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Diffstat (limited to 'release/src/router/busybox/TODO')
| -rw-r--r-- | release/src/router/busybox/TODO | 302 |
1 files changed, 265 insertions, 37 deletions
diff --git a/release/src/router/busybox/TODO b/release/src/router/busybox/TODO index 3d9af20a..d6a60d1d 100644 --- a/release/src/router/busybox/TODO +++ b/release/src/router/busybox/TODO @@ -1,57 +1,285 @@ -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. +Busybox TODO -* 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). +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. -* 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. +Rob Landley suggested these: + Add a libbb/platform.c + Implement fdprintf() for platforms that haven't got one. + Implement bb_realpath() that can handle NULL on non-glibc. + Cleanup bb_asprintf() + Remove obsolete _() wrapper crud for internationalization we don't do. + Figure out where we need utf8 support, and add it. - -Erik + sh + The command shell situation is a big mess. We have three 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. + lash is phased out. hush can be configured down to be nearly as small, + but less buggy :) + init + General cleanup (should use ENABLE_FEATURE_INIT_SYSLOG). + 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? -Possible apps to include some time: + 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?) -* hwclock -* start-stop-daemon -* group/commonize strings, remove dups (for i18n, l10n) + 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?) -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. + 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. -Run the following: + 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. - rm -f busybox && make LDFLAGS+=-nostdlib 2>&1 | \ - sed -ne 's/.*undefined reference to `\(.*\)..*/\1/gp' | sort | uniq + 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. -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. + 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 + bbsh, 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... -Compile with debugging on, run 'nm --size-sort ./busybox' -and then start with the biggest things and make them smaller... ------------------------ +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! - du.c probably ought to have an -x switch like GNU du does... +As yet unclaimed: ------------------------ +---- +diff + Make sure we handle empty files properly: + From the patch man page: -xargs could use a -l option + 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 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 +--- +ar + Write support! +--- +stty / catv + stty's visible() function and catv's guts are identical. Merge them into + an appropriate libbb function. +--- +struct suffix_mult + Several duplicate users of: grep -r "1024\*1024" * -B2 -A1 + Merge to a single size_suffixes[] in libbb. + Users: head tail od_bloaty hexdump and (partially as it wouldn't hurt) svlogd +--- +tail + ./busybox tail -f foo.c~ TODO + should not print fmt=header_fmt for subsequent date >> TODO; i.e. only + fmt+ if another (not the current) file did change + +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 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. + + 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 + 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 or + mksquashfs someday, if they become relevant. +--- +Text buffer support. + 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. +--- +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 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" +--- + possible code duplication ingroup() and is_a_group_member() +--- + Move __get_hz() to a better place and (re)use it in route.c, ash.c, msh.c +--- + See grep -r strtod + Alot of duplication that wants cleanup. +--- + in_ether duplicated in network/{interface,ifconfig}.c +--- + unify progress_meter. wget, flash_eraseall, pipe_progress, fbsplash, setfiles. + + +Code cleanup: + +Replace deprecated functions. + +--- +vdprintf() -> similar sized functionality +--- |