tools/testing/selftests/efivarfs/open-unlink.c

   1 #include <errno.h>
   2 #include <stdio.h>
   3 #include <stdint.h>
   4 #include <stdlib.h>
   5 #include <unistd.h>
   6 #include <sys/ioctl.h>
   7 #include <sys/types.h>
   8 #include <sys/stat.h>
   9 #include <fcntl.h>
  10 #include <linux/fs.h>
  11
  12 static int set_immutable(const char *path, int immutable)
  13 {
  14         unsigned int flags;
  15         int fd;
  16         int rc;
  17         int error;
  18
  19         fd = open(path, O_RDONLY);
  20         if (fd < 0)
  21                 return fd;
  22
  23         rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
  24         if (rc < 0) {
  25                 error = errno;
  26                 close(fd);
  27                 errno = error;
  28                 return rc;
  29         }
  30
  31         if (immutable)
  32                 flags |= FS_IMMUTABLE_FL;
  33         else
  34                 flags &= ~FS_IMMUTABLE_FL;
  35
  36         rc = ioctl(fd, FS_IOC_SETFLAGS, &flags);
  37         error = errno;
  38         close(fd);
  39         errno = error;
  40         return rc;
  41 }
  42
  43 static int get_immutable(const char *path)
  44 {
  45         unsigned int flags;
  46         int fd;
  47         int rc;
  48         int error;
  49
  50         fd = open(path, O_RDONLY);
  51         if (fd < 0)
  52                 return fd;
  53
  54         rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
  55         if (rc < 0) {
  56                 error = errno;
  57                 close(fd);
  58                 errno = error;
  59                 return rc;
  60         }
  61         close(fd);
  62         if (flags & FS_IMMUTABLE_FL)
  63                 return 1;
  64         return 0;
  65 }
  66
  67 int main(int argc, char **argv)
  68 {
  69         const char *path;
  70         char buf[5];
  71         int fd, rc;
  72
  73         if (argc < 2) {
  74                 fprintf(stderr, "usage: %s <path>\n", argv[0]);
  75                 return EXIT_FAILURE;
  76         }
  77
  78         path = argv[1];
  79
  80         /* attributes: EFI_VARIABLE_NON_VOLATILE |
  81          *              EFI_VARIABLE_BOOTSERVICE_ACCESS |
  82          *              EFI_VARIABLE_RUNTIME_ACCESS
  83          */
  84         *(uint32_t *)buf = 0x7;
  85         buf[4] = 0;
  86
  87         /* create a test variable */
  88         fd = open(path, O_WRONLY | O_CREAT, 0600);
  89         if (fd < 0) {
  90                 perror("open(O_WRONLY)");
  91                 return EXIT_FAILURE;
  92         }
  93
  94         rc = write(fd, buf, sizeof(buf));
  95         if (rc != sizeof(buf)) {
  96                 perror("write");
  97                 return EXIT_FAILURE;
  98         }
  99
 100         close(fd);
 101
 102         rc = get_immutable(path);
 103         if (rc < 0) {
 104                 perror("ioctl(FS_IOC_GETFLAGS)");
 105                 return EXIT_FAILURE;
 106         } else if (rc) {
 107                 rc = set_immutable(path, 0);
 108                 if (rc < 0) {
 109                         perror("ioctl(FS_IOC_SETFLAGS)");
 110                         return EXIT_FAILURE;
 111                 }
 112         }
 113
 114         fd = open(path, O_RDONLY);
 115         if (fd < 0) {
 116                 perror("open");
 117                 return EXIT_FAILURE;
 118         }
 119
 120         if (unlink(path) < 0) {
 121                 perror("unlink");
 122                 return EXIT_FAILURE;
 123         }
 124
 125         rc = read(fd, buf, sizeof(buf));
 126         if (rc > 0) {
 127                 fprintf(stderr, "reading from an unlinked variable "
 128                                 "shouldn't be possible\n");
 129                 return EXIT_FAILURE;
 130         }
 131
 132         return EXIT_SUCCESS;
 133 }