[QT3] Temporary Folder Temporary File

[Senpai]

Dear All,

I would like to create a file in a directory where I am sure that the user have writing rights that's why I've choosed the temporary folder of the user. (TEMP, TMPDIR ...)

In QT4 there is a very useful class QtemporaryFile which woul enable me to do this easily but I use QT3 and this class does not exist.

Do you have information which could help me?
In advance Thank U

[jacek]

Maybe you could use tmpfile(3) together with QFile::open()?

[Senpai]

Maybe you could use tmpfile(3) together with QFile:pen()?

What do you mean? I don' t understand what is tmpfile(3).

Thank U

[jrideout]

from $man tempfile

NAME
tempfile - create a temporary file in a safe manner

SYNOPSIS
tempfile [-d DIR] [-p STRING] [-s STRING] [-m MODE] [-n FILE] [--directory=DIR] [--prefix=STRING] [--suffix=STRING] [--mode=MODE] [--name=FILE] [--help] [--version]

DESCRIPTION
tempfile creates a temporary file in a safe manner. It uses tempnam(3) to choose the name and opens it with O_RDWR | O_CREAT | O_EXCL. The filename is printed on standard output.

The directory to place the file is searched for in the following order:

a) The directory specified by the environment variable TMPDIR, if it is writable.

b) The directory specified by the --directory argument, if given.

c) The directory /tmp.

[Senpai]

Woua !!! I do not manage to follow you !
is tempfile(3) a Qt function ?

[jacek]

is tempfile(3) a Qt function ?

No, but it's part of standard C library.

[Senpai]

So, I suppose you are dealing with tmpfile function ?

[jacek]

So, I suppose you are dealing with tmpfile function ?

Yes, you can open a temporary file with tmpfile() and pass returned FILE * to QFile::open().

[jrideout]

tmpnam just finds a safe temp filename for you

#include <stdio.h>
 
int main ()
{
  char buffer [L_tmpnam];
  char * pointer;
 
  tmpnam (buffer);
  printf ("Tempname #1: %s\n",buffer);
 
  pointer = tmpnam (NULL);
  printf ("Tempname #2: %s\n",pointer);
 
  return 0;
}

#include <stdio.h>

int main ()
{
  char buffer [L_tmpnam];
  char * pointer;

  tmpnam (buffer);
  printf ("Tempname #1: %s\n",buffer);

  pointer = tmpnam (NULL);
  printf ("Tempname #2: %s\n",pointer);

  return 0;
}

To copy to clipboard, switch view to plain text mode 

[Senpai]

Using the tmpfile function should be a solution but I wonder where this temporary file is created.

[jrideout]

... I wonder where this temporary file is created.

That example i showed you prints the location of the file.


This example is more secure, but you have to specify a file name template

#include <stdlib.h>
#include <qfile.h>
 
int main ()
{
  const char* msg = "inside temp file";
  char nameTemplate[] = "/tmp/mytempfile-XXXXXX";
 
  QFile f;
  int file = mkstemp(nameTemplate) ;
  f.open( IO_WriteOnly,file );
  f.writeBlock( msg, qstrlen(msg) );
  f.close();
 
  return 0;
}

#include <stdlib.h>
#include <qfile.h>

int main ()
{
  const char* msg = "inside temp file";
  char nameTemplate[] = "/tmp/mytempfile-XXXXXX";

  QFile f;
  int file = mkstemp(nameTemplate) ;
  f.open( IO_WriteOnly,file );
  f.writeBlock( msg, qstrlen(msg) );
  f.close();

  return 0;
}

To copy to clipboard, switch view to plain text mode