2. Unimplemented Functions

The DJGPP standard C library is ANSI- and POSIX-compliant, and provides many additional functions for compatibility with Unix/Linux systems. However, some of the functions needed for this compatibility are very hard or impossible to implement using DOS facilities.

Therefore, a small number of library functions are really just stubs: they are provided because POSIX requires them to be present in a compliant library, or because they are widely available on Unix systems, but they either always fail, or handle only the trivial cases and fail for all the others. An example of the former behavior is the function fork: it always returns a failure indication; an example of the latter behavior is the function mknode: it handles the cases of regular files and existing character devices, but fails for all other file types.

This chapter lists all such functions. This list is here for the benefit of programmers who write portable programs or port Unix packages to DJGPP.

Each function below is labeled as either "always fails" or "trivial", depending on which of the two classes described above it belongs to. An additional class, labeled "no-op", includes functions which pretend to succeed, but have no real effect, since the underlying functionality is either always available or always ignored.

addmntent		Always fails.
cfgetispeed		No-op.
cfgetospeed		No-op.
cfsetispeed		No-op.
cfsetospeed		No-op.
chown		Trivial.
fchown		Trivial.
fork		Always fails.
getgrgid		Trivial.
getgrnam		Trivial.
getgroups		Trivial.
getpwnam		Trivial.
getpwuid		Trivial.
lchown		Trivial.
mkfifo		Always fails.
mknod		Trivial.
nice		No-op.
setgid		Trivial.
setpgid		Trivial.
setsid		Trivial.
setuid		Trivial.
tcdrain		No-op.
tcsendbreak		No-op.
tcsetpgrp		Trivial.
umask		Trivial.
vfork		Always fails.
wait		Always fails.
waitpid		Always fails.