old_code.txt

old_code.c - a small Museum of Horrors

Some extensive parts of EmuTOS were written using a very old C language.
This file gives example of problems that actually occurred, and gives
the *right* way to write code.

If you fix a bug that is due to obsolete C language, please add a note in
this file to help other developers imagine what kind of nasty bug may
still exist...

- do not assign to a variable and use the old value in the same
  expression. Replace
    // BAD  envLen = ((i = strlen (path)) + (i ? 5 : 0) + 2);
  by
    i = strlen (path);
    envLen = i + (i ? 5 : 0) + 2;

- do not write code making assumptions about the sign of 'char':
    char *prntEnvPtr;
    /* look for two consecutive 0 */
    // BAD while ((prntEnvPtr[i] + prntEnvPtr[i + 1]) != 0)

- do not use 0xffffffff instead of -1. 0xffffffff is the biggest
  unsigned long value. Comparisons such as
    long value;
    // BAD if ((value & 0xFFFFFFFF) < 0)
  will fail, because due to integer promotion rules the test
  is done using unsigned longs.