INSTALLATION INSTRUCTIONS:

   $ ./configure
   $ make
   # make install

This will not install the documentation, which is shipped as
pre-prepared HTML and PostScript as well as debiandoc-sgml source.
Put that (spec.html/ and spec.ps) where you will.

SYSTEM REQUIREMENTS:

Programs:

* md5sum (Colin Plumb's or the GNU version)
* GNU m4
* GNU make
* GNU flex
* GCC is preferred but other compilers ought to work (though
  no portability testing has yet been done).  ANSI C only.
  ints must be at least 32 bits.
* A sensible /bin/cat which notices write errors (ie not
  SunOS4, BSD 4.3, or many others.)

C Library:

* [v]snprintf - a real version, not just [v]sprintf with a wrapper
  that throws the argument away.
* strsignal;
* fnmatch;
* BSD syslog(3);
* strtoul;
* memcpy, memset, memcpy;
* realloc(0,size) must work and be equivalent to malloc(size).
* free(0) must work and do nothing
* <stdarg.h> (not varargs) and v[sf][n]printf.

System interfaces:

* setreuid(2), getreuid(2), getgroups(2), initgroups(3), with
  the ability for root to (a) swap euid and ruid and
  (b) give away all privilege by calling setreuid(ruid,ruid)
  twice.
* wait3 and waitpid, <wait.h> with WNOHANG, WIFSIGNALED,
  WIFEXITEED, WTERMSIG, WEXITSTATUS and WCOREDUMP.
* gid_t, uid_t, pid_t.
* Unix-domain (AF_UNIX) stream sockets, for use with:
  * BSD sockets - socket(), bind(), listen(), accept(), connect();
  * socketpair(2);
* lstat(2) (though stat(2) will be safe on systems without symlinks,
  if you say -Dlstat=stat).
* Pipes:
  * creating using pipe(2) and mkfifo(2);
  * proper interaction between open(O_RDWR), open(O_RDONLY),
    open(O_WRONLY), close(), dup2, EPIPE, SIGPIPE, &c.
    (ie, opening pipes with O_RDWR never blocks; EPIPE happens
    if you write with no readers; EOF happens if you read with
    no buffered data and writers)
* POSIX signal handling - sigaction(2), sigprocmask(2), sigsuspend(2);

To format the documentation:

* debiandoc-sgml, and hence sp (aka nsgmls) and sgmlspm.
* For PostScript output, Lout and possibly psutils.

For debugging version (./configure --enable-debug):

* initgroups(3) must use setgroups(2) and dynamic
  linking must allow overriding setgroups(2) for initgroups(3);

REENTRANCY IN THE LIBC:

We assume, both in the client and server, that it is safe to use one
stdio stream in a signal handler which interrupts use of a _different_
stdio stream in another.  We make sure using setvbuf that we have
pre-allocated buffers so that stdio doesn't need to use malloc() when
we actually read or write.  stdio had better not do anything else
weird.

Furthermore, we assume that it is safe to use syslog in a signal
handler which has interrupted a stdio operation (but we don't require
that it be safe to invoke when the signal has interrupted a call to
malloc, unless stdio makes gratuitous mallocs).  openlog will already
have been called (but syslog will not necessarily have been called).

We assume that strerror is completely reentrant.