gh-96305: Fix AIX build by avoiding subprocess during bootstrap (#96429)

* Fix AIX build by avoiding `subprocess` during bootstrap.

Author: ayappanec

Lib/_aix_support.py

@@ -1,10 +1,28 @@
 """Shared AIX support functions."""
 
-importsubprocess
 importsys
 importsysconfig
 
 
+# Taken from _osx_support _read_output function
+def_read_cmd_output(commandstring, capture_stderr=False):
+"""Output from successful command execution or None"""
+# Similar to os.popen(commandstring, "r").read(),
+# but without actually using os.popen because that
+# function is not usable during python bootstrap.
+importos
+importcontextlib
+fp=open("/tmp/_aix_support.%s"%(
+os.getpid(),), "w+b")
+
+withcontextlib.closing(fp) asfp:
+ifcapture_stderr:
+cmd="%s >'%s' 2>&1"% (commandstring, fp.name)
+else:
+cmd="%s 2>/dev/null >'%s'"% (commandstring, fp.name)
+returnfp.read() ifnotos.system(cmd) elseNone
+
+
 def_aix_tag(vrtl, bd):
 # type: (List[int], int) -> str
 # Infer the ABI bitwidth from maxsize (assuming 64 bit as the default)
@@ -30,7 +48,12 @@ def _aix_bos_rte():
  If no builddate is found give a value that will satisfy pep425 related queries
  """
 # All AIX systems to have lslpp installed in this location
-out=subprocess.check_output(["/usr/bin/lslpp", "-Lqc", "bos.rte"])
+# subprocess may not be available during python bootstrap
+try:
+importsubprocess
+out=subprocess.check_output(["/usr/bin/lslpp", "-Lqc", "bos.rte"])
+exceptImportError:
+out=_read_cmd_output("/usr/bin/lslpp -Lqc bos.rte")
 out=out.decode("utf-8")
 out=out.strip().split(":") # type: ignore
 _bd=int(out[-1]) ifout[-1] !=''else9988

Misc/NEWS.d/next/Build/2022-08-30-10-16-31.gh-issue-96305.274i8B.rst

@@ -0,0 +1,2 @@
+``_aix_support`` now uses a simple code to get platform details rather than
+the now non-existent ``_bootsubprocess`` during bootstrap.