From 7218bcd4c04081850075dfe4e3f07b97d99a2549 Mon Sep 17 00:00:00 2001
From: Jakob Buchgraber <buchgr@google.com>
Date: Mon, 27 Apr 2020 19:49:35 +0200
Subject: [PATCH] Fix incorrect usage of os.system().

The code wrongly assumed that os.system(cmd) returns the exit code of the
process. Instead, it returns a concatenation of the exit code and signal
number that terminated the process (if any). This change uses the proper
accessor methods to extract the exit code and signal number from the
return value. If a process terminated with exit(N) we return N. Else, we
return the negative signal number. This is in line with the behaviour of
subprocess.run.

Specfically, this change fixes a bug where nvcc would exit with 1 but
the wrapper script would exit with 0. This is because os.system() would
return 0x0100 which got truncated to 0x00 due to exit codes being
limited to 8-bit on Linux.
---
 .../crosstool_wrapper_driver_is_not_gcc.tpl   | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/third_party/gpus/crosstool/clang/bin/crosstool_wrapper_driver_is_not_gcc.tpl b/third_party/gpus/crosstool/clang/bin/crosstool_wrapper_driver_is_not_gcc.tpl
index de3e3cb9905..f3b2ae6846d 100755
--- a/third_party/gpus/crosstool/clang/bin/crosstool_wrapper_driver_is_not_gcc.tpl
+++ b/third_party/gpus/crosstool/clang/bin/crosstool_wrapper_driver_is_not_gcc.tpl
@@ -151,6 +151,21 @@ def GetNvccOptions(argv):
     return ' '.join(['--'+a for a in options])
   return ''
 
+def system(cmd):
+  """Invokes cmd with os.system().
+
+  Args:
+    cmd: The command.
+
+  Returns:
+    The exit code if the process exited with exit() or -signal
+    if the process was terminated by a signal.
+  """
+  retv = os.system(cmd)
+  if os.WIFEXITED(retv):
+    return os.WEXITSTATUS(retv)
+  else:
+    return -os.WTERMSIG(retv)
 
 def InvokeNvcc(argv, log=False):
   """Call nvcc with arguments assembled from argv.
@@ -160,7 +175,7 @@ def InvokeNvcc(argv, log=False):
     log: True if logging is requested.
 
   Returns:
-    The return value of calling os.system('nvcc ' + args)
+    The return value of calling system('nvcc ' + args)
   """
 
   host_compiler_options = GetHostCompilerOptions(argv)
@@ -231,7 +246,7 @@ def InvokeNvcc(argv, log=False):
            ' -I .' +
            ' -x cu ' + opt + includes + ' ' + srcs + ' -M -o ' + depfile)
     if log: Log(cmd)
-    exit_status = os.system(cmd)
+    exit_status = system(cmd)
     if exit_status != 0:
       return exit_status
 
@@ -245,7 +260,7 @@ def InvokeNvcc(argv, log=False):
   # Need to investigate and fix.
   cmd = 'PATH=' + PREFIX_DIR + ':$PATH ' + cmd
   if log: Log(cmd)
-  return os.system(cmd)
+  return system(cmd)
 
 
 def main():