auto merge of #4083 : mttr/servo/mach_debugger_flag, r=mbrubeck

Borrows two python modules from mozilla-central to give mach the ability to detect and pass arguments to a system's preferred debugger, and adds `--debug` and `--debugger` flags to `./mach run`. This works almost like the functionality described [here](https://developer.mozilla.org/en-US/docs/Debugging_Mozilla_with_gdb), but at the moment it lacks a `--debugparams`  argument.

Links to borrowed files:
http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/testing/mozbase/mozinfo/mozinfo/mozinfo.py
http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/testing/mozbase/mozdebug/mozdebug/mozdebug.py

python/mach_bootstrap.py

@@ -11,6 +11,8 @@ import sys
 SEARCH_PATHS = [
     "python/mach",
     "python/toml",
+    "python/mozinfo",
+    "python/mozdebug",
 ]
 
 # Individual files providing mach commands.

python/mozdebug/__init__.py

@@ -0,0 +1,30 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+This module contains a set of function to gather information about the
+debugging capabilities of the platform. It allows to look for a specific
+debugger or to query the system for a compatible/default debugger.
+
+The following simple example looks for the default debugger on the
+current platform and launches a debugger process with the correct
+debugger-specific arguments:
+
+::
+
+  import mozdebug
+
+  debugger = mozdebug.get_default_debugger_name()
+  debuggerInfo = mozdebug.get_debugger_info(debugger)
+
+  debuggeePath = "toDebug"
+
+  processArgs = [self.debuggerInfo.path] + self.debuggerInfo.args
+  processArgs.append(debuggeePath)
+
+  run_process(args, ...)
+
+"""
+
+from mozdebug import *

python/mozdebug/mozdebug.py

@@ -0,0 +1,168 @@
+#!/usr/bin/env python
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import mozinfo
+from collections import namedtuple
+from distutils.spawn import find_executable
+
+__all__ = ['get_debugger_info',
+           'get_default_debugger_name',
+           'DebuggerSearch']
+
+'''
+Map of debugging programs to information about them, like default arguments
+and whether or not they are interactive.
+
+To add support for a new debugger, simply add the relative entry in
+_DEBUGGER_INFO and optionally update the _DEBUGGER_PRIORITIES.
+'''
+_DEBUGGER_INFO = {
+    # gdb requires that you supply the '--args' flag in order to pass arguments
+    # after the executable name to the executable.
+    'gdb': {
+        'interactive': True,
+        'args': ['-q', '--args']
+    },
+
+    'cgdb': {
+        'interactive': True,
+        'args': ['-q', '--args']
+    },
+
+    'lldb': {
+        'interactive': True,
+        'args': ['--'],
+        'requiresEscapedArgs': True
+    },
+
+    # Visual Studio Debugger Support.
+    'devenv.exe': {
+        'interactive': True,
+        'args': ['-debugexe']
+    },
+
+    # Visual C++ Express Debugger Support.
+    'wdexpress.exe': {
+        'interactive': True,
+        'args': ['-debugexe']
+    },
+
+    # valgrind doesn't explain much about leaks unless you set the
+    # '--leak-check=full' flag. But there are a lot of objects that are
+    # semi-deliberately leaked, so we set '--show-possibly-lost=no' to avoid
+    # uninteresting output from those objects. We set '--smc-check==all-non-file'
+    # and '--vex-iropt-register-updates=allregs-at-mem-access' so that valgrind
+    # deals properly with JIT'd JavaScript code.
+    'valgrind': {
+        'interactive': False,
+        'args': ['--leak-check=full',
+                '--show-possibly-lost=no',
+                '--smc-check=all-non-file',
+                '--vex-iropt-register-updates=allregs-at-mem-access']
+    }
+}
+
+# Maps each OS platform to the preferred debugger programs found in _DEBUGGER_INFO.
+_DEBUGGER_PRIORITIES = {
+      'win': ['devenv.exe', 'wdexpress.exe'],
+      'linux': ['gdb', 'cgdb', 'lldb'],
+      'mac': ['lldb', 'gdb'],
+      'unknown': ['gdb']
+}
+
+def get_debugger_info(debugger, debuggerArgs = None, debuggerInteractive = False):
+    '''
+    Get the information about the requested debugger.
+
+    Returns a dictionary containing the |path| of the debugger executable,
+    if it will run in |interactive| mode, its arguments and whether it needs
+    to escape arguments it passes to the debugged program (|requiresEscapedArgs|).
+    If the debugger cannot be found in the system, returns |None|.
+
+    :param debugger: The name of the debugger.
+    :param debuggerArgs: If specified, it's the arguments to pass to the debugger,
+    as a string. Any debugger-specific separator arguments are appended after these
+    arguments.
+    :param debuggerInteractive: If specified, forces the debugger to be interactive.
+    '''
+
+    debuggerPath = None
+
+    if debugger:
+        # Append '.exe' to the debugger on Windows if it's not present,
+        # so things like '--debugger=devenv' work.
+        if (os.name == 'nt'
+            and not debugger.lower().endswith('.exe')):
+            debugger += '.exe'
+
+        debuggerPath = find_executable(debugger)
+
+    if not debuggerPath:
+        print 'Error: Could not find debugger %s.' % debugger
+        return None
+
+    debuggerName = os.path.basename(debuggerPath).lower()
+
+    def get_debugger_info(type, default):
+        if debuggerName in _DEBUGGER_INFO and type in _DEBUGGER_INFO[debuggerName]:
+            return _DEBUGGER_INFO[debuggerName][type]
+        return default
+
+    # Define a namedtuple to access the debugger information from the outside world.
+    DebuggerInfo = namedtuple(
+        'DebuggerInfo',
+        ['path', 'interactive', 'args', 'requiresEscapedArgs']
+    )
+
+    debugger_arguments = []
+
+    if debuggerArgs:
+        # Append the provided debugger arguments at the end of the arguments list.
+        debugger_arguments += debuggerArgs.split()
+
+    debugger_arguments += get_debugger_info('args', [])
+
+    # Override the default debugger interactive mode if needed.
+    debugger_interactive = get_debugger_info('interactive', False)
+    if debuggerInteractive:
+        debugger_interactive = debuggerInteractive
+
+    d = DebuggerInfo(
+        debuggerPath,
+        debugger_interactive,
+        debugger_arguments,
+        get_debugger_info('requiresEscapedArgs', False)
+    )
+
+    return d
+
+# Defines the search policies to use in get_default_debugger_name.
+class DebuggerSearch:
+  OnlyFirst = 1
+  KeepLooking = 2
+
+def get_default_debugger_name(search=DebuggerSearch.OnlyFirst):
+    '''
+    Get the debugger name for the default debugger on current platform.
+
+    :param search: If specified, stops looking for the debugger if the
+     default one is not found (|DebuggerSearch.OnlyFirst|) or keeps
+     looking for other compatible debuggers (|DebuggerSearch.KeepLooking|).
+    '''
+
+    # Find out which debuggers are preferred for use on this platform.
+    debuggerPriorities = _DEBUGGER_PRIORITIES[mozinfo.os if mozinfo.os in _DEBUGGER_PRIORITIES else 'unknown']
+
+    # Finally get the debugger information.
+    for debuggerName in debuggerPriorities:
+        debuggerPath = find_executable(debuggerName)
+        if debuggerPath:
+            return debuggerName
+        elif not search == DebuggerSearch.KeepLooking:
+            return None
+
+    return None

python/mozinfo/__init__.py

@@ -0,0 +1,56 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+"""
+interface to transform introspected system information to a format palatable to
+Mozilla
+
+Module variables:
+
+.. attribute:: bits
+
+   32 or 64
+
+.. attribute:: isBsd
+
+   Returns ``True`` if the operating system is BSD
+
+.. attribute:: isLinux
+
+   Returns ``True`` if the operating system is Linux
+
+.. attribute:: isMac
+
+   Returns ``True`` if the operating system is Mac
+
+.. attribute:: isWin
+
+   Returns ``True`` if the operating system is Windows
+
+.. attribute:: os
+
+   Operating system [``'win'``, ``'mac'``, ``'linux'``, ...]
+
+.. attribute:: processor
+
+   Processor architecture [``'x86'``, ``'x86_64'``, ``'ppc'``, ...]
+
+.. attribute:: version
+
+   Operating system version string. For windows, the service pack information is also included
+
+.. attribute:: info
+
+   Returns information identifying the current system.
+
+   * :attr:`bits`
+   * :attr:`os`
+   * :attr:`processor`
+   * :attr:`version`
+
+"""
+
+import mozinfo
+from mozinfo import *
+__all__ = mozinfo.__all__

python/mozinfo/mozinfo.py

@@ -0,0 +1,233 @@
+#!/usr/bin/env python
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# TODO: it might be a good idea of adding a system name (e.g. 'Ubuntu' for
+# linux) to the information; I certainly wouldn't want anyone parsing this
+# information and having behaviour depend on it
+
+import os
+import platform
+import re
+import sys
+
+# keep a copy of the os module since updating globals overrides this
+_os = os
+
+class unknown(object):
+    """marker class for unknown information"""
+    def __nonzero__(self):
+        return False
+    def __str__(self):
+        return 'UNKNOWN'
+unknown = unknown() # singleton
+
+# get system information
+info = {'os': unknown,
+        'processor': unknown,
+        'version': unknown,
+        'os_version': unknown,
+        'bits': unknown,
+        'has_sandbox': unknown }
+(system, node, release, version, machine, processor) = platform.uname()
+(bits, linkage) = platform.architecture()
+
+# get os information and related data
+if system in ["Microsoft", "Windows"]:
+    info['os'] = 'win'
+    # There is a Python bug on Windows to determine platform values
+    # http://bugs.python.org/issue7860
+    if "PROCESSOR_ARCHITEW6432" in os.environ:
+        processor = os.environ.get("PROCESSOR_ARCHITEW6432", processor)
+    else:
+        processor = os.environ.get('PROCESSOR_ARCHITECTURE', processor)
+    system = os.environ.get("OS", system).replace('_', ' ')
+    (major, minor, _, _, service_pack) = os.sys.getwindowsversion()
+    info['service_pack'] = service_pack
+    os_version = "%d.%d" % (major, minor)
+elif system == "Linux":
+    if hasattr(platform, "linux_distribution"):
+        (distro, os_version, codename) = platform.linux_distribution()
+    else:
+        (distro, os_version, codename) = platform.dist()
+    if not processor:
+        processor = machine
+    version = "%s %s" % (distro, os_version)
+    info['os'] = 'linux'
+    info['linux_distro'] = distro
+elif system in ['DragonFly', 'FreeBSD', 'NetBSD', 'OpenBSD']:
+    info['os'] = 'bsd'
+    version = os_version = sys.platform
+elif system == "Darwin":
+    (release, versioninfo, machine) = platform.mac_ver()
+    version = "OS X %s" % release
+    versionNums = release.split('.')[:2]
+    os_version = "%s.%s" % (versionNums[0], versionNums[1])
+    info['os'] = 'mac'
+elif sys.platform in ('solaris', 'sunos5'):
+    info['os'] = 'unix'
+    os_version = version = sys.platform
+else:
+    os_version = version = unknown
+
+info['version'] = version
+info['os_version'] = os_version
+
+# processor type and bits
+if processor in ["i386", "i686"]:
+    if bits == "32bit":
+        processor = "x86"
+    elif bits == "64bit":
+        processor = "x86_64"
+elif processor.upper() == "AMD64":
+    bits = "64bit"
+    processor = "x86_64"
+elif processor == "Power Macintosh":
+    processor = "ppc"
+bits = re.search('(\d+)bit', bits).group(1)
+info.update({'processor': processor,
+             'bits': int(bits),
+            })
+
+if info['os'] == 'linux':
+    import ctypes
+    import errno
+    PR_SET_SECCOMP = 22
+    SECCOMP_MODE_FILTER = 2
+    ctypes.CDLL("libc.so.6", use_errno=True).prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, 0)
+    info['has_sandbox'] = ctypes.get_errno() == errno.EFAULT
+else:
+    info['has_sandbox'] = True
+
+# standard value of choices, for easy inspection
+choices = {'os': ['linux', 'bsd', 'win', 'mac', 'unix'],
+           'bits': [32, 64],
+           'processor': ['x86', 'x86_64', 'ppc']}
+
+
+def sanitize(info):
+    """Do some sanitization of input values, primarily
+    to handle universal Mac builds."""
+    if "processor" in info and info["processor"] == "universal-x86-x86_64":
+        # If we're running on OS X 10.6 or newer, assume 64-bit
+        if release[:4] >= "10.6": # Note this is a string comparison
+            info["processor"] = "x86_64"
+            info["bits"] = 64
+        else:
+            info["processor"] = "x86"
+            info["bits"] = 32
+
+# method for updating information
+def update(new_info):
+    """
+    Update the info.
+
+    :param new_info: Either a dict containing the new info or a path/url
+                     to a json file containing the new info.
+    """
+
+    if isinstance(new_info, basestring):
+        # lazy import
+        import mozfile
+        import json
+        f = mozfile.load(new_info)
+        new_info = json.loads(f.read())
+        f.close()
+
+    info.update(new_info)
+    sanitize(info)
+    globals().update(info)
+
+    # convenience data for os access
+    for os_name in choices['os']:
+        globals()['is' + os_name.title()] = info['os'] == os_name
+    # unix is special
+    if isLinux or isBsd:
+        globals()['isUnix'] = True
+
+def find_and_update_from_json(*dirs):
+    """
+    Find a mozinfo.json file, load it, and update the info with the
+    contents.
+
+    :param dirs: Directories in which to look for the file. They will be
+                 searched after first looking in the root of the objdir
+                 if the current script is being run from a Mozilla objdir.
+
+    Returns the full path to mozinfo.json if it was found, or None otherwise.
+    """
+    # First, see if we're in an objdir
+    try:
+        from mozbuild.base import MozbuildObject, BuildEnvironmentNotFoundException
+        build = MozbuildObject.from_environment()
+        json_path = _os.path.join(build.topobjdir, "mozinfo.json")
+        if _os.path.isfile(json_path):
+            update(json_path)
+            return json_path
+    except ImportError:
+        pass
+    except BuildEnvironmentNotFoundException:
+        pass
+
+    for d in dirs:
+        d = _os.path.abspath(d)
+        json_path = _os.path.join(d, "mozinfo.json")
+        if _os.path.isfile(json_path):
+            update(json_path)
+            return json_path
+
+    return None
+
+update({})
+
+# exports
+__all__ = info.keys()
+__all__ += ['is' + os_name.title() for os_name in choices['os']]
+__all__ += [
+    'info',
+    'unknown',
+    'main',
+    'choices',
+    'update',
+    'find_and_update_from_json',
+    ]
+
+def main(args=None):
+
+    # parse the command line
+    from optparse import OptionParser
+    parser = OptionParser(description=__doc__)
+    for key in choices:
+        parser.add_option('--%s' % key, dest=key,
+                          action='store_true', default=False,
+                          help="display choices for %s" % key)
+    options, args = parser.parse_args()
+
+    # args are JSON blobs to override info
+    if args:
+        # lazy import
+        import json
+        for arg in args:
+            if _os.path.exists(arg):
+                string = file(arg).read()
+            else:
+                string = arg
+            update(json.loads(string))
+
+    # print out choices if requested
+    flag = False
+    for key, value in options.__dict__.items():
+        if value is True:
+            print '%s choices: %s' % (key, ' '.join([str(choice)
+                                                     for choice in choices[key]]))
+            flag = True
+    if flag: return
+
+    # otherwise, print out all info
+    for key, value in info.items():
+        print '%s: %s' % (key, value)
+
+if __name__ == '__main__':
+    main()

python/servo/post_build_commands.py

@@ -1,10 +1,12 @@
 from __future__ import print_function, unicode_literals
 
+import argparse
 import os.path as path
 from os import chdir
 import subprocess
 import SimpleHTTPServer
 import SocketServer
+import mozdebug
 from shutil import copytree, rmtree, ignore_patterns
 
 from mach.decorators import (
@@ -21,14 +23,44 @@ class MachCommands(CommandBase):
     @Command('run',
              description='Run Servo',
              category='post-build')
+    @CommandArgument('--debug', action='store_true',
+                     help='Enable the debugger. Not specifying a '
+                          '--debugger option will result in the default '
+                          'debugger being used. The following arguments '
+                          'have no effect without this.')
+    @CommandArgument('--debugger', default=None, type=str,
+        help='Name of debugger to use.')
     @CommandArgument(
         'params', nargs='...',
         help="Command-line arguments to be passed through to Servo")
-    def run(self, params):
+    def run(self, params, debug=False, debugger=None):
         env = self.build_env()
         env["RUST_BACKTRACE"] = "1"
-        subprocess.check_call([path.join("target", "servo")] + params,
+
-                              env=env)
+        args = [path.join("target", "servo")]
+
+        # Borrowed and modified from:
+        # http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/python/mozbuild/mozbuild/mach_commands.py#l883
+        if debug:
+            import mozdebug
+            if not debugger:
+                # No debugger name was provided. Look for the default ones on
+                # current OS.
+                debugger = mozdebug.get_default_debugger_name(
+                    mozdebug.DebuggerSearch.KeepLooking)
+
+            self.debuggerInfo = mozdebug.get_debugger_info(debugger)
+            if not self.debuggerInfo:
+                print("Could not find a suitable debugger in your PATH.")
+                return 1
+
+            # Prepend the debugger args.
+            args = ([self.debuggerInfo.path] + self.debuggerInfo.args
+                    + args + params)
+        else:
+            args = args + params
+
+        subprocess.check_call(args, env=env)
 
     @Command('doc',
              description='Generate documentation',