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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.


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