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setattrlist(2)              BSD System Calls Manual             setattrlist(2)


NAME

     setattrlist, fsetattrlist -- set file system attributes


SYNOPSIS

     #include <sys/attr.h>
     #include <unistd.h>

     int
     setattrlist(const char* path, struct attrlist * attrList, void * attrBuf,
         size_t attrBufSize, unsigned long options);

     int
     fsetattrlist(int fd, struct attrlist * attrList, void * attrBuf,
         size_t attrBufSize, unsigned long options);


DESCRIPTION

     The setattrlist() and fsetattrlist() functions set attributes (that is,
     metadata) of file system objects.  They are the logical opposite of
     getattrlist(2).  The setattrlist() function sets attributes about the
     file system object specified by path from the values in the buffer speci-
     fied by attrBuf and attrBufSize; the fsetattrlist() function does the
     same for the fd file descriptor.  The attrList parameter determines what
     attributes are set.  The options parameter lets you control specific
     aspects of the function's behaviour.

     The functions are only supported by certain volume format implementa-
     tions.  For maximum compatibility, client programs should use high-level
     APIs (such as the Carbon File Manager) to access file system attributes.
     These high-level APIs include logic to emulate file system attributes on
     volumes that don't support setattrlist() and fsetattrlist().

     The path parameter for setattrlist() must reference a valid file system
     object.  All directories listed in the path name leading to the object
     must be searchable.  The fd parameter for fsetattrlist() must be a valid
     file descriptor for the calling process.  You must own the file system
     object in order to set any of the following attributes:

     ATTR_CMN_GRPID
     ATTR_CMN_ACCESSMASK
     ATTR_CMN_FLAGS
     ATTR_CMN_CRTIME
     ATTR_CMN_MODTIME
     ATTR_CMN_CHGTIME
     ATTR_CMN_ACCTIME

     You must be root (that is, your process's effective UID must be 0) in
     order to change the ATTR_CMN_OWNERID attribute.  Setting other attributes
     requires that you have write access to the object.

     The attrList parameter is a pointer to an attrlist structure.  You are
     responsible for filling out all fields of this structure before calling
     the function.  See the discussion of the getattrlist(2) function for a
     detailed description of this structure.  To set an attribute you must set
     the corresponding bit in the appropriate attrgroup_t field of the
     attrlist structure.

     The attrBuf and attrBufSize parameters specify a buffer that contains the
     attribute values to set.  Attributes are packed in exactly the same way
     as they are returned from getattrlist(2) except that, when setting
     attributes, the buffer does not include the leading u_int32_t length
     value.

     The options parameter is a bit set that controls the behaviour of
     setattrlist().  The following option bits are defined.

     FSOPT_NOFOLLOW  If this bit is set, setattrlist() will not follow a sym-
                     link if it occurs as the last component of path.


RETURN VALUES

     Upon successful completion a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.


COMPATIBILITY

     Not all volumes support setattrlist().  However, if a volume supports
     getattrlist(2), it must also support setattrlist().  See the documenta-
     tion for getattrlist(2) for details on how to tell whether a volume sup-
     ports it.

     The setattrlist() function has been undocumented for more than two years.
     In that time a number of volume format implementations have been created
     without a proper specification for the behaviour of this routine.  You
     may encounter volume format implementations with slightly different be-
     haviour than what is described here.  Your program is expected to be tol-
     erant of this variant behaviour.

     If you're implementing a volume format that supports setattrlist(), you
     should be careful to support the behaviour specified by this document.


ERRORS

     setattrlist() and fsetattrlist() will fail if:

     [ENOTSUP]          The call is not supported by the volume.

     [ENOTDIR]          A component of the path for setattrlist() prefix is
                        not a directory.

     [ENAMETOOLONG]     A component of a path name for setattrlist() exceeded
                        NAME_MAX characters, or an entire path name exceeded
                        PATH_MAX characters.

     [ENOENT]           The file system object for setattrlist() does not
                        exist.

     [EBADF]            The file descriptor argument for fsetattrlist() is not
                        a valid file descriptor.

     [EROFS]            The volume is read-only.

     [EACCES]           Search permission is denied for a component of the
                        path prefix for setattrlist().

     [ELOOP]            Too many symbolic links were encountered in translat-
                        ing the pathname for setattrlist().

     [EFAULT]           path, attrList or attrBuf points to an invalid
                        address.

     [EINVAL]           The bitmapcount field of attrList is not
                        ATTR_BIT_MAP_COUNT.

     [EINVAL]           You try to set an invalid attribute.

     [EINVAL]           You try to set an attribute that is read-only.

     [EINVAL]           You try to set volume attributes and directory or file
                        attributes at the same time.

     [EINVAL]           You try to set volume attributes but path does not
                        reference the root of the volume.

     [EPERM]            You try to set an attribute that can only be set by
                        the owner.

     [EACCES]           You try to set an attribute that's only settable if
                        you have write permission, and you do not have write
                        permission.

     [EINVAL]           The buffer size you specified in attrBufSize is too
                        small to hold all the attributes that you are trying
                        to set.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.


CAVEATS

     If you try to set any volume attributes, you must set ATTR_VOL_INFO in
     the volattr field, even though it consumes no data from the attribute
     buffer.

     For more caveats, see also the compatibility notes above.


EXAMPLES

     The following code shows how to set the file type and creator of a file
     by getting the ATTR_CMN_FNDRINFO attribute using getattrlist(2), modify-
     ing the appropriate fields of the 32-byte Finder information structure,
     and then setting the attribute back using setattrlist().  This assumes
     that the target volume supports the required attributes

     #include <assert.h>
     #include <stdio.h>
     #include <stddef.h>
     #include <string.h>
     #include <sys/attr.h>
     #include <sys/errno.h>
     #include <unistd.h>
     #include <sys/vnode.h>

     typedef struct attrlist attrlist_t;

     struct FInfoAttrBuf {
         u_int32_t       length;
         fsobj_type_t    objType;
         char            finderInfo[32];
     };
     typedef struct FInfoAttrBuf FInfoAttrBuf;

     static int FInfoDemo(
         const char *path,
         const char *type,
         const char *creator
     )
     {
         int             err;
         attrlist_t      attrList;
         FInfoAttrBuf    attrBuf;

         assert( strlen(type)    == 4 );
         assert( strlen(creator) == 4 );

         memset(&attrList, 0, sizeof(attrList));
         attrList.bitmapcount = ATTR_BIT_MAP_COUNT;
         attrList.commonattr  = ATTR_CMN_OBJTYPE | ATTR_CMN_FNDRINFO;

         err = getattrlist(path, &attrList, &attrBuf, sizeof(attrBuf), 0);
         if (err != 0) {
             err = errno;
         }

         if ( (err == 0) && (attrBuf.objType != VREG) ) {
             fprintf(stderr, "Not a standard file.\n");
             err = EINVAL;
         } else {
             memcpy( &attrBuf.finderInfo[0], type,    4 );
             memcpy( &attrBuf.finderInfo[4], creator, 4 );

             attrList.commonattr = ATTR_CMN_FNDRINFO;
             err = setattrlist(
                 path,
                 &attrList,
                 attrBuf.finderInfo,
                 sizeof(attrBuf.finderInfo),
                 0
             );
         }

         return err;
     }


SEE ALSO

     chflags(2), chmod(2), chown(2), getattrlist(2), getdirentriesattr(2),
     searchfs(2), utimes(2)


HISTORY

     A setattrlist() function call appeared in Darwin 1.3.1 (Mac OS X version
     10.0).

Darwin                         December 15, 2003                        Darwin

Mac OS X 10.9.1 - Generated Mon Jan 6 14:09:29 CST 2014