Copyright (C) 2000-2015 Julian Seward
jseward@acm.org
+ Rust demangler components are
+ Copyright (C) 2016-2016 David Tolnay
+ dtolnay@gmail.com
+
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
#include "vg_libciface.h"
#include "demangle.h"
+/* fwds */
+static Bool rust_is_mangled ( const HChar* );
+static void rust_demangle_sym ( HChar* );
+
+
+/*------------------------------------------------------------*/
+/*--- ---*/
+/*------------------------------------------------------------*/
+
/* The demangler's job is to take a raw symbol name and turn it into
- something a Human Bean can understand. There are two levels of
- mangling.
+ something a Human Bean can understand. Our mangling model
+ comprises a three stage pipeline. Mangling pushes names forward
+ through the pipeline (0, then 1, then 2) and demangling is
+ obviously the reverse. In practice it is highly unlikely that a
+ name would require all stages, but it is not impossible either.
+
+ 0. If we're working with Rust, Rust names are lightly mangled by
+ the Rust front end.
- 1. First, C++ names are mangled by the compiler. So we'll have to
- undo that.
+ 1. Then the name is subject to standard C++ mangling.
2. Optionally, in relatively rare cases, the resulting name is then
itself encoded using Z-escaping (see pub_core_redir.h) so as to
Therefore, VG_(demangle) first tries to undo (2). If successful,
the soname part is discarded (humans don't want to see that).
- Then, it tries to undo (1) (using demangling code from GNU/FSF).
+ Then, it tries to undo (1) (using demangling code from GNU/FSF) and
+ finally it tries to undo (0).
- Finally, change the name of all symbols which are known to be
+ Finally, it changes the name of all symbols which are known to be
functions below main() to "(below main)". This helps reduce
variability of stack traces, something which has been a problem for
the testsuite for a long time.
--------
- If do_cxx_demangle == True, does all the above stages:
+ If do_cxx_demangle == True, it does all the above stages:
- undo (2) [Z-encoding]
- undo (1) [C++ mangling]
+ - if (1) succeeds, undo (0) [Rust mangling]
- do the below-main hack
- If do_cxx_demangle == False, the middle stage is skipped:
+ Rust demangling (0) is only done if C++ demangling (1) succeeds
+ because Rust demangling is performed in-place, and it is difficult
+ to prove that we "own" the storage -- hence, that the in-place
+ operation is safe -- unless it is clear that it has come from the
+ C++ demangler, which returns its output in a heap-allocated buffer
+ which we can be sure we own. In practice (Nov 2016) this does not
+ seem to be a problem, since the Rust compiler appears to apply C++
+ mangling after Rust mangling, so we never encounter symbols that
+ require Rust demangling but not C++ demangling.
+
+ If do_cxx_demangle == False, the C++ and Rust stags are skipped:
- undo (2) [Z-encoding]
- do the below-main hack
*/
that buffer is owned by VG_(demangle). That means two things:
(1) Users of VG_(demangle) must not free that buffer.
(2) If the demangled name needs to be stashed away for later use,
- the contents of the buffer needs to be copied. It is not sufficient
+ the contents of the buffer need to be copied. It is not sufficient
to just store the pointer as it will point to deallocated memory
after the next VG_(demangle) invocation. */
void VG_(demangle) ( Bool do_cxx_demangling, Bool do_z_demangling,
/* Possibly undo (1) */
if (do_cxx_demangling && VG_(clo_demangle)) {
+ /* !!! vvv STATIC vvv !!! */
static HChar* demangled = NULL;
+ /* !!! ^^^ STATIC ^^^ !!! */
/* Free up previously demangled name */
- if (demangled) VG_(arena_free) (VG_AR_DEMANGLE, demangled);
-
+ if (demangled) {
+ VG_(arena_free) (VG_AR_DEMANGLE, demangled);
+ demangled = NULL;
+ }
demangled = ML_(cplus_demangle) ( orig, DMGL_ANSI | DMGL_PARAMS );
*result = (demangled == NULL) ? orig : demangled;
+
+ if (demangled) {
+ /* Possibly undo (0). This is the only place where it is
+ safe, from a storage management perspective, to
+ Rust-demangle the symbol. That's because Rust demangling
+ happens in place, so we need to be sure that the storage
+ it is happening in is actually owned by us, and non-const.
+ In this case, the value returned by ML_(cplus_demangle)
+ does have that property. */
+ if (rust_is_mangled(demangled)) {
+ rust_demangle_sym(demangled);
+ }
+ *result = demangled;
+ } else {
+ *result = orig;
+ }
+
} else {
*result = orig;
}
}
+/*------------------------------------------------------------*/
+/*--- DEMANGLE RUST NAMES ---*/
+/*------------------------------------------------------------*/
+
+/*
+ * 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 HChar *hash_prefix = "::h";
+static const SizeT hash_prefix_len = 3;
+static const SizeT hash_len = 16;
+
+static Bool is_prefixed_hash(const HChar *start);
+static Bool looks_like_rust(const HChar *sym, SizeT len);
+static Bool unescape(const HChar **in, HChar **out,
+ const HChar *seq, HChar value);
+
+/*
+ * INPUT:
+ * sym: symbol that has been through BFD-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 $-sign sequences.
+ *
+ * 5. There must be no sequence of three or more dots in a row ("...").
+ */
+static Bool rust_is_mangled(const HChar *sym)
+{
+ SizeT len, len_without_hash;
+
+ if (!sym)
+ return False;
+
+ len = VG_(strlen)(sym);
+ if (len <= hash_prefix_len + hash_len)
+ /* Not long enough to contain "::h" + hash + something else */
+ return False;
+
+ len_without_hash = len - (hash_prefix_len + hash_len);
+ if (!is_prefixed_hash(sym + len_without_hash))
+ return False;
+
+ return looks_like_rust(sym, len_without_hash);
+}
+
+/*
+ * A hash is the prefix "::h" followed by 16 lowercase hex digits. The hex
+ * digits must comprise between 5 and 15 (inclusive) distinct digits.
+ */
+static Bool is_prefixed_hash(const HChar *str)
+{
+ const HChar *end;
+ Bool seen[16];
+ SizeT i;
+ Int count;
+
+ if (VG_(strncmp)(str, hash_prefix, hash_prefix_len))
+ return False;
+ str += hash_prefix_len;
+
+ VG_(memset)(seen, False, sizeof(seen));
+ for (end = str + hash_len; str < end; str++)
+ if (*str >= '0' && *str <= '9')
+ seen[*str - '0'] = True;
+ else if (*str >= 'a' && *str <= 'f')
+ seen[*str - 'a' + 10] = True;
+ else
+ return False;
+
+ /* Count how many distinct digits seen */
+ count = 0;
+ for (i = 0; i < 16; i++)
+ if (seen[i])
+ count++;
+
+ return count >= 5 && count <= 15;
+}
+
+static Bool looks_like_rust(const HChar *str, SizeT len)
+{
+ const HChar *end = str + len;
+
+ while (str < end) {
+ switch (*str) {
+ case '$':
+ if (!VG_(strncmp)(str, "$C$", 3))
+ str += 3;
+ else if (!VG_(strncmp)(str, "$SP$", 4)
+ || !VG_(strncmp)(str, "$BP$", 4)
+ || !VG_(strncmp)(str, "$RF$", 4)
+ || !VG_(strncmp)(str, "$LT$", 4)
+ || !VG_(strncmp)(str, "$GT$", 4)
+ || !VG_(strncmp)(str, "$LP$", 4)
+ || !VG_(strncmp)(str, "$RP$", 4))
+ str += 4;
+ else if (!VG_(strncmp)(str, "$u20$", 5)
+ || !VG_(strncmp)(str, "$u22$", 5)
+ || !VG_(strncmp)(str, "$u27$", 5)
+ || !VG_(strncmp)(str, "$u2b$", 5)
+ || !VG_(strncmp)(str, "$u3b$", 5)
+ || !VG_(strncmp)(str, "$u5b$", 5)
+ || !VG_(strncmp)(str, "$u5d$", 5)
+ || !VG_(strncmp)(str, "$u7b$", 5)
+ || !VG_(strncmp)(str, "$u7d$", 5)
+ || !VG_(strncmp)(str, "$u7e$", 5))
+ str += 5;
+ else
+ return False;
+ break;
+ case '.':
+ /* Do not allow three or more consecutive dots */
+ if (!VG_(strncmp)(str, "...", 3))
+ return False;
+ /* Fall through */
+ case 'a' ... 'z':
+ case 'A' ... 'Z':
+ case '0' ... '9':
+ case '_':
+ case ':':
+ str++;
+ break;
+ default:
+ return False;
+ }
+ }
+
+ return True;
+}
+
+/*
+ * INPUT:
+ * sym: symbol for which rust_is_mangled(sym) returns True
+ *
+ * The input is demangled in-place because the mangled name is always longer
+ * than the demangled one.
+ */
+static void rust_demangle_sym(HChar *sym)
+{
+ const HChar *in;
+ HChar *out;
+ const HChar *end;
+
+ if (!sym)
+ return;
+
+ const SizeT sym_len = VG_(strlen)(sym);
+ const HChar* never_after = sym + sym_len;
+
+ in = sym;
+ out = sym;
+ end = sym + sym_len - (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$", '~'))) {
+ goto fail;
+ }
+ break;
+ case '_':
+ /*
+ * If this is the start of a path component and the next
+ * character is an escape sequence, ignore the
+ * underscore. The mangler inserts an underscore to make
+ * sure the path component begins with a XID_Start
+ * character.
+ */
+ if ((in == sym || in[-1] == ':') && in[1] == '$')
+ in++;
+ else
+ *out++ = *in++;
+ break;
+ case '.':
+ if (in[1] == '.') {
+ /* ".." becomes "::" */
+ *out++ = ':';
+ *out++ = ':';
+ in += 2;
+ } else {
+ /* "." becomes "-" */
+ *out++ = '-';
+ in++;
+ }
+ break;
+ case 'a' ... 'z':
+ case 'A' ... 'Z':
+ case '0' ... '9':
+ case ':':
+ *out++ = *in++;
+ break;
+ default:
+ goto fail;
+ }
+ }
+ goto done;
+
+ fail:
+ *out++ = '?'; /* This is pretty lame, but it's hard to do better. */
+ done:
+ *out++ = '\0';
+
+ vg_assert(out <= never_after);
+}
+
+static Bool unescape(const HChar **in, HChar **out,
+ const HChar *seq, HChar value)
+{
+ SizeT len = VG_(strlen)(seq);
+
+ if (VG_(strncmp)(*in, seq, len))
+ return False;
+
+ **out = value;
+
+ *in += len;
+ *out += 1;
+
+ return True;
+}
+
+
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
projects / thirdparty / valgrind.git / commitdiff
