FAT_IOCTL_SET_ATTRIBUTES(2const)

NAME

FAT_IOCTL_GET_ATTRIBUTES, FAT_IOCTL_SET_ATTRIBUTES - get and set file attributes in a FAT filesystem

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

#include <linux/msdos_fs.h>  /* Definition of FAT_* and
                                ATTR_* constants */
#include <sys/ioctl.h>

int ioctl(int fd, FAT_IOCTL_GET_ATTRIBUTES, uint32_t *attr);
int ioctl(int fd, FAT_IOCTL_SET_ATTRIBUTES, uint32_t *attr);

DESCRIPTION

Files and directories in the FAT filesystem possess an attribute bit mask that can be read with FAT_IOCTL_GET_ATTRIBUTES and written with FAT_IOCTL_SET_ATTRIBUTES.

The fd argument contains a file descriptor for a file or directory. It is sufficient to create the file descriptor by calling open(2) with the O_RDONLY flag.

The attr argument contains a pointer to a bit mask. The bits of the bit mask are:

ATTR_RO: This bit specifies that the file or directory is read-only.
ATTR_HIDDEN: This bit specifies that the file or directory is hidden.
ATTR_SYS: This bit specifies that the file is a system file.
ATTR_VOLUME: This bit specifies that the file is a volume label. This attribute is read-only.
ATTR_DIR: This bit specifies that this is a directory. This attribute is read-only.
ATTR_ARCH: This bit indicates that this file or directory should be archived. It is set when a file is created or modified. It is reset by an archiving system.

The zero value ATTR_NONE can be used to indicate that no attribute bit is set.

RETURN VALUE

On success, 0 is returned. On error, -1 is returned, and errno is set to indicate the error.

STANDARDS

Linux.

HISTORY

Linux 2.6.12.

EXAMPLES

The following program demonstrates the usage of ioctl(2) to manipulate file attributes. The program reads and displays the archive attribute of a file. After inverting the value of the attribute, the program reads and displays the attribute again.

The following was recorded when applying the program for the file /mnt/user/foo:

# ./toggle_fat_archive_flag /mnt/user/foo
Archive flag is set
Toggling archive flag
Archive flag is not set

Program source (toggle_fat_archive_flag.c)

#include <fcntl.h>
#include <linux/msdos_fs.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <unistd.h>
/*
 * Read file attributes of a file on a FAT filesystem.
 * Output the state of the archive flag.
 */
static uint32_t
readattr(int fd)
{
    int       ret;
    uint32_t  attr;
    ret = ioctl(fd, FAT_IOCTL_GET_ATTRIBUTES, &attr);
    if (ret == -1) {
        perror("ioctl");
        exit(EXIT_FAILURE);
    }
    if (attr & ATTR_ARCH)
        printf("Archive flag is set\n");
    else
        printf("Archive flag is not set\n");
    return attr;
}
int
main(int argc, char *argv[])
{
    int       fd;
    int       ret;
    uint32_t  attr;
    if (argc != 2) {
        printf("Usage: %s FILENAME\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    fd = open(argv[1], O_RDONLY);
    if (fd == -1) {
        perror("open");
        exit(EXIT_FAILURE);
    }
    /*
     * Read and display the FAT file attributes.
     */
    attr = readattr(fd);
    /*
     * Invert archive attribute.
     */
    printf("Toggling archive flag\n");
    attr ^= ATTR_ARCH;
    /*
     * Write the changed FAT file attributes.
     */
    ret = ioctl(fd, FAT_IOCTL_SET_ATTRIBUTES, &attr);
    if (ret == -1) {
        perror("ioctl");
        exit(EXIT_FAILURE);
    }
    /*
     * Read and display the FAT file attributes.
     */
    readattr(fd);
    close(fd);
    exit(EXIT_SUCCESS);
}