I am trying to use fopen() in a program in which I am creating a new file and then using that file into another function. The function is created as follows:-
FILE* check=NULL;
check =fopen(convert_wchartoString(file_Name.c_str()).c_str(), "rb");
if(check==NULL)
{
cout<<"Unable to open";
}
Now, the issue is that fopen is returning NULL in linux but, in windows it is working. I am not sure why this issue is coming. I have debugged the value of file_name and it is coming fine on both the platforms. Please advice something which could be potentially wrong in this?
UPDATE:-
Seems like it is a path issue. Currently, the file_name has path to C:\files but when i try to run the same code in wsl, it doesn't work. The path in wsl is /mnt/c/files. But when trying to give this path to file_name. It is also not working. Is there any permission issues for the same or should I need to modify the path?
Related
Wrote the .pdf file to the disk by using fopen and fwrite.
FILE * fp = fopen("/Users/test/Documents/1.pdf", "w+");
if (fp) {
fwrite(pdf_data, size_of_pdf_data, 1, fp);
fclose(fp);
}
And then open 1.pdf within Preview.app by using applescript.
system("osascript -e \'tell app \"Preview\" to open \"/Users/test/Documents/1.pdf\"");
when the system function executes, the file permission issue occurred like the following image:
File Permission Issue
How can I fix this issue? I am using macOS Catalina 10.15.7 and xcode 11.3.1.
AppleScript is 100% completely the wrong tool for this job.
Were you in ObjC you’d use NSWorkspace. Since you’re in C[++], use LaunchServices’ LSOpenFromURLSpec.
So I am running a C++ app, built with CMake (not by me). It works fine on other people testing with it, but not found anyone to test on centos7 yet.
The issue seems to arrise at this snippet of code:
struct stat fileStat;
if ( stat( pszFilePath, &fileStat) == -1 )
{
DEBUG_ERR(( "Can't open input dir [%s]\n", pszFilePath ));
return( false );
}
Which is the first part of the ReadFileInfo call here:
time_t dateChange;
DWORD dwSize;
if ( ! CFileList::ReadFileInfo( GetFilePath(), dateChange, dwSize ))
{
DEBUG_ERR(( "Can't get stats info for file '%s'\n", static_cast<LPCTSTR>(GetFilePath()) ));
return false;
}
Now, pszFilePath is many value, a few examples are:
'scripts/sphere_template_vend.scp'
'scripts/sphere_serv_triggers.scp'
The application is owned by root, the whole folder it all sits in is owned by root. The scripts folder is there and has read/write permissions as do all files (all also owned by root)
Running the application triggers both errors in the above code, there is nothing before them that influences anything.
Im not a C++ developer and do not have the tools to compile with debugs for checking the current path and so on, but I see no reason why it throws these errors. The files exist, the files are accessible, no one else seems to have this problem.
I do have cPanel on the server, but it shouldn't be causing any issues as I am using root user and also keeping out of the /home/ directory
Anyone know of any issue this could be because of? I tried with a '/sphere/' prepending the paths but it still has the same issue, it seems the application does not have access to the files (the application oddly reports line errors within the files it says it cannot read, but they do not match, so assuming its not correct).
Issue reported on the Github for the project here: https://github.com/Sphereserver/Source/issues/64
But no one seems to know whats going on
Problem: my C++ program cannot write to a file after reboot because it is denied access.
The program is added into the registry at the following location, thus enabling it during start up:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
The following snipper within the code is similar to the one that is causing the problems:
ofstream myfile;
myfile.open ("example.txt", ios:app);
myfile << "Writing this to a file.\n";
myfile.close();
Because this snippet of code runs within a loop the file is repeatedly opened and closed, but when the computer is rebooted the program seems to loose file permissions to it, and .open says it got an Acess Denied error with respect to the file.
What is the problem here? How come the program runs when it is initiated by me without admin rights, but not when Windows initiates it?
As I understand the problem is not in C++ libs but in rights that your application has when windows run it. So, try the following:
1) create shortcut for your exe-file;
2) in HKEY_CURRENT_USER\...\Run change name of application from *.exe to *.lnk (just to run application with help of shortcut);
3) in the shortcut's properties in the Advanced Security Settings section change OWNER to SYSTEM.
perhaps this helps.
"example.txt" is relative to your working directory, which is probably different when run at startup. Add a hardcoded path to test this hypothesis.
I'm trying to compile and run the app, which was created 4 years ago. It was developed for Windows in Embarcadero RAD Studio C++ builder. Now I try to compile and run it in Windows in VirtualBox using the latest version of RAD Studio. I have a system call to another app in my app:
system("dot.exe -Tjpg -o nfa.jpg NFA_graph.txt");
It keeps returning 1 and the file is not created. I also tried
system("Echo %CD% >> z:\log.txt");
and the file is not created. I also tried like this:
FILE *fpipe;
char *command = "Echo %CD% >> z:\log.txt";
char line[256];
if (0 == (fpipe = (FILE*)_popen(command, "r")))
{
perror("popen() failed.");
exit(1);
}
while (fread(line, sizeof line, 1, fpipe))
{
ShowMessage(line);
}
_pclose(fpipe);
And nothing I get. I wonder if the reason of such strange behaviour is that I'm running this all in VirtualBox?
You're not escaping your \ characters. You should use / in file paths, or \\ if you must. In addition, Windows 7 won't let you write to the root directory of a hard drive w/o administrator access.
To determine if a command environment is available, first do this:
if (!system(NULL)) {
// Can't make any system() calls
}
If your command environment is available, then you need to fully specify the path, making sure to escape the \'s like I mentioned above, and don't write anything to a drive's root directory. Also make note that opening files does not default create directories.
No, it's very unlikely. I see few issues with your code: you did not check errno if system() returns 1. It can help you to spot a real problem. Also, all backslashes must be Esc'ed.
I'm suggesting that dot.exe is not in PATH environment variable, that's the reason of the system() failure.
I'm using VS2010 and I would like to call an exe file which I've created in another directory.
I've tried the following:
int main(){
system("C:\\Users\\Li\\Desktop\\Debug\\modelExample_4pcs.exe");
return 0;
};
but I get "The system could not find the file specified" error.
I've tried to run the exe file directly from the command line, and it only works when I'm inside its directory.
Could you please tell me how can I run it from a different directory?
(I'm using win7)
Thanks,
Li.
You should try using CreateProcess Windows API funcion: http://msdn.microsoft.com/en-us/library/ms682425%28VS.85%29.aspx
Try opening the file for reading, just to check that you have the path right:
char* filename = "C:\\Users\\Li\\Desktop\\Debug\\modelExample_4pcs.exe" ;
FILE* fp = fopen (filename, "rb") ; // Open for reading, binayr mode
if (fp == 0) {
printf ("Duh! File not found\n") ;
exit (0) ;
}
printf ("File found\n") ;
fclose (fp) ;
// Now try the system call, as before:
system(filename);
What happens?
You should be able to use ShellExecute like so: (adjusting the params sent to ShellExecute for your situation) http://msdn.microsoft.com/en-us/library/bb762153(VS.85).aspx?ppud=4
HINSTANCE hinst = ShellExecute( NULL, _T("open"), commandLine.c_str(), additionalParams.c_str(), NULL, SW_RESTORE );
if(hinst <= (HINSTANCE)SHELLEXERROR)// see: http://msdn2.microsoft.com/en-us/library/bb762153.aspx for further info on the return values
Now given that you are using Win7, you may be having a privilege issue and you need to run at an elevated level (i.e. administrator) you can test this by opening cmd as admin and running your exe from another directory
and as Steve mentioned above you can certainly use CreateProcess.
HTH,
EB
System() may not be able to find cmd.exe to open your environment.
Try using cmd.exe to execute your app via the /C option.
System("C:\\WINDOWS\\system32\cmd.exe /C \"C:\\Users\\Li\\Desktop\\Debug\\modelExample_4pcs.exe\"");
Try this using CreateProcess. Less (or at least different) environmental dependencies than using system(). At least you will get a nice Win32 error code if this still fails.
http://msdn.microsoft.com/en-us/library/ms682425(VS.85).aspx
Check your path, and make sure you escape all characters: C:\\Users\Li..
Is the error from running the main program, not from launching modelExample_4pcs.exe? Try commenting out the system() call and see if you get the same error.
Your main program is not on the path when you're outside its folder...
Is modelExample_4pcs.exe trying to load another file from the current working folder, and THAT's what's generating the error?
Maybe try chdir() before the call to system().
Just change to the directory first, like you would do from the command prompt:
system("C: && CD \\Users\\Li\\Desktop\\Debug\\ && modelExample_4pcs.exe");