X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=TODO;h=92fd403a9e5ff9e0b89a18e24862bb83defcfc3a;hb=a75c180e538bb8adc0bb280c61dd933fd8d3e56d;hp=3eb2834cf6f79df7ebb654aeaa889202c37acf4c;hpb=d38eaef70bd8e3045992d95057088b65d0fa254f;p=oweals%2Fbusybox.git diff --git a/TODO b/TODO index 3eb2834cf..92fd403a9 100644 --- a/TODO +++ b/TODO @@ -1,29 +1,204 @@ -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 in libcrypt). - - -Erik - ------------ - -* mknod --help segfaults - -* Allow tar to create archives with sockets, devices, and other special files -* Make insmod actually work -* init clearly needs to support some type of minimalist /etc/inittab. I - currently have _way_ too much policy hardcoded in the source. Adding - support for getty has made me realize how much that sucks. -* dnsdomainname -* traceroute/nslookup/netstat -* rdate -* hwclock -* killall -* stty -* wc -* tr -* expr (maybe?) (ash builtin?) +Busybox TODO +Stuff that needs to be done + +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. + + Note: Rob Landley (rob@landley.net) is working on this one, but very slowly... +--- +diff + We should have a diff -u command. We have patch, we should have diff + (we only need to support unified diffs though). +--- +patch + 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 +--- +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 +--- +bzip2 + Compression-side support. +--- +init + General cleanup. + +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 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. + 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. +--- +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. + (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. + + 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. + + 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 (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 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 +--- +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.