Issue #27407: Add prepare_ssl.py to 2.7
diff --git a/PCbuild/prepare_ssl.py b/PCbuild/prepare_ssl.py
new file mode 100644
index 0000000..f6170f5
--- /dev/null
+++ b/PCbuild/prepare_ssl.py
@@ -0,0 +1,196 @@
+#! /usr/bin/env python3
+# Script for preparing OpenSSL for building on Windows.
+# Uses Perl to create nmake makefiles and otherwise prepare the way
+# for building on 32 or 64 bit platforms.
+
+# Script originally authored by Mark Hammond.
+# Major revisions by:
+#   Martin v. Löwis
+#   Christian Heimes
+#   Zachary Ware
+
+# THEORETICALLY, you can:
+# * Unpack the latest OpenSSL release where $(opensslDir) in
+#   PCbuild\pyproject.props expects it to be.
+# * Install ActivePerl and ensure it is somewhere on your path.
+# * Run this script with the OpenSSL source dir as the only argument.
+#
+# it should configure OpenSSL such that it is ready to be built by
+# ssl.vcxproj on 32 or 64 bit platforms.
+
+import os
+import re
+import sys
+import subprocess
+from shutil import copy
+
+# Find all "foo.exe" files on the PATH.
+def find_all_on_path(filename, extras=None):
+    entries = os.environ["PATH"].split(os.pathsep)
+    ret = []
+    for p in entries:
+        fname = os.path.abspath(os.path.join(p, filename))
+        if os.path.isfile(fname) and fname not in ret:
+            ret.append(fname)
+    if extras:
+        for p in extras:
+            fname = os.path.abspath(os.path.join(p, filename))
+            if os.path.isfile(fname) and fname not in ret:
+                ret.append(fname)
+    return ret
+
+
+# Find a suitable Perl installation for OpenSSL.
+# cygwin perl does *not* work.  ActivePerl does.
+# Being a Perl dummy, the simplest way I can check is if the "Win32" package
+# is available.
+def find_working_perl(perls):
+    for perl in perls:
+        try:
+            subprocess.check_output([perl, "-e", "use Win32;"])
+        except subprocess.CalledProcessError:
+            continue
+        else:
+            return perl
+
+    if perls:
+        print("The following perl interpreters were found:")
+        for p in perls:
+            print(" ", p)
+        print(" None of these versions appear suitable for building OpenSSL")
+    else:
+        print("NO perl interpreters were found on this machine at all!")
+    print(" Please install ActivePerl and ensure it appears on your path")
+
+
+def create_asms(makefile, tmp_d):
+    #create a custom makefile out of the provided one
+    asm_makefile = os.path.splitext(makefile)[0] + '.asm.mak'
+    with open(makefile) as fin, open(asm_makefile, 'w') as fout:
+        for line in fin:
+            # Keep everything up to the install target (it's convenient)
+            if line.startswith('install: all'):
+                break
+            fout.write(line)
+        asms = []
+        for line in fin:
+            if '.asm' in line and line.strip().endswith('.pl'):
+                asms.append(line.split(':')[0])
+                while line.strip():
+                    fout.write(line)
+                    line = next(fin)
+                fout.write('\n')
+
+        fout.write('asms: $(TMP_D) ')
+        fout.write(' '.join(asms))
+        fout.write('\n')
+    os.system('nmake /f {} PERL=perl TMP_D={} asms'.format(asm_makefile, tmp_d))
+
+
+def copy_includes(makefile, suffix):
+    dir = 'include'+suffix+'\\openssl'
+    os.makedirs(dir, exist_ok=True)
+    copy_if_different = r'$(PERL) $(SRC_D)\util\copy-if-different.pl'
+    with open(makefile) as fin:
+        for line in fin:
+            if copy_if_different in line:
+                perl, script, src, dest = line.split()
+                if not '$(INCO_D)' in dest:
+                    continue
+                # We're in the root of the source tree
+                src = src.replace('$(SRC_D)', '.').strip('"')
+                dest = dest.strip('"').replace('$(INCO_D)', dir)
+                print('copying', src, 'to', dest)
+                copy(src, dest)
+
+
+def run_configure(configure, do_script):
+    print("perl Configure "+configure+" no-idea no-mdc2")
+    os.system("perl Configure "+configure+" no-idea no-mdc2")
+    print(do_script)
+    os.system(do_script)
+
+
+def prep(arch):
+    makefile_template = "ms\\nt{}.mak"
+    generated_makefile = makefile_template.format('')
+    if arch == "x86":
+        configure = "VC-WIN32"
+        do_script = "ms\\do_nasm"
+        suffix = "32"
+    elif arch == "amd64":
+        configure = "VC-WIN64A"
+        do_script = "ms\\do_win64a"
+        suffix = "64"
+        #os.environ["VSEXTCOMP_USECL"] = "MS_OPTERON"
+    else:
+        raise ValueError('Unrecognized platform: %s' % arch)
+
+    print("Creating the makefiles...")
+    sys.stdout.flush()
+    # run configure, copy includes, create asms
+    run_configure(configure, do_script)
+    makefile = makefile_template.format(suffix)
+    try:
+        os.unlink(makefile)
+    except FileNotFoundError:
+        pass
+    os.rename(generated_makefile, makefile)
+    copy_includes(makefile, suffix)
+
+    print('creating asms...')
+    create_asms(makefile, 'tmp'+suffix)
+
+
+def main():
+    if len(sys.argv) == 1:
+        print("Not enough arguments: directory containing OpenSSL",
+              "sources must be supplied")
+        sys.exit(1)
+
+    if len(sys.argv) > 2:
+        print("Too many arguments supplied, all we need is the directory",
+              "containing OpenSSL sources")
+        sys.exit(1)
+
+    ssl_dir = sys.argv[1]
+
+    if not os.path.isdir(ssl_dir):
+        print(ssl_dir, "is not an existing directory!")
+        sys.exit(1)
+
+    # perl should be on the path, but we also look in "\perl" and "c:\\perl"
+    # as "well known" locations
+    perls = find_all_on_path("perl.exe", [r"\perl\bin",
+                                          r"C:\perl\bin",
+                                          r"\perl64\bin",
+                                          r"C:\perl64\bin",
+                                         ])
+    perl = find_working_perl(perls)
+    if perl:
+        print("Found a working perl at '%s'" % (perl,))
+    else:
+        sys.exit(1)
+    if not find_all_on_path('nmake.exe'):
+        print('Could not find nmake.exe, try running env.bat')
+        sys.exit(1)
+    if not find_all_on_path('nasm.exe'):
+        print('Could not find nasm.exe, please add to PATH')
+        sys.exit(1)
+    sys.stdout.flush()
+
+    # Put our working Perl at the front of our path
+    os.environ["PATH"] = os.path.dirname(perl) + \
+                                os.pathsep + \
+                                os.environ["PATH"]
+
+    old_cwd = os.getcwd()
+    try:
+        os.chdir(ssl_dir)
+        for arch in ['amd64', 'x86']:
+            prep(arch)
+    finally:
+        os.chdir(old_cwd)
+
+if __name__=='__main__':
+    main()