在我开启另一个问题之前，这个问题与我几天前开的另一个问题有关：
C++ Program Always Crashes While doing a std::string assign
根据一些答案进一步调查后，我提出了更多问题和更多可能有助于调试问题的信息。
所以这里......
问题代码：
bool peopleSProtocol::SignalProtocolCreated(BaseProtocol *pProtocol,
Variant customParameters) {
LOG("peopleSProtocol::SignalProtocolCreated");
SetOutboundConnectParameters(customParameters);
// Tie up the peopleSProtocol Instance to the BaseOutboundStream Instance.
BaseClientApplication *pApplication = ClientApplicationManager::FindAppByName("peoplestreamer");
std::string lStreamName;
printf("1b [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str()); // line 217
SetApplication(pApplication); // line 218
printf("1c [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str()); // line 219
BaseRTAppProtocolHandler *pProtocolHandler = (BaseRTAppProtocolHandler *)pApplication->GetProtocolHandler(PT_OUTBOUNDRT);
printf("1d [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
uint32_t protocolId = customParameters["customParameters"]["outboundRTProtocolId"];
uint32_t streamId = customParameters["customParameters"]["streamId"];
printf("1d [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
BaseOutboundStream *lpBaseOutboundStream = (BaseOutboundStream*)pProtocolHandler->FindByProtocolIdById(protocolId,streamId);
printf("1e [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
RegisterOutboundStream(lpBaseOutboundStream);
printf("2 [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
// Get the address of our peer (the RT peer, NOT the peopleS peer)...
int32_t lRTClientFd = lpBaseOutboundStream->GetProtocol()->GetIOHandler()->GetFd();
struct sockaddr_in lPeerAddressStruct;
int lPeerLength = sizeof(lPeerAddressStruct);
getpeername(lRTClientFd,(sockaddr*)&lPeerAddressStruct,(socklen_t*)&lPeerLength);
string lPeerIpAddressString = inet_ntoa(lPeerAddressStruct.sin_addr);
uint16_t lPeerPort = ntohs(lPeerAddressStruct.sin_port);
printf("3 [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
// Get the name of the file in accordance with the RT spec...
GetStreamName(STR(M_INVOKE_PARAM(customParameters,1)), lStreamName); // line 247
return SendPlayCommand(lStreamName,lPeerIpAddressString,lPeerPort);
}
bool peopleSProtocol::GetStreamName(const char* pRawPath, std::string &pStreamName)
{
vector<string> parts = split(pRawPath,"/"); // line 260
pStreamName = parts.back(); // line 261
parts = split(pStreamName.c_str(),":");
pStreamName = parts.back();
return true;
}
#define ADD_VECTOR_END(v,i) (v).push_back((i))
vector<string> split(string str, string separator) {
vector<string> result;
string::size_type position = str.find(separator);
uint32_t separatorLength = separator.length();
while (position != str.npos) {
string temp = str.substr(0, position);
ADD_VECTOR_END(result, temp);
str = str.substr(position + separatorLength);
position = str.find(separator);
}
ADD_VECTOR_END(result, str);
return result;
}
GDB回溯：
(gdb) b 217
Breakpoint 3, peopleSProtocol::SignalProtocolCreated (this=0x3c52020, pProtocol=<value optimized out>, customParameters=@0x413f9eb0) at peopleRTstreamer/src/peoplesprotocol.cpp:217
217 printf("1b [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
(gdb) p lStreamName
$1 = {static npos = 18446744073709551615, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data fields>}, _M_p = 0x3c52020 "\220R̪�*"}}
(gdb) c
[DEBUG] cpeopleTcpConnection - Connected to 127.0.0.1:37255
[DEBUG] cpeopleTcpConnection - Connected from server address : 127.0.0.1
[New Thread 1096964416 (LWP 10941)]
Breakpoint 4, peopleSProtocol::SignalProtocolCreated (this=0x3c52020, pProtocol=<value optimized out>, customParameters=@0x413f9eb0) at peopleRTstreamer/src/peoplesprotocol.cpp:218
218 SetApplication(pApplication);
(gdb) p lStreamName
$2 = {static npos = 18446744073709551615, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data fields>}, _M_p = 0x2abbad098e78 ""}}
(gdb) c
Breakpoint 5, peopleSProtocol::SignalProtocolCreated (this=0x3c52020, pProtocol=<value optimized out>, customParameters=@0x413f9eb0) at peopleRTstreamer/src/peoplesprotocol.cpp:219
219 printf("1c [%d] [%s]", (int) lStreamName.size(), lStreamName.c_str());
(gdb) p lStreamName
$3 = {static npos = 18446744073709551615, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data fields>}, _M_p = 0x2abbad098e78 ""}}
(gdb) c
[New Thread 1097099584 (LWP 11010)]
1b [0] []1c [0] []1d [0] []1d [0] [][DEBUG] peopleStreamingServer.RTServer - Opening connection from 127.0.0.1
[DEBUG] peopleStreamingServer.RTServer - Using server IP address 127.0.0.1
Breakpoint 6, peopleSProtocol::SignalProtocolCreated (this=0x3c52020, pProtocol=<value optimized out>, customParameters=@0x413f9eb0) at peopleRTstreamer/src/peoplesprotocol.cpp:247
247 GetStreamName(STR(M_INVOKE_PARAM(customParameters,1)), lStreamName);
(gdb) p lStreamName
$4 = {static npos = 18446744073709551615, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data fields>}, _M_p = 0x2abbad098e78 ""}}
(gdb) c
Breakpoint 7, peopleSProtocol::GetStreamName (this=0x3c52020, pRawPath=0x3c40808 "RT://127.0.0.1/mp4:popeye.mp4", pStreamName=@0x413f9e10) at peopleRTstreamer/src/peoplesprotocol.cpp:260
260 vector<string> parts = split(pRawPath,"/");
(gdb) p pStreamName
$5 = (string &) @0x413f9e10: {static npos = 18446744073709551615, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No data fields>},
_M_p = 0x2abbad098e78 ""}}
(gdb) c
*** glibc detected *** /home/ml01/t-live/TEngine/StreamingServer/.libs/peoplestreamingserver: free(): invalid pointer: 0x00002abbad098e60 ***
======= Backtrace: =========
/lib64/libc.so.6[0x3560871634]
/lib64/libc.so.6(cfree+0x8c)[0x3560874c5c]
/home/ml01/t-HEAD/gcc/4.2.4/lib/../lib64/libstdc++.so.6(_ZNSs6assignERKSs+0x90)[0x2abbace3fd20]
/home/ml01/usr/local/lib/RTserver/libpeopleRTstreamer.so(_ZN12peopleSProtocol13GetStreamNameEPKcRSs+0x9a)[0x2aaaaaabd16a]
/home/ml01/usr/local/lib/RTserver/libpeopleRTstreamer.so(_ZN12peopleSProtocol21SignalProtocolCreatedEP12BaseProtocol7Variant+0x2e4)[0x2aaaaaabd894]
/home/ml01/usr/local/lib/RTserver/libpeopleRTstreamer.so(_ZN12TCPConnectorI12peopleSProtocolE7OnEventER11epoll_event+0x1a6)[0x2aaaaaabf046]
/home/ml01/t-HEAD/cRTserver/20091229/lib/libthelib.so(_ZN16IOHandlerManager5PulseEv+0x4a6)[0x2abbad425620]
/home/ml01/usr/local/lib/libpeopleRT.so.0(_ZN3people15cRTServerLoop19RTProtocolHandlerEv+0x55)[0x2abba2d2df45]
/home/ml01/usr/local/lib/libpeopleRT.so.0(_Z19HandleTrafficThreadPv+0x9)[0x2abba2d2e009]
/home/ml01/t-HEAD/glib/2.18.0/lib/libglib-2.0.so.0[0x2abbabc84394]
/lib64/libpthread.so.0[0x35614062f7]
/lib64/libc.so.6(clone+0x6d)[0x35608d1b6d]
(gdb) where
#0 0x0000003560830155 in raise () from /lib64/libc.so.6
#1 0x0000003560831bf0 in abort () from /lib64/libc.so.6
#2 0x000000356086a38b in __libc_message () from /lib64/libc.so.6
#3 0x0000003560871634 in _int_free () from /lib64/libc.so.6
#4 0x0000003560874c5c in free () from /lib64/libc.so.6
#5 0x00002abbace3fd20 in std::string::assign (this=0x413f9e10, __str=<value optimized out>) at /home/ml01/ThirdParty/sources/gcc-4.2.4/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/basic_string.h:238
#6 0x00002aaaaaabd16a in peopleSProtocol::GetStreamName (this=<value optimized out>, pRawPath=0x3c40808 "RT://127.0.0.1/mp4:popeye.mp4", pStreamName=@0x413f9e10)
at /home/ml01/t-HEAD/gcc/4.2.4/lib/gcc/x86_64-pc-linux-gnu/4.2.4/../../../../include/c++/4.2.4/bits/basic_string.h:491
#7 0x00002aaaaaabd894 in peopleSProtocol::SignalProtocolCreated (this=0x3c52020, pProtocol=<value optimized out>, customParameters=@0x413f9eb0) at peopleRTstreamer/src/peoplesprotocol.cpp:247
#8 0x00002aaaaaabf046 in TCPConnector<peopleSProtocol>::OnEvent (this=0x3c40aa0, event=<value optimized out>) at /home/ml01/t-HEAD/cRTserver/20091229/include/cRTserver/netio/epoll/tcpconnector.h:90
#9 0x00002abbad425620 in IOHandlerManager::Pulse () at /home/ml01/ThirdParty/sources/cRTserver/sources/thelib/src/netio/epoll/iohandlermanager.cpp:260
#10 0x00002abba2d2df45 in people::cRTServerLoop::RTProtocolHandler (this=0x3c4c180) at src/RTServerLoop.cpp:77
#11 0x00002abba2d2e009 in HandleTrafficThread (ipData=0x60bc) at src/RTServerLoop.cpp:39
#12 0x00002abbabc84394 in g_thread_create_proxy (data=0x3c4e060) at gthread.c:635
#13 0x00000035614062f7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000035608d1b6d in clone () from /lib64/libc.so.6
因此，为了解释上述情况，在字符串分配期间，第261行（请参阅代码中的行号注释）发生崩溃。由于某种原因，它试图释放无效的记忆，但我不确定为什么？它试图释放的地址不是我认为是第217行分配的空字符串的地址（_M_p = 0x3c52020设置为_M_p = 0x2abbad098e78，即空字符串），但其他一些地址不太远。
任何可能导致此问题的想法？我想知道这是否可能是一个优化问题，因为它不会出现在-O0中，我通过一系列测试运行代码，试图找到一大堆内存损坏问题，可能会导致这种奇怪的行为......空手而归！
另一个有趣的注意事项是，如果我设置std :: string lStreamName =“”;而不是std :: string lStreamName;该程序不再崩溃???什么可能导致这个？为什么这个字符串的简单初始化会消除崩溃？
谢谢！
答案 0 :(得分：2)
如果不保证split不返回空向量，我会添加一个检查是否为空。否则，将空向量的back（）分配给字符串可能会导致您收到的行为。
bool GetStreamName(const char* pRawPath, std::string& pStreamName)
{
std::vector<std::string> parts = split(pRawPath,'/'); // line 260
if( parts.size() == 0 )
{
cout << "Cannot parse '" << pRawPaths << "'" << endl;
return false;
}
pStreamName = parts.back(); // line 261
parts = split(pStreamName.c_str(),':');
pStreamName = parts.back();
return true;
}
答案 1 :(得分：0)
您应尝试使用自包含示例重现崩溃。使用您提供给我们的信息，我测试了以下代码。
请注意，我需要一个split功能。不知道你用了什么，我从this question拿了一个。如果您使用自己撰写的boost::split或split函数，请将其包含在您的问题中。
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
std::vector<std::string> &split(const std::string &s, char delim, std::vector<std::string> &elems) {
std::stringstream ss(s);
std::string item;
while(std::getline(ss, item, delim)) {
elems.push_back(item);
}
return elems;
}
std::vector<std::string> split(const std::string &s, char delim) {
std::vector<std::string> elems;
return split(s, delim, elems);
}
bool GetStreamName(const char* pRawPath, std::string& pStreamName)
{
std::vector<std::string> parts = split(pRawPath,'/'); // line 260
pStreamName = parts.back(); // line 261
parts = split(pStreamName.c_str(),':');
pStreamName = parts.back();
return true;
}
int main()
{
std::string streamName;
GetStreamName("/some:weird/path/of:x/a:/stream:foo", streamName);
std::cout << streamName << std::endl;
}
尝试运行此代码（使用-O2，您可以想到任何g ++优化，使用valgrind等）并查看它是否再次崩溃。
使用一个简单的自包含示例，您可以确定崩溃的来源是否是您的代码中的错误或其他任何错误（例如冲突的C ++库，就像您在上一个问题中所做的那样）。