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char *file_name;

/* Initialize file_name */

FILE *fd = fopen(file_name, "w");
if (fd == NULL) {
  /* Handle error */
}

/*... writeWrite to file ...*/

fclose(fd);
fd = NULL;

/*
 * A race condition here allows for an attacker to switch 
 * to switch out the file for another. 
 */

/* ... */

fd = fopen(file_name, "r");
if (fd == NULL) {
  /* Handle error */
}

/*... readRead from file ...*/

fclose(fd);
fd = NULL;

struct stat orig_st;
struct stat new_st;
char *file_name;

/* Initialize file_name */

int fd = open(file_name, O_WRONLY);
if (fd == -1) {
  /* Handle error */
}

/*... writeWrite to file ...*/

if (fstat(fd, &orig_st) == -1) {
  /* Handle error */
}
close(fd);
fd = -1;

/* ... */

fd = open(file_name, O_RDONLY);
if (fd == -1) {
  /* Handle error */
}

if (fstat(fd, &new_st) == -1) {
  /* Handle error */
}

if ((orig_st.st_dev != new_st.st_dev) ||
    (orig_st.st_ino != new_st.st_ino)) {
  /* fileFile was tampered with! */
}

/*... readRead from file ...*/

close(fd);
fd = -1;

char *file_name;
FILE *fd;

/* Initialize file_name */

fd = fopen(file_name, "w+");
if (fd == NULL) {
  /* Handle error */
}

/*... writeWrite to file ...*/

/* goGo to beginning of file */
fseek(fd, 0, SEEK_SET);

/*... readRead from file ...*/

fclose(fd);
fd = NULL;

struct stat st;
char *file_name;

/* Initialize file_name */

int fd = open(file_name, O_RDONLY);
if (fd == -1) {
  /* Handle error */
}

if ((fstat(fd, &st) == -1) ||
   (st.st_uid != getuid()) ||
   (st.st_gid != getgid())) {
  /* File does not belong to user */
}

/*... readRead from file ...*/

close(fd);
fd = -1;