Contents of /trunk/mkinitrd-magellan/busybox/docs/new-applet-HOWTO.txt
Parent Directory | Revision Log
Revision 532 -
(show annotations)
(download)
Sat Sep 1 22:45:15 2007 UTC (17 years ago) by niro
File MIME type: text/plain
File size: 3983 byte(s)
Sat Sep 1 22:45:15 2007 UTC (17 years ago) by niro
File MIME type: text/plain
File size: 3983 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
1 | How to Add a New Applet to BusyBox |
2 | ================================== |
3 | |
4 | This document details the steps you must take to add a new applet to BusyBox. |
5 | |
6 | Credits: |
7 | Matt Kraai - initial writeup |
8 | Mark Whitley - the remix |
9 | Thomas Lundquist - Added stuff for the new directory layout. |
10 | |
11 | Initial Write |
12 | ------------- |
13 | |
14 | First, write your applet. Be sure to include copyright information at the top, |
15 | such as who you stole the code from and so forth. Also include the mini-GPL |
16 | boilerplate. Be sure to name the main function <applet>_main instead of main. |
17 | And be sure to put it in <applet>.c. Usage does not have to be taken care of by |
18 | your applet. |
19 | Make sure to #include "busybox.h" as the first include file in your applet so |
20 | the bb_config.h and appropriate platform specific files are included properly. |
21 | |
22 | For a new applet mu, here is the code that would go in mu.c: |
23 | |
24 | ----begin example code------ |
25 | |
26 | /* vi: set sw=4 ts=4: */ |
27 | /* |
28 | * Mini mu implementation for busybox |
29 | * |
30 | * Copyright (C) [YEAR] by [YOUR NAME] <YOUR EMAIL> |
31 | * |
32 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
33 | */ |
34 | |
35 | #include "busybox.h" |
36 | #include <other.h> |
37 | |
38 | int mu_main(int argc, char **argv) |
39 | { |
40 | int fd; |
41 | char mu; |
42 | |
43 | fd = xopen("/dev/random", O_RDONLY); |
44 | |
45 | if ((n = safe_read(fd, &mu, 1)) < 1) |
46 | bb_perror_msg_and_die("/dev/random"); |
47 | |
48 | return mu; |
49 | } |
50 | |
51 | ----end example code------ |
52 | |
53 | |
54 | Coding Style |
55 | ------------ |
56 | |
57 | Before you submit your applet for inclusion in BusyBox, (or better yet, before |
58 | you _write_ your applet) please read through the style guide in the docs |
59 | directory and make your program compliant. |
60 | |
61 | |
62 | Some Words on libbb |
63 | ------------------- |
64 | |
65 | As you are writing your applet, please be aware of the body of pre-existing |
66 | useful functions in libbb. Use these instead of reinventing the wheel. |
67 | |
68 | Additionally, if you have any useful, general-purpose functions in your |
69 | applet that could be useful in other applets, consider putting them in libbb. |
70 | |
71 | |
72 | Placement / Directory |
73 | --------------------- |
74 | |
75 | Find the appropriate directory for your new applet. |
76 | |
77 | Make sure you find the appropriate places in the files, the applets are |
78 | sorted alphabetically. |
79 | |
80 | Add the applet to Makefile.in in the chosen directory: |
81 | |
82 | obj-$(CONFIG_MU) += mu.o |
83 | |
84 | Add the applet to Config.in in the chosen directory: |
85 | |
86 | config CONFIG_MU |
87 | bool "MU" |
88 | default n |
89 | help |
90 | Returns an indeterminate value. |
91 | |
92 | |
93 | Usage String(s) |
94 | --------------- |
95 | |
96 | Next, add usage information for you applet to include/usage.h. |
97 | This should look like the following: |
98 | |
99 | #define mu_trivial_usage \ |
100 | "-[abcde] FILES" |
101 | #define mu_full_usage \ |
102 | "Returns an indeterminate value.\n\n" \ |
103 | "Options:\n" \ |
104 | "\t-a\t\tfirst function\n" \ |
105 | "\t-b\t\tsecond function\n" \ |
106 | ... |
107 | |
108 | If your program supports flags, the flags should be mentioned on the first |
109 | line (-[abcde]) and a detailed description of each flag should go in the |
110 | mu_full_usage section, one flag per line. (Numerous examples of this |
111 | currently exist in usage.h.) |
112 | |
113 | |
114 | Header Files |
115 | ------------ |
116 | |
117 | Next, add an entry to include/applets.h. Be *sure* to keep the list |
118 | in alphabetical order, or else it will break the binary-search lookup |
119 | algorithm in busybox.c and the Gods of BusyBox smite you. Yea, verily: |
120 | |
121 | /* all programs above here are alphabetically "less than" 'mu' */ |
122 | #ifdef CONFIG_MU |
123 | APPLET("mu", mu_main, _BB_DIR_USR_BIN, mu_usage) |
124 | #endif |
125 | /* all programs below here are alphabetically "greater than" 'mu' */ |
126 | |
127 | |
128 | Documentation |
129 | ------------- |
130 | |
131 | If you're feeling especially nice, you should also document your applet in the |
132 | docs directory (but nobody ever does that). |
133 | |
134 | Adding some text to docs/Configure.help is a nice start. |
135 | |
136 | |
137 | The Grand Announcement |
138 | ---------------------- |
139 | |
140 | Then create a diff -urN of the files you added and/or modified. Typically: |
141 | <appletdir>/<applet>.c |
142 | include/usage.c |
143 | include/applets.h |
144 | <appletdir>/Makefile.in |
145 | <appletdir>/config.in |
146 | and send it to the mailing list: |
147 | busybox@busybox.net |
148 | http://busybox.net/mailman/listinfo/busybox |
149 | |
150 | Sending patches as attachments is preferred, but not required. |