This module provides support for manipulating POSIX.1e ACLS
Depending on the operating system support for POSIX.1e, the ACL type will have more or less capabilities:
- level 1, only basic support, you can create ACLs from files and text descriptions; once created, the type is immutable
- level 2, complete support, you can alter the ACL once it is created
Also, in level 2, more types are available, corresponding to acl_entry_t (the Entry type), acl_permset_t (the Permset type).
The existence of level 2 support and other extensions can be checked by the constants:
- HAS_ACL_ENTRY for level 2 and the Entry/Permset classes
- HAS_ACL_FROM_MODE for ACL(mode=...) usage
- HAS_ACL_CHECK for the ACL.check() function
- HAS_EXTENDED_CHECK for the module-level has_extended() function
- HAS_EQUIV_MODE for the ACL.equiv_mode() method
Example:
>>> import posix1e
>>> acl1 = posix1e.ACL(file="file.txt")
>>> print acl1
user::rw-
group::rw-
other::r--
>>>
>>> b = posix1e.ACL(text="u::rx,g::-,o::-")
>>> print b
user::r-x
group::---
other::---
>>>
>>> b.applyto("file.txt")
>>> print posix1e.ACL(file="file.txt")
user::r-x
group::---
other::---
>>>
Denotes a specific user entry in an ACL.
Denotes the user owner entry in an ACL.
Denotes the a group entry in an ACL.
Denotes the group owner entry in an ACL.
Denotes the ‘others’ entry in an ACL.
Denotes the mask entry in an ACL, representing the maximum access granted other users, the owner group and other groups.
An undefined tag in an ACL.
Read permission in a permission set.
Write permission in a permission set.
Execute permission in a permission set.
denotes support for level 2 and the Entry/Permset classes
denotes support for building an ACL from an octal mode
denotes support for extended checks of an ACL’s validity
denotes support for checking whether an ACL is basic or extended
denotes support for the equiv_mode function
Type which represents a POSIX ACL
Note
only one keyword parameter should be provided
Parameters: |
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If no parameters are passed, an empty ACL will be created; this makes sense only when your OS supports ACL modification (i.e. it implements full POSIX.1e support), otherwise the ACL won’t be useful.
Append a new Entry to the ACL and return it.
This is a convenience function to create a new Entry and append it to the ACL. If a parameter of type Entry instance is given, the entry will be a copy of that one (as if copied with Entry.copy()), otherwise, the new entry will be empty.
Return type: | Entry |
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Returns: | the newly created entry |
Apply the ACL to a file or filehandle.
Parameters: |
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Compute the file group class mask.
The calc_mask() method calculates and sets the permissions associated with the ACL_MASK Entry of the ACL. The value of the new permissions is the union of the permissions granted by all entries of tag type ACL_GROUP, ACL_GROUP_OBJ, or ACL_USER. If the ACL already contains an ACL_MASK entry, its permissions are overwritten; if it does not contain an ACL_MASK Entry, one is added.
The order of existing entries in the ACL is undefined after this function.
Check the ACL validity.
This is a non-portable, Linux specific extension that allow more information to be retrieved in case an ACL is not valid than via the valid() method.
This method will return either False (the ACL is valid), or a tuple with two elements. The first element is one of the following constants:
The second element of the tuple is the index of the entry that is invalid (in the same order as by iterating over the ACL entry)
Deletes an entry from the ACL.
Note
Only available with level 2.
Parameters: | entry – the Entry object which should be deleted; note that after this function is called, that object is unusable any longer and should be deleted |
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Return the octal mode the ACL is equivalent to.
This is a non-portable, Linux specific extension that checks if the ACL is a basic ACL and returns the corresponding mode.
Return type: | integer |
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Raises IOError: | An IOerror exception will be raised if the ACL is an extended ACL. |
x.next() -> the next value, or raise StopIteration
Convert the ACL to a custom text format.
This method encapsulates the acl_to_any_text() function. It allows a customized text format to be generated for the ACL. See acl_to_any_text(3) for more details.
Parameters: |
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Return type: | string |
Test the ACL for validity.
This method tests the ACL to see if it is a valid ACL in terms of the file-system. More precisely, it checks that:
The ACL contains exactly one entry with each of the ACL_USER_OBJ, ACL_GROUP_OBJ, and ACL_OTHER tag types. Entries with ACL_USER and ACL_GROUP tag types may appear zero or more times in an ACL. An ACL that contains entries of ACL_USER or ACL_GROUP tag types must contain exactly one entry of the ACL_MASK tag type. If an ACL contains no entries of ACL_USER or ACL_GROUP tag types, the ACL_MASK entry is optional.
All user ID qualifiers must be unique among all entries of the ACL_USER tag type, and all group IDs must be unique among all entries of ACL_GROUP tag type.
The method will return 1 for a valid ACL and 0 for an invalid one. This has been chosen because the specification for acl_valid(3) in the POSIX.1e standard documents only one possible value for errno in case of an invalid ACL, so we can’t differentiate between classes of errors. Other suggestions are welcome.
Returns: | 0 or 1 |
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Return type: | integer |
Type which represents an entry in an ACL.
The type exists only if the OS has full support for POSIX.1e Can be created either by:
>>> e = posix1e.Entry(myACL) # this creates a new entry in the ACL
>>> e = myACL.append() # another way for doing the same thing
or by:
>>> for entry in myACL:
... print entry
Note that the Entry keeps a reference to its ACL, so even if you delete the ACL, it won’t be cleaned up and will continue to exist until its Entry(ies) will be deleted.
Copies an ACL entry.
This method sets all the parameters to those of another entry (either of the same ACL or belonging to another ACL).
Parameters: | src (Entry) – instance of type Entry |
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The parent ACL of this entry
The permission set of this ACL entry
The qualifier of the current entry
If the tag type is ACL_USER, this should be a user id. If the tag type if ACL_GROUP, this should be a group id. Else it doesn’t matter.
The tag type of the current entry
Type which represents the permission set in an ACL entry
The type exists only if the OS has full support for POSIX.1e Can be retrieved either by:
>>> perms = myEntry.permset
or by:
>>> perms = posix1e.Permset(myEntry)
Note that the Permset keeps a reference to its Entry, so even if you delete the entry, it won’t be cleaned up and will continue to exist until its Permset will be deleted.
Add a permission to the permission set.
This function adds the permission contained in the argument perm to the permission set. An attempt to add a permission that is already contained in the permission set is not considered an error.
Parameters: | perm – a permission (ACL_WRITE, ACL_READ, ACL_EXECUTE, ...) |
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Raises IOError: | in case the argument is not a valid descriptor |
Clears all permissions from the permission set.
Delete a permission from the permission set.
This function deletes the permission contained in the argument perm from the permission set. An attempt to delete a permission that is not contained in the permission set is not considered an error.
Parameters: | perm – a permission (ACL_WRITE, ACL_READ, ACL_EXECUTE, ...) |
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Raises IOError: | in case the argument is not a valid descriptor |
Execute permission property
This is a convenience method of retrieving and setting the execute permission in the permission set; the same effect can be achieved using the functions add(), test(), delete(), and those can take any permission defined by your platform.
Read permission property
This is a convenience method of retrieving and setting the read permission in the permission set; the same effect can be achieved using the functions add(), test(), delete(), and those can take any permission defined by your platform.
Test if a permission exists in the permission set.
The test() function tests if the permission represented by the argument perm exists in the permission set.
Parameters: | perm – a permission (ACL_WRITE, ACL_READ, ACL_EXECUTE, ...) |
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Return type: | Boolean |
Raises IOError: | in case the argument is not a valid descriptor |
Write permission property
This is a convenience method of retrieving and setting the write permission in the permission set; the same effect can be achieved using the functions add(), test(), delete(), and those can take any permission defined by your platform.
Delete the default ACL from a directory.
This function deletes the default ACL associated with a directory (the ACL which will be ANDed with the mode parameter to the open, creat functions).
Parameters: | path (string) – the directory whose default ACL should be deleted |
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Check if a file or file handle has an extended ACL.
Parameters: | item – either a file name or a file-like object or an integer; it represents the file-system object on which to act |
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