/* * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.invoke.util; /** * Utility routines for dealing with bytecode-level names. * Includes universal mangling rules for the JVM. * *

Avoiding Dangerous Characters

* *

* The JVM defines a very small set of characters which are illegal * in name spellings. We will slightly extend and regularize this set * into a group of dangerous characters. * These characters will then be replaced, in mangled names, by escape sequences. * In addition, accidental escape sequences must be further escaped. * Finally, a special prefix will be applied if and only if * the mangling would otherwise fail to begin with the escape character. * This happens to cover the corner case of the null string, * and also clearly marks symbols which need demangling. *

*

* Dangerous characters are the union of all characters forbidden * or otherwise restricted by the JVM specification, * plus their mates, if they are brackets * ([ and ], * < and >), * plus, arbitrarily, the colon character :. * There is no distinction between type, method, and field names. * This makes it easier to convert between mangled names of different * types, since they do not need to be decoded (demangled). *

*

* The escape character is backslash \ * (also known as reverse solidus). * This character is, until now, unheard of in bytecode names, * but traditional in the proposed role. * *

*

Replacement Characters

* * *

* Every escape sequence is two characters * (in fact, two UTF8 bytes) beginning with * the escape character and followed by a * replacement character. * (Since the replacement character is never a backslash, * iterated manglings do not double in size.) *

*

* Each dangerous character has some rough visual similarity * to its corresponding replacement character. * This makes mangled symbols easier to recognize by sight. *

*

* The dangerous characters are * / (forward slash, used to delimit package components), * . (dot, also a package delimiter), * ; (semicolon, used in signatures), * $ (dollar, used in inner classes and synthetic members), * < (left angle), * > (right angle), * [ (left square bracket, used in array types), * ] (right square bracket, reserved in this scheme for language use), * and : (colon, reserved in this scheme for language use). * Their replacements are, respectively, * | (vertical bar), * , (comma), * ? (question mark), * % (percent), * ^ (caret), * _ (underscore), and * { (left curly bracket), * } (right curly bracket), * ! (exclamation mark). * In addition, the replacement character for the escape character itself is * - (hyphen), * and the replacement character for the null prefix is * = (equal sign). *

*

* An escape character \ * followed by any of these replacement characters * is an escape sequence, and there are no other escape sequences. * An equal sign is only part of an escape sequence * if it is the second character in the whole string, following a backslash. * Two consecutive backslashes do not form an escape sequence. *

*

* Each escape sequence replaces a so-called original character * which is either one of the dangerous characters or the escape character. * A null prefix replaces an initial null string, not a character. *

*

* All this implies that escape sequences cannot overlap and may be * determined all at once for a whole string. Note that a spelling * string can contain accidental escapes, apparent escape * sequences which must not be interpreted as manglings. * These are disabled by replacing their leading backslash with an * escape sequence (\-). To mangle a string, three logical steps * are required, though they may be carried out in one pass: *

*
    *
  1. In each accidental escape, replace the backslash with an escape sequence * (\-).
    2. *
  2. Replace each dangerous character with an escape sequence * (\| for /, etc.).
    3. *
  3. If the first two steps introduced any change, and * if the string does not already begin with a backslash, prepend a null prefix (\=).
    4. *
* * To demangle a mangled string that begins with an escape, * remove any null prefix, and then replace (in parallel) * each escape sequence by its original character. *

Spelling strings which contain accidental * escapes must have them replaced, even if those * strings do not contain dangerous characters. * This restriction means that mangling a string always * requires a scan of the string for escapes. * But then, a scan would be required anyway, * to check for dangerous characters. * *

*

Nice Properties

* *

* If a bytecode name does not contain any escape sequence, * demangling is a no-op: The string demangles to itself. * Such a string is called self-mangling. * Almost all strings are self-mangling. * In practice, to demangle almost any name “found in nature”, * simply verify that it does not begin with a backslash. *

*

* Mangling is a one-to-one function, while demangling * is a many-to-one function. * A mangled string is defined as validly mangled if * it is in fact the unique mangling of its spelling string. * Three examples of invalidly mangled strings are \=foo, * \-bar, and baz\!, which demangle to foo, \bar, and * baz\!, but then remangle to foo, \bar, and \=baz\-!. * If a language back-end or runtime is using mangled names, * it should never present an invalidly mangled bytecode * name to the JVM. If the runtime encounters one, * it should also report an error, since such an occurrence * probably indicates a bug in name encoding which * will lead to errors in linkage. * However, this note does not propose that the JVM verifier * detect invalidly mangled names. *

*

* As a result of these rules, it is a simple matter to * compute validly mangled substrings and concatenations * of validly mangled strings, and (with a little care) * these correspond to corresponding operations on their * spelling strings. *

* *

If languages that include non-Java symbol spellings use this * mangling convention, they will enjoy the following advantages: *

* * * *

Suggestions for Human Readable Presentations

* * *

* For human readable displays of symbols, * it will be better to present a string-like quoted * representation of the spelling, because JVM users * are generally familiar with such tokens. * We suggest using single or double quotes before and after * mangled symbols which are not valid Java identifiers, * with quotes, backslashes, and non-printing characters * escaped as if for literals in the Java language. *

*

* For example, an HTML-like spelling * <pre> mangles to * \^pre\_ and could * display more cleanly as * '<pre>', * with the quotes included. * Such string-like conventions are not suitable * for mangled bytecode names, in part because * dangerous characters must be eliminated, rather * than just quoted. Otherwise internally structured * strings like package prefixes and method signatures * could not be reliably parsed. *

*

* In such human-readable displays, invalidly mangled * names should not be demangled and quoted, * for this would be misleading. Likewise, JVM symbols * which contain dangerous characters (like dots in field * names or brackets in method names) should not be * simply quoted. The bytecode names * \=phase\,1 and * phase.1 are distinct, * and in demangled displays they should be presented as * 'phase.1' and something like * 'phase'.1, respectively. *

* * @author John Rose * @version 1.2, 02/06/2008 * @see http://blogs.sun.com/jrose/entry/symbolic_freedom_in_the_vm */ public class BytecodeName { private BytecodeName() { } // static only class /** Given a source name, produce the corresponding bytecode name. * The source name should not be qualified, because any syntactic * markers (dots, slashes, dollar signs, colons, etc.) will be mangled. * @param s the source name * @return a valid bytecode name which represents the source name */ public static String toBytecodeName(String s) { String bn = mangle(s); assert((Object)bn == s || looksMangled(bn)) : bn; assert(s.equals(toSourceName(bn))) : s; return bn; } /** Given an unqualified bytecode name, produce the corresponding source name. * The bytecode name must not contain dangerous characters. * In particular, it must not be qualified or segmented by colon {@code ':'}. * @param s the bytecode name * @return the source name, which may possibly have unsafe characters * @throws IllegalArgumentException if the bytecode name is not {@link #isSafeBytecodeName safe} * @see #isSafeBytecodeName(java.lang.String) */ public static String toSourceName(String s) { checkSafeBytecodeName(s); String sn = s; if (looksMangled(s)) { sn = demangle(s); assert(s.equals(mangle(sn))) : s+" => "+sn+" => "+mangle(sn); } return sn; } /** * Given a bytecode name from a classfile, separate it into * components delimited by dangerous characters. * Each resulting array element will be either a dangerous character, * or else a safe bytecode name. * (The safe name might possibly be mangled to hide further dangerous characters.) * For example, the qualified class name {@code java/lang/String} * will be parsed into the array {@code {"java", '/', "lang", '/', "String"}}. * The name {@code <init>} will be parsed into { '<', "init", '>'}} * The name {@code foo/bar$:baz} will be parsed into * {@code {"foo", '/', "bar", '$', ':', "baz"}}. * The name {@code ::\=:foo:\=bar\!baz} will be parsed into * {@code {':', ':', "", ':', "foo", ':', "bar:baz"}}. */ public static Object[] parseBytecodeName(String s) { int slen = s.length(); Object[] res = null; for (int pass = 0; pass <= 1; pass++) { int fillp = 0; int lasti = 0; for (int i = 0; i <= slen; i++) { int whichDC = -1; if (i < slen) { whichDC = DANGEROUS_CHARS.indexOf(s.charAt(i)); if (whichDC < DANGEROUS_CHAR_FIRST_INDEX) continue; } // got to end of string or next dangerous char if (lasti < i) { // normal component if (pass != 0) res[fillp] = toSourceName(s.substring(lasti, i)); fillp++; lasti = i+1; } if (whichDC >= DANGEROUS_CHAR_FIRST_INDEX) { if (pass != 0) res[fillp] = DANGEROUS_CHARS_CA[whichDC]; fillp++; lasti = i+1; } } if (pass != 0) break; // between passes, build the result array res = new Object[fillp]; if (fillp <= 1 && lasti == 0) { if (fillp != 0) res[0] = toSourceName(s); break; } } return res; } /** * Given a series of components, create a bytecode name for a classfile. * This is the inverse of {@link #parseBytecodeName(java.lang.String)}. * Each component must either be an interned one-character string of * a dangerous character, or else a safe bytecode name. * @param components a series of name components * @return the concatenation of all components * @throws IllegalArgumentException if any component contains an unsafe * character, and is not an interned one-character string * @throws NullPointerException if any component is null */ public static String unparseBytecodeName(Object[] components) { Object[] components0 = components; for (int i = 0; i < components.length; i++) { Object c = components[i]; if (c instanceof String) { String mc = toBytecodeName((String) c); if (i == 0 && components.length == 1) return mc; // usual case if ((Object)mc != c) { if (components == components0) components = components.clone(); components[i] = c = mc; } } } return appendAll(components); } private static String appendAll(Object[] components) { if (components.length <= 1) { if (components.length == 1) { return String.valueOf(components[0]); } return ""; } int slen = 0; for (Object c : components) { if (c instanceof String) slen += String.valueOf(c).length(); else slen += 1; } StringBuilder sb = new StringBuilder(slen); for (Object c : components) { sb.append(c); } return sb.toString(); } /** * Given a bytecode name, produce the corresponding display name. * This is the source name, plus quotes if needed. * If the bytecode name contains dangerous characters, * assume that they are being used as punctuation, * and pass them through unchanged. * Non-empty runs of non-dangerous characters are demangled * if necessary, and the resulting names are quoted if * they are not already valid Java identifiers, or if * they contain a dangerous character (i.e., dollar sign "$"). * Single quotes are used when quoting. * Within quoted names, embedded single quotes and backslashes * are further escaped by prepended backslashes. * * @param s the original bytecode name (which may be qualified) * @return a human-readable presentation */ public static String toDisplayName(String s) { Object[] components = parseBytecodeName(s); for (int i = 0; i < components.length; i++) { if (!(components[i] instanceof String)) continue; String sn = (String) components[i]; // note that the name is already demangled! //sn = toSourceName(sn); if (!isJavaIdent(sn) || sn.indexOf('$') >=0 ) { components[i] = quoteDisplay(sn); } } return appendAll(components); } private static boolean isJavaIdent(String s) { int slen = s.length(); if (slen == 0) return false; if (!Character.isJavaIdentifierStart(s.charAt(0))) return false; for (int i = 1; i < slen; i++) { if (!Character.isJavaIdentifierPart(s.charAt(i))) return false; } return true; } private static String quoteDisplay(String s) { // TO DO: Replace wierd characters in s by C-style escapes. return "'"+s.replaceAll("['\\\\]", "\\\\$0")+"'"; } private static void checkSafeBytecodeName(String s) throws IllegalArgumentException { if (!isSafeBytecodeName(s)) { throw new IllegalArgumentException(s); } } /** * Report whether a simple name is safe as a bytecode name. * Such names are acceptable in class files as class, method, and field names. * Additionally, they are free of "dangerous" characters, even if those * characters are legal in some (or all) names in class files. * @param s the proposed bytecode name * @return true if the name is non-empty and all of its characters are safe */ public static boolean isSafeBytecodeName(String s) { if (s.length() == 0) return false; // check occurrences of each DANGEROUS char for (char xc : DANGEROUS_CHARS_A) { if (xc == ESCAPE_C) continue; // not really that dangerous if (s.indexOf(xc) >= 0) return false; } return true; } /** * Report whether a character is safe in a bytecode name. * This is true of any unicode character except the following * dangerous characters: {@code ".;:$[]<>/"}. * @param c the proposed character * @return true if the character is safe to use in classfiles */ public static boolean isSafeBytecodeChar(char c) { return DANGEROUS_CHARS.indexOf(c) < DANGEROUS_CHAR_FIRST_INDEX; } private static boolean looksMangled(String s) { return s.charAt(0) == ESCAPE_C; } private static String mangle(String s) { if (s.length() == 0) return NULL_ESCAPE; // build this lazily, when we first need an escape: StringBuilder sb = null; for (int i = 0, slen = s.length(); i < slen; i++) { char c = s.charAt(i); boolean needEscape = false; if (c == ESCAPE_C) { if (i+1 < slen) { char c1 = s.charAt(i+1); if ((i == 0 && c1 == NULL_ESCAPE_C) || c1 != originalOfReplacement(c1)) { // an accidental escape needEscape = true; } } } else { needEscape = isDangerous(c); } if (!needEscape) { if (sb != null) sb.append(c); continue; } // build sb if this is the first escape if (sb == null) { sb = new StringBuilder(s.length()+10); // mangled names must begin with a backslash: if (s.charAt(0) != ESCAPE_C && i > 0) sb.append(NULL_ESCAPE); // append the string so far, which is unremarkable: sb.append(s.substring(0, i)); } // rewrite \ to \-, / to \|, etc. sb.append(ESCAPE_C); sb.append(replacementOf(c)); } if (sb != null) return sb.toString(); return s; } private static String demangle(String s) { // build this lazily, when we first meet an escape: StringBuilder sb = null; int stringStart = 0; if (s.startsWith(NULL_ESCAPE)) stringStart = 2; for (int i = stringStart, slen = s.length(); i < slen; i++) { char c = s.charAt(i); if (c == ESCAPE_C && i+1 < slen) { // might be an escape sequence char rc = s.charAt(i+1); char oc = originalOfReplacement(rc); if (oc != rc) { // build sb if this is the first escape if (sb == null) { sb = new StringBuilder(s.length()); // append the string so far, which is unremarkable: sb.append(s.substring(stringStart, i)); } ++i; // skip both characters c = oc; } } if (sb != null) sb.append(c); } if (sb != null) return sb.toString(); return s.substring(stringStart); } static char ESCAPE_C = '\\'; // empty escape sequence to avoid a null name or illegal prefix static char NULL_ESCAPE_C = '='; static String NULL_ESCAPE = ESCAPE_C+""+NULL_ESCAPE_C; static final String DANGEROUS_CHARS = "\\/.;:$[]<>"; // \\ must be first static final String REPLACEMENT_CHARS = "-|,?!%{}^_"; static final int DANGEROUS_CHAR_FIRST_INDEX = 1; // index after \\ static char[] DANGEROUS_CHARS_A = DANGEROUS_CHARS.toCharArray(); static char[] REPLACEMENT_CHARS_A = REPLACEMENT_CHARS.toCharArray(); static final Character[] DANGEROUS_CHARS_CA; static { Character[] dcca = new Character[DANGEROUS_CHARS.length()]; for (int i = 0; i < dcca.length; i++) dcca[i] = Character.valueOf(DANGEROUS_CHARS.charAt(i)); DANGEROUS_CHARS_CA = dcca; } static final long[] SPECIAL_BITMAP = new long[2]; // 128 bits static { String SPECIAL = DANGEROUS_CHARS + REPLACEMENT_CHARS; //System.out.println("SPECIAL = "+SPECIAL); for (char c : SPECIAL.toCharArray()) { SPECIAL_BITMAP[c >>> 6] |= 1L << c; } } static boolean isSpecial(char c) { if ((c >>> 6) < SPECIAL_BITMAP.length) return ((SPECIAL_BITMAP[c >>> 6] >> c) & 1) != 0; else return false; } static char replacementOf(char c) { if (!isSpecial(c)) return c; int i = DANGEROUS_CHARS.indexOf(c); if (i < 0) return c; return REPLACEMENT_CHARS.charAt(i); } static char originalOfReplacement(char c) { if (!isSpecial(c)) return c; int i = REPLACEMENT_CHARS.indexOf(c); if (i < 0) return c; return DANGEROUS_CHARS.charAt(i); } static boolean isDangerous(char c) { if (!isSpecial(c)) return false; return (DANGEROUS_CHARS.indexOf(c) >= DANGEROUS_CHAR_FIRST_INDEX); } static int indexOfDangerousChar(String s, int from) { for (int i = from, slen = s.length(); i < slen; i++) { if (isDangerous(s.charAt(i))) return i; } return -1; } static int lastIndexOfDangerousChar(String s, int from) { for (int i = Math.min(from, s.length()-1); i >= 0; i--) { if (isDangerous(s.charAt(i))) return i; } return -1; } }