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/*
* Copyright (C) 2012 Google, Inc.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package de.waldheinz.fs.fat;
import java.security.SecureRandom;
/**
* Generates dummy 8.3 buffers that are associated with the long names.
*
* @author Daniel Galpin <dgalpin@google.com> based upon the work of
* Andrew Tridgell <tridge@samba.org>
*/
final class Dummy83BufferGenerator {
final SecureRandom mRandom;
/**
* Creates a new instance of {@code Dummy83BufferGenerator} that uses
* randomness only to avoid short name collisions.
*/
public Dummy83BufferGenerator() {
mRandom = new SecureRandom();
}
/*
* Its in the DOS manual!(DOS 5: page 72) Valid: A..Z 0..9 _ ^ $ ~ ! # % & - {} () @ ' `
*
* Invalid: spaces/periods,
*/
public static boolean validChar(char toTest) {
if (toTest >= 'A' && toTest <= 'Z') return true;
if (toTest >= 'a' && toTest <= 'z') return true;
if (toTest >= '0' && toTest <= '9') return true;
if (toTest == '_' || toTest == '^' || toTest == '$' || toTest == '~' ||
toTest == '!' || toTest == '#' || toTest == '%' || toTest == '&' ||
toTest == '-' || toTest == '{' || toTest == '}' || toTest == '(' ||
toTest == ')' || toTest == '@' || toTest == '\'' || toTest == '`')
return true;
return false;
}
public static boolean isSkipChar(char c) {
return (c == '.') || (c == ' ');
}
public static String tidyString(String dirty) {
final StringBuilder result = new StringBuilder();
/* epurate it from alien characters */
for (int src=0; src < dirty.length(); src++) {
final char toTest = Character.toUpperCase(dirty.charAt(src));
if (isSkipChar(toTest)) continue;
if (validChar(toTest)) {
result.append(toTest);
} else {
result.append('_');
}
}
return result.toString();
}
public static boolean cleanString(String s) {
for (int i=0; i < s.length(); i++) {
if (isSkipChar(s.charAt(i))) return false;
if (!validChar(s.charAt(i))) return false;
}
return true;
}
public static String stripLeadingPeriods(String str) {
final StringBuilder sb = new StringBuilder(str.length());
for (int i=0; i < str.length(); i++) {
if (str.charAt(i) != '.') { //NOI18N
sb.append(str.substring(i));
break;
}
}
return sb.toString();
} /*
* These characters are all invalid in 8.3 names, plus have been shown to be
* harmless on all tested devices
*/
static final private char[] invalidchar = {
(char) 0x01, (char) 0x02, (char) 0x03, (char) 0x04, (char) 0x05, (char) 0x06,
(char) 0x0B,
(char) 0x0C, (char) 0x0E, (char) 0x0F, (char) 0x10, (char) 0x11, (char) 0x12,
(char) 0x13,
(char) 0x14, (char) 0x15, (char) 0x16, (char) 0x17, (char) 0x18, (char) 0x19,
(char) 0x1A,
(char) 0x1B, (char) 0x1C, (char) 0x1D, (char) 0x1E, (char) 0x1F, (char) 0x22,
(char) 0x2a,
(char) 0x3a, (char) 0x3c, (char) 0x3e, (char) 0x3f, (char) 0x5b, (char) 0x5d,
(char) 0x7c
};
/**
* See original C Linux patch by Andrew Tridgell <tridge@samba.org>
* build a 11 byte 8.3 buffer which is not a short filename. We want 11
* bytes which: - will be seen as a constant string to all APIs on Linux and
* Windows - cannot be matched with wildcard patterns - cannot be used to
* access the file - has a low probability of collision within a directory -
* has an invalid 3 byte extension - contains at least one non-space and
* non-nul byte
*
* @param longFullName the long file name to generate the buffer for
* @return the generated 8.3 buffer
*/
public ShortName generate83BufferNew(String longFullName)
throws IllegalStateException {
char[] retBuffer = new char[11];
boolean hasRealShortName = false;// getRealShortNameInstead(longFullName,
// retBuffer);
if (!hasRealShortName) {
int i, tilde_pos, slash_pos;
int randomNumber = Math.abs(mRandom.nextInt());
/*
* the '/' makes sure that even unpatched Linux systems can't get at
* files by the 8.3 entry.
*/
slash_pos = randomNumber % 8;
randomNumber >>= 3;
/*
* fill in the first 8 bytes with invalid characters. Note that we
* need to be careful not to run out of randomness. We use the same
* extension for all buffers.
*/
for (i = 0; i < 8; i++) {
if (i == slash_pos)
retBuffer[i] = '/';
else {
retBuffer[i] =
invalidchar[randomNumber % invalidchar.length];
randomNumber /= invalidchar.length;
if (randomNumber < invalidchar.length)
randomNumber = Math.abs(mRandom.nextInt());
}
}
for ( i = 0; i < 8; i ++ ) {
if (retBuffer[i] == 0xe5) {
throw new RuntimeException();
}
}
retBuffer[8] = 'i';
retBuffer[9] = 'f';
retBuffer[10] = 'l';
}
ShortName retName = new ShortName(retBuffer);
retName.setHasShortNameOnly(hasRealShortName);
return retName;
}
}
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