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gh-136097: Fix sysconfig._parse_makefile() #136166

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gh-136097: Fix sysconfig._parse_makefile() #136166

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146 changes: 60 additions & 86 deletions Lib/sysconfig/__main__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,9 @@
# Regexes needed for parsing Makefile (and similar syntaxes,
# like old-style Setup files).
_variable_rx = r"([a-zA-Z][a-zA-Z0-9_]+)\s*=\s*(.*)"
_findvar1_rx = r"\$\(([A-Za-z][A-Za-z0-9_]*)\)"
_findvar2_rx = r"\${([A-Za-z][A-Za-z0-9_]*)}"
_findvar_rx = (r"\$(\([A-Za-z][A-Za-z0-9_]*\)"
r"|\{[A-Za-z][A-Za-z0-9_]*\}"
r"|\$?)")


def _parse_makefile(filename, vars=None, keep_unresolved=True):
Expand All @@ -49,99 +50,72 @@ def _parse_makefile(filename, vars=None, keep_unresolved=True):
m = re.match(_variable_rx, line)
if m:
n, v = m.group(1, 2)
v = v.strip()
# `$$' is a literal `$' in make
tmpv = v.replace('$$', '')

if "$" in tmpv:
notdone[n] = v
else:
try:
if n in _ALWAYS_STR:
raise ValueError

v = int(v)
except ValueError:
# insert literal `$'
done[n] = v.replace('$$', '$')
else:
done[n] = v

# do variable interpolation here
variables = list(notdone.keys())
notdone[n] = v.strip()

# Variables with a 'PY_' prefix in the makefile. These need to
# be made available without that prefix through sysconfig.
# Special care is needed to ensure that variable expansion works, even
# if the expansion uses the name without a prefix.
renamed_variables = ('CFLAGS', 'LDFLAGS', 'CPPFLAGS')

while len(variables) > 0:
for name in tuple(variables):
value = notdone[name]
m1 = re.search(_findvar1_rx, value)
m2 = re.search(_findvar2_rx, value)
if m1 and m2:
m = m1 if m1.start() < m2.start() else m2
else:
m = m1 if m1 else m2
if m is not None:
n = m.group(1)
found = True
if n in done:
item = str(done[n])
elif n in notdone:
# get it on a subsequent round
found = False
elif n in os.environ:
# do it like make: fall back to environment
item = os.environ[n]

elif n in renamed_variables:
if (name.startswith('PY_') and
name[3:] in renamed_variables):
item = ""

elif 'PY_' + n in notdone:
found = False

else:
item = str(done['PY_' + n])

def resolve_var(name):
def repl(m):
n = m[1]
if n == '$':
return '$'
elif n == '':
# bogus variable reference (e.g. "prefix=$/opt/python")
if keep_unresolved:
return m[0]
raise ValueError
elif n[0] == '(' and n[-1] == ')':
n = n[1:-1]
elif n[0] == '{' and n[-1] == '}':
n = n[1:-1]

if n in done:
return str(done[n])
elif n in notdone:
return str(resolve_var(n))
elif n in os.environ:
# do it like make: fall back to environment
return os.environ[n]
elif n in renamed_variables:
if name.startswith('PY_') and name[3:] in renamed_variables:
return ""
n = 'PY_' + n
if n in notdone:
return str(resolve_var(n))
else:
done[n] = item = ""

if found:
after = value[m.end():]
value = value[:m.start()] + item + after
if "$" in after:
notdone[name] = value
else:
try:
if name in _ALWAYS_STR:
raise ValueError
value = int(value)
except ValueError:
done[name] = value.strip()
else:
done[name] = value
variables.remove(name)

if name.startswith('PY_') \
and name[3:] in renamed_variables:

name = name[3:]
if name not in done:
done[name] = value

assert n not in done
return ""
else:
# Adds unresolved variables to the done dict.
# This is disabled when called from distutils.sysconfig
if keep_unresolved:
done[name] = value
# bogus variable reference (e.g. "prefix=$/opt/python");
# just drop it since we can't deal
variables.remove(name)
done[n] = ""
return ""

assert name not in done
done[name] = ""
try:
value = re.sub(_findvar_rx, repl, notdone[name])
except ValueError:
del done[name]
return ""
value = value.strip()
if name not in _ALWAYS_STR:
try:
value = int(value)
except ValueError:
pass
done[name] = value
if name.startswith('PY_') and name[3:] in renamed_variables:
name = name[3:]
if name not in done:
done[name] = value
return value

for n in notdone:
if n not in done:
resolve_var(n)

# strip spurious spaces
for k, v in done.items():
Expand Down
71 changes: 70 additions & 1 deletion Lib/test/test_sysconfig.py
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Original file line number Diff line number Diff line change
Expand Up @@ -757,8 +757,12 @@ def test_parse_makefile(self):
print("var3=42", file=makefile)
print("var4=$/invalid", file=makefile)
print("var5=dollar$$5", file=makefile)
print("var6=${var3}/lib/python3.5/config-$(VAR2)$(var5)"
print("var6=${var7}/lib/python3.5/config-$(VAR2)$(var5)"
"-x86_64-linux-gnu", file=makefile)
print("var7=${var3}", file=makefile)
print("var8=$$(var3)", file=makefile)
print("var9=$(var10)(var3)", file=makefile)
print("var10=$$", file=makefile)
vars = _parse_makefile(TESTFN)
self.assertEqual(vars, {
'var1': 'ab42',
Expand All @@ -767,6 +771,71 @@ def test_parse_makefile(self):
'var4': '$/invalid',
'var5': 'dollar$5',
'var6': '42/lib/python3.5/config-b42dollar$5-x86_64-linux-gnu',
'var7': 42,
'var8': '$(var3)',
'var9': '$(var3)',
'var10': '$',
})

def _test_parse_makefile_recursion(self):
self.addCleanup(unlink, TESTFN)
with open(TESTFN, "w") as makefile:
print("var1=var1=$(var1)", file=makefile)
print("var2=var3=$(var3)", file=makefile)
print("var3=var2=$(var2)", file=makefile)
vars = _parse_makefile(TESTFN)
self.assertEqual(vars, {
'var1': 'var1=',
'var2': 'var3=var2=',
'var3': 'var2=',
})

def test_parse_makefile_renamed_vars(self):
self.addCleanup(unlink, TESTFN)
with open(TESTFN, "w") as makefile:
print("var1=$(CFLAGS)", file=makefile)
print("PY_CFLAGS=-Wall $(CPPFLAGS)", file=makefile)
print("PY_LDFLAGS=-lm", file=makefile)
print("var2=$(LDFLAGS)", file=makefile)
print("var3=$(CPPFLAGS)", file=makefile)
vars = _parse_makefile(TESTFN)
self.assertEqual(vars, {
'var1': '-Wall',
'CFLAGS': '-Wall',
'PY_CFLAGS': '-Wall',
'LDFLAGS': '-lm',
'PY_LDFLAGS': '-lm',
'var2': '-lm',
'var3': '',
})

def test_parse_makefile_keep_unresolved(self):
self.addCleanup(unlink, TESTFN)
with open(TESTFN, "w") as makefile:
print("var1=value", file=makefile)
print("var2=$/", file=makefile)
print("var3=$/$(var1)", file=makefile)
print("var4=var5=$(var5)", file=makefile)
print("var5=$/$(var1)", file=makefile)
print("var6=$(var1)$/", file=makefile)
print("var7=var8=$(var8)", file=makefile)
print("var8=$(var1)$/", file=makefile)
vars = _parse_makefile(TESTFN)
self.assertEqual(vars, {
'var1': 'value',
'var2': '$/',
'var3': '$/value',
'var4': 'var5=$/value',
'var5': '$/value',
'var6': 'value$/',
'var7': 'var8=value$/',
'var8': 'value$/',
})
vars = _parse_makefile(TESTFN, keep_unresolved=False)
self.assertEqual(vars, {
'var1': 'value',
'var4': 'var5=',
'var7': 'var8=',
})


Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2025-07-01-14-44-03.gh-issue-136097.bI1n14.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix potential infinite recursion and KeyError in ``sysconfig
--generate-posix-vars``.
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