llapi_ioctl(3)

NAME

llapi_ioctl - call ioctl() with possible command remapping

SYNOPSIS

#include <lustre/lustreapi.h>
#include <linux/lustre/lustre_ioctl.h>

int llapi_ioctl(int fd, unsigned int cmd, void *buf);

DESCRIPTION

llapi_ioctl() calls the ioctl(2) system call with the supplied arguments. However, if the ioctl() fails and sets errno to ENOTTY (no such ioctl) then if cmd has been remapped from an older ioctl command number the ioctl() call will be retried with the old ioctl command number.

RETURN VALUES

llapi_ioctl() typically returns:

>=0

on success, the value returned by the ioctl(2).

-EBADF

if fd is negative, without calling ioctl(2). errno is also set to EBADF.

-1

on failure, with errno set by ioctl(2). Note: If ioctl command is not supported, errno will be set to ENOTTY. For this specific case, llapi_ioctl() may retry calling ioctl again and return its result.

Due to the variety of ioctl commands, it may return different values and errno as appropriate for the fd, cmd number, and argument buf passed.

EXAMPLES

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <lustre/lustreapi.h>
#include <linux/lustre/lustre_ioctl.h>
int main(int argc, char *argv[])
{


        char lov_name[MAX_OBD_NAME];


        int rc, fd;


        if (argc != 2) {


                fprintf(stderr, "Usage: %s <filename>\n", argv[0]);


                return 1;


        }


        fd = open(argv[1], O_RDONLY);


        if (fd < 0) {


                fprintf(stderr, "error opening file '%s': %s\n",


                        argv[1], strerror(errno));


                return 1;


        }


        rc = llapi_ioctl(fd, OBD_IOC_GETDTNAME, lov_name);


        if (rc < 0) {


                fprintf(stderr, "%s: ioctl error: %s\n",


                        argv[1], strerror(errno));


                return 1;


        }


        printf("%s: LOV device name %s\n", argv[1], lov_name);


        return 0;
}

AVAILABILITY

llapi_ioctl() is part of the lustre(7) user application interface library since release 2.16.0

SEE ALSO

ioctl(2), lustre(7), lustreapi(7)