107 lines
2.6 KiB
C
107 lines
2.6 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Copyright (C) 2017 Denys Vlasenko <vda.linux@googlemail.com>
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//config:config SHRED
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//config: bool "shred (5 kb)"
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//config: default y
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//config: help
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//config: Overwrite a file to hide its contents, and optionally delete it
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//applet:IF_SHRED(APPLET(shred, BB_DIR_USR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_SHRED) += shred.o
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//usage:#define shred_trivial_usage
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//usage: "FILE..."
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//usage:#define shred_full_usage "\n\n"
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//usage: "Overwrite/delete FILEs\n"
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//usage: "\n -f Chmod to ensure writability"
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//usage: "\n -n N Overwrite N times (default 3)"
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//usage: "\n -z Final overwrite with zeros"
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//usage: "\n -u Remove file"
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//-x and -v are accepted but have no effect
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/* shred (GNU coreutils) 8.25:
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-f, --force change permissions to allow writing if necessary
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-u truncate and remove file after overwriting
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-z, --zero add a final overwrite with zeros to hide shredding
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-n, --iterations=N overwrite N times instead of the default (3)
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-v, --verbose show progress
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-x, --exact do not round file sizes up to the next full block; this is the default for non-regular files
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--random-source=FILE get random bytes from FILE
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-s, --size=N shred this many bytes (suffixes like K, M, G accepted)
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--remove[=HOW] like -u but give control on HOW to delete; See below
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*/
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#include "libbb.h"
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int shred_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int shred_main(int argc UNUSED_PARAM, char **argv)
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{
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int rand_fd = rand_fd; /* for compiler */
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int zero_fd;
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unsigned num_iter = 3;
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unsigned opt;
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enum {
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OPT_f = (1 << 0),
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OPT_u = (1 << 1),
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OPT_z = (1 << 2),
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OPT_n = (1 << 3),
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OPT_v = (1 << 4),
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OPT_x = (1 << 5),
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};
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opt = getopt32(argv, "fuzn:+vx", &num_iter);
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argv += optind;
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zero_fd = xopen("/dev/zero", O_RDONLY);
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if (num_iter != 0)
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rand_fd = xopen("/dev/urandom", O_RDONLY);
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if (!*argv)
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bb_show_usage();
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for (;;) {
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struct stat sb;
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const char *fname;
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unsigned i;
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int fd;
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fname = *argv++;
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if (!fname)
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break;
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fd = -1;
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if (opt & OPT_f) {
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fd = open(fname, O_WRONLY);
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if (fd < 0)
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chmod(fname, 0666);
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}
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if (fd < 0)
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fd = xopen(fname, O_WRONLY);
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if (fstat(fd, &sb) == 0 && sb.st_size > 0) {
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off_t size = sb.st_size;
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for (i = 0; i < num_iter; i++) {
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bb_copyfd_size(rand_fd, fd, size);
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fdatasync(fd);
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xlseek(fd, 0, SEEK_SET);
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}
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if (opt & OPT_z) {
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bb_copyfd_size(zero_fd, fd, size);
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fdatasync(fd);
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}
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if (opt & OPT_u) {
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ftruncate(fd, 0);
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xunlink(fname);
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}
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xclose(fd);
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}
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}
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return EXIT_SUCCESS;
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}
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