-TODO list for busybox in no particular order. Just because something
-is listed here doesn't mean that it is going to be added to busybox,
-or that doing so is even a good idea. It just means that I _might_ get
-around to it some time. If you have any good ideas, please let me know.
+Busybox TODO
-* login/sulogin/passwd/getty/etc are part of tinylogin, and so are not
- needed or wanted in busybox (or else I'd have to link to libcrypt).
+Stuff that needs to be done. All of this is fair game for 1.2.
-* Networking apps are going to be split out to a new package called netkit-tiny
- before the next release of Busybox. This will remove the following items
- from BusyBox: hostid, hostname, nc, nslookup, telnet, and ping. nfs
- mounting and syslogd (network logging) will remain in BusyBox.
+build system
+ make -j is broken, -j1 is forced atm
+----
+find
+ doesn't understand (), lots of susv3 stuff.
+----
+sh
+ The command shell situation is a big mess. We have three or four different
+ shells that don't really share any code, and the "standalone shell" doesn't
+ work all that well (especially not in a chroot environment), due to apps not
+ being reentrant. Unifying the various shells and figuring out a configurable
+ way of adding the minimal set of bash features a given script uses is a big
+ job, but it would be a big improvement.
- -Erik
+ Note: Rob Landley (rob@landley.net) is working on a new unified shell called
+ bbsh, but it's a low priority...
+---
+diff
+ We should have a diff -u command. We have patch, we should have diff
+ (we only need to support unified diffs though).
------------
+ Also, make sure we handle empty files properly:
+ From the patch man page:
-Possible apps to include some time:
+ you can remove a file by sending out a context diff that compares
+ the file to be deleted with an empty file dated the Epoch. The
+ file will be removed unless patch is conforming to POSIX and the
+ -E or --remove-empty-files option is not given.
+---
+patch
+ Should have simple fuzz factor support to apply patches at an offset which
+ shouldn't take up too much space.
-* hwclock
-* stty
-* group/commonize strings, remove dups (for i18n, l10n)
+ And while we're at it, a new patch filename quoting format is apparently
+ coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2
+---
+man
+ It would be nice to have a man command. Not one that handles troff or
+ anything, just one that can handle preformatted ascii man pages, possibly
+ compressed. This could probably be a script in the extras directory that
+ calls cat/zcat/bzcat | less
------------------------
+ (How doclifter might work into this is anybody's guess.)
+---
+bzip2
+ Compression-side support.
+---
+init
+ General cleanup.
+---
+ar
+ Write support?
+---
+mdev
+ Micro-udev.
-The Busybox lash shell needs to be taught Bourne shell grammer. This
-is planned for the next release of Busybox. Look out ash, we are coming
-for you...
+Architectural issues:
------------------------
+bb_close() with fsync()
+ We should have a bb_close() in place of normal close, with a CONFIG_ option
+ to not just check the return value of close() for an error, but fsync().
+ Close can't reliably report anything useful because if write() accepted the
+ data then it either went out to the network or it's in cache or a pipe
+ buffer. Either way, there's no guarantee it'll make it to its final
+ destination before close() gets called, so there's no guarantee that any
+ error will be reported.
-Running the following:
+ You need to call fsync() if you care about errors that occur after write(),
+ but that can have a big performance impact. So make it a config option.
+---
+Unify base64 handling.
+ There's base64 encoding and decoding going on in:
+ networking/wget.c:base64enc()
+ coreutils/uudecode.c:read_base64()
+ coreutils/uuencode.c:tbl_base64[]
+ networking/httpd.c:decodeBase64()
+ And probably elsewhere. That needs to be unified into libbb functions.
+---
+Do a SUSv3 audit
+ Look at the full Single Unix Specification version 3 (available online at
+ "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and
+ figure out which of our apps are compliant, and what we're missing that
+ we might actually care about.
- rm -f busybox && make LDFLAGS+=-nostdlib 2>&1 | \
- sed -ne 's/.*undefined reference to `\(.*\)..*/\1/gp' | sort | uniq
+ Even better would be some kind of automated compliance test harness that
+ exercises each command line option and the various corner cases.
+---
+Internationalization
+ How much internationalization should we do?
-reveals the list of all external (i.e. libc) things that BusyBox depends on.
-It would be a very nice thing to reduce this list to an absolute minimum, to
-reduce the footprint of busybox when staticly linking with libraries such as
-uClibc.
+ The low hanging fruit is UTF-8 character set support. We should do this.
+ (Vodz pointed out the shell's cmdedit as needing work here. What else?)
------------------------
+ We also have lots of hardwired english text messages. Consolidating this
+ into some kind of message table not only makes translation easier, but
+ also allows us to consolidate redundant (or close) strings.
-Currently, busybox bypasses libc NSS. Some folks might want that,
-so perhaps adding in the option to choose whether to go to libc for
-things like getpwnam() or whether to use the busybox version might
-be nice.
+ We probably don't want to be bloated with locale support. (Not unless we can
+ cleanly export it from our underlying C library without having to concern
+ ourselves with it directly. Perhaps a few specific things like a config
+ option for "date" are low hanging fruit here?)
------------------------
+ What level should things happen at? How much do we care about
+ internationalizing the text console when X11 and xterms are so much better
+ at it? (There's some infrastructure here we don't implement: The
+ "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a
+ --unicode option to loadkeys. That implies a real loadkeys/dumpkeys
+ implementation to replace loadkmap/dumpkmap. Plus messing with console font
+ loading. Is it worth it, or do we just say "use X"?)
+---
+Unify archivers
+ Lots of archivers have the same general infrastructure. The directory
+ traversal code should be factored out, and the guts of each archiver could
+ be some setup code and a series of callbacks for "add this file",
+ "add this directory", "add this symlink" and so on.
-Most wanted list:
+ This could clean up tar and zip, and make it cheaper to add cpio and ar
+ write support, and possibly even cheaply add things like mkisofs or
+ mksquashfs someday, if they become relevant.
+---
+Text buffer support.
+ Several existing applets (sort, vi, less...) read
+ a whole file into memory and act on it. There might be an opportunity
+ for shared code in there that could be moved into libbb...
+---
+Individual compilation of applets.
+ It would be nice if busybox had the option to compile to individual applets,
+ for people who want an alternate implementation less bloated than the gnu
+ utils (or simply with less political baggage), but without it being one big
+ executable.
- [andersen@slag busybox]$ grep -l getgroups *.[ch]
- test.c
+ Turning libbb into a real dll is another possibility, especially if libbb
+ could export some of the other library interfaces we've already more or less
+ got the code for (like zlib).
+---
+buildroot - Make a "dogfood" option
+ Busybox 1.1 will be capable of replacing most gnu packages for real world use,
+ such as developing software or in a live CD. It needs wider testing.
-Policy violation. getgroups uses libc nss, which is unlikely
-to be present in an embedded system.
+ Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file,
+ findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps,
+ sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting
+ system should be self-hosting (I.E. able to rebuild itself from source code).
+ This means it would need (at least) binutils, gcc, and make, or equivalents.
------------------------
+ It would be a good "eating our own dogfood" test if buildroot had the option
+ of using a "make allyesconfig" busybox instead of the all of the above
+ packages. Anything that's wrong with the resulting system, we can fix. (It
+ would be nice to be able to upgrade busybox to be able to replace bash and
+ diffutils as well, but we're not there yet.)
-Compile with debugging on, run 'nm --size-sort ./busybox'
-and then start with the biggest things and make them smaller...
+ One example of an existing system that does this already is Firmware Linux:
+ http://www.landley.net/code/firmware
+---
+initramfs
+ Busybox should have a sample initramfs build script. This depends on
+ bbsh, mdev, and switch_root.
+---
+Memory Allocation
+ We have a CONFIG_BUFFER mechanism that lets us select whether to do memory
+ allocation on the stack or the heap. Unfortunately, we're not using it much.
+ We need to audit our memory allocations and turn a lot of malloc/free calls
+ into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER.
------------------------
+ And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be
+ optimized out by the compiler in the stack allocation case (since there's no
+ free for an alloca()), and this means that various cleanup loops that just
+ call free might also be optimized out by the compiler if written right, so
+ we can yank those #ifdefs too, and generally clean up the code.
+---
+Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS
- du.c probably ought to have an -x switch like GNU du does...
+ In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS
+ that were either defined or undefined to indicate whether the symbol was
+ selected in the .config file. They were used with #ifdefs, ala:
+
+ #ifdef CONFIG_SYMBOL
+ if (other_test) {
+ do_code();
+ }
+ #endif
+
+ In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1),
+ meaning you can still use them for preprocessor tests by replacing
+ "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we
+ can use them as a true or false test in normal C code:
+
+ if (ENABLE_SYMBOL && other_test) {
+ do_code();
+ }
+
+ (Optimizing away if() statements that resolve to a constant value
+ is known as "dead code elimination", an optimization so old and simple that
+ Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers
+ like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC)
+ perform dead code elimination.)
+
+ Right now, busybox.h is #including both "config.h" (defining the
+ CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some
+ point in the future, it would be nice to wean ourselves off of the
+ CONFIG versions. (Among other things, some defective build environments
+ leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include
+ files. We've experienced collisions before.)
+---
+FEATURE_CLEAN_UP
+ This is more an unresolved issue than a to-do item. More thought is needed.
+
+ Normally we rely on exit() to free memory, close files, and unmap segments
+ for us. This makes most calls to free(), close(), and unmap() optional in
+ busybox applets that don't intend to run for very long, and optional stuff
+ can be omitted to save size.
+
+ The idea was raised that we could simulate fork/exit with setjmp/longjmp
+ for _really_ brainless embedded systems, or speed up the standalone shell
+ by not forking. Doing so would require a reliable FEATURE_CLEAN_UP.
+ Unfortunately, this isn't as easy as it sounds.
+
+ The problem is, lots of things exit(), sometimes unexpectedly (xmalloc())
+ and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This
+ jumps out of the normal flow control and bypasses any cleanup code we
+ put at the end of our applets.
+
+ It's possible to add hooks to libbb functions like xmalloc() and bb_xopen()
+ to add their entries to a linked list, which could be traversed and
+ freed/closed automatically. (This would need to be able to free just the
+ entries after a checkpoint to be usable for a forkless standalone shell.
+ You don't want to free the shell's own resources.)
+
+ Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things
+ like valgrind happy. It's also documentation of _what_ we're trusting
+ exit() to clean up for us. But new infrastructure to auto-free stuff would
+ render the existing FEATURE_CLEAN_UP code redundant.
+
+ For right now, exit() handles it just fine.
+
+
+
+Minor stuff:
+ watchdog.c could autodetect the timer duration via:
+ if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2);
+ Unfortunately, that needs linux/watchdog.h and that contains unfiltered
+ kernel types on some distros, which breaks the build.
+
+
+Code cleanup:
+
+Replace deprecated functions.
+
+bzero() -> memset()
+---
+sigblock(), siggetmask(), sigsetmask(), sigmask() -> sigprocmask et al
+---
-------------------------------------------------------------------
projects / oweals / busybox.git / blobdiff