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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 specified by attrBuf and
     attrBufSize; the fsetattrlist() function does the same for the fd file descriptor.  The attrList param-eter parameter
     eter 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 implementations.  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) func-tion function
     tion 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 symlink 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 sup-port support
     port setattrlist().  See the documentation for getattrlist(2) for details on how to tell whether a vol-ume volume
     ume supports 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 behaviour than
     what is described here.  Your program is expected to be tolerant 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 translating 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), modifying 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

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