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// Copyright (c) 2009, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ---
// Author: Craig Silverstein
//
// This forks out to pprof to do the actual symbolizing. We might
// be better off writing our own in C++.
#include "config.h"
#include "symbolize.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h> // for write()
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h> // for socketpair() -- needed by Symbolize
#endif
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h> // for wait() -- needed by Symbolize
#endif
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#include <string>
#include "base/commandlineflags.h"
#include "base/sysinfo.h"
using std::string;
using tcmalloc::DumpProcSelfMaps; // from sysinfo.h
DEFINE_string(symbolize_pprof,
EnvToString("PPROF_PATH", "pprof"),
"Path to pprof to call for reporting function names.");
// heap_profile_table_pprof may be referenced after destructors are
// called (since that's when leak-checking is done), so we make
// a more-permanent copy that won't ever get destroyed.
static string* g_pprof_path = new string(FLAGS_symbolize_pprof);
// Updates symbolization_table with the pointers to symbol names corresponding
// to its keys. The symbol names are stored in out, which is allocated and
// freed by the caller of this routine.
// Note that the forking/etc is not thread-safe or re-entrant. That's
// ok for the purpose we need -- reporting leaks detected by heap-checker
// -- but be careful if you decide to use this routine for other purposes.
extern bool Symbolize(char *out, int out_size,
SymbolMap *symbolization_table) {
#if !defined(HAVE_UNISTD_H) || !defined(HAVE_SYS_SOCKET_H) || !defined(HAVE_SYS_WAIT_H)
return false;
#elif !defined(HAVE_PROGRAM_INVOCATION_NAME)
return false; // TODO(csilvers): get argv[0] somehow
#else
// All this work is to do two-way communication. ugh.
extern char* program_invocation_name; // gcc provides this
int child_in[2]; // file descriptors
int child_out[2]; // for now, we don't worry about child_err
if (socketpair(AF_UNIX, SOCK_STREAM, 0, child_in) == -1) {
return false;
}
if (socketpair(AF_UNIX, SOCK_STREAM, 0, child_out) == -1) {
close(child_in[0]);
close(child_in[1]);
return false;
}
switch (fork()) {
case -1: { // error
close(child_in[0]);
close(child_in[1]);
close(child_out[0]);
close(child_out[1]);
return false;
}
case 0: { // child
close(child_in[1]); // child uses the 0's, parent uses the 1's
close(child_out[1]); // child uses the 0's, parent uses the 1's
close(0);
close(1);
if (dup2(child_in[0], 0) == -1) _exit(1);
if (dup2(child_out[0], 1) == -1) _exit(2);
// Unset vars that might cause trouble when we fork
unsetenv("CPUPROFILE");
unsetenv("HEAPPROFILE");
unsetenv("HEAPCHECK");
unsetenv("PERFTOOLS_VERBOSE");
execlp(g_pprof_path->c_str(), g_pprof_path->c_str(),
"--symbols", program_invocation_name, NULL);
_exit(3); // if execvp fails, it's bad news for us
}
default: { // parent
close(child_in[0]); // child uses the 0's, parent uses the 1's
close(child_out[0]); // child uses the 0's, parent uses the 1's
#ifdef HAVE_POLL_H
// For maximum safety, we check to make sure the execlp
// succeeded before trying to write. (Otherwise we'll get a
// SIGPIPE.) For systems without poll.h, we'll just skip this
// check, and trust that the user set PPROF_PATH correctly!
struct pollfd pfd = { child_in[1], POLLOUT, 0 };
if (!poll(&pfd, 1, 0) || !(pfd.revents & POLLOUT) ||
(pfd.revents & (POLLHUP|POLLERR))) {
return false;
}
#endif
DumpProcSelfMaps(child_in[1]); // what pprof expects on stdin
char pcstr[64]; // enough for a single address
for (SymbolMap::const_iterator iter = symbolization_table->begin();
iter != symbolization_table->end(); ++iter) {
snprintf(pcstr, sizeof(pcstr), // pprof expects format to be 0xXXXXXX
"0x%" PRIxPTR "\n", iter->first);
// TODO(glider): the number of write()s can be reduced by using
// snprintf() here.
write(child_in[1], pcstr, strlen(pcstr));
}
close(child_in[1]); // that's all we need to write
int total_bytes_read = 0;
memset(out, '\0', out_size);
while (1) {
int bytes_read = read(child_out[1], out + total_bytes_read,
out_size - total_bytes_read);
if (bytes_read < 0) {
close(child_out[1]);
return false;
} else if (bytes_read == 0) {
close(child_out[1]);
wait(NULL);
break;
} else {
total_bytes_read += bytes_read;
}
}
// We have successfully read the output of pprof into out. Make sure
// the last symbol is full (we can tell because it ends with a \n).
// TODO(glider): even when the last symbol is full, the list of symbols
// may be incomplete. We should check for that and return the number of
// symbols we actually get from pprof.
if (total_bytes_read == 0 || out[total_bytes_read - 1] != '\n')
return false;
// make the symbolization_table values point to the output vector
SymbolMap::iterator fill = symbolization_table->begin();
const char *current_name = out;
for (int i = 0; i < total_bytes_read; i++) {
if (out[i] == '\n') {
fill->second = current_name;
out[i] = '\0';
current_name = out + i + 1;
fill++;
}
}
return true;
}
}
return false; // shouldn't be reachable
#endif
}
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