Mercurial > hg > toybox
annotate toys/other/shred.c @ 1776:7bf68329eb3b draft default tip
Repository switched to git at https://github.com/landley/toybox
| author | Rob Landley <rob@landley.net> |
|---|---|
| date | Thu, 09 Apr 2015 02:28:32 -0500 |
| parents | 9eebbebbc219 |
| children |
| rev | line source |
|---|---|
| 1598 | 1 /* shred.c - Overwrite a file to securely delete |
| 2 * | |
| 3 * Copyright 2014 Rob Landley <rob@landley.net> | |
| 4 * | |
| 5 * No standard | |
| 6 | |
| 7 USE_SHRED(NEWTOY(shred, "<1zxus#<1n#<1o#<0f", TOYFLAG_USR|TOYFLAG_BIN)) | |
| 8 | |
| 9 config SHRED | |
| 10 bool "shred" | |
|
1735
9eebbebbc219
Implement shred -u and switch to default y in defconfig.
Rob Landley <rob@landley.net>
parents:
1598
diff
changeset
|
11 default y |
| 1598 | 12 help |
| 13 usage: shred [-fuz] [-n COUNT] [-s SIZE] FILE... | |
| 14 | |
| 15 Securely delete a file by overwriting its contents with random data. | |
| 16 | |
| 17 -f Force (chmod if necessary) | |
| 18 -n COUNT Random overwrite iterations (default 1) | |
| 19 -o OFFSET Start at OFFSET | |
| 20 -s SIZE Use SIZE instead of detecting file size | |
| 21 -u unlink (actually delete file when done) | |
| 22 -x Use exact size (default without -s rounds up to next 4k) | |
| 23 -z zero at end | |
| 24 | |
| 25 Note: data journaling filesystems render this command useless, you must | |
| 26 overwrite all free space (fill up disk) to erase old data on those. | |
| 27 */ | |
| 28 | |
| 29 #define FOR_shred | |
| 30 #include "toys.h" | |
| 31 | |
| 32 GLOBALS( | |
| 33 long offset; | |
| 34 long iterations; | |
| 35 long size; | |
| 36 | |
| 37 int ufd; | |
| 38 ) | |
| 39 | |
| 40 void shred_main(void) | |
| 41 { | |
| 42 char **try; | |
| 43 | |
| 44 if (!(toys.optflags & FLAG_n)) TT.iterations++; | |
| 45 TT.ufd = xopen("/dev/urandom", O_RDONLY); | |
| 46 | |
| 47 // We don't use loopfiles() here because "-" isn't stdin, and want to | |
| 48 // respond to files we can't open via chmod. | |
| 49 | |
| 50 for (try = toys.optargs; *try; try++) { | |
| 51 off_t pos = 0, len = TT.size; | |
| 52 int fd = open(*try, O_RDWR), iter = 0, throw; | |
| 53 | |
| 54 // do -f chmod if necessary | |
| 55 if (fd == -1 && (toys.optflags & FLAG_f)) { | |
| 56 chmod(*try, 0600); | |
| 57 fd = open(*try, O_RDWR); | |
| 58 } | |
| 59 if (fd == -1) { | |
| 60 perror_msg("%s", *try); | |
| 61 continue; | |
| 62 } | |
| 63 | |
| 64 // determine length | |
| 65 if (!len) len = fdlength(fd); | |
| 66 if (len<1) { | |
| 67 error_msg("%s: needs -s", *try); | |
| 68 close(fd); | |
| 69 continue; | |
| 70 } | |
| 71 | |
| 72 // Loop through, writing to this file | |
| 73 for (;;) { | |
| 74 // Advance to next -n or -z? | |
| 75 | |
| 76 if (pos >= len) { | |
| 77 pos = -1; | |
| 78 if (++iter == TT.iterations && (toys.optargs && FLAG_z)) { | |
| 79 memset(toybuf, 0, sizeof(toybuf)); | |
| 80 continue; | |
| 81 } | |
| 82 if (iter >= TT.iterations) break; | |
| 83 } | |
| 84 | |
| 85 if (pos < TT.offset) { | |
| 86 if (TT.offset != lseek(fd, TT.offset, SEEK_SET)) { | |
| 87 perror_msg("%s", *try); | |
| 88 break; | |
| 89 } | |
| 90 pos = TT.offset; | |
| 91 } | |
| 92 | |
| 93 // Determine length, read random data if not zeroing, write. | |
| 94 | |
| 95 throw = sizeof(toybuf); | |
| 96 if (toys.optflags & FLAG_x) | |
| 97 if (len-pos < throw) throw = len-pos; | |
| 98 | |
| 99 if (iter != TT.iterations) xread(TT.ufd, toybuf, throw); | |
| 100 if (throw != writeall(fd, toybuf, throw)) perror_msg("%s"); | |
| 101 pos += throw; | |
| 102 } | |
|
1735
9eebbebbc219
Implement shred -u and switch to default y in defconfig.
Rob Landley <rob@landley.net>
parents:
1598
diff
changeset
|
103 if (toys.optflags & FLAG_u) |
|
9eebbebbc219
Implement shred -u and switch to default y in defconfig.
Rob Landley <rob@landley.net>
parents:
1598
diff
changeset
|
104 if (unlink(*try)) perror_msg("unlink '%s'", *try); |
| 1598 | 105 } |
| 106 } |