FAT_IOCTL_GET_ATTRIBUTES2const

Usage

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

Library

Standard C library (libc, -lc)

Overview

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.

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

#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);
}