recommended programming practices for writing (was Linux 2.6.29)

From: Adam Turk
Date: Thu Mar 26 2009 - 15:04:15 EST



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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