Annotation of /trunk/mkinitrd-magellan/busybox/TODO
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Sun May 30 11:32:42 2010 UTC (14 years, 4 months ago) by niro
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Sun May 30 11:32:42 2010 UTC (14 years, 4 months ago) by niro
File size: 15233 byte(s)
-updated to busybox-1.16.1 and enabled blkid/uuid support in default config
1 | niro | 532 | Busybox TODO |
2 | |||
3 | Stuff that needs to be done. This is organized by who plans to get around to | ||
4 | doing it eventually, but that doesn't mean they "own" the item. If you want to | ||
5 | do one of these bounce an email off the person it's listed under to see if they | ||
6 | have any suggestions how they plan to go about it, and to minimize conflicts | ||
7 | between your work and theirs. But otherwise, all of these are fair game. | ||
8 | |||
9 | niro | 984 | Rob Landley suggested this: |
10 | Implement bb_realpath() that can handle NULL on non-glibc. | ||
11 | niro | 532 | |
12 | Remove obsolete _() wrapper crud for internationalization we don't do. | ||
13 | Figure out where we need utf8 support, and add it. | ||
14 | |||
15 | sh | ||
16 | niro | 984 | The command shell situation is a mess. We have two different |
17 | niro | 532 | shells that don't really share any code, and the "standalone shell" doesn't |
18 | work all that well (especially not in a chroot environment), due to apps not | ||
19 | niro | 816 | being reentrant. |
20 | niro | 984 | |
21 | niro | 532 | Do a SUSv3 audit |
22 | Look at the full Single Unix Specification version 3 (available online at | ||
23 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and | ||
24 | figure out which of our apps are compliant, and what we're missing that | ||
25 | we might actually care about. | ||
26 | |||
27 | Even better would be some kind of automated compliance test harness that | ||
28 | exercises each command line option and the various corner cases. | ||
29 | niro | 984 | |
30 | niro | 532 | Internationalization |
31 | How much internationalization should we do? | ||
32 | |||
33 | The low hanging fruit is UTF-8 character set support. We should do this. | ||
34 | (Vodz pointed out the shell's cmdedit as needing work here. What else?) | ||
35 | |||
36 | We also have lots of hardwired english text messages. Consolidating this | ||
37 | into some kind of message table not only makes translation easier, but | ||
38 | also allows us to consolidate redundant (or close) strings. | ||
39 | |||
40 | We probably don't want to be bloated with locale support. (Not unless we | ||
41 | can cleanly export it from our underlying C library without having to | ||
42 | concern ourselves with it directly. Perhaps a few specific things like a | ||
43 | config option for "date" are low hanging fruit here?) | ||
44 | |||
45 | What level should things happen at? How much do we care about | ||
46 | internationalizing the text console when X11 and xterms are so much better | ||
47 | at it? (There's some infrastructure here we don't implement: The | ||
48 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a | ||
49 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys | ||
50 | implementation to replace loadkmap/dumpkmap. Plus messing with console font | ||
51 | loading. Is it worth it, or do we just say "use X"?) | ||
52 | |||
53 | Individual compilation of applets. | ||
54 | It would be nice if busybox had the option to compile to individual applets, | ||
55 | for people who want an alternate implementation less bloated than the gnu | ||
56 | utils (or simply with less political baggage), but without it being one big | ||
57 | executable. | ||
58 | |||
59 | Turning libbb into a real dll is another possibility, especially if libbb | ||
60 | could export some of the other library interfaces we've already more or less | ||
61 | got the code for (like zlib). | ||
62 | buildroot - Make a "dogfood" option | ||
63 | Busybox 1.1 will be capable of replacing most gnu packages for real world | ||
64 | use, such as developing software or in a live CD. It needs wider testing. | ||
65 | |||
66 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file, | ||
67 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps, | ||
68 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting | ||
69 | system should be self-hosting (I.E. able to rebuild itself from source | ||
70 | code). This means it would need (at least) binutils, gcc, and make, or | ||
71 | equivalents. | ||
72 | |||
73 | It would be a good "eating our own dogfood" test if buildroot had the option | ||
74 | of using a "make allyesconfig" busybox instead of the all of the above | ||
75 | packages. Anything that's wrong with the resulting system, we can fix. (It | ||
76 | would be nice to be able to upgrade busybox to be able to replace bash and | ||
77 | diffutils as well, but we're not there yet.) | ||
78 | |||
79 | One example of an existing system that does this already is Firmware Linux: | ||
80 | http://www.landley.net/code/firmware | ||
81 | initramfs | ||
82 | Busybox should have a sample initramfs build script. This depends on | ||
83 | bbsh, mdev, and switch_root. | ||
84 | mkdep | ||
85 | Write a mkdep that doesn't segfault if there's a directory it doesn't | ||
86 | have permission to read, isn't based on manually editing the output of | ||
87 | lexx and yacc, doesn't make such a mess under include/config, etc. | ||
88 | Group globals into unions of structures. | ||
89 | Go through and turn all the global and static variables into structures, | ||
90 | and have all those structures be in a big union shared between processes, | ||
91 | so busybox uses less bss. (This is a big win on nommu machines.) See | ||
92 | sed.c and mdev.c for examples. | ||
93 | Go through bugs.busybox.net and close out all of that somehow. | ||
94 | This one's open to everybody, but I'll wind up doing it... | ||
95 | |||
96 | |||
97 | niro | 816 | Bernhard Reutner-Fischer <busybox@busybox.net> suggests to look at these: |
98 | niro | 532 | New debug options: |
99 | -Wlarger-than-127 | ||
100 | Cleanup any big users | ||
101 | Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE | ||
102 | make bb_common_bufsiz1 configurable, size wise. | ||
103 | make pipesize configurable, size wise. | ||
104 | Use bb_common_bufsiz1 throughout applets! | ||
105 | |||
106 | As yet unclaimed: | ||
107 | |||
108 | ---- | ||
109 | diff | ||
110 | Make sure we handle empty files properly: | ||
111 | From the patch man page: | ||
112 | |||
113 | you can remove a file by sending out a context diff that compares | ||
114 | the file to be deleted with an empty file dated the Epoch. The | ||
115 | file will be removed unless patch is conforming to POSIX and the | ||
116 | -E or --remove-empty-files option is not given. | ||
117 | --- | ||
118 | patch | ||
119 | Should have simple fuzz factor support to apply patches at an offset which | ||
120 | shouldn't take up too much space. | ||
121 | |||
122 | And while we're at it, a new patch filename quoting format is apparently | ||
123 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2 | ||
124 | --- | ||
125 | ar | ||
126 | niro | 816 | Write support! |
127 | --- | ||
128 | niro | 532 | stty / catv |
129 | stty's visible() function and catv's guts are identical. Merge them into | ||
130 | an appropriate libbb function. | ||
131 | niro | 816 | --- |
132 | struct suffix_mult | ||
133 | Several duplicate users of: grep -r "1024\*1024" * -B2 -A1 | ||
134 | Merge to a single size_suffixes[] in libbb. | ||
135 | Users: head tail od_bloaty hexdump and (partially as it wouldn't hurt) svlogd | ||
136 | --- | ||
137 | tail | ||
138 | ./busybox tail -f foo.c~ TODO | ||
139 | should not print fmt=header_fmt for subsequent date >> TODO; i.e. only | ||
140 | fmt+ if another (not the current) file did change | ||
141 | niro | 532 | |
142 | Architectural issues: | ||
143 | |||
144 | bb_close() with fsync() | ||
145 | We should have a bb_close() in place of normal close, with a CONFIG_ option | ||
146 | to not just check the return value of close() for an error, but fsync(). | ||
147 | Close can't reliably report anything useful because if write() accepted the | ||
148 | data then it either went out to the network or it's in cache or a pipe | ||
149 | buffer. Either way, there's no guarantee it'll make it to its final | ||
150 | destination before close() gets called, so there's no guarantee that any | ||
151 | error will be reported. | ||
152 | |||
153 | You need to call fsync() if you care about errors that occur after write(), | ||
154 | but that can have a big performance impact. So make it a config option. | ||
155 | --- | ||
156 | Unify archivers | ||
157 | Lots of archivers have the same general infrastructure. The directory | ||
158 | traversal code should be factored out, and the guts of each archiver could | ||
159 | be some setup code and a series of callbacks for "add this file", | ||
160 | "add this directory", "add this symlink" and so on. | ||
161 | |||
162 | This could clean up tar and zip, and make it cheaper to add cpio and ar | ||
163 | write support, and possibly even cheaply add things like mkisofs or | ||
164 | mksquashfs someday, if they become relevant. | ||
165 | --- | ||
166 | Text buffer support. | ||
167 | Several existing applets (sort, vi, less...) read | ||
168 | niro | 984 | a whole file into memory and act on it. Use open_read_close(). |
169 | niro | 532 | --- |
170 | Memory Allocation | ||
171 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory | ||
172 | allocation on the stack or the heap. Unfortunately, we're not using it much. | ||
173 | We need to audit our memory allocations and turn a lot of malloc/free calls | ||
174 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER. | ||
175 | For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64 | ||
176 | |||
177 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be | ||
178 | optimized out by the compiler in the stack allocation case (since there's no | ||
179 | free for an alloca()), and this means that various cleanup loops that just | ||
180 | call free might also be optimized out by the compiler if written right, so | ||
181 | we can yank those #ifdefs too, and generally clean up the code. | ||
182 | --- | ||
183 | Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS | ||
184 | |||
185 | In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS | ||
186 | that were either defined or undefined to indicate whether the symbol was | ||
187 | selected in the .config file. They were used with #ifdefs, ala: | ||
188 | |||
189 | #ifdef CONFIG_SYMBOL | ||
190 | if (other_test) { | ||
191 | do_code(); | ||
192 | } | ||
193 | #endif | ||
194 | |||
195 | In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1), | ||
196 | meaning you can still use them for preprocessor tests by replacing | ||
197 | "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we | ||
198 | can use them as a true or false test in normal C code: | ||
199 | |||
200 | if (ENABLE_SYMBOL && other_test) { | ||
201 | do_code(); | ||
202 | } | ||
203 | |||
204 | (Optimizing away if() statements that resolve to a constant value | ||
205 | is known as "dead code elimination", an optimization so old and simple that | ||
206 | Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers | ||
207 | like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC) | ||
208 | perform dead code elimination.) | ||
209 | |||
210 | Right now, busybox.h is #including both "config.h" (defining the | ||
211 | CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some | ||
212 | point in the future, it would be nice to wean ourselves off of the | ||
213 | CONFIG versions. (Among other things, some defective build environments | ||
214 | leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include | ||
215 | files. We've experienced collisions before.) | ||
216 | --- | ||
217 | FEATURE_CLEAN_UP | ||
218 | This is more an unresolved issue than a to-do item. More thought is needed. | ||
219 | |||
220 | niro | 984 | Normally we rely on exit() to free memory, close files and unmap segments |
221 | niro | 532 | for us. This makes most calls to free(), close(), and unmap() optional in |
222 | busybox applets that don't intend to run for very long, and optional stuff | ||
223 | can be omitted to save size. | ||
224 | |||
225 | The idea was raised that we could simulate fork/exit with setjmp/longjmp | ||
226 | for _really_ brainless embedded systems, or speed up the standalone shell | ||
227 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP. | ||
228 | Unfortunately, this isn't as easy as it sounds. | ||
229 | |||
230 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc()) | ||
231 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This | ||
232 | jumps out of the normal flow control and bypasses any cleanup code we | ||
233 | put at the end of our applets. | ||
234 | |||
235 | It's possible to add hooks to libbb functions like xmalloc() and xopen() | ||
236 | to add their entries to a linked list, which could be traversed and | ||
237 | freed/closed automatically. (This would need to be able to free just the | ||
238 | entries after a checkpoint to be usable for a forkless standalone shell. | ||
239 | You don't want to free the shell's own resources.) | ||
240 | |||
241 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things | ||
242 | like valgrind happy. It's also documentation of _what_ we're trusting | ||
243 | exit() to clean up for us. But new infrastructure to auto-free stuff would | ||
244 | render the existing FEATURE_CLEAN_UP code redundant. | ||
245 | |||
246 | For right now, exit() handles it just fine. | ||
247 | |||
248 | |||
249 | Minor stuff: | ||
250 | watchdog.c could autodetect the timer duration via: | ||
251 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2); | ||
252 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered | ||
253 | kernel types on some distros, which breaks the build. | ||
254 | --- | ||
255 | use bb_error_msg where appropriate: See | ||
256 | egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))" | ||
257 | --- | ||
258 | use bb_perror_msg where appropriate: See | ||
259 | egrep "[^_]perror" | ||
260 | --- | ||
261 | possible code duplication ingroup() and is_a_group_member() | ||
262 | --- | ||
263 | niro | 984 | Move __get_hz() to a better place and (re)use it in route.c, ash.c |
264 | niro | 532 | --- |
265 | niro | 816 | See grep -r strtod |
266 | Alot of duplication that wants cleanup. | ||
267 | --- | ||
268 | in_ether duplicated in network/{interface,ifconfig}.c | ||
269 | --- | ||
270 | niro | 984 | unify progress_meter. wget, flash_eraseall, pipe_progress, fbsplash, setfiles. |
271 | --- | ||
272 | support start-stop-daemon -d <chdir-path> | ||
273 | niro | 532 | |
274 | Code cleanup: | ||
275 | |||
276 | Replace deprecated functions. | ||
277 | |||
278 | --- | ||
279 | vdprintf() -> similar sized functionality | ||
280 | --- | ||
281 | niro | 984 | |
282 | (TODO list after discussion 11.05.2009) | ||
283 | |||
284 | * shrink tc/brctl/ip | ||
285 | tc/brctl seem like fairly large things to try and tackle in your timeframe, | ||
286 | and i think people have posted attempts in the past. Adding additional | ||
287 | options to ip though seems reasonable. | ||
288 | |||
289 | * add tests for some applets | ||
290 | |||
291 | * implement POSIX utilities and audit them for POSIX conformance. then | ||
292 | audit them for GNU conformance. then document all your findings in a new | ||
293 | doc/conformance.txt file while perhaps implementing some of the missing | ||
294 | features. | ||
295 | you can find the latest POSIX documentation (1003.1-2008) here: | ||
296 | http://www.opengroup.org/onlinepubs/9699919799/ | ||
297 | and the complete list of all utilities that POSIX covers: | ||
298 | http://www.opengroup.org/onlinepubs/9699919799/idx/utilities.html | ||
299 | The first step would to generate a file/matrix what is already archived | ||
300 | (also IPV6) | ||
301 | |||
302 | * ntpdate/ntpd (see ntpclient and openntp for examples) | ||
303 | |||
304 | * implement 'at' | ||
305 | |||
306 | * rpcbind (former portmap) or equivalent | ||
307 | so that we don't have to use -o nolock on nfs mounts | ||
308 | |||
309 | * check IPV6 compliance | ||
310 | |||
311 | * generate a mini example using kernel+busybox only (+libc) for example | ||
312 | |||
313 | * more support for advanced linux 2.6.x features, see: iotop | ||
314 | most likely there is more | ||
315 | |||
316 | * even more support for statistics: mpstat, iostat, powertop.... | ||
317 | |||
318 | |||
319 | Unicode work needed: | ||
320 | |||
321 | Unicode support uses libc multibyte functions if LOCALE_SUPPORT is on | ||
322 | (in this case, the code will also support many more encodings), | ||
323 | or uses a limited subset of re-implemented multibyte functions | ||
324 | which only understand "one byte == one char" and unicode. | ||
325 | This is useful if you build against uclibc with locale support disabled. | ||
326 | |||
327 | Unicode-dependent applets must call check_unicode_in_env() when they | ||
328 | begin executing. | ||
329 | |||
330 | Applet code may conditionalize on FEATURE_ASSUME_UNICODE | ||
331 | in order to use more efficient code if unicode support is not requested. | ||
332 | |||
333 | Available functions (if you need more, implement them in libbb/unicode.c | ||
334 | so that they work without LOCALE_SUPPORT too): | ||
335 | |||
336 | int bb_mbstrlen(str) - multibyte-aware strlen | ||
337 | size_t mbstowcs(wdest, src, n) | ||
338 | size_t wcstombs(dest, wsrc, n) | ||
339 | size_t wcrtomb(str, wc, wstate) | ||
340 | int iswspace(wc) | ||
341 | int iswalnum(wc) | ||
342 | int iswpunct(wc) | ||
343 | |||
344 | Applets which only need to align columns on screen correctly: | ||
345 | |||
346 | ls - already done, use source as an example | ||
347 | df | ||
348 | dumpleases | ||
349 | lsmod | ||
350 | |||
351 | Applets which need to account for Unicode chars | ||
352 | while processing the output: | ||
353 | |||
354 | [un]expand | ||
355 | fold | ||
356 | man | ||
357 | watch | ||
358 | cut (-b and -c are currently the same, needs fixing) | ||
359 | |||
360 | These applets need to ensure that unicode input | ||
361 | is handled correctly (say, <unicode><backspace> sequence): | ||
362 | |||
363 | getty, login | ||
364 | rm -i | ||
365 | unzip (overwrite prompt) | ||
366 | |||
367 | Viewers/editors are more difficult (many cases to get right). | ||
368 | libbb/lineedit.c is an example how to do it: | ||
369 | |||
370 | less, most, ed, vi | ||
371 | awk | ||
372 | [ef]grep | ||
373 | sed | ||
374 | |||
375 | Probably needs some specialized work: | ||
376 | |||
377 | loadkeys |