nc: show help text on bad parameters

[oweals/busybox.git] / docs / new-applet-HOWTO.txt

diff --git a/docs/new-applet-HOWTO.txt b/docs/new-applet-HOWTO.txt
index 1c2383f351970d4ede4e4ca8229ade6024f21cf8..2f237564d5680c846cb70ff8ff3caa5cdf864a8a 100644 (file)
--- a/docs/new-applet-HOWTO.txt
+++ b/docs/new-applet-HOWTO.txt
@@ -6,7 +6,10 @@ This document details the steps you must take to add a new applet to BusyBox.
 Credits:
 Matt Kraai - initial writeup
 Mark Whitley - the remix
-Thomas Lundquist - Added stuff for the new directory layout.
+Thomas Lundquist - Trying to keep it updated.
+
+When doing this you should consider using the latest git HEAD.
+This is a good thing if you plan to getting it committed into mainline.
 
 Initial Write
 -------------
@@ -16,11 +19,15 @@ such as who you stole the code from and so forth. Also include the mini-GPL
 boilerplate. Be sure to name the main function <applet>_main instead of main.
 And be sure to put it in <applet>.c. Usage does not have to be taken care of by
 your applet.
-Make sure to #include "busybox.h" as the first include file in your applet so
+Make sure to #include "libbb.h" as the first include file in your applet so
 the bb_config.h and appropriate platform specific files are included properly.
 
 For a new applet mu, here is the code that would go in mu.c:
 
+(busybox.h already includes most usual header files. You do not need
+#include <stdio.h> etc...)
+
+
 ----begin example code------
 
 /* vi: set sw=4 ts=4: */
@@ -29,15 +36,17 @@ For a new applet mu, here is the code that would go in mu.c:
  *
  * Copyright (C) [YEAR] by [YOUR NAME] <YOUR EMAIL>
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 
-#include "busybox.h"
-#include <other.h>
+#include "libbb.h"
+#include "other.h"
 
+int mu_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int mu_main(int argc, char **argv)
 {
        int fd;
+       ssize_t n;
        char mu;
 
        fd = xopen("/dev/random", O_RDONLY);
@@ -68,6 +77,38 @@ useful functions in libbb. Use these instead of reinventing the wheel.
 Additionally, if you have any useful, general-purpose functions in your
 applet that could be useful in other applets, consider putting them in libbb.
 
+And it may be possible that some of the other applets uses functions you
+could use. If so, you have to rip the function out of the applet and make
+a libbb function out of it.
+
+Adding a libbb function:
+------------------------
+
+Make a new file named <function_name>.c
+
+----start example code------
+
+#include "libbb.h"
+#include "other.h"
+
+int function(char *a)
+{
+       return *a;
+}
+
+----end example code------
+
+Add <function_name>.o in the right alphabetically sorted place
+in libbb/Kbuild. You should look at the conditional part of
+libbb/Kbuild aswell.
+
+You should also try to find a suitable place in include/libbb.h for
+the function declaration. If not, add it somewhere anyway, with or without
+ifdefs to include or not.
+
+You can look at libbb/Config.in and try to find out if the function is
+tunable and add it there if it is.
+
 
 Placement / Directory
 ---------------------
@@ -77,13 +118,13 @@ Find the appropriate directory for your new applet.
 Make sure you find the appropriate places in the files, the applets are
 sorted alphabetically.
 
-Add the applet to Makefile.in in the chosen directory:
+Add the applet to Kbuild in the chosen directory:
 
-obj-$(CONFIG_MU)               += mu.o
+lib-$(CONFIG_MU)               += mu.o
 
 Add the applet to Config.in in the chosen directory:
 
-config CONFIG_MU
+config MU
        bool "MU"
        default n
        help
@@ -118,31 +159,23 @@ Next, add an entry to include/applets.h.  Be *sure* to keep the list
 in alphabetical order, or else it will break the binary-search lookup
 algorithm in busybox.c and the Gods of BusyBox smite you. Yea, verily:
 
+Be sure to read the top of applets.h before adding your applet.
+
        /* all programs above here are alphabetically "less than" 'mu' */
-       #ifdef CONFIG_MU
-               APPLET("mu", mu_main, _BB_DIR_USR_BIN, mu_usage)
-       #endif
+       IF_MU(APPLET(mu, _BB_DIR_USR_BIN, _BB_SUID_DROP))
        /* all programs below here are alphabetically "greater than" 'mu' */
 
 
-Documentation
--------------
-
-If you're feeling especially nice, you should also document your applet in the
-docs directory (but nobody ever does that).
-
-Adding some text to docs/Configure.help is a nice start.
-
-
 The Grand Announcement
 ----------------------
 
-Then create a diff -urN of the files you added and/or modified. Typically:
-       <appletdir>/<applet>.c
-       include/usage.c
-       include/applets.h
-       <appletdir>/Makefile.in
-       <appletdir>/config.in
+Then create a diff by adding the new files to git (remember your libbb files)
+       git add <where you put it>/mu.c
+eventually also:
+       git add libbb/function.c
+then
+       git commit
+       git format-patch HEAD^
 and send it to the mailing list:
        busybox@busybox.net
        http://busybox.net/mailman/listinfo/busybox