Message-ID: <COL112-W81AF4A8C222B9941D8295FC8910@phx.gbl>
From: Adam Turk <bofh1234@hotmail.com>
To: <linux-kernel@vger.kernel.org>
Subject: recommended programming practices for writing (was Linux 2.6.29)
Date: Thu, 26 Mar 2009 15:03:28 -0400
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I have been reading the Linux 2.6.29 thread with interest.  I have written several (10 or so) C programs that write large amounts of data (between 1 and 2 GB file sizes are common).  A snippet of code looks like this:

if((fptr = fopen(outfilename,"w")) == NULL) {
  printf("File %s could not be created\n", outfilename);
}
else {
  fprintf(fptr,"%s\n",datablock);
  while(!writeouput(datablock,amount,tax)) {
    getnext(dtablock)
    fprintf(fptr,"%s\n",datablock);
  }
  fclose(fptr);
}

I learned C about 15 years ago and there was no mention of a fsync.  My C book doesn't mention fsync either.  Granted I have written only 25-30 applications in the last 15 years or so so I am not an expert C programmer. 

>From what Linus posted about git and checking the return from fclose I think I going to start doing that.  I also think I am going to start checking the return from fprintf and maybe write to a /tmp/file and then rename it.

So is there a C fsync that I should add before my fclose?
What is the proper way to write to files?

Is what I am thinking about doing something that would be good or is it just a lack of my understanding the problem?

Thanks,
Adam

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