#include <windows.h>
int main()
{
CreateSymbolicLink(L"d:\\symbolic_link_to_notepad.exe",
L"c:\\windows\\notepad.exe", 0); // Success!
}
However, when I double-click d:\symbolic_link_to_notepad.exe to start notepad, an error message box pops and says the path is not found.
What's the root cause?
Related
Hello and good evening ,
This is centered for FTP File upload using C++. I have been trying to upload an FTP File and i get Error 12003 been searching out on the web, i havent seen anything useful.. seems annoying.
My code looks like this
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <wininet.h>
#pragma comment (lib, "wininet.lib")
int main()
{
HINTERNET hInternet;
HINTERNET hFtpSession;
hInternet = InternetOpen(NULL, INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0);
if(!hInternet)
{
printf("Error : %d\n",GetLastError());
}
hFtpSession = InternetConnect(hInternet, "myohyip8.5gbfree.com", INTERNET_DEFAULT_FTP_PORT, "myohyip8", "WxqHjNGv", INTERNET_SERVICE_FTP, 0, 0);
if(!hFtpSession)
{
printf("Error : %d\n",GetLastError());
}
if (!FtpPutFile(hFtpSession, "C:\\ivan.txt", "myivan.txt", FTP_TRANSFER_TYPE_BINARY, 0))
{
printf("Error : %d\n", GetLastError());
}
else{
printf("File Upload Successful :)\n");
}
InternetCloseHandle(hFtpSession);
InternetCloseHandle(hInternet);
system("PAUSE");
return 0;
}
This has been giving me worries, i dont have a single Idea on where to go from here , seems to me like a file system error.
The first thing I do when troubleshooting an ftp problem is to try getting a regular ftp program (e.g. filezilla, or whatever) to connect and perform the same operation on that same machine. If it can connect, you'll be able to see a log of the server conversation in that software that will give you good parameters to work with. If you cannot connect, you'll see in that same log what the problem might be.
Without using such software to be sure, my best guess is that have a problem trying to connect in regular mode and you should be in passive (essentially a firewall issue). You can pass in INTERNET_FLAG_PASSIVE in the 2nd to last parameter of your InternetConnect call. That will switch it to passive mode.
e.g.
hFtpSession = InternetConnect(hInternet, "myohyip8.5gbfree.com", INTERNET_DEFAULT_FTP_PORT, "myohyip8", "WxqHjNGv", INTERNET_SERVICE_FTP, INTERNET_FLAG_PASSIVE, 0);
In Windows environments (XP and Win 7):
What is the best way to automatically have a crash dump generated when processes crash on the system?
Can an installer (MSI) package do this?
One of the best way to have an automatic dump for any/specific process on Windows is to configure a set of entries in the registry. I tried the below on Windows 7 64 bit.
Open notepad.exe, paste the below entry and save it as "EnableDump.reg". You can give any name you wish.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps]
"DumpFolder"=hex(2):44,00,3a,00,5c,00,64,00,75,00,6d,00,70,00,00,00
"DumpCount"=dword:00000010
"DumpType"=dword:00000002
"CustomDumpFlags"=dword:00000000
Double click the "EnableDump.reg" and select 'Yes'. I have given the dump folder as 'd:\dump'. You can change it to whatever folder you wish.
Try to execute a crashing application, Windows will display the error dialog. Choose 'Close the Program' option. After that you will see the dump in the configured folder. The name of the dump file will be .exe..dmp.
For more details, you can refer the below link.
http://msdn.microsoft.com/en-us/library/bb787181(VS.85).aspx
Below explanation is based on another answer, but the logic is mine (without attribution need, as said on my profile);
Having your own dump generation framework which automatically creates a process dump when any Unhandled exception is encountered, would avoid clients having to install WinDbg.
At the application start up use SetUnhandledExceptionFilter(...) Win32 API to register a callback (i.e. application level exception-handler).
Now the registered callback function is called whenever there is any exception which is not handled. You may then create the process dump using MiniDumpWriteDump(...) API from DbgHelp.dll.
C++ Sample (unicode-enabled)
header-file
#ifndef CRASH_REPORTER_H
#define CRASH_REPORTER_H
//Exclude rarely used content from the Windows headers.
#ifndef WIN32_LEAN_AND_MEAN
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# undef WIN32_LEAN_AND_MEAN
#else
# include <windows.h>
#endif
#include <tchar.h>
#include <DbgHelp.h>
class CrashReporter {
public:
inline CrashReporter() { Register(); }
inline ~CrashReporter() { Unregister(); }
inline static void Register() {
if(m_lastExceptionFilter != NULL) {
fprintf(stdout, "CrashReporter: is already registered\n");
fflush(stdout);
}
SetErrorMode(SEM_FAILCRITICALERRORS);
//ensures UnHandledExceptionFilter is called before App dies.
m_lastExceptionFilter = SetUnhandledExceptionFilter(UnHandledExceptionFilter);
}
inline static void Unregister() {
SetUnhandledExceptionFilter(m_lastExceptionFilter);
}
private:
static LPTOP_LEVEL_EXCEPTION_FILTER m_lastExceptionFilter;
static LONG WINAPI UnHandledExceptionFilter(_EXCEPTION_POINTERS *);
};
#endif // CRASH_REPORTER_H
source-file
#include "crash-report.h"
#include <stdio.h>
LPTOP_LEVEL_EXCEPTION_FILTER CrashReporter::m_lastExceptionFilter = NULL;
typedef BOOL (WINAPI *MiniDumpWriteDumpFunc)(HANDLE hProcess, DWORD ProcessId
, HANDLE hFile
, MINIDUMP_TYPE DumpType
, const MINIDUMP_EXCEPTION_INFORMATION *ExceptionInfo
, const MINIDUMP_USER_STREAM_INFORMATION *UserStreamInfo
, const MINIDUMP_CALLBACK_INFORMATION *Callback
);
LONG WINAPI CrashReporter::UnHandledExceptionFilter(struct _EXCEPTION_POINTERS *exceptionPtr)
{
//we load DbgHelp.dll dynamically, to support Windows 2000
HMODULE hModule = ::LoadLibraryA("DbgHelp.dll");
if (hModule) {
MiniDumpWriteDumpFunc dumpFunc = reinterpret_cast<MiniDumpWriteDumpFunc>(
::GetProcAddress(hModule, "MiniDumpWriteDump")
);
if (dumpFunc) {
//fetch system time for dump-file name
SYSTEMTIME SystemTime;
::GetLocalTime(&SystemTime);
//choose proper path for dump-file
wchar_t dumpFilePath[MAX_PATH] = {0};
_snwprintf_s(dumpFilePath, MAX_PATH, L"crash_%04d-%d-%02d_%d-%02d-%02d.dmp"
, SystemTime.wYear, SystemTime.wMonth, SystemTime.wDay
, SystemTime.wHour, SystemTime.wMinute, SystemTime.wSecond
);
//create and open the dump-file
HANDLE hFile = ::CreateFileW( dumpFilePath, GENERIC_WRITE
, FILE_SHARE_WRITE
, NULL
, CREATE_ALWAYS
, FILE_ATTRIBUTE_NORMAL | FILE_ATTRIBUTE_HIDDEN
, NULL
);
if (hFile != INVALID_HANDLE_VALUE) {
_MINIDUMP_EXCEPTION_INFORMATION exceptionInfo;
exceptionInfo.ThreadId = GetCurrentThreadId();
exceptionInfo.ExceptionPointers = exceptionPtr;
exceptionInfo.ClientPointers = NULL;
//at last write crash-dump to file
bool ok = dumpFunc(::GetCurrentProcess(), ::GetCurrentProcessId()
, hFile, MiniDumpNormal
, &exceptionInfo, NULL, NULL
);
//dump-data is written, and we can close the file
CloseHandle(hFile);
if (ok) {
//Return from UnhandledExceptionFilter and execute the associated exception handler.
// This usually results in process termination.
return EXCEPTION_EXECUTE_HANDLER;
}
}
}
}
//Proceed with normal execution of UnhandledExceptionFilter.
// That means obeying the SetErrorMode flags,
// or invoking the Application Error pop-up message box.
return EXCEPTION_CONTINUE_SEARCH;
}
usage
#include "3rdParty/crash-report.h"
int main(int argc, char *argv[])
{
CrashReporter crashReporter;
(void)crashReporter; //prevents unused warnings
// [application main loop should be here]
return 0;
}
Windows XP:
The following steps enable automatic crash dumps:
1) Open a command prompt, running as administrator
2) Run drwtsn32 -i. This will install Doctor Watson as the default debugger when something crashes
3) Click Ok
4) From the command prompt, run drwtsn32
5) Set the Crash Dump path to your favorite directory, or leave the default.
6) Set the Crash Dump Type to mini. Note that under some circumstances, we may ask you for a full crash dump.
7) Make sure the Dump All Thread Contexts and Create Crash Dump File options are selected.
8) Click Ok
9) If a user.dmp file already exists in the Crash Dump path, delete it.
Windows 7: Location is:
C:\Users[Current User when app crashed]\AppData\Local\Microsoft\Windows\WER\ReportArchive
I am trying to build my first opencv application, I added the include directories and the library directories and then added the linking input which is some opencv.lib files after running this code:
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
using namespace cv;
using namespace std;
int main()
{
Mat im = imread("c:/full/path/to/lena.jpg");
if (im.empty())
{
cout << "Cannot load image!" << endl;
return -1;
}
imshow("Image", im);
waitKey(0);
}
but I got this error:
The program can't start because libgcc_s_dw2-1.dll is missing from your computer.
the error list include:
Warning 1 warning D9002: ignoring unknown option '-static-libgcc' c:\Users\Kato\documents\visual studio 2010\Projects\cvtest\cvtest\cl cvtest
I added -static-libgcc to command line additional options but the same error.
According to the link below, I wrote a small test case. But it doesn't work. Any idea is appreciated!
Reference:
http://www.cppprog.com/boost_doc/doc/html/interprocess/synchronization_mechanisms.html#interprocess.synchronization_mechanisms.file_lock.file_lock_careful_iostream
#include <iostream>
#include <fstream>
#include <boost/interprocess/sync/file_lock.hpp>
#include <boost/interprocess/sync/scoped_lock.hpp>
using namespace std;
using namespace boost::interprocess;
int main()
{
ofstream file_out("fileLock.txt");
file_lock f_lock("fileLock.txt");
{
scoped_lock<file_lock> e_lock(f_lock); // it works if I comment this out
file_out << 10;
file_out.flush();
file_out.close();
}
return 0;
}
Running the test on Linux produces your desired output. I notice these two warnings:
The page you reference has this warning: "If you are using a std::fstream/native file handle to write to the file while using file locks on that file, don't close the file before releasing all the locks of the file."
Boost::file_lock apparently uses LockFileEx on Windows. MSDN has this to say: "If the locking process opens the file a second time, it cannot access the specified region through this second handle until it unlocks the region."
It seems like, on Windows at least, the file lock is per-handle, not per-file. As near as I can tell, that means that your program is guaranteed to fail under Windows.
Your code appears to be susceptible to this long-standing bug on the boost trac site: https://svn.boost.org/trac/boost/ticket/2796
The title of that bug is "interprocess::file_lock has incorrect behavior when win32 api is enabled".
Here is a workaround to append in a file with a file locking based on Boost 1.44.
#include "boost/format.hpp"
#include "boost/interprocess/detail/os_file_functions.hpp"
namespace ip = boost::interprocess;
namespace ipc = boost::interprocess::detail;
void fileLocking_withHandle()
{
static const string filename = "fileLocking_withHandle.txt";
// Get file handle
boost::interprocess::file_handle_t pFile = ipc::create_or_open_file(filename.c_str(), ip::read_write);
if ((pFile == 0 || pFile == ipc::invalid_file()))
{
throw runtime_error(boost::str(boost::format("File Writer fail to open output file: %1%") % filename).c_str());
}
// Lock file
ipc::acquire_file_lock(pFile);
// Move writing pointer to the end of the file
ipc::set_file_pointer(pFile, 0, ip::file_end);
// Write in file
ipc::write_file(pFile, (const void*)("bla"), 3);
// Unlock file
ipc::release_file_lock(pFile);
// Close file
ipc::close_file(pFile);
}
I usually use XCode but was having a problem opening a file with this code:
#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
int main(void )
{
printf("Hello");
FILE *filePtr;
filePtr = fopen( "test.txt", "r" );
if (filePtr == NULL)
{
fprintf(stderr, "Can't open \"test\"\n");
exit(EXIT_FAILURE);
}
else
{
int x;
printf("File open successful\n");
/* read one character at a time until EOF is reached */
while ((x = fgetc(filePtr)) != EOF)
{
//printf("%c", x);
fprintf(stderr, "%x\n",x);
}
}
fclose(filePtr);
system("pause");
return EXIT_FAILURE;
}
The console window closes so fast and at the bottom bar of VS it says: "'C_test.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_f863c71f\msvcr90d.dll'
The program '[1116] C_test.exe: Native' has exited with code 1 (0x1)."
What does that mean?
Also, can anyone point me to good VS starting points / tutorials?
See also How to keep the console window open in Visual C++?
The reason you can't see it is because there is no possibility for your program to pause during execution. In Visual Studio the typical behavior is to close the console window the second the program has completed its execution.
The bottom bar is telling you that the program complete and what the return value was (1 in this case).
What I would also do is add code right before the exit point of the program with #ifdefs:
#ifdef VS_DEBUG
fgetc(STDIN);
#endif
Now your program will pause when it's done and wait for a keypress then close the window.
I'm sure there is also a way in the project settings to prevent the closing, I've never looked myself.
I generally leave a breakpoint on the closing brace of main, so that the output of my window is visible while debugging, but Visual Studio will keep the console window open if you start the program without debugging (Ctrl+F5). Alternatively, you could simply ask for input, #MadcapLaugher's fgetc(STDIN); is probably your best bet - though I would add a prompt: "Press any key to continue... "
#include<stdio.h>
int main()
{
printf("Hello World from visual Studio \n");
//to prevent console window temination
system("pause");
return 0;
}