X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=TODO;h=dd9ae11f3f9e8b6176dea3979e83e6290cef4dc4;hb=94c3331d47ae08167e5122a3023ffc3340274698;hp=ffffd4f5329425bb2a4cddad15977fc1d33c8cc9;hpb=90d2bff4c67d65a4025451213d5028c539b7b91a;p=oweals%2Fbusybox.git diff --git a/TODO b/TODO index ffffd4f53..dd9ae11f3 100644 --- a/TODO +++ b/TODO @@ -2,10 +2,181 @@ Busybox TODO Stuff that needs to be done ----- -tr - missing SuS3 features in busybox 1.0pre10 +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.