Busybox TODO
-Stuff that needs to be done
+Harvest patches from
+http://git.openembedded.org/cgit.cgi/openembedded/tree/recipes/busybox/
+https://dev.openwrt.org/browser/trunk/package/busybox/patches/
-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).
+Stuff that needs to be done. This is organized by who plans to get around to
+doing it eventually, but that doesn't mean they "own" the item. If you want to
+do one of these bounce an email off the person it's listed under to see if they
+have any suggestions how they plan to go about it, and to minimize conflicts
+between your work and theirs. But otherwise, all of these are fair game.
+
+Rob Landley suggested this:
+ Implement bb_realpath() that can handle NULL on non-glibc.
+
+ sh
+ The command shell situation is a mess. We have two 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.
+
+ 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.
+
+ Internationalization
+ How much internationalization should we do?
+
+ The low hanging fruit is UTF-8 character set support. We should do this.
+ See TODO_unicode file.
+
+ 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.
+
+ 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"?)
+
+ 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 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.
+
+ 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.)
+
+ 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
+ shell, mdev, and switch_root.
+
+ mkdep
+ Write a mkdep that doesn't segfault if there's a directory it doesn't
+ have permission to read, isn't based on manually editing the output of
+ lexx and yacc, doesn't make such a mess under include/config, etc.
+
+ Group globals into unions of structures.
+ Go through and turn all the global and static variables into structures,
+ and have all those structures be in a big union shared between processes,
+ so busybox uses less bss. (This is a big win on nommu machines.) See
+ sed.c and mdev.c for examples.
+
+ Go through bugs.busybox.net and close out all of that somehow.
+ This one's open to everybody, but I'll wind up doing it...
+
+Bernhard Reutner-Fischer <busybox@busybox.net> suggests to look at these:
+ New debug options:
+ -Wlarger-than-127
+ Cleanup any big users
+ Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE
+ make bb_common_bufsiz1 configurable, size wise.
+ make pipesize configurable, size wise.
+ Use bb_common_bufsiz1 throughout applets!
+
+As yet unclaimed:
+
----
-comm
- Perl needs "comm" to build. It's small and simple, but we haven't got it.
----
-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.
----
-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).
+ Make sure we handle empty files properly:
+ From the patch man page:
+
+ 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 -i support, and simple fuzz factor support to apply patches
- at an offset 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
----
-less
- More sucks if you're used to less. A tiny less implementation would be
- very nice.
----
-bzip2
- Compression-side support.
+ Should have simple fuzz factor support to apply patches at an offset which
+ shouldn't take up too much space.
+ 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
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.
+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.
- Even better would be some kind of automated compliance test harness that
- exercises each command line option and the various corner cases.
---
+ 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 archivers
Lots of archivers have the same general infrastructure. The directory
traversal code should be factored out, and the guts of each archiver could
"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.
+ write support, and possibly even cheaply add things like mkisofs or
+ mksquashfs someday, if they become 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...
+ Several existing applets (sort, vi, less...) read
+ a whole file into memory and act on it. Use open_read_close().
+---
+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.
+ For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64
+
+ 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.
+---
+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 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.
+---
+ use bb_error_msg where appropriate: See
+ egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))"
+---
+ use bb_perror_msg where appropriate: See
+ egrep "[^_]perror"
---
-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).
+ possible code duplication ingroup() and is_a_group_member()
---
-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.)
+ Move __get_hz() to a better place and (re)use it in route.c, ash.c
+---
+ See grep -r strtod
+ Alot of duplication that wants cleanup.
+---
+ unify progress_meter. wget, flash_eraseall, pipe_progress, fbsplash, setfiles.
+---
+ support start-stop-daemon -d <chdir-path>
+---
+vdprintf() -> similar sized functionality
+---
+
+(TODO list after discussion 11.05.2009)
+
+* shrink tc/brctl/ip
+ tc/brctl seem like fairly large things to try and tackle in your timeframe,
+ and i think people have posted attempts in the past. Adding additional
+ options to ip though seems reasonable.
+
+* add tests for some applets
+
+* implement POSIX utilities and audit them for POSIX conformance. then
+ audit them for GNU conformance. then document all your findings in a new
+ doc/conformance.txt file while perhaps implementing some of the missing
+ features.
+ you can find the latest POSIX documentation (1003.1-2008) here:
+ http://www.opengroup.org/onlinepubs/9699919799/
+ and the complete list of all utilities that POSIX covers:
+ http://www.opengroup.org/onlinepubs/9699919799/idx/utilities.html
+ The first step would to generate a file/matrix what is already archived
+ (also IPV6)
+
+* implement 'at'
+
+* rpcbind (former portmap) or equivalent
+ so that we don't have to use -o nolock on nfs mounts
+
+* check IPV6 compliance
+
+* generate a mini example using kernel+busybox only (+libc) for example
+
+* more support for advanced linux 2.6.x features, see: iotop
+ most likely there is more
+
+* even more support for statistics: mpstat, iostat, powertop....
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