Edit File: augeas.py
"""Pure python bindings for the augeas library Augeas is a library for programmatically editing configuration files. Augeas parses configuration files into a tree structure, which it exposes through its public API. Changes made through the API are written back to the initially read files. The transformation works very hard to preserve comments and formatting details. It is controlled by ``lens'' definitions that describe the file format and the transformation into a tree. """ # # Copyright (C) 2008 Nathaniel McCallum # Copyright (C) 2008 Jeff Schroeder <jeffschroeder@computer.org> # Copyright (C) 2009 Red Hat, Inc. # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 2.1 of the License, or (at your option) any later version. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA # # Author: Nathaniel McCallum <nathaniel@natemccallum.com> __author__ = "Nathaniel McCallum <nathaniel@natemccallum.com>" __credits__ = """Jeff Schroeder <jeffschroeder@computer.org> Harald Hoyer <harald@redhat.com> - initial python bindings, packaging Nils Philippsen <nils@redhat.com> """ import types import ctypes import ctypes.util from sys import version_info as _pyver from functools import reduce PY3 = _pyver >= (3,) AUGENC = 'utf8' if PY3: string_types = str else: string_types = basestring def enc(st): if st: return st.encode(AUGENC) def dec(st): if st: return st.decode(AUGENC) def _dlopen(*args): """Search for one of the libraries given as arguments and load it. Returns the library. """ libs = [l for l in [ ctypes.util.find_library(a) for a in args ] if l] lib = reduce(lambda x, y: x or ctypes.cdll.LoadLibrary(y), libs, None) if not lib: raise ImportError("Unable to import lib%s!" % args[0]) return lib class Augeas(object): "Class wrapper for the augeas library" # Load libaugeas _libaugeas = _dlopen("augeas") _libaugeas.aug_init.restype = ctypes.c_void_p # Augeas Flags NONE = 0 SAVE_BACKUP = 1 << 0 SAVE_NEWFILE = 1 << 1 TYPE_CHECK = 1 << 2 NO_STDINC = 1 << 3 SAVE_NOOP = 1 << 4 NO_LOAD = 1 << 5 NO_MODL_AUTOLOAD = 1 << 6 ENABLE_SPAN = 1 << 7 def __init__(self, root=None, loadpath=None, flags=NONE): """Initialize the library. Use 'root' as the filesystem root. If 'root' is None, use the value of the environment variable AUGEAS_ROOT. If that doesn't exist either, use "/". 'loadpath' is a colon-spearated list of directories that modules should be searched in. This is in addition to the standard load path and the directories in AUGEAS_LENS_LIB. 'flags' is a bitmask made up of values from AUG_FLAGS.""" # Sanity checks if not isinstance(root, string_types) and root != None: raise TypeError("root MUST be a string or None!") if not isinstance(loadpath, string_types) and loadpath != None: raise TypeError("loadpath MUST be a string or None!") if not isinstance(flags, int): raise TypeError("flag MUST be a flag!") # Create the Augeas object self.__handle = Augeas._libaugeas.aug_init(enc(root), enc(loadpath), flags) if not self.__handle: raise RuntimeError("Unable to create Augeas object!") # Make sure self.__handle is a void*, not an integer self.__handle = ctypes.c_void_p(self.__handle) def __del__(self): self.close() def get(self, path): """Lookup the value associated with 'path'. Returns the value at the path specified. It is an error if more than one node matches 'path'.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Create the char * value value = ctypes.c_char_p() # Call the function and pass value by reference (char **) ret = Augeas._libaugeas.aug_get(self.__handle, enc(path), ctypes.byref(value)) if ret > 1: raise ValueError("path specified had too many matches!") return dec(value.value) def label(self, path): """Lookup the label associated with 'path'. Returns the label of the path specified. It is an error if more than one node matches 'path'.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Create the char * value label = ctypes.c_char_p() # Call the function and pass value by reference (char **) ret = Augeas._libaugeas.aug_label(self.__handle, enc(path), ctypes.byref(label)) if ret > 1: raise ValueError("path specified had too many matches!") return dec(label.value) def set(self, path, value): """Set the value associated with 'path' to 'value'. Intermediate entries are created if they don't exist. It is an error if more than one node matches 'path'.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not isinstance(value, string_types) and type(value) != type(None): raise TypeError("value MUST be a string or None!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_set(self.__handle, enc(path), enc(value)) if ret != 0: raise ValueError("Unable to set value to path!") def setm(self, base, sub, value): """Set the value of multiple nodes in one operation. Find or create a node matching 'sub' by interpreting 'sub' as a path expression relative to each node matching 'base'. 'sub' may be None, in which case all the nodes matching 'base' will be modified.""" # Sanity checks if type(base) != str: raise TypeError("base MUST be a string!") if type(sub) != str and sub != None: raise TypeError("sub MUST be a string or None!") if type(value) != str: raise TypeError("value MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_setm( self.__handle, enc(base), enc(sub), enc(value)) if ret < 0: raise ValueError("Unable to set value to path!") return ret def text_store(self, lens, node, path): """Use the value of node 'node' as a string and transform it into a tree using the lens 'lens' and store it in the tree at 'path', which will be overwritten. 'path' and 'node' are path expressions.""" # Sanity checks if not isinstance(lens, string_types): raise TypeError("lens MUST be a string!") if not isinstance(node, string_types): raise TypeError("node MUST be a string!") if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_text_store( self.__handle, enc(lens), enc(node), enc(path)) if ret != 0: raise ValueError("Unable to store text at node!") return ret def text_retrieve(self, lens, node_in, path, node_out): """Transform the tree at 'path' into a string using lens 'lens' and store it in the node 'node_out', assuming the tree was initially generated using the value of node 'node_in'. 'path', 'node_in', and 'node_out' are path expressions.""" # Sanity checks if not isinstance(lens, string_types): raise TypeError("lens MUST be a string!") if not isinstance(node_in, string_types): raise TypeError("node_in MUST be a string!") if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not isinstance(node_out, string_types): raise TypeError("node_out MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_text_retrieve( self.__handle, enc(lens), enc(node_in), enc(path), enc(node_out)) if ret != 0: raise ValueError("Unable to store text at node!") return ret def defvar(self, name, expr): """Define a variable 'name' whose value is the result of evaluating 'expr'. If a variable 'name' already exists, its name will be replaced with the result of evaluating 'expr'. If 'expr' is None, the variable 'name' will be removed if it is defined. Path variables can be used in path expressions later on by prefixing them with '$'.""" # Sanity checks if type(name) != str: raise TypeError("name MUST be a string!") if type(expr) != str and expr != None: raise TypeError("expr MUST be a string or None!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_defvar(self.__handle, enc(name), enc(expr)) if ret < 0: raise ValueError("Unable to register variable!") return ret def defnode(self, name, expr, value): """Define a variable 'name' whose value is the result of evaluating 'expr', which must not be None and evaluate to a nodeset. If a variable 'name' already exists, its name will be replaced with the result of evaluating 'expr'. If 'expr' evaluates to an empty nodeset, a node is created, equivalent to calling set(expr, value) and 'name' will be the nodeset containing that single node.""" # Sanity checks if type(name) != str: raise TypeError("name MUST be a string!") if type(expr) != str: raise TypeError("expr MUST be a string!") if type(value) != str: raise TypeError("value MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_defnode( self.__handle, enc(name), enc(expr), enc(value), None) if ret < 0: raise ValueError("Unable to register node!") return ret def move(self, src, dst): """Move the node 'src' to 'dst'. 'src' must match exactly one node in the tree. 'dst' must either match exactly one node in the tree, or may not exist yet. If 'dst' exists already, it and all its descendants are deleted before moving 'src' there. If 'dst' does not exist yet, it and all its missing ancestors are created.""" # Sanity checks if not isinstance(src, string_types): raise TypeError("src MUST be a string!") if not isinstance(dst, string_types): raise TypeError("dst MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_mv(self.__handle, enc(src), enc(dst)) if ret != 0: raise ValueError("Unable to move src to dst!") def rename(self, src, dst): """Rename the label of all nodes matching 'src' to 'lbl'.""" # Sanity checks if not isinstance(src, string_types): raise TypeError("src MUST be a string!") if not isinstance(dst, string_types): raise TypeError("dst MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_rename(self.__handle, enc(src), enc(dst)) if ret < 0: raise ValueError("Unable to rename src as dst!") return ret def insert(self, path, label, before=True): """Create a new sibling 'label' for 'path' by inserting into the tree just before 'path' (if 'before' is True) or just after 'path' (if 'before' is False). 'path' must match exactly one existing node in the tree, and 'label' must be a label, i.e. not contain a '/', '*' or end with a bracketed index '[N]'.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not isinstance(label, string_types): raise TypeError("label MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_insert(self.__handle, enc(path), enc(label), before and 1 or 0) if ret != 0: raise ValueError("Unable to insert label!") def remove(self, path): """Remove 'path' and all its children. Returns the number of entries removed. All nodes that match 'path', and their descendants, are removed.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function return Augeas._libaugeas.aug_rm(self.__handle, enc(path)) def match(self, path): """Return the matches of the path expression 'path'. The returned paths are sufficiently qualified to make sure that they match exactly one node in the current tree. Path expressions use a very simple subset of XPath: the path 'path' consists of a number of segments, separated by '/'; each segment can either be a '*', matching any tree node, or a string, optionally followed by an index in brackets, matching tree nodes labelled with exactly that string. If no index is specified, the expression matches all nodes with that label; the index can be a positive number N, which matches exactly the Nth node with that label (counting from 1), or the special expression 'last()' which matches the last node with the given label. All matches are done in fixed positions in the tree, and nothing matches more than one path segment.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Create a void ** (this is so python won't mangle the char **, # when we free it) array = ctypes.POINTER(ctypes.c_void_p)() # Call the function and pass the void ** by reference (void ***) ret = Augeas._libaugeas.aug_match(self.__handle, enc(path), ctypes.byref(array)) if ret < 0: raise RuntimeError("Error during match procedure!", path) # Loop through the string array matches = [] for i in range(ret): if array[i]: # Create a python string and append it to our matches list matches.append(dec(ctypes.cast(array[i], ctypes.c_char_p).value)) # Free the string at this point in the array # Wrap the string as a void* as it was not allocated by Python ctypes.pythonapi.PyMem_Free(ctypes.c_void_p(array[i])) # Free the array itself ctypes.pythonapi.PyMem_Free(array) return matches def span(self, path): """Get the span according to input file of the node associated with PATH. If the node is associated with a file, un tuple of 5 elements is returned: (filename, label_start, label_end, value_start, value_end, span_start, span_end). If the node associated with PATH doesn't belong to a file or is doesn't exists, ValueError is raised.""" # Sanity checks if not isinstance(path, string_types): raise TypeError("path MUST be a string!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") filename = ctypes.c_char_p() label_start = ctypes.c_uint() label_end = ctypes.c_uint() value_start = ctypes.c_uint() value_end = ctypes.c_uint() span_start = ctypes.c_uint() span_end = ctypes.c_uint() r = ctypes.byref ret = Augeas._libaugeas.aug_span(self.__handle, enc(path), r(filename), r(label_start), r(label_end), r(value_start), r(value_end), r(span_start), r(span_end)) if (ret < 0): raise ValueError("Error during span procedure") return (dec(filename.value), label_start.value, label_end.value, value_start.value, value_end.value, span_start.value, span_end.value) def save(self): """Write all pending changes to disk. Only files that had any changes made to them are written. If SAVE_NEWFILE is set in the creation 'flags', create changed files as new files with the extension ".augnew", and leave the original file unmodified. Otherwise, if SAVE_BACKUP is set in the creation 'flags', move the original file to a new file with extension ".augsave". If neither of these flags is set, overwrite the original file.""" # Sanity checks if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") # Call the function ret = Augeas._libaugeas.aug_save(self.__handle) if ret != 0: raise IOError("Unable to save to file!") def load(self): """Load files into the tree. Which files to load and what lenses to use on them is specified under /augeas/load in the tree; each entry /augeas/load/NAME specifies a 'transform', by having itself exactly one child 'lens' and any number of children labelled 'incl' and 'excl'. The value of NAME has no meaning. The 'lens' grandchild of /augeas/load specifies which lens to use, and can either be the fully qualified name of a lens 'Module.lens' or '@Module'. The latter form means that the lens from the transform marked for autoloading in MODULE should be used. The 'incl' and 'excl' grandchildren of /augeas/load indicate which files to transform. Their value are used as glob patterns. Any file that matches at least one 'incl' pattern and no 'excl' pattern is transformed. The order of 'incl' and 'excl' entries is irrelevant. When AUG_INIT is first called, it populates /augeas/load with the transforms marked for autoloading in all the modules it finds. Before loading any files, AUG_LOAD will remove everything underneath /augeas/files and /files, regardless of whether any entries have been modified or not.""" # Sanity checks if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") ret = Augeas._libaugeas.aug_load(self.__handle) if ret != 0: raise RuntimeError("aug_load() failed!") def clear_transforms(self): """Clear all transforms beneath /augeas/load. If load() is called right after this, there will be no files beneath /files.""" self.remove("/augeas/load/*") def add_transform(self, lens, incl, name=None, excl=()): """Add a transform beneath /augeas/load. lens: the (file)name of the lens to use incl: one or more glob patterns for the files to transform name: deprecated parameter excl: zero or more glob patterns of files to exclude from transforming """ if name: import warnings warnings.warn("name is now deprecated in this function", DeprecationWarning, stacklevel=2) if isinstance (incl, string_types): incl = [incl] if isinstance (excl, string_types): excl = [excl] for i in range(len(incl)): self.transform(lens, incl[i], False) for i in range(len(excl)): self.transform(lens, excl[i], True) def transform(self, lens, file, excl=False): """Add a transform for 'file' using 'lens'. 'excl' specifies if this the file is to be included (False) or excluded (True) from the 'lens'. The 'lens' may be a module name or a full lens name. If a module name is given, then lns will be the lens assumed. """ if not isinstance(lens, string_types): raise TypeError("lens MUST be a string!") if not isinstance(file, string_types): raise TypeError("file MUST be a string!") if not isinstance(excl, bool): raise TypeError("excl MUST be a boolean!") if not self.__handle: raise RuntimeError("The Augeas object has already been closed!") ret = Augeas._libaugeas.aug_transform(self.__handle, enc(lens), enc(file), excl) if ret != 0: raise RuntimeError("Unable to add transform!") def close(self): """Close this Augeas instance and free any storage associated with it. After this call, this Augeas instance is invalid and can not be used for any more operations.""" # If we are already closed, return if not self.__handle: return # Call the function Augeas._libaugeas.aug_close(self.__handle) # Mark the object as closed self.__handle = None # for backwards compatibility # pylint: disable-msg=C0103 class augeas(Augeas): "Compat class, obsolete. Use class Augeas directly." def __init__(self, *p, **k): import warnings warnings.warn("use Augeas instead of augeas", DeprecationWarning, stacklevel=2) super(augeas, self).__init__(*p, **k)