fsctl(2) fsctl(2)
NAME [Toc] [Back]
fsctl - file system control
SYNOPSIS [Toc] [Back]
#include <sys/unistd.h>
int fsctl(
int fildes,
int command,
void *outbuf,
size_t outlen
);
DESCRIPTION [Toc] [Back]
fsctl() provides access to file-system-specific information. fildes
is an open file descriptor for a file in the file system of interest.
The possible values for command depend on the type of file system.
Currently, defined commands exist only for the CDFS file system (see
sys/cdfsdir.h).
outbuf is a pointer to the data area in which data is returned from
the file system. outlen gives the length of the data area pointed to
by outbuf.
The CDFS commands are:
CDFS_DIR_REC Returns the directory record for the file or
directory indicated by fildes. The record is
returned in a structure of type cddir, defined
in <sys/cdfsdir.h>.
CDFS_XAR Returns the extended attribute record, if any,
for the file or directory indicated by fildes.
Because the size of an extended attribute
record varies, be sure outbuf points to a data
area of sufficient size. To find the necessary
size, do the following:
1. Use statfs(2). to get the logical block
size of the CDFS volume.
2. Use an fsctl() call with the CDFS_DIR_REC
command to get the extended attribute
record size (in blocks) for the file or
directory of interest. The mincdd_xar_len
field in the returned structure contains
the size of the extended attribute record
in logical blocks. (If this field is
zero, the file or directory has no
extended attribute record.)
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: August 2003
fsctl(2) fsctl(2)
3. Multiply mincdd_xar_len by the logical
block size obtained in step 1 to get the
total space needed.
4. Once you get the extended attribute
record, cast outbuf into a pointer to a
structure of type cdxar_iso (defined in
<sys/cdfsdir.h>). This enables you to
access those fields that are common to all
extended attribute records. (See EXAMPLES
below for an example of this process.)
If the extended attribute record contains
additional system use or application use
data, that data will have to be accessed
manually.
CDFS_AFID Returns the abstract file identifier for the
primary volume whose root directory is
specified by fildes, terminated with a NULL
character. Note that the constant CDMAXNAMLEN
defined in <sys/cdfsdir.h> gives the maximum
length a file identifier can have. Thus,
CDMAXNAMLEN + 1 can be used for outlen and the
size of outbuf.
CDFS_BFID Returns the bibliographic file identifier for
the primary volume whose root directory is
specified by fildes, terminated with a NULL
character. CDMAXNAMLEN + 1 can be used for the
value of outlen and the size of outbuf.
CDFS_CFID Returns the copyright file identifier for the
primary volume whose root directory is
specified by fildes, terminated with a NULL
character. CDMAXNAMLEN + 1 can be used for the
value of outlen and the size of outbuf.
CDFS_VOL_ID Returns the volume ID for the primary volume
specified by fildes, terminated with a NULL
character. The maximum size of the volume ID
is 32 bytes, so a length of 33 can be used for
outlen and the size of utbuf.
CDFS_VOL_SET_ID Returns the volume set ID for the primary
volume specified by fildes, terminated with a
NULL character. The maximum size of the volume
set ID is 128 bytes, so a length of 129 can be
used for outlen and the size of outbuf.
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: August 2003
fsctl(2) fsctl(2)
EXAMPLES [Toc] [Back]
The following code fragment gets the extended attribute record for a
file on a CDFS volume. The filename is passed in as the first
argument to the routine. Note that error checking is omitted for
brevity.
#include <sys/types.h>
#include <sys/vfs.h>
#include <fcntl.h>
#include <sys/cdfsdir.h>
main(argc, argv)
int argc;
char *argv[];
{
int fildes, size = 0;
char *malloc(), *outbuf;
struct statfs buf;
struct cddir cdrec;
struct cdxar_iso *xar;
.
.
.
statfs(argv[1], &buf); /* get logical block size */
fildes = open(argv[1], O_RDONLY); /* open file arg */
/* get directory record for file arg */
fsctl(fildes, CDFS_DIR_REC, &cdrec, sizeof(cdrec));
size = buf.f_bsize * cdrec.cdd_min.mincdd_xar_len; /* compute size */
if(size) { /* if size != 0 then there is an xar */
outbuf = malloc(size); /* malloc sufficient memory */
fsctl(fildes, CDFS_XAR, outbuf, size); /* get xar */
xar = (struct cdxar_iso *)outbuf; /* cast outbuf to access fields */
.
.
.
}
.
.
.
}
RETURN VALUE [Toc] [Back]
fsctl() returns the number of bytes read if successful. If an error
occurs, -1 is returned and errno is set to indicate the error.
Hewlett-Packard Company - 3 - HP-UX 11i Version 2: August 2003
fsctl(2) fsctl(2)
ERRORS [Toc] [Back]
fsctl() fails if any of the following conditions are encountered:
[EBADF] fildes is not a valid open file descriptor.
[EFAULT] outbuf points to an invalid address.
[ENOENT] The requested information does not exist.
[EINVAL] command is not a valid command.
[EINVAL] fildes does not refer to a CDFS file system.
SEE ALSO [Toc] [Back]
statfs(2), cdfs(4), cdfsdir(4), cdnode(4), cdrom(4).
Hewlett-Packard Company - 4 - HP-UX 11i Version 2: August 2003 [ Back ] |
