From b365592777245343156e701d311ae5a1ecd10fb5 Mon Sep 17 00:00:00 2001
From: Erwan Le Pape <lepaperwan3@gmail.com>
Date: Mon, 17 Sep 2018 18:47:19 +0200
Subject: [PATCH 1/2] bpo-34689: _parse_makefile no longer expands $${}

The sysconfig._parse_makefile function expanded $${} formatted text
if another variable was present in a value. This change splits values
on $$ before searching for variables to avoid that.
---
 Lib/sysconfig.py                              | 28 +++++++++++++------
 Lib/test/test_sysconfig.py                    |  2 ++
 .../2018-09-17-19-11-17.bpo-34689.RtyOE3.rst  |  2 ++
 3 files changed, 23 insertions(+), 9 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst

diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index e0f9c18531b674..d3b4f300577808 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -254,12 +254,21 @@ def _parse_makefile(filename, vars=None):
     while len(variables) > 0:
         for name in tuple(variables):
             value = notdone[name]
-            m1 = _findvar1_rx.search(value)
-            m2 = _findvar2_rx.search(value)
-            if m1 and m2:
-                m = m1 if m1.start() < m2.start() else m2
-            else:
-                m = m1 if m1 else m2
+            m = None
+            offset = 0
+            for substr in value.split('$$'):
+                m1 = _findvar1_rx.search(substr)
+                m2 = _findvar2_rx.search(substr)
+                if m1 and m2:
+                    m = m1 if m1.start() < m2.start() else m2
+                else:
+                    m = m1 if m1 else m2
+                if m is not None:
+                    break
+
+                # Add 2 to account for the $$ which were removed by split('$$')
+                offset += 2 + len(substr)
+
             if m is not None:
                 n = m.group(1)
                 found = True
@@ -287,11 +296,12 @@ def _parse_makefile(filename, vars=None):
                     done[n] = item = ""
 
                 if found:
-                    after = value[m.end():]
-                    value = value[:m.start()] + item + after
-                    if "$" in after:
+                    after = value[offset + m.end():]
+                    value = value[:offset + m.start()] + item.replace('$', '$$') + after
+                    if "$" in after.replace('$$', ''):
                         notdone[name] = value
                     else:
+                        value = value.replace('$$', '$')
                         try:
                             value = int(value)
                         except ValueError:
diff --git a/Lib/test/test_sysconfig.py b/Lib/test/test_sysconfig.py
index 20252be0a41b00..2ce0e6064d8c10 100644
--- a/Lib/test/test_sysconfig.py
+++ b/Lib/test/test_sysconfig.py
@@ -419,6 +419,7 @@ def test_parse_makefile(self):
             print("var5=dollar$$5", file=makefile)
             print("var6=${var3}/lib/python3.5/config-$(VAR2)$(var5)"
                   "-x86_64-linux-gnu", file=makefile)
+            print("var7=$${ORIGIN}${var5}", file=makefile)
         vars = sysconfig._parse_makefile(TESTFN)
         self.assertEqual(vars, {
             'var1': 'ab42',
@@ -427,6 +428,7 @@ def test_parse_makefile(self):
             'var4': '$/invalid',
             'var5': 'dollar$5',
             'var6': '42/lib/python3.5/config-b42dollar$5-x86_64-linux-gnu',
+            'var7': '${ORIGIN}dollar$5',
         })
 
 
diff --git a/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst b/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst
new file mode 100644
index 00000000000000..878a6ccdf766a4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst
@@ -0,0 +1,2 @@
+Split strings prior to parsing in :func:`sysconfig._parse_makefile` so it
+doesn't expand variables formatted as ``$${variable}``.

From e15e47c724bd861d0a91411408f9650f5e8c1bb7 Mon Sep 17 00:00:00 2001
From: Erwan Le Pape <lepaperwan3@gmail.com>
Date: Mon, 6 Jul 2020 21:38:33 +0200
Subject: [PATCH 2/2] Fix formatting issues

---
 Lib/sysconfig.py                                              | 3 ++-
 .../next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst     | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 08e0f06be6da67..f3198d666080b0 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -302,7 +302,8 @@ def _parse_makefile(filename, vars=None):
 
                 if found:
                     after = value[offset + m.end():]
-                    value = value[:offset + m.start()] + item.replace('$', '$$') + after
+                    value = value[:offset + m.start()] + \
+                            item.replace('$', '$$') + after
                     if "$" in after.replace('$$', ''):
                         notdone[name] = value
                     else:
diff --git a/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst b/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst
index 878a6ccdf766a4..1751dcb7bb77a6 100644
--- a/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst
+++ b/Misc/NEWS.d/next/Library/2018-09-17-19-11-17.bpo-34689.RtyOE3.rst
@@ -1,2 +1,2 @@
-Split strings prior to parsing in :func:`sysconfig._parse_makefile` so it
-doesn't expand variables formatted as ``$${variable}``.
+Split strings prior to parsing in `sysconfig._parse_makefile` so it doesn't
+expand variables formatted as ``$${variable}``.