| 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 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). |
| --- |
| 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. |
| |
| 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. |
| |
| |
| 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 (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. |