main.c

   1 /* This program is free software. It comes without any warranty, to
   2  * the extent permitted by applicable law. You can redistribute it
   3  * and/or modify it under the terms of the Do What The Fuck You Want
   4  * To Public License, Version 2, as published by Sam Hocevar. See
   5  * http://sam.zoy.org/wtfpl/COPYING for more details. */
   6
   7 #include <sys/stat.h>
   8
   9 #include <err.h>
  10 #define __USE_XOPEN_EXTENDED
  11 #include <ftw.h>
  12 #include <fcntl.h>
  13 #include <libgen.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <time.h>
  18 #include <unistd.h>
  19
  20 #include "util.h"
  21
  22 int verbose = 0;
  23
  24 static char *randstr(size_t len) {
  25     const char *chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
  26
  27     char *name;
  28     size_t i;
  29
  30     name = emalloc(len+1);
  31
  32     for (i = 0; i < len; i++) {
  33         name[i] = chars[rand() % strlen(chars)];
  34     }
  35     name[len+1] = '\0';
  36
  37     return name;
  38 }
  39
  40 static char *randren(const char *path) {
  41     unsigned long newpathlen = 0;
  42     unsigned int error = 0;
  43
  44     char *dname, *rname, *pathcopy, *newpath;
  45
  46     /* glibc dirname modifies its argument */
  47     pathcopy = strdup(path);
  48
  49     dname = dirname(pathcopy);
  50
  51     /* Calling pathconf directly on a symlink will return the value for
  52      * the file that it links to or, if it's a dangling symlink, -1
  53      * (failure) so we use the directory it's stored in instead. */
  54     rname = randstr(pathconf(dname, _PC_NAME_MAX));
  55
  56     newpathlen += strlen(dname);
  57     newpathlen += strlen(rname);
  58     newpathlen += 2; /* '/' & '\0' */
  59
  60     newpath = emalloc(newpathlen);
  61
  62     strcpy(newpath, dname);
  63     strcpy(newpath + strlen(newpath), "/");
  64     strcpy(newpath + strlen(newpath), rname);
  65     strcpy(newpath + strlen(newpath), "\0");
  66
  67     /* check whether the file exists */
  68     if (access(newpath, F_OK) == 0) {
  69         warnx("randren: File exists");
  70         error = 1;
  71     } else {
  72         if (rename(path, newpath) == -1) {
  73             warn("randren");
  74             error = 1;
  75         }
  76     }
  77
  78     free(pathcopy);
  79     free(rname);
  80
  81     if (error == 1) {
  82         free(newpath);
  83         return NULL;
  84     } else {
  85         return newpath;
  86     }
  87 }
  88
  89 static int fzero(const char *path) {
  90     ssize_t written = 0;
  91
  92     int fd;
  93     void *buf;
  94     struct stat stbuf;
  95
  96     if (stat(path, &stbuf) == -1) {
  97         warn("fzero");
  98         return -1;
  99     }
 100
 101     buf = emalloc(stbuf.st_blksize);
 102
 103     if ((fd = open(path, O_WRONLY)) == -1) {
 104         warn("fzero");
 105         return -1;
 106     }
 107
 108     while (written < stbuf.st_size) {
 109         written += write(fd, buf, stbuf.st_blksize);
 110         if (verbose) {
 111             putchar('.');
 112         }
 113     }
 114     if (verbose) {
 115         putchar('\n');
 116     }
 117
 118     fdatasync(fd);
 119
 120     close(fd);
 121     free(buf);
 122
 123     return 0;
 124 }
 125
 126 int can_write(const struct stat *sb) {
 127     uid_t id;
 128
 129     id = geteuid();
 130     if (sb->st_uid == id) {
 131         return 1;
 132     } else {
 133         return 0;
 134     }
 135 }
 136
 137 int fn(const char *fpath, const struct stat *sb, int typeflag,
 138        struct FTW *ftwbuf) {
 139     char *path;
 140
 141     if (!can_write(sb)) {
 142         return 0;
 143     }
 144
 145     path = randren(fpath);
 146     if (path == NULL) {
 147         return 1;
 148     }
 149
 150     switch (typeflag) {
 151         case FTW_SL:
 152             unlink(path);
 153             break;
 154         case FTW_F:
 155             if (fzero(path) != -1) {
 156                 unlink(path);
 157             }
 158             break;
 159         case FTW_DP:
 160             rmdir(path);
 161             break;
 162     }
 163     free(path);
 164
 165     return 0;
 166 }
 167
 168 int main(int argc, char *argv[]) {
 169     int i, c;
 170
 171     while ((c = getopt(argc, argv, "+v")) != -1) {
 172         switch (c) {
 173             case 'v':
 174                 verbose = 1;
 175                 break;
 176         }
 177     }
 178
 179     if (optind == argc) {
 180         fprintf(stderr, "usage: %s [-rv] [file ...]\n", argv[0]);
 181         return 1;
 182     }
 183
 184     srand(time(NULL));
 185
 186     for (i = optind; i < argc; i++) {
 187         nftw(argv[i], fn, 10, FTW_DEPTH | FTW_PHYS);
 188     }
 189
 190     return 0;
 191 }