I need to read data added to the end of an executable from within that executable .
On win32 I have a problem that I cannot open the .exe for reading. I have tried CreateFile and std::ifstream.
Is there a way of specifying non-exclusive read access to a file that wasn't initially opened with sharing.
EDIT- Great thing about stackoverflow, you ask the wrong question and get the right answer.
Why not just use resources which are designed for this functionality. It won't be at the end, but it will be in the executable.
If you are adding to the .exe after it is built -- you don't have to add to the end, you can update resources on a built .exe
http://msdn.microsoft.com/en-us/library/ms648049(VS.85).aspx
We do this in one of our projects. What's the problem with it? If the EXE is running, then it's already held open for reading, and you can continue to open it read-only multiple times. I just checked our code, we just use:
HANDLE file=CreateFile(filename, GENERIC_READ, FILE_SHARE_READ, 0, OPEN_EXISTING, 0, 0);
This works without problem on all versions of 32- and 64-bit Windows to date.
I have no problem opening the executable image of a process using either of these statements:
FILE* f = fopen( fname, "rb");
hFile = CreateFile( fname, FILE_READ_DATA, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
What's your code?
Related
Is there a way to determine with C+++ if any file is open in a given directory tree?
Cmd.exe knows instantly if I attempt to rename a folder and a file within that directory tree is currently open. I've used API Monitor to determine that cmd.exe uses NtOpenFile() followed by NtSetInformationFile with FileRenameInformation and that returns STATUS_ACCESS_DENIED when a file is open but I've not been able to determine what's happening at a lower level.
I'm trying to ensure no files are open before beginning a batch process without having to check each file individually as there could be hundreds of thousands of files in the directory tree.
Can anyone expand on this?
Thanks,
Steve Thresher.
You will have to check each file individually, I think. That said, this should do it:
HANDLE hFile = CreateFile
(my_filename, GENERIC_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (hFile == INVALID_HANDLE_VALUE)
{
DWORD err = GetLastError ();
if (err == ERROR_SHARING_VIOLATION)
{
// File is already open
}
}
else
CloseHandle (hFile);
Note that dwShareMode is passed as 0, which prevents Windows opening the file if it is already opened elsewhere.
I am having an issue with my application as while reading a file that consists of Unicode characters too. As I am using the CreateFileA method to get the data but it doesn't get the Unicode characters properly for which I am facing a lot of issues. Also, I don't know the difference between CreateFileA and CreateFileW.
I'm sorry I couldn't able to share my code. I will share my that portion of code with you.
HANDLE systemFileHandle = INVALID_HANDLE_VALUE;
systemFileHandle = CreateFileA(Filename, GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
char* inBuffer=new char[totalFileSize+2];
memset(inBuffer, 0, totalFileSize+2);
ReadFile(systemFileHandle, inBuffer, totalFileSize, &bytesRead, nullptr);
And, I am getting the results on inBuffer array be like : Fernw�rmestationSW Au�en.
Can't I get it the original way they are?
So can you please help me out with this. It can be very helpful.
CreateFileA takes an ANSI-based file name, while CreateFileW takes a Unicode-based file name. There's nothing to say about the content of the file, both will return a HANDLE to the file where you can then read/write Unicode content as needed.
so I am new to the whole c++ windows API. I'm creating a simple dialogbox in which the user types in a directory into a textbox for a time file which has already been created. the program will then read the file and display the time in another edit control. Im having a few problems making the directory entered the parameter for CreateFile(). If I hard code the directory in, the program will work correctly. But I cant figure out how to take the textbox data and plug it into the CreateFile() function. if this doesn't make sense i can try an explain differently. Ive searched an can't seem to find anything.
Thanks
for example:
if the user types c:\test\time.txt into the text box I want "c:\test\time.txt" to be the put into CreateFile();
CHAR temp[20] = "";
HANDLE hFile;
GetDlgItemText(hDlg, IDC_TEXTIN, temp, 20);//IDC_TEXTIN is name of edit control
//open file
hFile = CreateFile(
temp,
GENERIC_READ | GENERIC_WRITE,
0, // no sharing
NULL, // no security
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL // no template
);
I wrote a simple XOR crypter and need help with fixing the crypted file's sharing permissions.
Basically, the output file from Builder.exe has a state of Shared. I have to change the file's share permissions to Nobody before I can run it.
Is there something wrong with the way I'm using Windows API?
This is the code for the handle that I wrote:
HANDLE efile = CreateFile(name, GENERIC_ALL,FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
Full source code on GitHub: https://github.com/Jyang772/XOR_Crypter
Error message:
I shouldnt be able to delete a file with an open handle, correct? So i create a file, then i straight away try to delete it, expecting this to fail. Or am i wrong and the handle doesnt have to be closed before deleting the file?
HANDLE hFile = CreateFile (TEXT(file),
GENERIC_WRITE,
0,
NULL,
OPEN_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (hFile == INVALID_HANDLE_VALUE)
{
//FAIL
}
if(DeleteFile(file))
{
//Should it ever get here cos i dont close the handle?
}
It depends on how the file has been opened. If the share mode has FILE_SHARE_DELETE specified, then it may be deleted by others.
Even if you memory map the file, and it has been opened with this flag (and read/write sharing), then it can still be deleted by the shell (at least I've tried this and it happens, but perhaps the file has simply been renamed and moved to the recycle bin). In such cases, subsequently accessing the memory will result in an 'InPageError' C-style exception.
Yes, it would fail.
The DeleteFile function fails if an application attempts to delete a
file that is open for normal I/O or as a memory-mapped file.
Have you tried this? MS documentation states that:
The DeleteFile function fails if an application attempts to delete a file that is open for normal I/O or as a memory-mapped file.
So if you're not getting that behaviour I'd suggest it's down to the way you've opened the file. Are you sure that your check on whether the file is open is completely comprehensive?Have you tried writing to the file first? Can you see the file outside of your own code? (i.e. from Explorer) Look here for more details.