path: root/src/engine/SCons/Platform/posix.py

"""SCons.Platform.posix

Platform-specific initialization for POSIX (Linux, UNIX, etc.) systems.

There normally shouldn't be any need to import this module directly.  It
will usually be imported through the generic SCons.Platform.Platform()
selection method.
"""

#
# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 The SCons Foundation
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#

__revision__ = "src/engine/SCons/Platform/posix.py 4577 2009/12/27 19:44:43 scons"

import errno
import os
import os.path
import string
import subprocess
import sys
import select

import SCons.Util
from SCons.Platform import TempFileMunge

exitvalmap = {
    2 : 127,
    13 : 126,
}

def escape(arg):
    "escape shell special characters"
    slash = '\\'
    special = '"$()'

    arg = string.replace(arg, slash, slash+slash)
    for c in special:
        arg = string.replace(arg, c, slash+c)

    return '"' + arg + '"'

def exec_system(l, env):
    stat = os.system(string.join(l))
    if stat & 0xff:
        return stat | 0x80
    return stat >> 8

def exec_spawnvpe(l, env):
    stat = os.spawnvpe(os.P_WAIT, l[0], l, env)
    # os.spawnvpe() returns the actual exit code, not the encoding
    # returned by os.waitpid() or os.system().
    return stat

def exec_fork(l, env): 
    pid = os.fork()
    if not pid:
        # Child process.
        exitval = 127
        try:
            os.execvpe(l[0], l, env)
        except OSError, e:
            exitval = exitvalmap.get(e[0], e[0])
            sys.stderr.write("scons: %s: %s\n" % (l[0], e[1]))
        os._exit(exitval)
    else:
        # Parent process.
        pid, stat = os.waitpid(pid, 0)
        if stat & 0xff:
            return stat | 0x80
        return stat >> 8

def _get_env_command(sh, escape, cmd, args, env):
    s = string.join(args)
    if env:
        l = ['env', '-'] + \
            map(lambda t, e=escape: e(t[0])+'='+e(t[1]), env.items()) + \
            [sh, '-c', escape(s)]
        s = string.join(l)
    return s

def env_spawn(sh, escape, cmd, args, env):
    return exec_system([_get_env_command( sh, escape, cmd, args, env)], env)

def spawnvpe_spawn(sh, escape, cmd, args, env):
    return exec_spawnvpe([sh, '-c', string.join(args)], env)

def fork_spawn(sh, escape, cmd, args, env):
    return exec_fork([sh, '-c', string.join(args)], env)

def process_cmd_output(cmd_stdout, cmd_stderr, stdout, stderr):
    stdout_eof = stderr_eof = 0
    while not (stdout_eof and stderr_eof):
        try:
            (i,o,e) = select.select([cmd_stdout, cmd_stderr], [], [])
            if cmd_stdout in i:
                str = cmd_stdout.read()
                if len(str) == 0:
                    stdout_eof = 1
                elif stdout is not None:
                    stdout.write(str)
            if cmd_stderr in i:
                str = cmd_stderr.read()
                if len(str) == 0:
                    #sys.__stderr__.write( "stderr_eof=1\n" )
                    stderr_eof = 1
                else:
                    #sys.__stderr__.write( "str(stderr) = %s\n" % str )
                    stderr.write(str)
        except select.error, (_errno, _strerror):
            if _errno != errno.EINTR:
                raise

def exec_popen3(l, env, stdout, stderr):
    proc = subprocess.Popen(string.join(l),
                            stdout=stdout,
                            stderr=stderr,
                            shell=True)
    stat = proc.wait()
    if stat & 0xff:
        return stat | 0x80
    return stat >> 8

def exec_piped_fork(l, env, stdout, stderr):
    # spawn using fork / exec and providing a pipe for the command's
    # stdout / stderr stream
    if stdout != stderr:
        (rFdOut, wFdOut) = os.pipe()
        (rFdErr, wFdErr) = os.pipe()
    else:
        (rFdOut, wFdOut) = os.pipe()
        rFdErr = rFdOut
        wFdErr = wFdOut
    # do the fork
    pid = os.fork()
    if not pid:
        # Child process
        os.close( rFdOut )
        if rFdOut != rFdErr:
            os.close( rFdErr )
        os.dup2( wFdOut, 1 ) # is there some symbolic way to do that ?
        os.dup2( wFdErr, 2 )
        os.close( wFdOut )
        if stdout != stderr:
            os.close( wFdErr )
        exitval = 127
        try:
            os.execvpe(l[0], l, env)
        except OSError, e:
            exitval = exitvalmap.get(e[0], e[0])
            stderr.write("scons: %s: %s\n" % (l[0], e[1]))
        os._exit(exitval)
    else:
        # Parent process
        pid, stat = os.waitpid(pid, 0)
        os.close( wFdOut )
        if stdout != stderr:
            os.close( wFdErr )
        childOut = os.fdopen( rFdOut )
        if stdout != stderr:
            childErr = os.fdopen( rFdErr )
        else:
            childErr = childOut
        process_cmd_output(childOut, childErr, stdout, stderr)
        os.close( rFdOut )
        if stdout != stderr:
            os.close( rFdErr )
        if stat & 0xff:
            return stat | 0x80
        return stat >> 8

def piped_env_spawn(sh, escape, cmd, args, env, stdout, stderr):
    # spawn using Popen3 combined with the env command
    # the command name and the command's stdout is written to stdout
    # the command's stderr is written to stderr
    return exec_popen3([_get_env_command(sh, escape, cmd, args, env)],
                       env, stdout, stderr)

def piped_fork_spawn(sh, escape, cmd, args, env, stdout, stderr):
    # spawn using fork / exec and providing a pipe for the command's
    # stdout / stderr stream
    return exec_piped_fork([sh, '-c', string.join(args)],
                           env, stdout, stderr)



def generate(env):
    # If os.spawnvpe() exists, we use it to spawn commands.  Otherwise
    # if the env utility exists, we use os.system() to spawn commands,
    # finally we fall back on os.fork()/os.exec().  
    #
    # os.spawnvpe() is prefered because it is the most efficient.  But
    # for Python versions without it, os.system() is prefered because it
    # is claimed that it works better with threads (i.e. -j) and is more
    # efficient than forking Python.
    #
    # NB: Other people on the scons-users mailing list have claimed that
    # os.fork()/os.exec() works better than os.system().  There may just
    # not be a default that works best for all users.

    if os.__dict__.has_key('spawnvpe'):
        spawn = spawnvpe_spawn
    elif env.Detect('env'):
        spawn = env_spawn
    else:
        spawn = fork_spawn

    if env.Detect('env'):
        pspawn = piped_env_spawn
    else:
        pspawn = piped_fork_spawn

    if not env.has_key('ENV'):
        env['ENV']        = {}
    env['ENV']['PATH']    = '/usr/local/bin:/opt/bin:/bin:/usr/bin'
    env['OBJPREFIX']      = ''
    env['OBJSUFFIX']      = '.o'
    env['SHOBJPREFIX']    = '$OBJPREFIX'
    env['SHOBJSUFFIX']    = '$OBJSUFFIX'
    env['PROGPREFIX']     = ''
    env['PROGSUFFIX']     = ''
    env['LIBPREFIX']      = 'lib'
    env['LIBSUFFIX']      = '.a'
    env['SHLIBPREFIX']    = '$LIBPREFIX'
    env['SHLIBSUFFIX']    = '.so'
    env['LIBPREFIXES']    = [ '$LIBPREFIX' ]
    env['LIBSUFFIXES']    = [ '$LIBSUFFIX', '$SHLIBSUFFIX' ]
    env['PSPAWN']         = pspawn
    env['SPAWN']          = spawn
    env['SHELL']          = 'sh'
    env['ESCAPE']         = escape
    env['TEMPFILE']       = TempFileMunge
    env['TEMPFILEPREFIX'] = '@'
    #Based on LINUX: ARG_MAX=ARG_MAX=131072 - 3000 for environment expansion
    #Note: specific platforms might rise or lower this value
    env['MAXLINELENGTH']  = 128072

    # This platform supports RPATH specifications.
    env['__RPATH'] = '$_RPATH'

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