Allows sel_ldr.py to run arm binaries through qemu-arm.

native_client_sdk/src/tools/sel_ldr.py

 #!/usr/bin/env python
 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Wrapper script for launching application within the sel_ldr.
 """
 
 import optparse
 import os
@@ skipping 14 matching lines @@
 class Error(Exception):
   pass
 
 
 def Log(msg):
   if Log.verbose:
     sys.stderr.write(str(msg) + '\n')
 Log.verbose = False
 
 
+def FindQemu():
+  qemu_locations = [os.path.join(SCRIPT_DIR, 'qemu_arm'),
+                    os.path.join(SCRIPT_DIR, 'qemu-arm')]
+  qemu_locations += [os.path.join(path, 'qemu_arm')
+                     for path in os.environ["PATH"].split(os.pathsep)]
+  qemu_locations += [os.path.join(path, 'qemu-arm')
+                     for path in os.environ["PATH"].split(os.pathsep)]
+  # See if qemu is in any of these locations.
+  qemu_bin = None
+  for loc in qemu_locations:
+    if os.path.isfile(loc) and os.access(loc, os.X_OK):
+      qemu_bin = loc
+      break
+  return qemu_bin
+
+
 def main(argv):
   usage = 'Usage: %prog [options] <.nexe>'
   epilog = 'Example: sel_ldr.py my_nexe.nexe'
   parser = optparse.OptionParser(usage, description=__doc__, epilog=epilog)
   parser.add_option('-v', '--verbose', action='store_true',
                     help='Verbose output')
   parser.add_option('-d', '--debug', action='store_true',
                     help='Enable debug stub')
   parser.add_option('--debug-libs', action='store_true',
                     help='For dynamic executables, reference debug '
@@ skipping 17 matching lines @@
     Log.verbose = True
 
   osname = getos.GetPlatform()
   if not os.path.exists(nexe):
     raise Error('executable not found: %s' % nexe)
   if not os.path.isfile(nexe):
     raise Error('not a file: %s' % nexe)
 
   arch, dynamic = create_nmf.ParseElfHeader(nexe)
 
-  if arch == 'arm':
-    raise Error('Cannot run ARM executables under sel_ldr')
+  if arch == 'arm' and osname != 'linux':
+    raise Error('Cannot run ARM executables under sel_ldr on ' + osname)
 
   arch_suffix = arch.replace('-', '_')
 
   sel_ldr = os.path.join(SCRIPT_DIR, 'sel_ldr_%s' % arch_suffix)
   irt = os.path.join(SCRIPT_DIR, 'irt_core_%s.nexe' % arch_suffix)
   if osname == 'win':
     sel_ldr += '.exe'
   Log('ROOT    = %s' % NACL_SDK_ROOT)
   Log('SEL_LDR = %s' % sel_ldr)
   Log('IRT     = %s' % irt)
   cmd = [sel_ldr]
 
   if osname == 'linux':
     # Run sel_ldr under nacl_helper_bootstrap
     helper = os.path.join(SCRIPT_DIR, 'nacl_helper_bootstrap_%s' % arch_suffix)
     Log('HELPER  = %s' % helper)
     cmd.insert(0, helper)
     cmd.append('--r_debug=0xXXXXXXXXXXXXXXXX')
     cmd.append('--reserved_at_zero=0xXXXXXXXXXXXXXXXX')
 
   cmd += ['-a', '-B', irt]
 
   if options.debug:
     cmd.append('-g')
 
   if not options.verbose:
     cmd += ['-l', os.devnull]
 
+  if arch == 'arm':
+    # Use the QEMU arm emulator if available.
+    qemu_bin = FindQemu()
+    if qemu_bin:
+      qemu = [qemu_bin, '-cpu', 'cortex-a8', '-L',
+              os.path.abspath(os.path.join(NACL_SDK_ROOT, 'toolchain',
+                                           'linux_arm_trusted'))]
+      # '-Q' disables platform qualification, allowing arm binaries to run.
+      cmd = qemu + cmd + ['-Q']
+    else:
+      raise Error('Cannot run ARM executables under sel_ldr without an emulator'
+                  '. Try installing QEMU (http://wiki.qemu.org/).')
+
   if dynamic:
     if options.debug_libs:
       libpath = os.path.join(NACL_SDK_ROOT, 'lib',
                             'glibc_%s' % arch_suffix, 'Debug')
     else:
       libpath = os.path.join(NACL_SDK_ROOT, 'lib',
                             'glibc_%s' % arch_suffix, 'Release')
     toolchain = '%s_x86_glibc' % osname
     sdk_lib_dir = os.path.join(NACL_SDK_ROOT, 'toolchain',
                                toolchain, 'x86_64-nacl')
@@ skipping 17 matching lines @@
   rtn = subprocess.call(cmd)
   return rtn
 
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except Error as e:
     sys.stderr.write(str(e) + '\n')
     sys.exit(1)