libiberty: Add Rust symbol demangling.

Adds Rust symbol demangler. Rust mangles symbols using GNU_V3 style,
adding a hash and various special character subtitutions. This adds
a new rust style to cplus_demangle and adds 3 helper functions
rust_demangle, rust_demangle_sym and rust_is_mangled.

rust-demangle.c was written by David. Mark did the code formatting to
GNU style and integration into the gcc/libiberty build system and
testsuite.

include/ChangeLog:

2016-11-03  David Tolnay <dtolnay@gmail.com>
           Mark Wielaard  <mark@klomp.org>

       * demangle.h (DMGL_RUST): New macro.
       (DMGL_STYLE_MASK): Add DMGL_RUST.
       (demangling_styles): Add dlang_rust.
       (RUST_DEMANGLING_STYLE_STRING): New macro.
       (RUST_DEMANGLING): New macro.
       (rust_demangle): New prototype.
       (rust_is_mangled): Likewise.
       (rust_demangle_sym): Likewise.

libiberty/ChangeLog:

2016-11-03  David Tolnay <dtolnay@gmail.com>
           Mark Wielaard  <mark@klomp.org>

       * Makefile.in (CFILES): Add rust-demangle.c.
       (REQUIRED_OFILES): Add rust-demangle.o.
       * cplus-dem.c (libiberty_demanglers): Add rust_demangling case.
       (cplus_demangle): Handle RUST_DEMANGLING.
       (rust_demangle): New function.
       * rust-demangle.c: New file.
       * testsuite/Makefile.in (really-check): Add check-rust-demangle.
       (check-rust-demangle): New rule.
       * testsuite/rust-demangle-expected: New file.

Co-Authored-By: Mark Wielaard <mark@klomp.org>

From-SVN: r242524

1 files changed, 348 insertions, 0 deletions

diff --git a/libiberty/rust-demangle.c b/libiberty/rust-demangle.c
new file mode 100644
index 00000000000..326881e48f7
--- /dev/null
+++ b/libiberty/rust-demangle.c
@@ -0,0 +1,348 @@
+/* Demangler for the Rust programming language
+   Copyright 2016 Free Software Foundation, Inc.
+   Written by David Tolnay (dtolnay@gmail.com).
+
+This file is part of the libiberty library.
+Libiberty is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+In addition to the permissions in the GNU Library General Public
+License, the Free Software Foundation gives you unlimited permission
+to link the compiled version of this file into combinations with other
+programs, and to distribute those combinations without any restriction
+coming from the use of this file.  (The Library Public License
+restrictions do apply in other respects; for example, they cover
+modification of the file, and distribution when not linked into a
+combined executable.)
+
+Libiberty 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with libiberty; see the file COPYING.LIB.
+If not, see <http://www.gnu.org/licenses/>.  */
+
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "safe-ctype.h"
+
+#include <sys/types.h>
+#include <string.h>
+#include <stdio.h>
+
+#ifdef HAVE_STRING_H
+#include <string.h>
+#else
+extern size_t strlen(const char *s);
+extern int strncmp(const char *s1, const char *s2, size_t n);
+extern void *memset(void *s, int c, size_t n);
+#endif
+
+#include <demangle.h>
+#include "libiberty.h"
+
+
+/* Mangled Rust symbols look like this:
+     _$LT$std..sys..fd..FileDesc$u20$as$u20$core..ops..Drop$GT$::drop::hc68340e1baa4987a
+
+   The original symbol is:
+     <std::sys::fd::FileDesc as core::ops::Drop>::drop
+
+   The last component of the path is a 64-bit hash in lowercase hex,
+   prefixed with "h". Rust does not have a global namespace between
+   crates, an illusion which Rust maintains by using the hash to
+   distinguish things that would otherwise have the same symbol.
+
+   Any path component not starting with a XID_Start character is
+   prefixed with "_".
+
+   The following escape sequences are used:
+
+   ","  =>  $C$
+   "@"  =>  $SP$
+   "*"  =>  $BP$
+   "&"  =>  $RF$
+   "<"  =>  $LT$
+   ">"  =>  $GT$
+   "("  =>  $LP$
+   ")"  =>  $RP$
+   " "  =>  $u20$
+   "\"" =>  $u22$
+   "'"  =>  $u27$
+   "+"  =>  $u2b$
+   ";"  =>  $u3b$
+   "["  =>  $u5b$
+   "]"  =>  $u5d$
+   "{"  =>  $u7b$
+   "}"  =>  $u7d$
+   "~"  =>  $u7e$
+
+   A double ".." means "::" and a single "." means "-".
+
+   The only characters allowed in the mangled symbol are a-zA-Z0-9 and _.:$  */
+
+static const char *hash_prefix = "::h";
+static const size_t hash_prefix_len = 3;
+static const size_t hash_len = 16;
+
+static int is_prefixed_hash (const char *start);
+static int looks_like_rust (const char *sym, size_t len);
+static int unescape (const char **in, char **out, const char *seq, char value);
+
+/* INPUT: sym: symbol that has been through C++ (gnu v3) demangling
+
+   This function looks for the following indicators:
+
+   1. The hash must consist of "h" followed by 16 lowercase hex digits.
+
+   2. As a sanity check, the hash must use between 5 and 15 of the 16
+      possible hex digits. This is true of 99.9998% of hashes so once
+      in your life you may see a false negative. The point is to
+      notice path components that could be Rust hashes but are
+      probably not, like "haaaaaaaaaaaaaaaa". In this case a false
+      positive (non-Rust symbol has an important path component
+      removed because it looks like a Rust hash) is worse than a false
+      negative (the rare Rust symbol is not demangled) so this sets
+      the balance in favor of false negatives.
+
+   3. There must be no characters other than a-zA-Z0-9 and _.:$
+
+   4. There must be no unrecognized $-sign sequences.
+
+   5. There must be no sequence of three or more dots in a row ("...").  */
+
+int
+rust_is_mangled (const char *sym)
+{
+  size_t len, len_without_hash;
+
+  if (!sym)
+    return 0;
+
+  len = strlen (sym);
+  if (len <= hash_prefix_len + hash_len)
+    /* Not long enough to contain "::h" + hash + something else */
+    return 0;
+
+  len_without_hash = len - (hash_prefix_len + hash_len);
+  if (!is_prefixed_hash (sym + len_without_hash))
+    return 0;
+
+  return looks_like_rust (sym, len_without_hash);
+}
+
+/* A hash is the prefix "::h" followed by 16 lowercase hex digits. The
+   hex digits must comprise between 5 and 15 (inclusive) distinct
+   digits.  */
+
+static int
+is_prefixed_hash (const char *str)
+{
+  const char *end;
+  char seen[16];
+  size_t i;
+  int count;
+
+  if (strncmp (str, hash_prefix, hash_prefix_len))
+    return 0;
+  str += hash_prefix_len;
+
+  memset (seen, 0, sizeof(seen));
+  for (end = str + hash_len; str < end; str++)
+    if (*str >= '0' && *str <= '9')
+      seen[*str - '0'] = 1;
+    else if (*str >= 'a' && *str <= 'f')
+      seen[*str - 'a' + 10] = 1;
+    else
+      return 0;
+
+  /* Count how many distinct digits seen */
+  count = 0;
+  for (i = 0; i < 16; i++)
+    if (seen[i])
+      count++;
+
+  return count >= 5 && count <= 15;
+}
+
+static int
+looks_like_rust (const char *str, size_t len)
+{
+  const char *end = str + len;
+
+  while (str < end)
+    switch (*str)
+      {
+      case '$':
+	if (!strncmp (str, "$C$", 3))
+	  str += 3;
+	else if (!strncmp (str, "$SP$", 4)
+		 || !strncmp (str, "$BP$", 4)
+		 || !strncmp (str, "$RF$", 4)
+		 || !strncmp (str, "$LT$", 4)
+		 || !strncmp (str, "$GT$", 4)
+		 || !strncmp (str, "$LP$", 4)
+		 || !strncmp (str, "$RP$", 4))
+	  str += 4;
+	else if (!strncmp (str, "$u20$", 5)
+		 || !strncmp (str, "$u22$", 5)
+		 || !strncmp (str, "$u27$", 5)
+		 || !strncmp (str, "$u2b$", 5)
+		 || !strncmp (str, "$u3b$", 5)
+		 || !strncmp (str, "$u5b$", 5)
+		 || !strncmp (str, "$u5d$", 5)
+		 || !strncmp (str, "$u7b$", 5)
+		 || !strncmp (str, "$u7d$", 5)
+		 || !strncmp (str, "$u7e$", 5))
+	  str += 5;
+	else
+	  return 0;
+	break;
+      case '.':
+	/* Do not allow three or more consecutive dots */
+	if (!strncmp (str, "...", 3))
+	  return 0;
+	/* Fall through */
+      case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
+      case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
+      case 'm': case 'n': case 'o': case 'p': case 'q': case 'r':
+      case 's': case 't': case 'u': case 'v': case 'w': case 'x':
+      case 'y': case 'z':
+      case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
+      case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':
+      case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':
+      case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
+      case 'Y': case 'Z':
+      case '0': case '1': case '2': case '3': case '4': case '5':
+      case '6': case '7': case '8': case '9':
+      case '_':
+      case ':':
+	str++;
+	break;
+      default:
+	return 0;
+      }
+
+  return 1;
+}
+
+/*
+  INPUT: sym: symbol for which rust_is_mangled(sym) returned 1.
+
+  The input is demangled in-place because the mangled name is always
+  longer than the demangled one.  */
+
+void
+rust_demangle_sym (char *sym)
+{
+  const char *in;
+  char *out;
+  const char *end;
+
+  if (!sym)
+    return;
+
+  in = sym;
+  out = sym;
+  end = sym + strlen (sym) - (hash_prefix_len + hash_len);
+
+  while (in < end)
+    switch (*in)
+      {
+      case '$':
+	if (!(unescape (&in, &out, "$C$", ',')
+	      || unescape (&in, &out, "$SP$", '@')
+	      || unescape (&in, &out, "$BP$", '*')
+	      || unescape (&in, &out, "$RF$", '&')
+	      || unescape (&in, &out, "$LT$", '<')
+	      || unescape (&in, &out, "$GT$", '>')
+	      || unescape (&in, &out, "$LP$", '(')
+	      || unescape (&in, &out, "$RP$", ')')
+	      || unescape (&in, &out, "$u20$", ' ')
+	      || unescape (&in, &out, "$u22$", '\"')
+	      || unescape (&in, &out, "$u27$", '\'')
+	      || unescape (&in, &out, "$u2b$", '+')
+	      || unescape (&in, &out, "$u3b$", ';')
+	      || unescape (&in, &out, "$u5b$", '[')
+	      || unescape (&in, &out, "$u5d$", ']')
+	      || unescape (&in, &out, "$u7b$", '{')
+	      || unescape (&in, &out, "$u7d$", '}')
+	      || unescape (&in, &out, "$u7e$", '~'))) {
+	  /* unexpected escape sequence, not looks_like_rust. */
+	  goto fail;
+	}
+	break;
+      case '_':
+	/* If this is the start of a path component and the next
+	   character is an escape sequence, ignore the underscore. The
+	   mangler inserts an underscore to make sure the path
+	   component begins with a XID_Start character. */
+	if ((in == sym || in[-1] == ':') && in[1] == '$')
+	  in++;
+	else
+	  *out++ = *in++;
+	break;
+      case '.':
+	if (in[1] == '.')
+	  {
+	    /* ".." becomes "::" */
+	    *out++ = ':';
+	    *out++ = ':';
+	    in += 2;
+	  }
+	else
+	  {
+	    /* "." becomes "-" */
+	    *out++ = '-';
+	    in++;
+	  }
+	break;
+      case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
+      case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
+      case 'm': case 'n': case 'o': case 'p': case 'q': case 'r':
+      case 's': case 't': case 'u': case 'v': case 'w': case 'x':
+      case 'y': case 'z':
+      case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
+      case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':
+      case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':
+      case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
+      case 'Y': case 'Z':
+      case '0': case '1': case '2': case '3': case '4': case '5':
+      case '6': case '7': case '8': case '9':
+      case ':':
+	*out++ = *in++;
+	break;
+      default:
+	/* unexpected character in symbol, not looks_like_rust.  */
+	goto fail;
+      }
+  goto done;
+
+fail:
+  *out++ = '?'; /* This is pretty lame, but it's hard to do better. */
+done:
+  *out = '\0';
+}
+
+static int
+unescape (const char **in, char **out, const char *seq, char value)
+{
+  size_t len = strlen (seq);
+
+  if (strncmp (*in, seq, len))
+    return 0;
+
+  **out = value;
+
+  *in += len;
+  *out += 1;
+
+  return 1;
+}