From ae010215e7a37469e88b77fab5bd585b981567a4 Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Sat, 16 Aug 2025 11:29:29 -0400
Subject: [PATCH] chelper: Build library first in temporary file and then
 rename

Try to avoid cases where an incomplete library build causes confusing
future failures.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 klippy/chelper/__init__.py | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/klippy/chelper/__init__.py b/klippy/chelper/__init__.py
index 6ed6ed5b..60ba91e7 100644
--- a/klippy/chelper/__init__.py
+++ b/klippy/chelper/__init__.py
@@ -274,6 +274,28 @@ def do_build_code(cmd):
         logging.error(msg)
         raise Exception(msg)
 
+# Build the main c_helper.so c code library
+def check_build_c_library():
+    srcdir = os.path.dirname(os.path.realpath(__file__))
+    srcfiles = get_abs_files(srcdir, SOURCE_FILES)
+    ofiles = get_abs_files(srcdir, OTHER_FILES)
+    destlib = get_abs_files(srcdir, [DEST_LIB])[0]
+    if not check_build_code(srcfiles+ofiles+[__file__], destlib):
+        # Code already built
+        return destlib
+    # Select command line options
+    if check_gcc_option(SSE_FLAGS):
+        cmd = "%s %s %s" % (GCC_CMD, SSE_FLAGS, COMPILE_ARGS)
+    else:
+        cmd = "%s %s" % (GCC_CMD, COMPILE_ARGS)
+    # Invoke compiler
+    logging.info("Building C code module %s", DEST_LIB)
+    tempdestlib = get_abs_files(srcdir, ["_temp_" + DEST_LIB])[0]
+    do_build_code(cmd % (tempdestlib, ' '.join(srcfiles)))
+    # Rename from temporary file to final file name
+    os.rename(tempdestlib, destlib)
+    return destlib
+
 FFI_main = None
 FFI_lib = None
 pyhelper_logging_callback = None
@@ -286,17 +308,9 @@ def logging_callback(msg):
 def get_ffi():
     global FFI_main, FFI_lib, pyhelper_logging_callback
     if FFI_lib is None:
-        srcdir = os.path.dirname(os.path.realpath(__file__))
-        srcfiles = get_abs_files(srcdir, SOURCE_FILES)
-        ofiles = get_abs_files(srcdir, OTHER_FILES)
-        destlib = get_abs_files(srcdir, [DEST_LIB])[0]
-        if check_build_code(srcfiles+ofiles+[__file__], destlib):
-            if check_gcc_option(SSE_FLAGS):
-                cmd = "%s %s %s" % (GCC_CMD, SSE_FLAGS, COMPILE_ARGS)
-            else:
-                cmd = "%s %s" % (GCC_CMD, COMPILE_ARGS)
-            logging.info("Building C code module %s", DEST_LIB)
-            do_build_code(cmd % (destlib, ' '.join(srcfiles)))
+        # Check if library needs to be built, and build if so
+        destlib = check_build_c_library()
+        # Open library
         FFI_main = cffi.FFI()
         for d in defs_all:
             FFI_main.cdef(d)