src/saveunlinkedinode.c

   1
   2 #include <sys/stat.h>
   3 #include <bits/posix1_lim.h>
   4 #include <fcntl.h>
   5 #include <time.h>
   6 #include <stdlib.h>
   7 #include <stdio.h>
   8 #include <dlfcn.h>
   9 #include <unistd.h>
  10
  11 int unlinkat(int dirfd, const char *pathname, int flags)
  12 {
  13         int (*real_unlinkat)(int dirfd, const char *pathname, int flags) = dlsym(RTLD_NEXT, "unlinkat");
  14         int retval;
  15
  16         char fdlinkname[_POSIX_PATH_MAX];
  17         char atdir[_POSIX_PATH_MAX];
  18         char bkfilename[_POSIX_PATH_MAX];
  19         char timebuf[20];
  20         time_t timer;
  21         struct tm* tm_info;
  22         struct stat st;
  23         FILE *fd;
  24
  25         atdir[0] = 0;
  26
  27
  28         if(fstatat(dirfd, pathname, &st, flags) == -1) {
  29                 perror("fstatat");
  30                 goto do_unlink;
  31         }
  32
  33         if(dirfd != AT_FDCWD) {
  34                 sprintf(fdlinkname, "/proc/self/fd/%d", dirfd);
  35                 if(readlink(fdlinkname, atdir, _POSIX_PATH_MAX) == -1) {
  36                         perror("readlink");
  37                         goto do_unlink;
  38                 }
  39         }
  40         else {
  41                 if(getcwd(atdir, _POSIX_PATH_MAX) == NULL) {
  42                         perror("getcwd");
  43                         goto do_unlink;
  44                 }
  45         }
  46
  47         time(&timer);
  48         tm_info = localtime(&timer);
  49         strftime(timebuf, 20, "%Y-%m-%d %H:%M:%S", tm_info);
  50
  51
  52         do_unlink:
  53         retval = real_unlinkat(dirfd, pathname, flags);
  54
  55         if(retval == 0 && atdir[0] != 0) {
  56                 sprintf(bkfilename, "%s/%s", getenv("HOME"), ".unlinked_inodes");
  57                 fd = fopen(bkfilename, "a");
  58                 if(fd != NULL) {
  59                         fprintf(fd, "%s %ld %s/%s\n", timebuf, (long)st.st_ino, atdir, pathname);
  60                         fclose(fd);
  61                 }
  62                 else {
  63                         perror("fopen");
  64                 }
  65         }
  66
  67         return retval;
  68 }
  69
  70 // Fordítás: gcc -s -x c saveunlinkedinode.c -fPIC -shared -ldl -o saveunlinkedinode.so
  71 // Futtatás: LD_PRELOAD=./saveunlinkedinode.so rm somefile