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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/fs.h>
static int set_immutable(const char *path, int immutable)
{
unsigned int flags;
int fd;
int rc;
int error;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (rc < 0) {
error = errno;
close(fd);
errno = error;
return rc;
}
if (immutable)
flags |= FS_IMMUTABLE_FL;
else
flags &= ~FS_IMMUTABLE_FL;
rc = ioctl(fd, FS_IOC_SETFLAGS, &flags);
error = errno;
close(fd);
errno = error;
return rc;
}
static int get_immutable(const char *path)
{
unsigned int flags;
int fd;
int rc;
int error;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (rc < 0) {
error = errno;
close(fd);
errno = error;
return rc;
}
close(fd);
if (flags & FS_IMMUTABLE_FL)
return 1;
return 0;
}
int main(int argc, char **argv)
{
const char *path;
char buf[5];
int fd, rc;
if (argc < 2) {
fprintf(stderr, "usage: %s <path>\n", argv[0]);
return EXIT_FAILURE;
}
path = argv[1];
/* attributes: EFI_VARIABLE_NON_VOLATILE |
* EFI_VARIABLE_BOOTSERVICE_ACCESS |
* EFI_VARIABLE_RUNTIME_ACCESS
*/
*(uint32_t *)buf = 0x7;
buf[4] = 0;
/* create a test variable */
fd = open(path, O_WRONLY | O_CREAT, 0600);
if (fd < 0) {
perror("open(O_WRONLY)");
return EXIT_FAILURE;
}
rc = write(fd, buf, sizeof(buf));
if (rc != sizeof(buf)) {
perror("write");
return EXIT_FAILURE;
}
close(fd);
rc = get_immutable(path);
if (rc < 0) {
perror("ioctl(FS_IOC_GETFLAGS)");
return EXIT_FAILURE;
} else if (rc) {
rc = set_immutable(path, 0);
if (rc < 0) {
perror("ioctl(FS_IOC_SETFLAGS)");
return EXIT_FAILURE;
}
}
fd = open(path, O_RDONLY);
if (fd < 0) {
perror("open");
return EXIT_FAILURE;
}
if (unlink(path) < 0) {
perror("unlink");
return EXIT_FAILURE;
}
rc = read(fd, buf, sizeof(buf));
if (rc > 0) {
fprintf(stderr, "reading from an unlinked variable "
"shouldn't be possible\n");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
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