[NaCl SDK] sel_ldr.py: Run sel_ldr in quiet mode by default

Also, use NACLVERBOSITY=-3 rather than logging to /dev/null.
This means we still see LOG_ERROR and LOG_FATAL messages such
as segfault information.

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_nacl_sdk;tryserver.chromium.mac:mac_nacl_sdk;tryserver.chromium.win:win_nacl_sdk
R=binji@chromium.org

Review URL: https://codereview.chromium.org/1256003002 .

Cr-Commit-Position: refs/heads/master@{#340332}

1 files changed, 12 insertions, 4 deletions

diff --git a/native_client_sdk/src/tools/sel_ldr.py b/native_client_sdk/src/tools/sel_ldr.py
index 45dfddc..7384528 100755
--- a/native_client_sdk/src/tools/sel_ldr.py
+++ b/native_client_sdk/src/tools/sel_ldr.py
@@ -111,7 +111,18 @@ def main(argv):
     cmd.append('--r_debug=0xXXXXXXXXXXXXXXXX')
     cmd.append('--reserved_at_zero=0xXXXXXXXXXXXXXXXX')
 
-  cmd += ['-a', '-B', irt]
+  # This script is provided mostly as way to run binaries during testing, not
+  # to run untrusted code in a production environment.  As such we want it be
+  # as invisible as possible.  So we pass -q (quiet) to disable most of output
+  # of sel_ldr itself, and -a (disable ACL) to enable local filesystem access.
+  cmd += ['-q', '-a', '-B', irt]
+
+  # Set the default NACLVERBOSITY level LOG_ERROR (-3).  This can still be
+  # overridden in the environment if debug information is desired.  However
+  # in most cases we don't want the application stdout/stderr polluted with
+  # sel_ldr logging.
+  if 'NACLVERBOSITY' not in os.environ and not options.verbose:
+    os.environ['NACLVERBOSITY'] = "-3"
 
   if options.debug:
     cmd.append('-g')
@@ -122,9 +133,6 @@ def main(argv):
   if options.passthrough_environment:
     cmd.append('-p')
 
-  if not options.verbose:
-    cmd += ['-l', os.devnull]
-
   if arch == 'arm':
     # Use the QEMU arm emulator if available.
     qemu_bin = FindQemu()