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/*
* Copyright (c) 2006-2007 The Regents of The University of Michigan
* 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 the copyright holders 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.
*
* Authors: Gabe Black
*/
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <cerrno>
#include <cstring>
#include <iostream>
#include "tracechild.hh"
using namespace std;
bool
TraceChild::startTracing(const char * pathToFile, char * const argv[])
{
instructions = 0;
pid = fork();
if (pid == -1) {
cout << "fork failed" << endl;
return false;
} else if (pid == 0) {
//We're the child. Get things ready and then exec the program to trace.
//Let our parent trace us
if (ptrace(PTRACE_TRACEME, 0, 0, 0) == -1) {
cout << "Failure calling TRACEME\n" << strerror(errno) << endl;
return false;
}
//Set up an empty environment for the child... We would want to
//specify this somehow at some point
char * env[] = {NULL};
//Start the program to trace
execve(pathToFile, argv, env);
//We should never get here, so this is an error!
cout << "Exec failed\n" << strerror(errno) << endl;
return false;
}
//From this point forward, we know we're in the parent process.
if (!doWait()) {
cout << "Didn't wait successfully" << endl;
return false;
}
tracing = true;
return true;
}
bool
TraceChild::stopTracing()
{
if (ptrace(PTRACE_KILL, pid, 0, 0) != 0)
return false;
tracing = false;
return true;
}
bool
TraceChild::step()
{
ptraceSingleStep();
}
bool
TraceChild::ptraceSingleStep()
{
if (!tracing) {
cout << "Not tracing!" << endl;
return false;
}
if (ptrace(PTRACE_SINGLESTEP, pid, 0, 0) != 0) {
switch (errno) {
case EBUSY: cout << "EBUSY" << endl; break;
case EFAULT: cout << "EFAULT" << endl; break;
case EIO: cout << "EIO" << endl; break;
case EPERM: cout << "EPERM" << endl; break;
case ESRCH: cout << "ESRCH" << endl; break;
default: cout << "Unknown error" << endl; break;
}
cout << "Not able to single step!" << endl;
tracing = false;
return false;
}
doWait();
update(pid);
}
bool
TraceChild::doWait()
{
int wait_val;
wait(&wait_val);
if (WIFEXITED(wait_val)) {
cerr << "Program exited! Exit status is "
<< WEXITSTATUS(wait_val) << endl;
cerr << "Executed " << instructions
<< " instructions." << endl;
tracing = false;
return false;
}
if (WIFSIGNALED(wait_val)) {
if (WTERMSIG(wait_val))
cerr << "Program terminated by signal "
<< WTERMSIG(wait_val) << endl;
if (WCOREDUMP(wait_val))
cerr << "Program core dumped!" << endl;
tracing = false;
cerr << "Executed " << instructions
<< " instructions." << endl;
return false;
}
if (WIFSTOPPED(wait_val) && WSTOPSIG(wait_val) != SIGTRAP) {
cerr << "Program stopped by signal " << WSTOPSIG(wait_val) << endl;
tracing = false;
cerr << "Executed " << instructions << " instructions." << endl;
return false;
}
return true;
}
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