ACL_TOTEXT(3SEC) File Access Control Library Functions ACL_TOTEXT(3SEC)


NAME


acl_totext, acl_fromtext - convert internal representation to or from
external representation

SYNOPSIS


cc [ flag... ] file... -lsec [ library... ]
#include <sys/acl.h>

char *acl_totext(acl_t *aclp, int flags);


int acl_fromtext(char *acltextp, acl_t **aclp);


DESCRIPTION


The acl_totext() function converts an internal ACL representation pointed
to by aclp into an external ACL representation. The memory for the
external text string is obtained using malloc(3C). The caller is
responsible for freeing the memory upon completion.


The format of the external ACL is controlled by the flags argument.
Values for flags are constructed by a bitwise-inclusive-OR of flags from
the following list, defined in <sys/acl.h>.

ACL_COMPACT_FMT
For NFSv4 ACLs, the ACL entries will be formatted
using the compact ACL format detailed in ls(1) for the
-V option.


ACL_APPEND_ID
Append the uid or gid for additional user or group
entries. This flag is used to construt ACL entries in
a manner that is suitable for archive utilities such
as tar(1). When the ACL is translated from the
external format to internal representation using
acl_fromtext(), the appended ID will be used to
populate the uid or gid field of the ACL entry when
the user or group name does not exist on the host
system. The appended id will be ignored when the user
or group name does exist on the system.


ACL_SID_FMT
For NFSv4 ACLs, the ACL entries for user or group
entries will use the usersid or groupsid format when
the "id" field in the ACL entry is an ephemeral uid or
gid. The raw sid format will only be used when the
"id" cannot be resolved to a windows name.


The acl_fromtext() function converts an external ACL representation
pointed to by acltextp into an internal ACL representation. The memory
for the list of ACL entries is obtained using malloc(3C). The caller is
responsible for freeing the memory upon completion. Depending on type of
ACLs a file system supports, one of two external external representations
are possible. For POSIX draft file systems such as ufs, the external
representation is described in acltotext(3SEC). The external ACL
representation For NFSv4-style ACLs is detailed as follows.


Each acl_entry contains one ACL entry. The external representation of an
ACL entry contains three, four or five colon separated fields. The first
field contains the ACL entry type. The entry type keywords are defined
as:

everyone@
This ACL entry specifies the access granted to any user or
group that does not match any previous ACL entry.


group
This ACL entry with a GID specifies the access granted to a
additional group of the object.


group@
This ACL entry with no GID specified in the ACL entry field
specifies the access granted to the owning group of the
object.


groupsid
This ACL entry with a SID or Windows name specifies the
access granted to a Windows group. This type of entry is for
a CIFS server created file.


owner@
This ACL entry with no UID specified in the ACL entry field
specifies the access granted to the owner of the object.


sid
This ACL entry with a SID or Windows name when the entry
could be either a group or a user.


user
This ACL entry with a UID specifies the access granted to a
additional user of the object.


usersid
This ACL entry with a SID or Windows name specifies the
access granted to a Windows user. This type of entry is for
a CIFS server created file.


The second field contains the ACL entry ID, and is used only for user or
group ACL entries. This field is not used for owner@, group@, or
everyone@ entries.

uid
This field contains a user-name or user-ID. If the user-name
cannot be resolved to a UID, then the entry is assumed to be a
numeric UID.


gid
This field contains a group-name or group-ID. If the group-name
can't be resolved to a GID, then the entry is assumed to be a
numeric GID.


The third field contains the discretionary access permissions. The format
of the permissions depends on whether ACL_COMPACT_FMT is specified. When
the flags field does not request ACL_COMPACT_FMT, the following format is
used with a forward slash (/) separating the permissions.

add_file
Add a file to a directory.


add_subdirectory
Add a subdirectory.


append
Append data.


delete
Delete.


delete_child
Delete child.


execute
Execute permission.


list_directory
List a directory.


read_acl
Read ACL.


read_data
Read permission.


read_attributes
Read attributes.


read_xattr
Read named attributes.


synchronize
Synchronize.


write_acl
Write ACL.


write_attributes
Write attributes.


write_data
Write permission.


write_owner
Write owner.


write_xattr
Write named attributes.


This format allows permissions to be specified as, for example:
read_data/read_xattr/read_attributes.


When ACL_COMPACT_FMT is specified, the permissions consist of 14 unique
letters. A hyphen (-) character is used to indicate that the permission
at that position is not specified.

a
read attributes


A
write attributes


c
read ACL


C
write ACL


d
delete


D
delete child


o
write owner


p
append


r
read_data


R
read named attributes


s
synchronize


w
write_data


W
write named attributes


x
execute


This format allows compact permissions to be represented as, for example:
rw--d-a-------


The fourth field is optional when ACL_COMPACT_FMT is not specified, in
which case the field will be present only when the ACL entry has
inheritance flags set. The following is the list of inheritance flags
separated by a slash (/) character.

dir_inherit
ACE_DIRECTORY_INHERIT_ACE


file_inherit
ACE_FILE_INHERIT_ACE


inherit_only
ACE_INHERIT_ONLY_ACE


no_propagate
ACE_NO_PROPAGATE_INHERIT_ACE


When ACL_COMPACT_FMT is specified the inheritance will always be present
and is represented as positional arguments. A hyphen (-) character is
used to indicate that the inheritance flag at that position is not
specified.

d
dir_inherit


f
file_inherit


F
failed access (not currently supported)


i
inherit_only


n
no_propagate


S
successful access (not currently supported)


The fifth field contains the type of the ACE (allow or deny):

allow
The mask specified in field three should be allowed.


deny
The mask specified in field three should be denied.


RETURN VALUES


Upon successful completion, the acl_totext() function returns a pointer
to a text string. Otherwise, it returns NULL.


Upon successful completion, the acl_fromtext() function returns 0.
Otherwise, the return value is set to one of the following:

EACL_FIELD_NOT_BLANK
A field that should be blank is not blank.


EACL_FLAGS_ERROR
An invalid ACL flag was specified.


EACL_INHERIT_ERROR
An invalid inheritance field was specified.


EACL_INVALID_ACCESS_TYPE
An invalid access type was specified.


EACL_INVALID_STR
The string is NULL.


EACL_INVALID_USER_GROUP
The required user or group name not found.


EACL_MISSING_FIELDS
The ACL needs more fields to be specified.


EACL_PERM_MASK_ERROR
The permission mask is invalid.


EACL_UNKNOWN_DATA
Unknown data was found in the ACL.


EXAMPLES


Example 1: Examples of permissions when ACL_COMPACT_FMT is not specified.



user:joe:read_data/write_data:file_inherit/dir_inherit:allow


owner@:read_acl:allow,user:tom:read_data:file_inherit/inherit_only:deny


Example 2: Examples of permissions when ACL_COMPACT_FMT is specified.



user:joe:rw------------:fd----:allow


owner@:----------c---:------allow,user:tom:r-------------:f-i---:deny


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Committed |
+--------------------+-----------------+
|MT-Level | Safe |
+--------------------+-----------------+

SEE ALSO


ls(1), tar(1), acl(2), malloc(3C), aclfromtext(3SEC), acl(5),
attributes(5)


June 16, 2008 ACL_TOTEXT(3SEC)