Credits:
Matt Kraai - initial writeup
Mark Whitley - the remix
+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
-------------
-First, write your applet. Be sure to include copyright information at the
-top, 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. For a new applet mu, here is
-the code that would go in mu.c:
+First, write your applet. Be sure to include copyright information at the top,
+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 "libbb.h" as the first include file in your applet.
+
+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------
/*
* Mini mu implementation for busybox
*
- *
* Copyright (C) [YEAR] by [YOUR NAME] <YOUR EMAIL>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- * 02111-1307 USA
- *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
*/
-#include "busybox.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;
- if ((fd = open("/dev/random", O_RDONLY)) < 0)
- perror_msg_and_die("/dev/random");
+ fd = xopen("/dev/random", O_RDONLY);
if ((n = safe_read(fd, &mu, 1)) < 1)
- perror_msg_and_die("/dev/random");
+ bb_perror_msg_and_die("/dev/random");
return mu;
}
directory and make your program compliant.
-Some Words on utility.c
------------------------
+Some Words on libbb
+-------------------
As you are writing your applet, please be aware of the body of pre-existing
-useful functions in utility.c. Use these instead of reinventing the wheel.
-
-If you use functions from utility.c, you may need to add to the preprocessor
-conditionals in that file, to make sure the routines you need are included.
-So, since your mu implementation used safe_read(), append "|| defined BB_MU" to
-the #if instruction that precedes the safe_read() function in utility.c .
+useful functions in libbb. Use these instead of reinventing the wheel.
Additionally, if you have any useful, general-purpose functions in your
-program that could be useful in another program, consider putting them in
-utility.c.
+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.src. You should look at the conditional part of
+libbb/Kbuild.src as well.
+
+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.src and try to find out if the function is
+tunable and add it there if it is.
+
+
+Placement / Directory
+---------------------
+
+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 Kbuild.src in the chosen directory:
+
+lib-$(CONFIG_MU) += mu.o
+
+Add the applet to Config.src in the chosen directory:
+
+config MU
+ bool "MU"
+ default n
+ help
+ Returns an indeterminate value.
Usage String(s)
---------------
-Next, add usage information for you applet to usage.c. This should look like
-the following:
+Next, add usage information for you applet to include/usage.src.h.
+This should look like the following:
- #if defined BB_MU
- const char mu_usage[] =
- "mu\n"
- #ifndef BB_FEATURE_TRIVIAL_HELP
- "\nReturns an indeterminate value.\n"
- #endif
- ;
+ #define mu_trivial_usage \
+ "-[abcde] FILES"
+ #define mu_full_usage \
+ "Returns an indeterminate value.\n\n" \
+ "Options:\n" \
+ "\t-a\t\tfirst function\n" \
+ "\t-b\t\tsecond function\n" \
+ ...
If your program supports flags, the flags should be mentioned on the first
-line (mu -[bcRovma]) and a detailed description of each flag should go in the
-BB_FEATURE_TRIVIAL_HELP section, one flag per line. (Numerous examples of this
-currently exist in usage.c.)
+line (-[abcde]) and a detailed description of each flag should go in the
+mu_full_usage section, one flag per line. (Numerous examples of this
+currently exist in usage.src.h.)
Header Files
------------
-Next, add an entry to 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:
+Next, add an entry to include/applets.src.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.src.h before adding your applet.
/* all programs above here are alphabetically "less than" 'mu' */
- #ifdef BB_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' */
-Finally, add a define for your applet to Config.h:
-
- #define BB_MU
-
-
-Documentation
--------------
-
-If you're feeling especially nice, you should also document your applet in the
-docs directory (but nobody ever does that).
-
-
The Grand Announcement
----------------------
-Then create a diff -urN of the files you added (<applet>.c, usage.c,
-applets.h, Config.h) and send it to the mailing list:
-busybox@opensource.lineo.com. Sending patches as attachments is preferred, but
-not required.
-
-
+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
+
+Sending patches as attachments is preferred, but not required.
projects / oweals / busybox.git / blobdiff