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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __SELFTESTS_FILESYSTEMS_FREEZE_LOOP_UTIL_H
#define __SELFTESTS_FILESYSTEMS_FREEZE_LOOP_UTIL_H
#include <errno.h>
#include <fcntl.h>
#include <linux/loop.h>
#include <stdbool.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <unistd.h>
/* How often to retry when somebody else binds the free device first. */
#define LOOP_BIND_TRIES 64
/* Bind a free loop device to @fd; its number or -errno. */
static inline int loop_bind(int fd)
{
for (int i = 0; i < LOOP_BIND_TRIES; i++) {
char dev[32];
int cfd, lfd, n, err;
cfd = open("/dev/loop-control", O_RDWR | O_CLOEXEC);
if (cfd < 0)
return -errno;
n = ioctl(cfd, LOOP_CTL_GET_FREE);
err = errno;
close(cfd);
if (n < 0)
return -err;
snprintf(dev, sizeof(dev), "/dev/loop%d", n);
lfd = open(dev, O_RDWR | O_CLOEXEC);
if (lfd < 0)
return -errno;
err = ioctl(lfd, LOOP_SET_FD, fd) ? errno : 0;
close(lfd);
if (!err)
return n;
if (err != EBUSY)
return -err;
}
return -EBUSY;
}
/* Did loop_bind() fail because there are no loop device nodes or no driver? */
static inline bool loop_missing(int ret)
{
return ret == -ENOENT || ret == -ENODEV;
}
static inline void loop_clear(int n)
{
char dev[32];
int fd;
snprintf(dev, sizeof(dev), "/dev/loop%d", n);
fd = open(dev, O_RDWR | O_CLOEXEC);
if (fd < 0)
return;
ioctl(fd, LOOP_CLR_FD, 0);
close(fd);
}
#endif /* __SELFTESTS_FILESYSTEMS_FREEZE_LOOP_UTIL_H */
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