The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Monday, April 28, 2008

I must have forgotten my cardboard programmer that day …


Smirk called today, saying a customer had a problem sending mail with one of their PHP scripts. The server in question was running my PHP/sendmail wrapper and the testing that Smirk did showed that the PHP mail() function wasn't returning anything! Funny, for a function that supposedly returns a bool

With Wlofie playing the part of cardboard programmer, I did some testing, found that indeed, there was a problem—at first, it looked like the system was terminating the program with random signals. One time it would terminate with a SIGXFSZ, then with SIGTTIN, then with SIGWINCH!

I then stared at the code until I bled …

else /* parent process */
  pid_t cstat;
  int   status;

  cstat = waitpid(child,&status,0);

  if (WIFEXITED(cstat))
    rc = WEXITSTATUS(cstat);
    rc = EXIT_FAILURE;

  unlink(tmpfile); /* make sure we clean up after ourselves */

It was then i saw my mistake—I was checking the wrong variable!


The type of mistake a statically typed language should catch. And before you say “unit testing” my tests were basically “did the email go through? Yup? Then it works”—the thought to check the return code of my program as a whole didn't occur to me (hey, the email got through, right? that meant that it worked).

I changed WIFEXITED(cstat) to WIFEXITED(status) and WEXITSTATUS(cstat) to WEXITSTATUS(status) and it worked.

I also checked PHP, and for the life of me, I can't figure out why it was returning undef, but then again, PHP is the scripting language du jour so it may be I didn't check the precise version we're running.

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