hw-mgmgt: script: Fix race conditions for write in thermal updater

Prevent race conditions by using atomic file writes. Replace open()/write()
with atomic_file_write() to ensure readers never see empty or partial
content when thermal attributes are updated.

Bug: 4647791

Author: sholeksandr

usr/usr/bin/hw_management_lib.py

@@ -38,9 +38,30 @@
 import syslog
 from threading import Lock
 import time
+import tempfile
 
 
 # ----------------------------------------------------------------------
+
+def atomic_file_write(file_name, value):
+    """
+    @summary:
+        Write value to file atomically
+    @param file_name: name of file
+    @param value: value to write
+    """
+    fd, f_path_tmp = tempfile.mkstemp(dir=os.path.dirname(file_name), prefix='.tmp_')
+    try:
+        with os.fdopen(fd, 'w', encoding="utf-8") as f:
+            f.write("{}".format(value))
+        os.replace(f_path_tmp, file_name)  # Atomic on POSIX
+    except Exception as e:
+        os.unlink(f_path_tmp)  # Cleanup on failure
+        raise Exception(f"Error writing {file_name}: {e}")
+
+# ----------------------------------------------------------------------
+
+
 def current_milli_time():
     """
     @summary:

usr/usr/bin/hw_management_sync.py

@@ -44,6 +44,7 @@
     import argparse
     import traceback
     from hw_management_lib import HW_Mgmt_Logger as Logger
+    from hw_management_lib import atomic_file_write
     from collections import Counter
 
     from hw_management_redfish_client import RedfishClient, BMCAccessor
@@ -680,9 +681,8 @@ def asic_temp_populate(arg_list, arg):
         # Write the temperature data to files
         for suffix, value in file_paths.items():
             f_name = "/var/run/hw-management/thermal/{}{}".format(asic_name, suffix)
-            with open(f_name, 'w', encoding="utf-8") as f:
-                f.write("{}\n".format(value))
-                LOGGER.debug(f"Write {asic_name}{suffix}: {value}")
+            atomic_file_write(f_name, str(value) + "\n")
+            LOGGER.debug(f"Write {asic_name}{suffix}: {value}")
 
     asic_chipup_completed_fname = os.path.join("/var/run/hw-management/config", "asic_chipup_completed")
     asic_num_fname = os.path.join("/var/run/hw-management/config", "asic_num")
@@ -704,11 +704,8 @@ def asic_temp_populate(arg_list, arg):
     else:
         asics_init_done = 0
 
-    with open(asics_init_done_fname, 'w+', encoding="utf-8") as f:
-        f.write(str(asics_init_done) + "\n")
-
-    with open(asic_chipup_completed_fname, 'w', encoding="utf-8") as f:
-        f.write(str(asic_chipup_completed) + "\n")
+    atomic_file_write(asics_init_done_fname, str(asics_init_done) + "\n")
+    atomic_file_write(asic_chipup_completed_fname, str(asic_chipup_completed) + "\n")
 
 # ----------------------------------------------------------------------
 
@@ -801,15 +798,13 @@ def module_temp_populate(arg_list, _dummy):
         for suffix, value in file_paths.items():
             f_name = "/var/run/hw-management/thermal/{}{}".format(module_name, suffix)
             if value is not None:
-                with open(f_name, 'w', encoding="utf-8") as f:
-                    f.write("{}\n".format(value))
-                    LOGGER.debug(f"Write {module_name}{suffix}: {value}")
+                atomic_file_write(f_name, str(value) + "\n")
+                LOGGER.debug(f"Write {module_name}{suffix}: {value}")
         module_updated = True
 
     if module_updated:
         LOGGER.debug("{} module_counter ({}) updated".format(module_name, module_count))
-        with open("/var/run/hw-management/config/module_counter", 'w+', encoding="utf-8") as f:
-            f.write("{}\n".format(module_count))
+        atomic_file_write("/var/run/hw-management/config/module_counter", str(module_count) + "\n")
     return
 
 # ----------------------------------------------------------------------