416     overrides_dirs = set()
 417     if '--installed' in subprocess.check_output(meson + ['introspect', '-h']).decode():
 418         installed_s = subprocess.check_output(meson + ['introspect', options.builddir, '--installed'])
 419         for path, installpath in json.loads(installed_s.decode()).items():
 420             installpath_parts = pathlib.Path(installpath).parts
 421
 422             # We want to add all python modules to the PYTHONPATH
 423             # in a manner consistent with the way they would be imported:
 424             # For example if the source path /home/meh/foo/bar.py
 425             # is to be installed in /usr/lib/python/site-packages/foo/bar.py,
 426             # we want to add /home/meh to the PYTHONPATH.
 427             # This will only work for projects where the paths to be installed
 428             # mirror the installed directory layout, for example if the path
 429             # is /home/meh/baz/bar.py and the install path is
 430             # /usr/lib/site-packages/foo/bar.py , we will not add anything
 431             # to PYTHONPATH, but the current approach works with pygobject
 432             # and gst-python at least.
 433             if 'site-packages' in installpath_parts:
 434                 install_subpath = os.path.join(*installpath_parts[installpath_parts.index('site-packages') + 1:])
 435                 if path.endswith(install_subpath):
 436                     if os.path.commonprefix(["gi/overrides", install_subpath]):
 437                         overrides_dirs.add(os.path.dirname(path))
 438                     else:
 439                         python_dirs.add(path[:len(install_subpath) * -1])
 440
 441             if path.endswith('.prs'):
 442                 presets.add(os.path.dirname(path))
 443             elif path.endswith('.gep'):
 444                 encoding_targets.add(
 445                     os.path.abspath(os.path.join(os.path.dirname(path), '..')))
 446
 447             if path.endswith('gstomx.conf'):
 448                 prepend_env_var(env, 'GST_OMX_CONFIG_DIR', os.path.dirname(path),
 449                                 options.sysroot)
 450
 451         for p in sorted(presets):
 452             prepend_env_var(env, 'GST_PRESET_PATH', p, options.sysroot)
 453
 454         for t in sorted(encoding_targets):
 455             prepend_env_var(env, 'GST_ENCODING_TARGET_PATH', t, options.sysroot)
 456
 457     # Check if meson has generated -uninstalled pkgconfig files
 458     meson_uninstalled = pathlib.Path(options.builddir) / 'meson-uninstalled'
 459     if meson_uninstalled.is_dir():
 460         prepend_env_var(env, 'PKG_CONFIG_PATH', str(meson_uninstalled), options.sysroot)
 461
 462     for python_dir in sorted(python_dirs):
 463         prepend_env_var(env, 'PYTHONPATH', python_dir, options.sysroot)
 464
 465     for python_dir in sorted(overrides_dirs):
 466         prepend_env_var(env, '_GI_OVERRIDES_PATH', python_dir, options.sysroot)
 467
 468     mesonpath = os.path.join(SCRIPTDIR, "meson")
 469     if os.path.join(mesonpath):
 470         # Add meson/ into PYTHONPATH if we are using a local meson
 471         prepend_env_var(env, 'PYTHONPATH', mesonpath, options.sysroot)
 472
 473     # Ensure that gst-python/gi is used first
 474     prepend_env_var(env, "PYTHONPATH", os.path.join(SCRIPTDIR, 'subprojects', 'gst-python'),
 475                     options.sysroot)
 476
 477     # For devhelp books
 478     if 'XDG_DATA_DIRS' not in env or not env['XDG_DATA_DIRS']:
 479         # Preserve default paths when empty
 480         prepend_env_var(env, 'XDG_DATA_DIRS', '/usr/local/share/:/usr/share/', '')
 481
 482     prepend_env_var(env, 'XDG_DATA_DIRS', os.path.join(options.builddir,
 483                                                        'subprojects',
 484                                                        'gst-docs',
 485                                                        'GStreamer-doc'),
 486                     options.sysroot)
 487
 488     if 'XDG_CONFIG_DIRS' not in env or not env['XDG_CONFIG_DIRS']:
 489         # Preserve default paths when empty
 490         prepend_env_var(env, 'XDG_CONFIG_DIRS', '/etc/local/xdg:/etc/xdg', '')
 491
 492     prepend_env_var(env, "XDG_CONFIG_DIRS", os.path.join(PREFIX_DIR, 'etc', 'xdg'),
 493                     options.sysroot)
 494
 495     return env
 496
 497
 498 def get_windows_shell():
 499     command = ['powershell.exe', '-noprofile', '-executionpolicy', 'bypass', '-file',
 500         os.path.join(SCRIPTDIR, 'data', 'misc', 'cmd_or_ps.ps1')]
 501     result = subprocess.check_output(command)
 502     return result.decode().strip()
 503
 504
 505 if __name__ == "__main__":
 506     parser = argparse.ArgumentParser(prog="gst-env")
 507
 508     parser.add_argument("--builddir",
 509                         default=DEFAULT_BUILDDIR,
 510                         help="The meson build directory")
 511     parser.add_argument("--srcdir",
 512                         default=SCRIPTDIR,
 513                         help="The top level source directory")
 514     parser.add_argument("--sysroot",
 515                         default='',
 516                         help="The sysroot path used during cross-compilation")
 517     parser.add_argument("--wine",
 518                         default='',
 519                         help="Build a wine env based on specified wine command")
 520     parser.add_argument("--winepath",
 521                         default='',
 522                         help="Extra path to set to WINEPATH.")
 523     parser.add_argument("--only-environment",
 524                         action='store_true',
 525                         default=False,
 526                         help="Do not start a shell, only print required environment.")
 527     options, args = parser.parse_known_args()
 528
 529     if not os.path.exists(options.builddir):
 530         print("GStreamer not built in %s\n\nBuild it and try again" %
 531               options.builddir)
 532         exit(1)
 533     options.builddir = os.path.abspath(options.builddir)
 534
 535     if not os.path.exists(options.srcdir):
 536         print("The specified source dir does not exist" %
 537               options.srcdir)
 538         exit(1)
 539
 540     # The following incantation will retrieve the current branch name.
 541     try:
 542         gst_version = git("rev-parse", "--symbolic-full-name", "--abbrev-ref", "HEAD",
 543                           repository_path=options.srcdir).strip('\n')
 544     except subprocess.CalledProcessError:
 545         gst_version = "unknown"
 546
 547     if options.wine:
 548         gst_version += '-' + os.path.basename(options.wine)
 549
 550     env = get_subprocess_env(options, gst_version)
 551     if os.name == 'nt':
 552         shell = get_windows_shell()
 553         if shell in ['powershell.exe', 'pwsh.exe']:
 554             new_args = [shell, '-NoLogo']
 555             if not args:
 556                 prompt = 'function global:prompt {  "[' + gst_version + '"+"] PS " + $PWD + "> "}'
 557                 new_args += ['-NoExit', '-Command', prompt]
 558             else:
 559                 new_args += ['-NonInteractive', '-Command'] + args
 560             args = new_args
 561         else:
 562             new_args = [os.environ.get("COMSPEC", r"C:\WINDOWS\system32\cmd.exe")]
 563             if not args:
 564                 new_args += ['/k', 'prompt [{}] $P$G'.format(gst_version)]
 565             else:
 566                 new_args += ['/c', 'start', '/b', '/wait'] + args
 567             args = new_args
 568     if not args:
 569         if os.name != 'nt':
 570             args = [os.environ.get("SHELL", os.path.realpath("/bin/sh"))]
 571         if args[0].endswith('bash') and not str_to_bool(os.environ.get("GST_BUILD_DISABLE_PS1_OVERRIDE", r"FALSE")):
 572             # Let the GC remove the tmp file
 573             tmprc = tempfile.NamedTemporaryFile(mode='w')
 574             bashrc = os.path.expanduser('~/.bashrc')
 575             if os.path.exists(bashrc):
 576                 with open(bashrc, 'r') as src:
 577                     shutil.copyfileobj(src, tmprc)
 578             tmprc.write('\nexport PS1="[%s] $PS1"' % gst_version)
 579             tmprc.flush()
 580             if is_bash_completion_available(options):
 581                 bash_completions_files = []
 582                 for p in BASH_COMPLETION_PATHS:
 583                     if os.path.exists(p):
 584                         bash_completions_files += os.listdir(path=p)
 585                 bc_rc = BC_RC.format(bash_completions=' '.join(bash_completions_files), bash_completions_paths=' '.join(BASH_COMPLETION_PATHS))
 586                 tmprc.write(bc_rc)
 587                 tmprc.flush()
 588             args.append("--rcfile")
 589             args.append(tmprc.name)
 590         elif args[0].endswith('fish'):
 591             # Ignore SIGINT while using fish as the shell to make it behave
 592             # like other shells such as bash and zsh.
 593             # See: https://gitlab.freedesktop.org/gstreamer/gst-build/issues/18
 594             signal.signal(signal.SIGINT, lambda x, y: True)
 595             # Set the prompt
 596             args.append('--init-command')
 597             prompt_cmd = '''functions --copy fish_prompt original_fish_prompt
 598             function fish_prompt
 599                 echo -n '[{}] '(original_fish_prompt)
 600             end'''.format(gst_version)
 601             args.append(prompt_cmd)
 602         elif args[0].endswith('zsh'):
 603             tmpdir = tempfile.TemporaryDirectory()
 604             # Let the GC remove the tmp file
 605             tmprc = open(os.path.join(tmpdir.name, '.zshrc'), 'w')
 606             zshrc = os.path.expanduser('~/.zshrc')
 607             if os.path.exists(zshrc):
 608                 with open(zshrc, 'r') as src:
 609                     shutil.copyfileobj(src, tmprc)
 610             tmprc.write('\nexport PROMPT="[{}] $PROMPT"'.format(gst_version))
 611             tmprc.flush()
 612             env['ZDOTDIR'] = tmpdir.name
 613     try:
 614         if options.only_environment:
 615             for name, value in env.items():
 616                 print('{}={}'.format(name, shlex.quote(value)))
 617                 print('export {}'.format(name))
 618         else:
 619             if os.environ.get("CI_PROJECT_NAME"):
 620                 print("Ignoring SIGINT when running on the CI,"
 621                       " as we get spurious sigint in there for some reason.")
 622                 signal.signal(signal.SIGINT, signal.SIG_IGN)
 623             exit(subprocess.call(args, close_fds=False, env=env))
 624
 625     except subprocess.CalledProcessError as e:
 626         exit(e.returncode)