Contents of /trunk/mkinitrd-magellan/busybox/TODO
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Sat Sep 1 22:45:15 2007 UTC (17 years ago) by niro
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Sat Sep 1 22:45:15 2007 UTC (17 years ago) by niro
File size: 14223 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
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 <rob@landley.net>: |
10 | Add BB_NOMMU to platform.h and migrate __uClinux__ tests to that. |
11 | #if defined __UCLIBC__ && !defined __ARCH_USE_MMU__ |
12 | Add a libbb/platform.c |
13 | Implement fdprintf() for platforms that haven't got one. |
14 | Implement bb_realpath() that can handle NULL on non-glibc. |
15 | Cleanup bb_asprintf() |
16 | |
17 | Migrate calloc() and bb_calloc() occurrences to bb_xzalloc(). |
18 | Remove obsolete _() wrapper crud for internationalization we don't do. |
19 | Figure out where we need utf8 support, and add it. |
20 | |
21 | sh |
22 | The command shell situation is a big mess. We have three or four different |
23 | shells that don't really share any code, and the "standalone shell" doesn't |
24 | work all that well (especially not in a chroot environment), due to apps not |
25 | being reentrant. I'm writing a new shell (bbsh) to unify the various |
26 | shells and configurably add the minimal set of bash features people |
27 | actually use. The hardest part is it has to configure down as small as |
28 | lash while providing lash's features. The rest is easy in comparison. |
29 | bzip2 |
30 | Compression-side support. |
31 | init |
32 | General cleanup (should use ENABLE_FEATURE_INIT_SYSLOG and ENABLE_FEATURE_INIT_DEBUG). |
33 | depmod |
34 | busybox lacks a way to update module deps when running from firmware without the |
35 | use of the depmod.pl (perl is to bloated for most embedded setups) and or orig |
36 | modutils. The orig depmod is rather pointless to have to add to a firmware image |
37 | in when we already have a insmod/rmmod and friends. |
38 | Unify base64 handling. |
39 | There's base64 encoding and decoding going on in: |
40 | networking/wget.c:base64enc() |
41 | coreutils/uudecode.c:read_base64() |
42 | coreutils/uuencode.c:tbl_base64[] |
43 | networking/httpd.c:decodeBase64() |
44 | And probably elsewhere. That needs to be unified into libbb functions. |
45 | Do a SUSv3 audit |
46 | Look at the full Single Unix Specification version 3 (available online at |
47 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and |
48 | figure out which of our apps are compliant, and what we're missing that |
49 | we might actually care about. |
50 | |
51 | Even better would be some kind of automated compliance test harness that |
52 | exercises each command line option and the various corner cases. |
53 | Internationalization |
54 | How much internationalization should we do? |
55 | |
56 | The low hanging fruit is UTF-8 character set support. We should do this. |
57 | (Vodz pointed out the shell's cmdedit as needing work here. What else?) |
58 | |
59 | We also have lots of hardwired english text messages. Consolidating this |
60 | into some kind of message table not only makes translation easier, but |
61 | also allows us to consolidate redundant (or close) strings. |
62 | |
63 | We probably don't want to be bloated with locale support. (Not unless we |
64 | can cleanly export it from our underlying C library without having to |
65 | concern ourselves with it directly. Perhaps a few specific things like a |
66 | config option for "date" are low hanging fruit here?) |
67 | |
68 | What level should things happen at? How much do we care about |
69 | internationalizing the text console when X11 and xterms are so much better |
70 | at it? (There's some infrastructure here we don't implement: The |
71 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a |
72 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys |
73 | implementation to replace loadkmap/dumpkmap. Plus messing with console font |
74 | loading. Is it worth it, or do we just say "use X"?) |
75 | |
76 | Individual compilation of applets. |
77 | It would be nice if busybox had the option to compile to individual applets, |
78 | for people who want an alternate implementation less bloated than the gnu |
79 | utils (or simply with less political baggage), but without it being one big |
80 | executable. |
81 | |
82 | Turning libbb into a real dll is another possibility, especially if libbb |
83 | could export some of the other library interfaces we've already more or less |
84 | got the code for (like zlib). |
85 | buildroot - Make a "dogfood" option |
86 | Busybox 1.1 will be capable of replacing most gnu packages for real world |
87 | use, such as developing software or in a live CD. It needs wider testing. |
88 | |
89 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file, |
90 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps, |
91 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting |
92 | system should be self-hosting (I.E. able to rebuild itself from source |
93 | code). This means it would need (at least) binutils, gcc, and make, or |
94 | equivalents. |
95 | |
96 | It would be a good "eating our own dogfood" test if buildroot had the option |
97 | of using a "make allyesconfig" busybox instead of the all of the above |
98 | packages. Anything that's wrong with the resulting system, we can fix. (It |
99 | would be nice to be able to upgrade busybox to be able to replace bash and |
100 | diffutils as well, but we're not there yet.) |
101 | |
102 | One example of an existing system that does this already is Firmware Linux: |
103 | http://www.landley.net/code/firmware |
104 | initramfs |
105 | Busybox should have a sample initramfs build script. This depends on |
106 | bbsh, mdev, and switch_root. |
107 | mkdep |
108 | Write a mkdep that doesn't segfault if there's a directory it doesn't |
109 | have permission to read, isn't based on manually editing the output of |
110 | lexx and yacc, doesn't make such a mess under include/config, etc. |
111 | Group globals into unions of structures. |
112 | Go through and turn all the global and static variables into structures, |
113 | and have all those structures be in a big union shared between processes, |
114 | so busybox uses less bss. (This is a big win on nommu machines.) See |
115 | sed.c and mdev.c for examples. |
116 | Go through bugs.busybox.net and close out all of that somehow. |
117 | This one's open to everybody, but I'll wind up doing it... |
118 | |
119 | |
120 | Bernhard Fischer <busybox@busybox.net> suggests to look at these: |
121 | New debug options: |
122 | -Wlarger-than-127 |
123 | Cleanup any big users |
124 | -Wunused-parameter |
125 | Facilitate applet PROTOTYPES to provide means for having applets that |
126 | do a) not take any arguments b) need only one of argc or argv c) need |
127 | both argc and argv. All of these three options should go for the most |
128 | feature complete denominator. |
129 | Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE |
130 | make bb_common_bufsiz1 configurable, size wise. |
131 | make pipesize configurable, size wise. |
132 | Use bb_common_bufsiz1 throughout applets! |
133 | Add chrt applet. Please CC Bernhard if you suggest a patch. |
134 | |
135 | As yet unclaimed: |
136 | |
137 | ---- |
138 | find |
139 | doesn't understand (), lots of susv3 stuff. |
140 | ---- |
141 | diff |
142 | Make sure we handle empty files properly: |
143 | From the patch man page: |
144 | |
145 | you can remove a file by sending out a context diff that compares |
146 | the file to be deleted with an empty file dated the Epoch. The |
147 | file will be removed unless patch is conforming to POSIX and the |
148 | -E or --remove-empty-files option is not given. |
149 | --- |
150 | patch |
151 | Should have simple fuzz factor support to apply patches at an offset which |
152 | shouldn't take up too much space. |
153 | |
154 | And while we're at it, a new patch filename quoting format is apparently |
155 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2 |
156 | --- |
157 | man |
158 | It would be nice to have a man command. Not one that handles troff or |
159 | anything, just one that can handle preformatted ascii man pages, possibly |
160 | compressed. This could probably be a script in the extras directory that |
161 | calls cat/zcat/bzcat | less |
162 | |
163 | (How doclifter might work into this is anybody's guess.) |
164 | --- |
165 | ar |
166 | Write support? |
167 | ---- |
168 | stty / catv |
169 | stty's visible() function and catv's guts are identical. Merge them into |
170 | an appropriate libbb function. |
171 | ---- |
172 | |
173 | Architectural issues: |
174 | |
175 | bb_close() with fsync() |
176 | We should have a bb_close() in place of normal close, with a CONFIG_ option |
177 | to not just check the return value of close() for an error, but fsync(). |
178 | Close can't reliably report anything useful because if write() accepted the |
179 | data then it either went out to the network or it's in cache or a pipe |
180 | buffer. Either way, there's no guarantee it'll make it to its final |
181 | destination before close() gets called, so there's no guarantee that any |
182 | error will be reported. |
183 | |
184 | You need to call fsync() if you care about errors that occur after write(), |
185 | but that can have a big performance impact. So make it a config option. |
186 | --- |
187 | Unify archivers |
188 | Lots of archivers have the same general infrastructure. The directory |
189 | traversal code should be factored out, and the guts of each archiver could |
190 | be some setup code and a series of callbacks for "add this file", |
191 | "add this directory", "add this symlink" and so on. |
192 | |
193 | This could clean up tar and zip, and make it cheaper to add cpio and ar |
194 | write support, and possibly even cheaply add things like mkisofs or |
195 | mksquashfs someday, if they become relevant. |
196 | --- |
197 | Text buffer support. |
198 | Several existing applets (sort, vi, less...) read |
199 | a whole file into memory and act on it. There might be an opportunity |
200 | for shared code in there that could be moved into libbb... |
201 | --- |
202 | Memory Allocation |
203 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory |
204 | allocation on the stack or the heap. Unfortunately, we're not using it much. |
205 | We need to audit our memory allocations and turn a lot of malloc/free calls |
206 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER. |
207 | For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64 |
208 | |
209 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be |
210 | optimized out by the compiler in the stack allocation case (since there's no |
211 | free for an alloca()), and this means that various cleanup loops that just |
212 | call free might also be optimized out by the compiler if written right, so |
213 | we can yank those #ifdefs too, and generally clean up the code. |
214 | --- |
215 | Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS |
216 | |
217 | In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS |
218 | that were either defined or undefined to indicate whether the symbol was |
219 | selected in the .config file. They were used with #ifdefs, ala: |
220 | |
221 | #ifdef CONFIG_SYMBOL |
222 | if (other_test) { |
223 | do_code(); |
224 | } |
225 | #endif |
226 | |
227 | In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1), |
228 | meaning you can still use them for preprocessor tests by replacing |
229 | "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we |
230 | can use them as a true or false test in normal C code: |
231 | |
232 | if (ENABLE_SYMBOL && other_test) { |
233 | do_code(); |
234 | } |
235 | |
236 | (Optimizing away if() statements that resolve to a constant value |
237 | is known as "dead code elimination", an optimization so old and simple that |
238 | Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers |
239 | like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC) |
240 | perform dead code elimination.) |
241 | |
242 | Right now, busybox.h is #including both "config.h" (defining the |
243 | CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some |
244 | point in the future, it would be nice to wean ourselves off of the |
245 | CONFIG versions. (Among other things, some defective build environments |
246 | leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include |
247 | files. We've experienced collisions before.) |
248 | --- |
249 | FEATURE_CLEAN_UP |
250 | This is more an unresolved issue than a to-do item. More thought is needed. |
251 | |
252 | Normally we rely on exit() to free memory, close files, and unmap segments |
253 | for us. This makes most calls to free(), close(), and unmap() optional in |
254 | busybox applets that don't intend to run for very long, and optional stuff |
255 | can be omitted to save size. |
256 | |
257 | The idea was raised that we could simulate fork/exit with setjmp/longjmp |
258 | for _really_ brainless embedded systems, or speed up the standalone shell |
259 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP. |
260 | Unfortunately, this isn't as easy as it sounds. |
261 | |
262 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc()) |
263 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This |
264 | jumps out of the normal flow control and bypasses any cleanup code we |
265 | put at the end of our applets. |
266 | |
267 | It's possible to add hooks to libbb functions like xmalloc() and xopen() |
268 | to add their entries to a linked list, which could be traversed and |
269 | freed/closed automatically. (This would need to be able to free just the |
270 | entries after a checkpoint to be usable for a forkless standalone shell. |
271 | You don't want to free the shell's own resources.) |
272 | |
273 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things |
274 | like valgrind happy. It's also documentation of _what_ we're trusting |
275 | exit() to clean up for us. But new infrastructure to auto-free stuff would |
276 | render the existing FEATURE_CLEAN_UP code redundant. |
277 | |
278 | For right now, exit() handles it just fine. |
279 | |
280 | |
281 | |
282 | Minor stuff: |
283 | watchdog.c could autodetect the timer duration via: |
284 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2); |
285 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered |
286 | kernel types on some distros, which breaks the build. |
287 | --- |
288 | use bb_error_msg where appropriate: See |
289 | egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))" |
290 | --- |
291 | use bb_perror_msg where appropriate: See |
292 | egrep "[^_]perror" |
293 | --- |
294 | Remove superfluous fmt occurances: e.g. |
295 | fprintf(stderr, "%s: %s not found\n", "unalias", *argptr); |
296 | -> fprintf(stderr, "unalias: %s not found\n", *argptr); |
297 | --- |
298 | possible code duplication ingroup() and is_a_group_member() |
299 | --- |
300 | Move __get_hz() to a better place and (re)use it in route.c, ash.c, msh.c |
301 | --- |
302 | |
303 | |
304 | Code cleanup: |
305 | |
306 | Replace deprecated functions. |
307 | |
308 | bzero() -> memset() |
309 | --- |
310 | sigblock(), siggetmask(), sigsetmask(), sigmask() -> sigprocmask et al |
311 | --- |
312 | vdprintf() -> similar sized functionality |
313 | --- |