1 files changed, 76 insertions, 0 deletions
diff --git a/sh/lib.sh/existence_python.sh b/sh/lib.sh/existence_python.sh
new file mode 100644
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+++ b/sh/lib.sh/existence_python.sh
@@ -0,0 +1,76 @@
+#!/bin/sh
+
+# This file is part of TALER
+# (C) 2019 GNUnet e.V.
+#
+# This is very simple POSIX sh script which
+# identifies the first matching
+# python3 identifier in $PATH and produces
+# configure.py from configure.py.in, and then
+# calls the new executable configure.py.
+#
+# It should be portable on Unices. Report bugs on
+# the bugtracker if you discover that it isn't
+# working as intended.
+#
+# Authors:
+# Author: ng0 <ng0@taler.net>
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE
+# LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES
+# OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+# ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+# THIS SOFTWARE.
+#
+# SPDX-License-Identifier: 0BSD
+
+existence_python()
+{
+    # We have to check every possible variant of the
+    # executable name because there is a PEP which
+    # defines the executable to be like this.
+    if existence python3; then
+        if test ! -z "`python3 --version | awk '$2 ~ /3.7/ { print }'`"; then
+            python="python3"
+        else
+            echo "*** At least python 3.7 is required for the buildsystem"
+            exit 1
+        fi
+        # elif existence python3.1; then
+        #     python="python3.1"
+        # elif existence python3.2; then
+        #     python="python3.2"
+        # elif existence python3.3; then
+        #     python="python3.3"
+        # elif existence python3.4; then
+        #     python="python3.4"
+        # elif existence python3.5; then
+        #     python="python3.5"
+        # elif existence python3.6; then
+        #     python="python3.6"
+    elif existence python3.7; then
+        python="python3.7"
+    elif existence python3.8; then
+        python="python3.8"
+    else
+        echo "*** No known python3 executable found in path ***"
+        echo "*** falling back to env(1) python             ***"
+        # Unreliable, but if env finds no python, we still can
+        # not assume python in a fixed location.
+        # TODO: Check this in a clean chroot!
+        python="env python"
+    fi
+
+    # we could check the return value here via || echo "blafoo"
+    # or fail anyway once configure.py is invoked because we
+    # don't have python if we reach the point to fail.
+    PYTHON=$($python -c 'import sys; print(sys.executable)')
+}
+
+existence_python