3 Stuff that needs to be done
5 tr - missing SuS3 features in busybox 1.0pre10
7 tr doesnt support [:blank:], [:digit:] or other predefined classes, [=equiv=]
8 support is also missing.
11 doesn't understand () or -exec, and these are actually used out in the real
12 world. The "make uninstall" of lots of things (including busybox itself)
13 breaks because of this, and sometimes even "make install" (like udev).
16 The command shell situation is a big mess. We have three or four different
17 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 being reentrant. Unifying the various shells and figuring out a configurable
20 way of adding the minimal set of bash features a given script uses is a big
21 job, but it be a big improvement.
23 Note: Rob Landley (rob@landley.net) is working on this one, but very slowly...
26 Can't handle compressing multiple files at once. (I don't mean making a
27 multiple file archive, I mean compressing more than one file at a time.)
28 Some global variables aren't re-initialized between runs.
31 same problem as gzip. "gunzip one.gz two.gz three.gz" doesn't work for
32 two.gz and three.gz due to global variables not getting reset.
35 We should have a diff -u command. We have patch, we should have diff
36 (we only need to support unified diffs though).
39 Would be nice. The basic susv3 options, plus fuser -k.
42 should have simple fuzz factor support to apply patches at an offset which
43 shouldn't take up too much space.
46 It would be nice to have a man command. Not one that handles troff or
47 anything, just one that can handle preformatted ascii man pages, possibly
48 compressed. This could probably be a script in the extras directory that
49 calls cat/zcatbzcat | more
52 Compression-side support.
58 Look at the full Single Unix Specification version 3 (available online at
59 "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and
60 figure out which of our apps are compliant, and what we're missing that
61 we might actually care about.
63 Even better would be some kind of automated compliance test harness that
64 exercises each command line option and the various corner cases.
67 Lots of archivers have the same general infrastructure. The directory
68 traversal code should be factored out, and the guts of each archiver could
69 be some setup code and a series of callbacks for "add this file",
70 "add this directory", "add this symlink" and so on.
72 This could clean up tar and zip, and make it cheaper to add cpio and ar
73 write support, and possibly even cheaply add things like mkisofs someday,
74 if it becomes relevant.
77 Several existing applets and potential additions (sort, vi, less...) read
78 a whole file into memory and act on it. There might be an opportunity
79 for shared code in there that could be moved into libbb...
81 Individual compilation of applets.
82 It would be nice if busybox had the option to compile to individual applets,
83 for people who want an alternate implementation less bloated than the gnu
84 utils (or simply with less political baggage), but without it being one big
87 Turning libbb into a real dll is another possibility, especially if libbb
88 could export some of the other library interfaces we've already more or less
89 got the code for (like zlib).
91 buildroot - Make a "dogfood" option
92 Busybox is now capable of replacing most gnu packages for real world use,
93 such as developing software or in a live CD. A system built from busybox
94 (1.00 with updated sort.c), uclibc 0.9.27, gcc, binutils, make, and a few
95 other development tools (http://www.landley.net/code/firmware has an example
96 system using autoconf, automake, bison, flex, libtools, m4, zlib,
97 and groff: dunno what subset of that is actually necessary) is capable of
98 rebuilding itself, from scratch, under itself.
100 It would be a good "eating our own dogfood" test if buildroot had the option
101 of using busybox instead of bzip2, coreutils, file, findutils, gawk, grep,
102 inetutils, modutils, net-tools, procps, sed, shadow, sysklogd, sysvinit, tar,
103 util-linux, and vim. Anything that's wrong with the resulting system, we
104 can fix. (It would be nice to be able to upgrade busybox to be able to
105 replace bash, diffutils, gzip, less, and patch as well.)
108 We have a CONFIG_BUFFER mechanism that lets us select whether to do memory
109 allocation on the stack or the heap. Unfortunately, we're not using it much.
110 We need to audit our memory allocations and turn a lot of malloc/free calls
111 into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER.
113 And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be
114 optimized out by the compiler in the stack allocation case (since there's no
115 free for an alloca()), and this means that various cleanup loops that just
116 call free might also be optimized out by the compiler if written right, so
117 we can yank those #ifdefs too, and generally clean up the code.
119 Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS
121 In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS
122 that were either defined or undefined to indicate whether the symbol was
123 selected in the .config file. They were used with #ifdefs, ala:
131 In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1),
132 meaning you can still use them for preprocessor tests by replacing
133 "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we
134 can use them as a true or false test in normal C code:
136 if (ENABLE_SYMBOL && other_test) {
140 (Optimizing away if() statements that resolve to a constant value
141 is known as "dead code elimination", an optimization so old and simple that
142 Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers
143 like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC)
144 perform dead code elimination.)
146 Right now, busybox.h is #including both "config.h" (defining the
147 CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some
148 point in the future, it would be nice to wean ourselves off of the
149 CONFIG versions. (Among other things, some defective build environments
150 leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include
151 files. We've experienced collisions before.)
154 This is more an unresolved issue than a to-do item. More thought is needed.
156 Normally we rely on exit() to free memory, close files, and unmap segments
157 for us. This makes most calls to free(), close(), and unmap() optional in
158 busybox applets that don't intend to run for very long, and optional stuff
159 can be omitted to save size.
161 The idea was raised that we could simulate fork/exit with setjmp/longjmp
162 for _really_ brainless embedded systems, or speed up the standalone shell
163 by not forking. Doing so would require a reliable FEATURE_CLEAN_UP.
164 Unfortunately, this isn't as easy as it sounds.
166 The problem is, lots of things exit(), sometimes unexpectedly (xmalloc())
167 and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This
168 jumps out of the normal flow control and bypasses any cleanup code we
169 put at the end of our applets.
171 It's possible to add hooks to libbb functions like xmalloc() and bb_xopen()
172 to add their entries to a linked list, which could be traversed and
173 freed/closed automatically. (This would need to be able to free just the
174 entries after a checkpoint to be usable for a forkless standalone shell.
175 You don't want to free the shell's own resources.)
177 Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things
178 like valgrind happy. It's also documentation of _what_ we're trusting
179 exit() to clean up for us. But new infrastructure to auto-free stuff would
180 render the existing FEATURE_CLEAN_UP code redundant.
182 For right now, exit() handles it just fine.