From 14086cfc5eed8c5e78342d79e5db87a135d75fa8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20G=C3=B3rny?= <mgorny@gentoo.org>
Date: Wed, 27 Sep 2017 07:45:06 +0200
Subject: [PATCH] closes bpo-22140: Prevent double substitution of prefix in
 python-config.sh (#3769)

Fix the logic in python-config.sh to avoid attempting to substitute
prefix in a variable that might have already been subject to
substitution. This e.g. happened if @exec_prefix@ was defined as
"${prefix}" (which is the default of the configure script) -- in which
case the exec_prefix_build variable was initialized with
already-subtituted prefix, and then another round of substitution was
performed which might have resulted in duplicate prefix.

To avoid that, rename the variables so that the variables matching
likely configure names (prefix, exec_prefix) retain their original
values and a '_real' suffix is used for the real values of prefix.

Furthermore, replace the unnecessary prefix and exec_prefix
substitutions with direct prefix_real references since the sed
always replaced the whole string anyway by design.
---
 .../2017-09-26-22-39-58.bpo-22140.ZRf7Wn.rst  |  1 +
 Misc/python-config.sh.in                      | 25 ++++++++++---------
 2 files changed, 14 insertions(+), 12 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Build/2017-09-26-22-39-58.bpo-22140.ZRf7Wn.rst

diff --git a/Misc/NEWS.d/next/Build/2017-09-26-22-39-58.bpo-22140.ZRf7Wn.rst b/Misc/NEWS.d/next/Build/2017-09-26-22-39-58.bpo-22140.ZRf7Wn.rst
new file mode 100644
index 00000000000..e20c0942f6c
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2017-09-26-22-39-58.bpo-22140.ZRf7Wn.rst
@@ -0,0 +1 @@
+Prevent double substitution of prefix in python-config.sh.
diff --git a/Misc/python-config.sh.in b/Misc/python-config.sh.in
index 30c69278710..d1d3275fa27 100644
--- a/Misc/python-config.sh.in
+++ b/Misc/python-config.sh.in
@@ -24,17 +24,18 @@ installed_prefix ()
     echo $RESULT
 }
 
-prefix_build="@prefix@"
 prefix_real=$(installed_prefix "$0")
 
 # Use sed to fix paths from their built-to locations to their installed-to
-# locations.
-prefix=$(echo "$prefix_build" | sed "s#$prefix_build#$prefix_real#")
-exec_prefix_build="@exec_prefix@"
-exec_prefix=$(echo "$exec_prefix_build" | sed "s#$exec_prefix_build#$prefix_real#")
-includedir=$(echo "@includedir@" | sed "s#$prefix_build#$prefix_real#")
-libdir=$(echo "@libdir@" | sed "s#$prefix_build#$prefix_real#")
-CFLAGS=$(echo "@CFLAGS@" | sed "s#$prefix_build#$prefix_real#")
+# locations. Keep prefix & exec_prefix using their original values in case
+# they are referenced in other configure variables, to prevent double
+# substitution, issue #22140.
+prefix="@prefix@"
+exec_prefix="@exec_prefix@"
+exec_prefix_real=${prefix_real}
+includedir=$(echo "@includedir@" | sed "s#$prefix#$prefix_real#")
+libdir=$(echo "@libdir@" | sed "s#$prefix#$prefix_real#")
+CFLAGS=$(echo "@CFLAGS@" | sed "s#$prefix#$prefix_real#")
 VERSION="@VERSION@"
 LIBM="@LIBM@"
 LIBC="@LIBC@"
@@ -47,8 +48,8 @@ LINKFORSHARED="@LINKFORSHARED@"
 OPT="@OPT@"
 PY_ENABLE_SHARED="@PY_ENABLE_SHARED@"
 LDVERSION="@LDVERSION@"
-LIBDEST=${prefix}/lib/python${VERSION}
-LIBPL=$(echo "@LIBPL@" | sed "s#$prefix_build#$prefix_real#")
+LIBDEST=${prefix_real}/lib/python${VERSION}
+LIBPL=$(echo "@LIBPL@" | sed "s#$prefix#$prefix_real#")
 SO="@EXT_SUFFIX@"
 PYTHONFRAMEWORK="@PYTHONFRAMEWORK@"
 INCDIR="-I$includedir/python${VERSION}${ABIFLAGS}"
@@ -73,10 +74,10 @@ for ARG in "$@"
 do
     case "$ARG" in
         --prefix)
-            echo "$prefix"
+            echo "$prefix_real"
         ;;
         --exec-prefix)
-            echo "$exec_prefix"
+            echo "$exec_prefix_real"
         ;;
         --includes)
             echo "$INCDIR $PLATINCDIR"