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 parameter deter-
mines 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 call-
ing 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 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 support setattrlist(). See the documenta-
tion for getattrlist(2) for details on how to tell whether a volume 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 dif-
ferent 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 docu-
ment.
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 char-
acters.
[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), mod-
ifying 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.
");
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