tracechild.cc revision 8108
1/* 2 * Copyright (c) 2006-2007 The Regents of The University of Michigan 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Gabe Black 29 */ 30 31#include "tracechild.hh" 32#include <cstring> 33#include <errno.h> 34#include <iostream> 35#include <sys/ptrace.h> 36#include <sys/wait.h> 37 38using namespace std; 39 40bool 41TraceChild::startTracing(const char * pathToFile, char * const argv[]) 42{ 43 instructions = 0; 44 pid = fork(); 45 if (pid == -1) { 46 cout << "fork failed" << endl; 47 return false; 48 } else if (pid == 0) { 49 //We're the child. Get things ready and then exec the program to trace. 50 //Let our parent trace us 51 if (ptrace(PTRACE_TRACEME, 0, 0, 0) == -1) { 52 cout << "Failure calling TRACEME\n" << strerror(errno) << endl; 53 return false; 54 } 55 56 //Set up an empty environment for the child... We would want to 57 //specify this somehow at some point 58 char * env[] = {NULL}; 59 60 //Start the program to trace 61 execve(pathToFile, argv, env); 62 63 //We should never get here, so this is an error! 64 cout << "Exec failed\n" << strerror(errno) << endl; 65 return false; 66 } 67 68 //From this point forward, we know we're in the parent process. 69 if (!doWait()) { 70 cout << "Didn't wait successfully" << endl; 71 return false; 72 } 73 tracing = true; 74 return true; 75} 76 77bool 78TraceChild::stopTracing() 79{ 80 if (ptrace(PTRACE_KILL, pid, 0, 0) != 0) 81 return false; 82 tracing = false; 83 return true; 84} 85 86bool 87TraceChild::step() 88{ 89 ptraceSingleStep(); 90} 91 92bool 93TraceChild::ptraceSingleStep() 94{ 95 if (!tracing) { 96 cout << "Not tracing!" << endl; 97 return false; 98 } 99 if (ptrace(PTRACE_SINGLESTEP, pid, 0, 0) != 0) { 100 switch (errno) { 101 case EBUSY: cout << "EBUSY" << endl; break; 102 case EFAULT: cout << "EFAULT" << endl; break; 103 case EIO: cout << "EIO" << endl; break; 104 case EPERM: cout << "EPERM" << endl; break; 105 case ESRCH: cout << "ESRCH" << endl; break; 106 default: cout << "Unknown error" << endl; break; 107 } 108 cout << "Not able to single step!" << endl; 109 tracing == false; 110 return false; 111 } 112 doWait(); 113 update(pid); 114} 115 116bool 117TraceChild::doWait() 118{ 119 int wait_val; 120 wait(&wait_val); 121 if (WIFEXITED(wait_val)) { 122 cerr << "Program exited! Exit status is " 123 << WEXITSTATUS(wait_val) << endl; 124 cerr << "Executed " << instructions 125 << " instructions." << endl; 126 tracing = false; 127 return false; 128 } 129 if (WIFSIGNALED(wait_val)) { 130 if (WTERMSIG(wait_val)) 131 cerr << "Program terminated by signal " 132 << WTERMSIG(wait_val) << endl; 133 if (WCOREDUMP(wait_val)) 134 cerr << "Program core dumped!" << endl; 135 tracing = false; 136 cerr << "Executed " << instructions 137 << " instructions." << endl; 138 return false; 139 } 140 if (WIFSTOPPED(wait_val) && WSTOPSIG(wait_val) != SIGTRAP) { 141 cerr << "Program stopped by signal " << WSTOPSIG(wait_val) << endl; 142 tracing = false; 143 cerr << "Executed " << instructions << " instructions." << endl; 144 return false; 145 } 146 return true; 147} 148