[PATCH rdma-core 3/7] build: Use the system PYTHON_EXECUTABLE for gen-sparse

[Jason Gunthorpe <jgg@xxxxxxxx>]

From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>

All python scripts run from cmake should use PYTHON_EXECUTABLE and must
support python3. Update gen-sparse's call to this standard.

Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
---
 CMakeLists.txt             | 30 +++++++++++++++---------------
 buildlib/RDMA_Sparse.cmake |  2 +-
 buildlib/gen-sparse.py     | 11 ++++++-----
 3 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 31100e267f2150..cfd4c3cbf9481e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -170,6 +170,21 @@ endif()
 RDMA_BuildType()
 include_directories(${BUILD_INCLUDE})
 
+# Look for Python. We prefer some variant of python 3 if the system has it.
+FIND_PACKAGE(PythonInterp 3 QUIET)
+if (PythonInterp_FOUND)
+  # pyverbs can only use python3:
+  if (NO_PYVERBS)
+    set(CYTHON_EXECUTABLE "")
+  else()
+    FIND_PACKAGE(cython)
+  endif()
+else()
+  # But we still must have python (be it 2) for the build process:
+  FIND_PACKAGE(PythonInterp REQUIRED)
+  set(CYTHON_EXECUTABLE "")
+endif()
+
 RDMA_CheckSparse()
 
 # Require GNU99 mode
@@ -364,21 +379,6 @@ else()
   set(HAVE_FULL_SYMBOL_VERSIONS 1)
 endif()
 
-# Look for Python. We prefer some variant of python 3 if the system has it.
-FIND_PACKAGE(PythonInterp 3 QUIET)
-if (PythonInterp_FOUND)
-  # pyverbs can only use python3:
-  if (NO_PYVERBS)
-    set(CYTHON_EXECUTABLE "")
-  else()
-    FIND_PACKAGE(cython)
-  endif()
-else()
-  # But we still must have python (be it 2) for the build process:
-  FIND_PACKAGE(PythonInterp REQUIRED)
-  set(CYTHON_EXECUTABLE "")
-endif()
-
 # A cython & python-devel installation that matches our selected interpreter.
 
 if (CYTHON_EXECUTABLE)
diff --git a/buildlib/RDMA_Sparse.cmake b/buildlib/RDMA_Sparse.cmake
index 8fcfb758d5284f..3d03ce6283eec4 100644
--- a/buildlib/RDMA_Sparse.cmake
+++ b/buildlib/RDMA_Sparse.cmake
@@ -19,7 +19,7 @@ int main(int argc,const char *argv[]) {return 0;}
     set(HAVE_SPARSE TRUE PARENT_SCOPE)
 
     # Replace various glibc headers with our own versions that have embedded sparse annotations.
-    execute_process(COMMAND "${BUILDLIB}/gen-sparse.py"
+    execute_process(COMMAND "${PYTHON_EXECUTABLE}" "${BUILDLIB}/gen-sparse.py"
       "--out" "${BUILD_INCLUDE}/"
       "--src" "${CMAKE_SOURCE_DIR}/"
       RESULT_VARIABLE retcode)
diff --git a/buildlib/gen-sparse.py b/buildlib/gen-sparse.py
index c289da31c19d75..84781f4528feef 100755
--- a/buildlib/gen-sparse.py
+++ b/buildlib/gen-sparse.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2015-2017 Obsidian Research Corp.
 # Licensed under BSD (MIT variant) or GPLv2. See COPYING.
 import argparse
@@ -66,10 +66,10 @@ def apply_patch(src,patch,dest):
         subprocess.check_output(["patch","-f","--follow-symlinks","-V","never","-i",patch,"-o",dest,src]);
 
         if os.path.exists(dest + ".rej"):
-            print "Patch from %r failed"%(patch);
+            print("Patch from %r failed"%(patch));
             return False;
     except subprocess.CalledProcessError:
-        print "Patch from %r failed"%(patch);
+        print("Patch from %r failed"%(patch));
         return False;
     return True;
 
@@ -81,7 +81,7 @@ def replace_header(fn):
             return;
         tries = tries + 1;
 
-    print "Unable to apply any patch to %r, tries %u"%(fn,tries);
+    print("Unable to apply any patch to %r, tries %u"%(fn,tries));
     global failed;
     failed = True;
 
@@ -119,7 +119,8 @@ args = parser.parse_args();
 
 if args.save:
     # Get the glibc version string
-    ver = subprocess.check_output(["ldd","--version"]).splitlines()[0].split(' ')[-1];
+    ver = subprocess.check_output(["ldd","--version"]).decode()
+    ver = ver.splitlines()[0].split(' ')[-1];
     ver = ver.partition(".")[-1];
     outdir = os.path.join(args.SRC,"buildlib","sparse-include",ver);
     if not os.path.isdir(outdir):
-- 
2.21.0