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 title: How to Compile Envy MUD
 date: 2011-09-07 12:00:00
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I have always been fascinated with MUDs, also known as Multi-User
Dungeons. They are the World of Warcraft before there was a world
to craft war in. It’s an interesting mesh between computers and
Dungeons and Dragons. Imagination is an important factor, and from
my experience, they are a great place for beginning programmers to
learn how to code. I first learned how to code in C by programming
for a few MUDs.

Compiling your first MUD can be a scary experience, though. Many of
the codebases are pre-y2k, thus making some of the processes
obsolete. For this demonstration, I will be using the EnvyMUD
source code. It is widely used enough that many people can relate
to it, and being directly related to DIKUMUD, the processes will be
very similar for other DIKU related subservers. The first step will
be to download the MUD source code. You can get it from the
MUDBytes [0] codebase repository here. The version of Envy I will
be using is **Envy 2.0** on a current Ubuntu server.

After downloading the Envy source code, you will need to un-tar and
un-gzip it:

```sh
tar -xvzf envy-20.tar.gz
```

Next, navigate to the `src` directory:

```sh
cd ./Envy20/src/
```

Now the fun starts. Run the `make` command and see what happens:

```
$ make
gcc -c -O -Wall -g act_comm.c
gcc -c -O -Wall -g act_info.c
gcc -c -O -Wall -g act_move.c
act_move.c: In function 'move_char':
act_move.c:230: warning: suggest explicit braces to avoid ambiguous
'else'
gcc -c -O -Wall -g act_obj.c
gcc -c -O -Wall -g act_wiz.c
act_wiz.c: In function 'do_sset':
act_wiz.c:2296: warning: suggest explicit braces to avoid ambiguous
'else'
gcc -c -O -Wall -g comm.c
comm.c:162: error: conflicting types for 'accept'
/usr/include/sys/socket.h:214: note: previous declaration of
'accept' was here
comm.c:163: error: conflicting types for 'bind'
/usr/include/sys/socket.h:115: note: previous declaration of 'bind'
was here
comm.c:165: error: conflicting types for 'getpeername'
/usr/include/sys/socket.h:133: note: previous declaration of
'getpeername' was here
comm.c:166: error: conflicting types for 'getsockname'
/usr/include/sys/socket.h:119: note: previous declaration of
'getsockname' was here
comm.c:169: error: conflicting types for 'read'
/usr/include/bits/unistd.h:35: note: previous definition of 'read'
was here
comm.c:173: error: conflicting types for 'write'
/usr/include/unistd.h:363: note: previous declaration of 'write'
was here
comm.c: In function 'init_socket':
comm.c:440: warning: ignoring return value of 'system', declared
with attribute warn_unused_result
comm.c:490: warning: ignoring return value of 'system', declared
with attribute warn_unused_result
comm.c: In function 'nanny':
comm.c:1829: warning: comparison with string literal results in
unspecified behavior
make: *** [comm.o] Error 1
```

## Fixing Prototypes

These errors are caused by prototype functions that are no longer
needed. To fix this, open up `comm.c` in your favorite text editor
and navigate to line 161. There, you will comment out the following
lines:

```c
$ #if	defined( linux )
// int	accept		args( ( int s, struct sockaddr *addr, int *addrlen )
);
// int	bind		args( ( int s, struct sockaddr *name, int namelen ) );
int	close		args( ( int fd ) );
// int	getpeername	args( ( int s, struct sockaddr *name, int
*namelen ) );
// int	getsockname	args( ( int s, struct sockaddr *name, int
*namelen ) );
// int	gettimeofday	args( ( struct timeval *tp, struct timezone
*tzp ) );
int	listen		args( ( int s, int backlog ) );
int	read		args( ( int fd, char *buf, int nbyte ) );
int	select		args( ( int width, fd_set *readfds, fd_set *writefds,
			    fd_set *exceptfds, struct timeval *timeout ) );
int	socket		args( ( int domain, int type, int protocol ) );
int	write		args( ( int fd, char *buf, int nbyte ) );
#endif
```

## Get Crypty With It

Now, you could re-run the `make` command, but there's a good chance
it will still error out because the `crypt` library hasn't been
properly setup or linked. I won't walk you through how to install
`libcrypt` in your operating system of choice (probably something
like `apt install libcrypt-dev`, but YMMV), but when it _is_
installed, you have to pull in the headers and make sure it is
linked in the compiler.

The first thing we need to do is open up both `act_info.c` and
`comm.c` and add the following line at the top of the file, _just_
before the `#include "merc.h"` directive:

```c
#include <crypt.h>
```

Next, we need to add the `-lcrypt` flag to the `envy` target in the
`Makefile`, like so:

```makefile
envy: $(O_FILES)
	rm -f envy
	$(CC) $(L_FLAGS) -o envy $(O_FILES) -lcrypt
```

## Bring It All Together

If we did everything above right, then run `make` again and you
should get a successful build:

```
$ make
gcc -c -O -Wall -g comm.c
comm.c: In function 'init_socket':
comm.c:440: warning: ignoring return value of 'system', declared
with attribute warn_unused_result
comm.c:490: warning: ignoring return value of 'system', declared
with attribute warn_unused_result
comm.c: In function 'new_descriptor':
comm.c:870: warning: pointer targets in passing argument 3 of
'getsockname' differ in signedness
/usr/include/sys/socket.h:119: note: expected 'socklen_t *
__restrict__' but argument is of type 'int *'
comm.c:871: warning: pointer targets in passing argument 3 of
'accept' differ in signedness
/usr/include/sys/socket.h:214: note: expected 'socklen_t *
__restrict__' but argument is of type 'int *'
comm.c:914: warning: pointer targets in passing argument 3 of
'getpeername' differ in signedness
/usr/include/sys/socket.h:133: note: expected 'socklen_t *
__restrict__' but argument is of type 'int *'
comm.c: In function 'nanny':
comm.c:1829: warning: comparison with string literal results in
unspecified behavior
gcc -c -O -Wall -g const.c
gcc -c -O -Wall -g db.c
gcc -c -O -Wall -g fight.c
gcc -c -O -Wall -g handler.c
gcc -c -O -Wall -g interp.c
interp.c:436:50: warning: trigraph ??' ignored, use -trigraphs to
enable
interp.c:437:50: warning: trigraph ??' ignored, use -trigraphs to
enable
interp.c:438:55: warning: trigraph ??' ignored, use -trigraphs to
enable
interp.c:439:56: warning: trigraph ??' ignored, use -trigraphs to
enable
interp.c:440:56: warning: trigraph ??' ignored, use -trigraphs to
enable
gcc -c -O -Wall -g magic.c
gcc -c -O -Wall -g save.c
save.c: In function 'load_char_obj':
save.c:406: warning: ignoring return value of 'system', declared
with attribute warn_unused_result
gcc -c -O -Wall -g special.c
gcc -c -O -Wall -g update.c
rm -f envy
gcc -O -lcrypt -o envy act_comm.o act_info.o act_move.o act_obj.o
act_wiz.o comm.o const.o db.o fight.o handler.o interp.o magic.o
save.o special.o update.o
```

Now, we need to start the game up. If you are on a modern Ubuntu
version like I am, run the following:

```sh
nohup ./startupSH &
```

That’s it! You have just started your first MUD on port 4000! To
log into your game from the localhost, just type the following:

```sh
telnet localhost 4000
```

Congratulations! You are officially an implementor!

---
[0]: http://www.mudbytes.net/file-172
---


EOF