Archived:Creating temporary files in Open C

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Article Metadata

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Tested with

Devices(s): Nokia N93

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Compatibility

Platform(s): S60 3rd Edition

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Article

Keywords: tmpnam(), tmpfile()

Created: nymanaki (02 Apr 2008)

Last edited: hamishwillee (18 Jun 2012)

Overview

Programs often need to create temporary files just for the life time of the program. In Open C tmpnam() and tempfile() functions exist to assist in this task.

• tmpnam() generates file names that can be used for a temporary file.
• tmpfile() creates a temporary file and opens a corresponding stream to the created file.

The tmpnam() and tmpfile() functions return a pointer to a file name on success or NULL pointer in case of an error.

Note: In order to use this code, you need to install the Open C plug-in.

This snippet can be self-signed.

MMP file

The following libraries are required:

LIBRARY libc.lib

Source file

#include <stdio.h> //fprintf, tmpnam, tmpfile, FILE
#include <sys/stat.h> //S_IWUSR
 
int main (void)
    {
    char *tmp_pathname = 0;
    char buffer[100];
 
    FILE *tmp_fileptr = 0;
    FILE *tmp_filestream = 0;
 
    /* create the tmp directory */
    mkdir("c:\\tmp", S_IWUSR);
 
    /* - tmpnam - */
    if (!(tmp_pathname = tmpnam(NULL)))
        {
        perror("Error creating temporary filename!");
        abort();
        }
 
    fprintf(stdout, "Temporary pathname %s\n", tmp_pathname);
 
    if (!(tmp_fileptr = fopen(tmp_pathname, "w")))
        {
        perror("Error opening temporary file");
        abort();
        }
    else
        {
        fclose(tmp_fileptr);
        remove(tmp_pathname);
        }
 
    /* - tmpfile - */
    if (!(tmp_filestream = tmpfile()))
        {
        perror("Error generating temporary stream!");
        abort();
        }
 
    /* write to temporary file */
    fprintf(tmp_filestream, "Temporary stream created by PID[%ld]", (long)getpid());
    fflush(tmp_filestream);
 
    /* read from temporary file */
    rewind(tmp_filestream);
    fgets(buffer, 100, tmp_filestream);
    fprintf(stdout, "Temporary stream: %s\n", buffer);
 
    if(tmp_filestream)
        fclose(tmp_filestream);
 
    return 0;
    }

Postconditions

Two temporary files are created. The tmpfile() created file is automatically deleted by the OS when all references to the file are closed.