Contents of /tags/mkinitrd-6_1_9/busybox/TODO
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Wed Oct 28 00:26:51 2009 UTC (14 years, 11 months ago) by niro
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Wed Oct 28 00:26:51 2009 UTC (14 years, 11 months ago) by niro
File size: 13305 byte(s)
tagged 'mkinitrd-6_1_9'
1 | 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 | Rob Landley suggested these: |
10 | Add a libbb/platform.c |
11 | Implement fdprintf() for platforms that haven't got one. |
12 | Implement bb_realpath() that can handle NULL on non-glibc. |
13 | Cleanup bb_asprintf() |
14 | |
15 | Remove obsolete _() wrapper crud for internationalization we don't do. |
16 | Figure out where we need utf8 support, and add it. |
17 | |
18 | sh |
19 | The command shell situation is a big mess. We have three different |
20 | shells that don't really share any code, and the "standalone shell" doesn't |
21 | work all that well (especially not in a chroot environment), due to apps not |
22 | being reentrant. |
23 | lash is phased out. hush can be configured down to be nearly as small, |
24 | but less buggy :) |
25 | init |
26 | General cleanup (should use ENABLE_FEATURE_INIT_SYSLOG and ENABLE_FEATURE_INIT_DEBUG). |
27 | Do a SUSv3 audit |
28 | Look at the full Single Unix Specification version 3 (available online at |
29 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and |
30 | figure out which of our apps are compliant, and what we're missing that |
31 | we might actually care about. |
32 | |
33 | Even better would be some kind of automated compliance test harness that |
34 | exercises each command line option and the various corner cases. |
35 | Internationalization |
36 | How much internationalization should we do? |
37 | |
38 | The low hanging fruit is UTF-8 character set support. We should do this. |
39 | (Vodz pointed out the shell's cmdedit as needing work here. What else?) |
40 | |
41 | We also have lots of hardwired english text messages. Consolidating this |
42 | into some kind of message table not only makes translation easier, but |
43 | also allows us to consolidate redundant (or close) strings. |
44 | |
45 | We probably don't want to be bloated with locale support. (Not unless we |
46 | can cleanly export it from our underlying C library without having to |
47 | concern ourselves with it directly. Perhaps a few specific things like a |
48 | config option for "date" are low hanging fruit here?) |
49 | |
50 | What level should things happen at? How much do we care about |
51 | internationalizing the text console when X11 and xterms are so much better |
52 | at it? (There's some infrastructure here we don't implement: The |
53 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a |
54 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys |
55 | implementation to replace loadkmap/dumpkmap. Plus messing with console font |
56 | loading. Is it worth it, or do we just say "use X"?) |
57 | |
58 | Individual compilation of applets. |
59 | It would be nice if busybox had the option to compile to individual applets, |
60 | for people who want an alternate implementation less bloated than the gnu |
61 | utils (or simply with less political baggage), but without it being one big |
62 | executable. |
63 | |
64 | Turning libbb into a real dll is another possibility, especially if libbb |
65 | could export some of the other library interfaces we've already more or less |
66 | got the code for (like zlib). |
67 | buildroot - Make a "dogfood" option |
68 | Busybox 1.1 will be capable of replacing most gnu packages for real world |
69 | use, such as developing software or in a live CD. It needs wider testing. |
70 | |
71 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file, |
72 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps, |
73 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting |
74 | system should be self-hosting (I.E. able to rebuild itself from source |
75 | code). This means it would need (at least) binutils, gcc, and make, or |
76 | equivalents. |
77 | |
78 | It would be a good "eating our own dogfood" test if buildroot had the option |
79 | of using a "make allyesconfig" busybox instead of the all of the above |
80 | packages. Anything that's wrong with the resulting system, we can fix. (It |
81 | would be nice to be able to upgrade busybox to be able to replace bash and |
82 | diffutils as well, but we're not there yet.) |
83 | |
84 | One example of an existing system that does this already is Firmware Linux: |
85 | http://www.landley.net/code/firmware |
86 | initramfs |
87 | Busybox should have a sample initramfs build script. This depends on |
88 | bbsh, mdev, and switch_root. |
89 | mkdep |
90 | Write a mkdep that doesn't segfault if there's a directory it doesn't |
91 | have permission to read, isn't based on manually editing the output of |
92 | lexx and yacc, doesn't make such a mess under include/config, etc. |
93 | Group globals into unions of structures. |
94 | Go through and turn all the global and static variables into structures, |
95 | and have all those structures be in a big union shared between processes, |
96 | so busybox uses less bss. (This is a big win on nommu machines.) See |
97 | sed.c and mdev.c for examples. |
98 | Go through bugs.busybox.net and close out all of that somehow. |
99 | This one's open to everybody, but I'll wind up doing it... |
100 | |
101 | |
102 | Bernhard Reutner-Fischer <busybox@busybox.net> suggests to look at these: |
103 | New debug options: |
104 | -Wlarger-than-127 |
105 | Cleanup any big users |
106 | -Wunused-parameter |
107 | Facilitate applet PROTOTYPES to provide means for having applets that |
108 | do a) not take any arguments b) need only one of argc or argv c) need |
109 | both argc and argv. All of these three options should go for the most |
110 | feature complete denominator. |
111 | Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE |
112 | make bb_common_bufsiz1 configurable, size wise. |
113 | make pipesize configurable, size wise. |
114 | Use bb_common_bufsiz1 throughout applets! |
115 | |
116 | As yet unclaimed: |
117 | |
118 | ---- |
119 | diff |
120 | Make sure we handle empty files properly: |
121 | From the patch man page: |
122 | |
123 | you can remove a file by sending out a context diff that compares |
124 | the file to be deleted with an empty file dated the Epoch. The |
125 | file will be removed unless patch is conforming to POSIX and the |
126 | -E or --remove-empty-files option is not given. |
127 | --- |
128 | patch |
129 | Should have simple fuzz factor support to apply patches at an offset which |
130 | shouldn't take up too much space. |
131 | |
132 | And while we're at it, a new patch filename quoting format is apparently |
133 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2 |
134 | --- |
135 | man |
136 | It would be nice to have a man command. Not one that handles troff or |
137 | anything, just one that can handle preformatted ascii man pages, possibly |
138 | compressed. This could probably be a script in the extras directory that |
139 | calls cat/zcat/bzcat | less |
140 | |
141 | (How doclifter might work into this is anybody's guess.) |
142 | --- |
143 | ar |
144 | Write support! |
145 | --- |
146 | stty / catv |
147 | stty's visible() function and catv's guts are identical. Merge them into |
148 | an appropriate libbb function. |
149 | --- |
150 | struct suffix_mult |
151 | Several duplicate users of: grep -r "1024\*1024" * -B2 -A1 |
152 | Merge to a single size_suffixes[] in libbb. |
153 | Users: head tail od_bloaty hexdump and (partially as it wouldn't hurt) svlogd |
154 | --- |
155 | tail |
156 | ./busybox tail -f foo.c~ TODO |
157 | should not print fmt=header_fmt for subsequent date >> TODO; i.e. only |
158 | fmt+ if another (not the current) file did change |
159 | |
160 | Architectural issues: |
161 | |
162 | bb_close() with fsync() |
163 | We should have a bb_close() in place of normal close, with a CONFIG_ option |
164 | to not just check the return value of close() for an error, but fsync(). |
165 | Close can't reliably report anything useful because if write() accepted the |
166 | data then it either went out to the network or it's in cache or a pipe |
167 | buffer. Either way, there's no guarantee it'll make it to its final |
168 | destination before close() gets called, so there's no guarantee that any |
169 | error will be reported. |
170 | |
171 | You need to call fsync() if you care about errors that occur after write(), |
172 | but that can have a big performance impact. So make it a config option. |
173 | --- |
174 | Unify archivers |
175 | Lots of archivers have the same general infrastructure. The directory |
176 | traversal code should be factored out, and the guts of each archiver could |
177 | be some setup code and a series of callbacks for "add this file", |
178 | "add this directory", "add this symlink" and so on. |
179 | |
180 | This could clean up tar and zip, and make it cheaper to add cpio and ar |
181 | write support, and possibly even cheaply add things like mkisofs or |
182 | mksquashfs someday, if they become relevant. |
183 | --- |
184 | Text buffer support. |
185 | Several existing applets (sort, vi, less...) read |
186 | a whole file into memory and act on it. There might be an opportunity |
187 | for shared code in there that could be moved into libbb... |
188 | --- |
189 | Memory Allocation |
190 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory |
191 | allocation on the stack or the heap. Unfortunately, we're not using it much. |
192 | We need to audit our memory allocations and turn a lot of malloc/free calls |
193 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER. |
194 | For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64 |
195 | |
196 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be |
197 | optimized out by the compiler in the stack allocation case (since there's no |
198 | free for an alloca()), and this means that various cleanup loops that just |
199 | call free might also be optimized out by the compiler if written right, so |
200 | we can yank those #ifdefs too, and generally clean up the code. |
201 | --- |
202 | Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS |
203 | |
204 | In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS |
205 | that were either defined or undefined to indicate whether the symbol was |
206 | selected in the .config file. They were used with #ifdefs, ala: |
207 | |
208 | #ifdef CONFIG_SYMBOL |
209 | if (other_test) { |
210 | do_code(); |
211 | } |
212 | #endif |
213 | |
214 | In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1), |
215 | meaning you can still use them for preprocessor tests by replacing |
216 | "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we |
217 | can use them as a true or false test in normal C code: |
218 | |
219 | if (ENABLE_SYMBOL && other_test) { |
220 | do_code(); |
221 | } |
222 | |
223 | (Optimizing away if() statements that resolve to a constant value |
224 | is known as "dead code elimination", an optimization so old and simple that |
225 | Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers |
226 | like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC) |
227 | perform dead code elimination.) |
228 | |
229 | Right now, busybox.h is #including both "config.h" (defining the |
230 | CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some |
231 | point in the future, it would be nice to wean ourselves off of the |
232 | CONFIG versions. (Among other things, some defective build environments |
233 | leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include |
234 | files. We've experienced collisions before.) |
235 | --- |
236 | FEATURE_CLEAN_UP |
237 | This is more an unresolved issue than a to-do item. More thought is needed. |
238 | |
239 | Normally we rely on exit() to free memory, close files, and unmap segments |
240 | for us. This makes most calls to free(), close(), and unmap() optional in |
241 | busybox applets that don't intend to run for very long, and optional stuff |
242 | can be omitted to save size. |
243 | |
244 | The idea was raised that we could simulate fork/exit with setjmp/longjmp |
245 | for _really_ brainless embedded systems, or speed up the standalone shell |
246 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP. |
247 | Unfortunately, this isn't as easy as it sounds. |
248 | |
249 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc()) |
250 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This |
251 | jumps out of the normal flow control and bypasses any cleanup code we |
252 | put at the end of our applets. |
253 | |
254 | It's possible to add hooks to libbb functions like xmalloc() and xopen() |
255 | to add their entries to a linked list, which could be traversed and |
256 | freed/closed automatically. (This would need to be able to free just the |
257 | entries after a checkpoint to be usable for a forkless standalone shell. |
258 | You don't want to free the shell's own resources.) |
259 | |
260 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things |
261 | like valgrind happy. It's also documentation of _what_ we're trusting |
262 | exit() to clean up for us. But new infrastructure to auto-free stuff would |
263 | render the existing FEATURE_CLEAN_UP code redundant. |
264 | |
265 | For right now, exit() handles it just fine. |
266 | |
267 | |
268 | |
269 | Minor stuff: |
270 | watchdog.c could autodetect the timer duration via: |
271 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2); |
272 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered |
273 | kernel types on some distros, which breaks the build. |
274 | --- |
275 | use bb_error_msg where appropriate: See |
276 | egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))" |
277 | --- |
278 | use bb_perror_msg where appropriate: See |
279 | egrep "[^_]perror" |
280 | --- |
281 | possible code duplication ingroup() and is_a_group_member() |
282 | --- |
283 | Move __get_hz() to a better place and (re)use it in route.c, ash.c, msh.c |
284 | --- |
285 | See grep -r strtod |
286 | Alot of duplication that wants cleanup. |
287 | --- |
288 | in_ether duplicated in network/{interface,ifconfig}.c |
289 | --- |
290 | |
291 | |
292 | Code cleanup: |
293 | |
294 | Replace deprecated functions. |
295 | |
296 | --- |
297 | vdprintf() -> similar sized functionality |
298 | --- |