cosmopolitan/tool/build/lib/demangle.c

123 lines
4.4 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ 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; version 2 of the License. │
│ │
│ This program 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 for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/safemacros.internal.h"
#include "libc/calls/calls.h"
#include "libc/calls/hefty/spawn.h"
#include "libc/calls/struct/iovec.h"
#include "libc/macros.h"
#include "libc/runtime/runtime.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"
#include "tool/build/lib/demangle.h"
struct CxxFilt {
int pid;
int fds[3];
} g_cxxfilt;
void CloseCxxFilt(void) {
close(g_cxxfilt.fds[0]);
close(g_cxxfilt.fds[1]);
g_cxxfilt.pid = -1;
}
void SpawnCxxFilt(void) {
int pid;
const char *cxxfilt;
char path[PATH_MAX];
cxxfilt = firstnonnull(getenv("CXXFILT"), "c++filt");
if (commandv(cxxfilt, path)) {
g_cxxfilt.fds[0] = -1;
g_cxxfilt.fds[1] = -1;
g_cxxfilt.fds[2] = 2;
if ((pid = spawnve(0, g_cxxfilt.fds, path, (char *const[]){cxxfilt, NULL},
environ)) != -1) {
atexit(CloseCxxFilt);
}
} else {
pid = -1;
}
g_cxxfilt.pid = pid;
}
char *CopySymbol(char *p, size_t pn, const char *s, size_t sn) {
size_t extra;
bool showdots, iscomplicated;
assert(pn >= 1 + 3 + 1 + 1);
iscomplicated = memchr(s, ' ', sn) || memchr(s, '(', sn);
extra = 1;
if (iscomplicated) extra += 2;
if (sn + extra > pn) {
sn = pn - extra - 3;
showdots = true;
} else {
showdots = false;
}
if (iscomplicated) *p++ = '"';
p = mempcpy(p, s, sn);
if (showdots) p = stpcpy(p, "...");
if (iscomplicated) *p++ = '"';
*p = '\0';
return p;
}
char *DemangleCxxFilt(char *p, size_t pn, const char *s, size_t sn) {
ssize_t rc;
size_t got;
struct iovec iov[2];
static char buf[PAGESIZE];
if (!g_cxxfilt.pid) SpawnCxxFilt();
if (g_cxxfilt.pid == -1) return NULL;
buf[0] = '\n';
iov[0].iov_base = s;
iov[0].iov_len = sn;
iov[1].iov_base = buf;
iov[1].iov_len = 1;
writev(g_cxxfilt.fds[0], iov, ARRAYLEN(iov));
if ((rc = read(g_cxxfilt.fds[1], buf, sizeof(buf))) != -1) {
got = rc;
if (got >= 2 && buf[got - 1] == '\n') {
if (buf[got - 2] == '\r') --got;
--got;
return CopySymbol(p, pn, buf, got);
}
}
CloseCxxFilt();
return NULL;
}
/**
* Decrypts C++ symbol.
*
* Decoding these takes roughly the same lines of code as an entire
* x86_64 disassembler. That's just for the GNU encoding scheme. So
* what we'll do, is just offload this work to the c++filt program.
*/
char *Demangle(char *p, const char *symbol, size_t n) {
char *r;
size_t sn;
sn = strlen(symbol);
if (startswith(symbol, "_Z")) {
if ((r = DemangleCxxFilt(p, n, symbol, sn))) return r;
}
return CopySymbol(p, n, symbol, sn);
}