Ticket #554: util.py

 #
 # Copyright 2004 Apache Software Foundation 
 # 
 # Licensed under the Apache License, Version 2.0 (the "License"); you
 # may not use this file except in compliance with the License.  You
 # may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 # implied.  See the License for the specific language governing
 # permissions and limitations under the License.
 #
 # Originally developed by Gregory Trubetskoy.
 #
 # $Id: util.py,v 1.21 2004/02/16 19:47:27 grisha Exp $

import _apache
import apache
import cStringIO
import tempfile

from types import *
from exceptions import *

parse_qs = _apache.parse_qs
parse_qsl = _apache.parse_qsl

""" The classes below are a (almost) a drop-in replacement for the
    standard cgi.py FieldStorage class. They should have pretty much the
    same functionality.

    These classes differ in that unlike cgi.FieldStorage, they are not
    recursive. The class FieldStorage contains a list of instances of
    Field class. Field class is incapable of storing anything in it.

    These objects should be considerably faster than the ones in cgi.py
    because they do not expect CGI environment, and are
    optimized specifically for Apache and mod_python.
"""

class Field:

    filename = None
    headers = {}

    def __init__(self, name, file, ctype, type_options,
                 disp, disp_options):
        self.name = name
        self.file = file
        self.type = ctype
        self.type_options = type_options
        self.disposition = disp
        self.disposition_options = disp_options

    def __repr__(self):
        """Return printable representation."""
        return "Field(%s, %s)" % (`self.name`, `self.value`)

    def __getattr__(self, name):
        if name != 'value':
            raise AttributeError, name
        if self.file:
            self.file.seek(0)
            value = self.file.read()
            self.file.seek(0)
        else:
            value = None
        return value

    def __del__(self):
        self.file.close()

class StringField(str):
    """ This class is basically a string with
    a value attribute for compatibility with std lib cgi.py
    """
    
    def __init__(self, str=""):
        str.__init__(self, str)
        self.value = self.__str__()

class FieldStorage:

    def __init__(self, req, keep_blank_values=0, strict_parsing=0):

        self.list = []

        # always process GET-style parameters
        if req.args:
            pairs = parse_qsl(req.args, keep_blank_values)
            for pair in pairs:
                file = cStringIO.StringIO(pair[1])
                self.list.append(Field(pair[0], file, "text/plain", {},
                                       None, {}))

        if req.method == "POST":

            try:
                clen = int(req.headers_in["content-length"])
            except (KeyError, ValueError):
                # absent content-length is not acceptable
                raise apache.SERVER_RETURN, apache.HTTP_LENGTH_REQUIRED

            if not req.headers_in.has_key("content-type"):
                ctype = "application/x-www-form-urlencoded"
            else:
                ctype = req.headers_in["content-type"]

            if ctype == "application/x-www-form-urlencoded":
                
                pairs = parse_qsl(req.read(clen), keep_blank_values)
                for pair in pairs:
                    file = cStringIO.StringIO(pair[1])
                    self.list.append(Field(pair[0], file, "text/plain",
                                     {}, None, {}))

            elif ctype[:10] == "multipart/":

                # figure out boundary
                try:
                    i = ctype.lower().rindex("boundary=")
                    boundary = ctype[i+9:]
                    if len(boundary) >= 2 and boundary[0] == boundary[-1] == '"':
                        boundary = boundary[1:-1]
                    boundary = "--" + boundary
                except ValueError:
                    raise apache.SERVER_RETURN, apache.HTTP_BAD_REQUEST

                #read until boundary
                line = req.readline()
                sline = line.strip()
                while line and sline != boundary:
                    line = req.readline()
                    sline = line.strip()

                while 1:

                    ## parse headers
                    
                    ctype, type_options = "text/plain", {}
                    disp, disp_options = None, {}
                    headers = apache.make_table()

                    line = req.readline()
                    sline = line.strip()
                    if not line or sline == (boundary + "--"):
                        break
                    
                    while line and line not in ["\n", "\r\n"]:
                        h, v = line.split(":", 1)
                        headers.add(h, v)
                        h = h.lower()
                        if h == "content-disposition":
                            disp, disp_options = parse_header(v)
                        elif h == "content-type":
                            ctype, type_options = parse_header(v)
                        line = req.readline()
                        sline = line.strip()

                    if disp_options.has_key("name"):
                        name = disp_options["name"]
                    else:
                        name = None

                    # is this a file?
                    if disp_options.has_key("filename"):
                        file = self.make_file()
                    else:
                        file = cStringIO.StringIO()

                    # read it in
                    self.read_to_boundary(req, boundary, file)
                    file.seek(0)

                    # make a Field
                    field = Field(name, file, ctype, type_options,
                                  disp, disp_options)
                    field.headers = headers
                    if disp_options.has_key("filename"):
                        field.filename = disp_options["filename"]

                    self.list.append(field)

            else:
                # we don't understand this content-type
                raise apache.SERVER_RETURN, apache.HTTP_NOT_IMPLEMENTED


    def make_file(self):
        return tempfile.TemporaryFile("w+b")

    def skip_to_boundary(self, req, boundary):
        line = req.readline()
        sline = line.strip()
        last_bound = boundary + "--"
        while line and sline != boundary and sline != last_bound:
            line = req.readline()
            sline = line.strip()

    def read_to_boundary(self, req, boundary, file):
        delim = ""
        line = req.readline()
        sline = line.strip()
        last_bound = boundary + "--"
        while line and sline != boundary and sline != last_bound:
            odelim = delim
            if line[-2:] == "\r\n":
                delim = "\r\n"
                line = line[:-2]
            elif line[-1:] == "\n":
                delim = "\n"
                line = line[:-1]
            file.write(odelim + line)
            line = req.readline()
            sline = line.strip()

    def __getitem__(self, key):
        """Dictionary style indexing."""
        if self.list is None:
            raise TypeError, "not indexable"
        found = []
        for item in self.list:
            if item.name == key:
                if isinstance(item.file, FileType):
                    found.append(item)
                else:
                    found.append(StringField(item.value))
        if not found:
            raise KeyError, key
        if len(found) == 1:
            return found[0]
        else:
            return found

    def get(self, key, default):
        try:
            return self.__getitem__(key)
        except KeyError:
            return default

    def keys(self):
        """Dictionary style keys() method."""
        if self.list is None:
            raise TypeError, "not indexable"
        keys = []
        for item in self.list:
            if item.name not in keys: keys.append(item.name)
        return keys

    def has_key(self, key):
        """Dictionary style has_key() method."""
        if self.list is None:
            raise TypeError, "not indexable"
        for item in self.list:
            if item.name == key: return 1
        return 0

    __contains__ = has_key

    def __len__(self):
        """Dictionary style len(x) support."""
        return len(self.keys())

    def getfirst(self, key, default=None):
        """ return the first value received """
        for item in self.list:
            if item.name == key:
                if isinstance(item.file, FileType):
                    return item
                else:
                    return StringField(item.value)
        return default
                                                                    
    def getlist(self, key):
        """ return a list of received values """
        if self.list is None:
            raise TypeError, "not indexable"
        found = []
        for item in self.list:
            if item.name == key:
                if isinstance(item.file, FileType):
                    found.append(item)
                else:
                    found.append(StringField(item.value))
        return found

def parse_header(line):
    """Parse a Content-type like header.

    Return the main content-type and a dictionary of options.

    """
    
    plist = map(lambda a: a.strip(), line.split(';'))
    key = plist[0].lower()
    del plist[0]
    pdict = {}
    for p in plist:
        i = p.find('=')
        if i >= 0:
            name = p[:i].strip().lower()
            value = p[i+1:].strip()
            if len(value) >= 2 and value[0] == value[-1] == '"':
                value = value[1:-1]
            pdict[name] = value
    return key, pdict

def apply_fs_data(object, fs, **args):
    """
    Apply FieldStorage data to an object - the object must be
    callable. Examine the args, and match then with fs data,
    then call the object, return the result.
    """

    # add form data to args
    for field in fs.list:
        if field.filename:
            val = field
        else:
            val = field.value
        args.setdefault(field.name, []).append(val)

    # replace lists with single values
    for arg in args:
        if ((type(args[arg]) is ListType) and
            (len(args[arg]) == 1)):
            args[arg] = args[arg][0]

    # we need to weed out unexpected keyword arguments
    # and for that we need to get a list of them. There
    # are a few options for callable objects here:

    if type(object) is InstanceType:
        # instances are callable when they have __call__()
        object = object.__call__

    expected = []
    if hasattr(object, "func_code"):
        # function
        fc = object.func_code
        expected = fc.co_varnames[0:fc.co_argcount]
    elif hasattr(object, 'im_func'):
        # method
        fc = object.im_func.func_code
        expected = fc.co_varnames[1:fc.co_argcount]
    elif type(object) is ClassType:
        # class
        fc = object.__init__.im_func.func_code
        expected = fc.co_varnames[1:fc.co_argcount]

    # remove unexpected args unless co_flags & 0x08,
    # meaning function accepts **kw syntax
    if not (fc.co_flags & 0x08):
        for name in args.keys():
            if name not in expected:
                del args[name]

    return object(**args)

def redirect(req, location, permanent=0, text=None):
    """
    A convenience function to provide redirection
    """

    if req.sent_bodyct:
        raise IOError, "Cannot redirect after headers have already been sent."

    req.err_headers_out["Location"] = location
    if permanent:
        req.status = apache.HTTP_MOVED_PERMANENTLY
    else:
        req.status = apache.HTTP_MOVED_TEMPORARILY

    if text is None:
        req.write('<p>The document has moved' 
                  ' <a href="%s">here</a></p>\n'
                  % location)
    else:
        req.write(text)

    raise apache.SERVER_RETURN, apache.OK