-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.
-
-* 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).
-
-* We _were_ going to split networking apps into a new package called
- netkit-tiny. Per discussions on the mailing list, this isn't going
- to happen. False alarm. Sorry about the confusion.
-
-* The default busybox shell, lash, is really too weak for serious use,
- although it is possible to run many simple systems with it. BusyBox
- 0.52 now contains a rewritten shell, hush, which understands most
- Bourne grammar, with only about a 4 Kbyte binary size penalty. You can
- engage hush at pre-compile time by "ln -sf hush.c sh.c; touch hush.c".
- Hush is young, and has plenty of bugs to shake out, so think twice before
- using it for production systems. We welcome bug reports and patches.
-
- -Erik
-
------------
-
-Possible apps to include some time:
-
-* hwclock
-* group/commonize strings, remove dups (for i18n, l10n)
-
------------
-
-With sysvinit, reboot, poweroff and halt all used a named pipe,
-/dev/initctl, to communicate with the init process. Busybox
-currently uses signals to communicate with init. This makes
-busybox incompatible with sysvinit. We should probably use
-a named pipe as well so we can be compatible.
-
------------------------
-
-Run the following:
-
- rm -f busybox && make LDFLAGS+=-nostdlib 2>&1 | \
- sed -ne 's/.*undefined reference to `\(.*\)..*/\1/gp' | sort | uniq
-
-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, especially when staticly linking with
-libraries such as uClibc.
-
------------------------
-
-Compile with debugging on, run 'nm --size-sort ./busybox'
-and then start with the biggest things and make them smaller...
-
------------------------
-
- du.c probably ought to have an -x switch like GNU du does...
-
------------------------
-
-xargs could use a -l option
-
-------------------------------------------------------------------
+Busybox TODO
+
+Stuff that needs to be done
+
+tr - missing SuS3 features in busybox 1.0pre10
+
+tr doesnt support [:blank:], [:digit:] or other predefined classes, [=equiv=]
+support is also missing.
+----
+find
+ doesn't understand () or -exec, and these are actually used out in the real
+ world. The "make uninstall" of lots of things (including busybox itself)
+ breaks because of this, and sometimes even "make install" (like udev).
+----
+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 be a big improvement.
+
+ Note: Rob Landley (rob@landley.net) is working on this one, but very slowly...
+---
+gzip
+ Can't handle compressing multiple files at once. (I don't mean making a
+ multiple file archive, I mean compressing more than one file at a time.)
+ Some global variables aren't re-initialized between runs.
+---
+gunzip
+ same problem as gzip. "gunzip one.gz two.gz three.gz" doesn't work for
+ two.gz and three.gz due to global variables not getting reset.
+---
+diff
+ We should have a diff -u command. We have patch, we should have diff
+ (we only need to support unified diffs though).
+---
+fuser
+ Would be nice. The basic susv3 options, plus fuser -k.
+---
+patch
+ should have simple fuzz factor support to apply patches at an offset which
+ shouldn't take up too much space.
+---
+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/zcatbzcat | more
+---
+bzip2
+ Compression-side support.
+
+
+Architectural issues:
+
+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.
+
+ Even better would be some kind of automated compliance test harness that
+ exercises each command line option and the various corner cases.
+--
+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.
+
+ 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 someday,
+ if it becomes relevant.
+---
+Text buffer support.
+ Several existing applets and potential additions (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.
+
+ 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 is now capable of replacing most gnu packages for real world use,
+ such as developing software or in a live CD. A system built from busybox
+ (1.00 with updated sort.c), uclibc 0.9.27, gcc, binutils, make, and a few
+ other development tools (http://www.landley.net/code/firmware has an example
+ system using autoconf, automake, bison, flex, libtools, m4, zlib,
+ and groff: dunno what subset of that is actually necessary) is capable of
+ rebuilding itself, from scratch, under itself.
+
+ It would be a good "eating our own dogfood" test if buildroot had the option
+ of using busybox instead of bzip2, coreutils, file, findutils, gawk, grep,
+ inetutils, modutils, net-tools, procps, sed, shadow, sysklogd, sysvinit, tar,
+ util-linux, and vim. 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, diffutils, gzip, less, and patch as well.)
+---
+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
+
+ 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.
projects / oweals / busybox.git / blobdiff