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1 | Busybox TODO |
2 | |
3 | Harvest patches from |
4 | http://git.openembedded.org/cgit.cgi/openembedded/tree/recipes/busybox/ |
5 | https://dev.openwrt.org/browser/trunk/package/busybox/patches/ |
6 | |
7 | |
8 | Stuff that needs to be done. This is organized by who plans to get around to |
9 | doing it eventually, but that doesn't mean they "own" the item. If you want to |
10 | do one of these bounce an email off the person it's listed under to see if they |
11 | have any suggestions how they plan to go about it, and to minimize conflicts |
12 | between your work and theirs. But otherwise, all of these are fair game. |
13 | |
14 | Rob Landley suggested this: |
15 | Implement bb_realpath() that can handle NULL on non-glibc. |
16 | |
17 | sh |
18 | The command shell situation is a mess. We have two different |
19 | shells that don't really share any code, and the "standalone shell" doesn't |
20 | work all that well (especially not in a chroot environment), due to apps not |
21 | being reentrant. |
22 | |
23 | Do a SUSv3 audit |
24 | Look at the full Single Unix Specification version 3 (available online at |
25 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and |
26 | figure out which of our apps are compliant, and what we're missing that |
27 | we might actually care about. |
28 | |
29 | Even better would be some kind of automated compliance test harness that |
30 | exercises each command line option and the various corner cases. |
31 | |
32 | Internationalization |
33 | How much internationalization should we do? |
34 | |
35 | The low hanging fruit is UTF-8 character set support. We should do this. |
36 | See TODO_unicode file. |
37 | |
38 | We also have lots of hardwired english text messages. Consolidating this |
39 | into some kind of message table not only makes translation easier, but |
40 | also allows us to consolidate redundant (or close) strings. |
41 | |
42 | We probably don't want to be bloated with locale support. (Not unless we |
43 | can cleanly export it from our underlying C library without having to |
44 | concern ourselves with it directly. Perhaps a few specific things like a |
45 | config option for "date" are low hanging fruit here?) |
46 | |
47 | What level should things happen at? How much do we care about |
48 | internationalizing the text console when X11 and xterms are so much better |
49 | at it? (There's some infrastructure here we don't implement: The |
50 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a |
51 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys |
52 | implementation to replace loadkmap/dumpkmap. Plus messing with console font |
53 | loading. Is it worth it, or do we just say "use X"?) |
54 | |
55 | Individual compilation of applets. |
56 | It would be nice if busybox had the option to compile to individual applets, |
57 | for people who want an alternate implementation less bloated than the gnu |
58 | utils (or simply with less political baggage), but without it being one big |
59 | executable. |
60 | |
61 | Turning libbb into a real dll is another possibility, especially if libbb |
62 | could export some of the other library interfaces we've already more or less |
63 | got the code for (like zlib). |
64 | |
65 | buildroot - Make a "dogfood" option |
66 | Busybox 1.1 will be capable of replacing most gnu packages for real world |
67 | use, such as developing software or in a live CD. It needs wider testing. |
68 | |
69 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file, |
70 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps, |
71 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting |
72 | system should be self-hosting (I.E. able to rebuild itself from source |
73 | code). This means it would need (at least) binutils, gcc, and make, or |
74 | equivalents. |
75 | |
76 | It would be a good "eating our own dogfood" test if buildroot had the option |
77 | of using a "make allyesconfig" busybox instead of the all of the above |
78 | packages. Anything that's wrong with the resulting system, we can fix. (It |
79 | would be nice to be able to upgrade busybox to be able to replace bash and |
80 | diffutils as well, but we're not there yet.) |
81 | |
82 | One example of an existing system that does this already is Firmware Linux: |
83 | http://www.landley.net/code/firmware |
84 | |
85 | initramfs |
86 | Busybox should have a sample initramfs build script. This depends on |
87 | shell, mdev, and switch_root. |
88 | |
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 | |
94 | Group globals into unions of structures. |
95 | Go through and turn all the global and static variables into structures, |
96 | and have all those structures be in a big union shared between processes, |
97 | so busybox uses less bss. (This is a big win on nommu machines.) See |
98 | sed.c and mdev.c for examples. |
99 | |
100 | Go through bugs.busybox.net and close out all of that somehow. |
101 | This one's open to everybody, but I'll wind up doing it... |
102 | |
103 | Bernhard Reutner-Fischer <busybox@busybox.net> suggests to look at these: |
104 | New debug options: |
105 | -Wlarger-than-127 |
106 | Cleanup any big users |
107 | Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE |
108 | make bb_common_bufsiz1 configurable, size wise. |
109 | make pipesize configurable, size wise. |
110 | Use bb_common_bufsiz1 throughout applets! |
111 | |
112 | As yet unclaimed: |
113 | |
114 | ---- |
115 | diff |
116 | Make sure we handle empty files properly: |
117 | From the patch man page: |
118 | |
119 | you can remove a file by sending out a context diff that compares |
120 | the file to be deleted with an empty file dated the Epoch. The |
121 | file will be removed unless patch is conforming to POSIX and the |
122 | -E or --remove-empty-files option is not given. |
123 | --- |
124 | patch |
125 | Should have simple fuzz factor support to apply patches at an offset which |
126 | shouldn't take up too much space. |
127 | |
128 | And while we're at it, a new patch filename quoting format is apparently |
129 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2 |
130 | |
131 | Architectural issues: |
132 | |
133 | bb_close() with fsync() |
134 | We should have a bb_close() in place of normal close, with a CONFIG_ option |
135 | to not just check the return value of close() for an error, but fsync(). |
136 | Close can't reliably report anything useful because if write() accepted the |
137 | data then it either went out to the network or it's in cache or a pipe |
138 | buffer. Either way, there's no guarantee it'll make it to its final |
139 | destination before close() gets called, so there's no guarantee that any |
140 | error will be reported. |
141 | |
142 | You need to call fsync() if you care about errors that occur after write(), |
143 | but that can have a big performance impact. So make it a config option. |
144 | --- |
145 | Unify archivers |
146 | Lots of archivers have the same general infrastructure. The directory |
147 | traversal code should be factored out, and the guts of each archiver could |
148 | be some setup code and a series of callbacks for "add this file", |
149 | "add this directory", "add this symlink" and so on. |
150 | |
151 | This could clean up tar and zip, and make it cheaper to add cpio and ar |
152 | write support, and possibly even cheaply add things like mkisofs or |
153 | mksquashfs someday, if they become relevant. |
154 | --- |
155 | Text buffer support. |
156 | Several existing applets (sort, vi, less...) read |
157 | a whole file into memory and act on it. Use open_read_close(). |
158 | --- |
159 | Memory Allocation |
160 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory |
161 | allocation on the stack or the heap. Unfortunately, we're not using it much. |
162 | We need to audit our memory allocations and turn a lot of malloc/free calls |
163 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER. |
164 | For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64 |
165 | |
166 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be |
167 | optimized out by the compiler in the stack allocation case (since there's no |
168 | free for an alloca()), and this means that various cleanup loops that just |
169 | call free might also be optimized out by the compiler if written right, so |
170 | we can yank those #ifdefs too, and generally clean up the code. |
171 | --- |
172 | FEATURE_CLEAN_UP |
173 | This is more an unresolved issue than a to-do item. More thought is needed. |
174 | |
175 | Normally we rely on exit() to free memory, close files and unmap segments |
176 | for us. This makes most calls to free(), close(), and unmap() optional in |
177 | busybox applets that don't intend to run for very long, and optional stuff |
178 | can be omitted to save size. |
179 | |
180 | The idea was raised that we could simulate fork/exit with setjmp/longjmp |
181 | for _really_ brainless embedded systems, or speed up the standalone shell |
182 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP. |
183 | Unfortunately, this isn't as easy as it sounds. |
184 | |
185 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc()) |
186 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This |
187 | jumps out of the normal flow control and bypasses any cleanup code we |
188 | put at the end of our applets. |
189 | |
190 | It's possible to add hooks to libbb functions like xmalloc() and xopen() |
191 | to add their entries to a linked list, which could be traversed and |
192 | freed/closed automatically. (This would need to be able to free just the |
193 | entries after a checkpoint to be usable for a forkless standalone shell. |
194 | You don't want to free the shell's own resources.) |
195 | |
196 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things |
197 | like valgrind happy. It's also documentation of _what_ we're trusting |
198 | exit() to clean up for us. But new infrastructure to auto-free stuff would |
199 | render the existing FEATURE_CLEAN_UP code redundant. |
200 | |
201 | For right now, exit() handles it just fine. |
202 | |
203 | |
204 | Minor stuff: |
205 | watchdog.c could autodetect the timer duration via: |
206 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2); |
207 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered |
208 | kernel types on some distros, which breaks the build. |
209 | --- |
210 | use bb_error_msg where appropriate: See |
211 | egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))" |
212 | --- |
213 | use bb_perror_msg where appropriate: See |
214 | egrep "[^_]perror" |
215 | --- |
216 | possible code duplication ingroup() and is_a_group_member() |
217 | --- |
218 | Move __get_hz() to a better place and (re)use it in route.c, ash.c |
219 | --- |
220 | See grep -r strtod |
221 | Alot of duplication that wants cleanup. |
222 | --- |
223 | unify progress_meter. wget, flash_eraseall, pipe_progress, fbsplash, setfiles. |
224 | --- |
225 | support start-stop-daemon -d <chdir-path> |
226 | --- |
227 | vdprintf() -> similar sized functionality |
228 | --- |
229 | |
230 | (TODO list after discussion 11.05.2009) |
231 | |
232 | * shrink tc/brctl/ip |
233 | tc/brctl seem like fairly large things to try and tackle in your timeframe, |
234 | and i think people have posted attempts in the past. Adding additional |
235 | options to ip though seems reasonable. |
236 | |
237 | * add tests for some applets |
238 | |
239 | * implement POSIX utilities and audit them for POSIX conformance. then |
240 | audit them for GNU conformance. then document all your findings in a new |
241 | doc/conformance.txt file while perhaps implementing some of the missing |
242 | features. |
243 | you can find the latest POSIX documentation (1003.1-2008) here: |
244 | http://www.opengroup.org/onlinepubs/9699919799/ |
245 | and the complete list of all utilities that POSIX covers: |
246 | http://www.opengroup.org/onlinepubs/9699919799/idx/utilities.html |
247 | The first step would to generate a file/matrix what is already archived |
248 | (also IPV6) |
249 | |
250 | * implement 'at' |
251 | |
252 | * rpcbind (former portmap) or equivalent |
253 | so that we don't have to use -o nolock on nfs mounts |
254 | |
255 | * check IPV6 compliance |
256 | |
257 | * generate a mini example using kernel+busybox only (+libc) for example |
258 | |
259 | * more support for advanced linux 2.6.x features, see: iotop |
260 | most likely there is more |
261 |