Glenn L McGrath | 90d2bff | 2004-05-01 00:49:49 +0000 | [diff] [blame] | 1 | Busybox TODO |
| 2 | |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 3 | Stuff that needs to be done. All of this is fair game for 1.2. |
Glenn L McGrath | 90d2bff | 2004-05-01 00:49:49 +0000 | [diff] [blame] | 4 | |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 5 | find |
Rob Landley | c58fd15 | 2005-10-25 20:22:50 +0000 | [diff] [blame] | 6 | doesn't understand (), lots of susv3 stuff. |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 7 | ---- |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 8 | sh |
| 9 | The command shell situation is a big mess. We have three or four different |
| 10 | shells that don't really share any code, and the "standalone shell" doesn't |
| 11 | work all that well (especially not in a chroot environment), due to apps not |
| 12 | being reentrant. Unifying the various shells and figuring out a configurable |
| 13 | way of adding the minimal set of bash features a given script uses is a big |
Rob Landley | dbc608b | 2005-10-31 23:52:02 +0000 | [diff] [blame] | 14 | job, but it would be a big improvement. |
Rob Landley | a937640 | 2005-08-23 23:08:17 +0000 | [diff] [blame] | 15 | |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 16 | Note: Rob Landley (rob@landley.net) is working on a new unified shell called |
| 17 | bbsh, but it's a low priority... |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 18 | --- |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 19 | diff |
| 20 | We should have a diff -u command. We have patch, we should have diff |
| 21 | (we only need to support unified diffs though). |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 22 | |
| 23 | Also, make sure we handle empty files properly: |
| 24 | From the patch man page: |
| 25 | |
| 26 | you can remove a file by sending out a context diff that compares |
| 27 | the file to be deleted with an empty file dated the Epoch. The |
| 28 | file will be removed unless patch is conforming to POSIX and the |
| 29 | -E or --remove-empty-files option is not given. |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 30 | --- |
| 31 | patch |
Rob Landley | c9c959c | 2005-10-27 00:57:50 +0000 | [diff] [blame] | 32 | Should have simple fuzz factor support to apply patches at an offset which |
Rob Landley | 078bacf | 2005-09-01 03:02:23 +0000 | [diff] [blame] | 33 | shouldn't take up too much space. |
Rob Landley | c9c959c | 2005-10-27 00:57:50 +0000 | [diff] [blame] | 34 | |
| 35 | And while we're at it, a new patch filename quoting format is apparently |
| 36 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2 |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 37 | --- |
| 38 | man |
| 39 | It would be nice to have a man command. Not one that handles troff or |
| 40 | anything, just one that can handle preformatted ascii man pages, possibly |
| 41 | compressed. This could probably be a script in the extras directory that |
Rob Landley | c58fd15 | 2005-10-25 20:22:50 +0000 | [diff] [blame] | 42 | calls cat/zcat/bzcat | less |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 43 | |
| 44 | (How doclifter might work into this is anybody's guess.) |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 45 | --- |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 46 | bzip2 |
| 47 | Compression-side support. |
Rob Landley | 7b7c99c | 2005-11-04 20:45:54 +0000 | [diff] [blame] | 48 | --- |
| 49 | init |
| 50 | General cleanup. |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 51 | --- |
| 52 | ar |
| 53 | Write support? |
| 54 | --- |
| 55 | mdev |
| 56 | Micro-udev. |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 57 | |
| 58 | Architectural issues: |
| 59 | |
Rob Landley | 7b7c99c | 2005-11-04 20:45:54 +0000 | [diff] [blame] | 60 | bb_close() with fsync() |
| 61 | We should have a bb_close() in place of normal close, with a CONFIG_ option |
| 62 | to not just check the return value of close() for an error, but fsync(). |
| 63 | Close can't reliably report anything useful because if write() accepted the |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 64 | data then it either went out to the network or it's in cache or a pipe |
| 65 | buffer. Either way, there's no guarantee it'll make it to its final |
| 66 | destination before close() gets called, so there's no guarantee that any |
| 67 | error will be reported. |
| 68 | |
Rob Landley | 7b7c99c | 2005-11-04 20:45:54 +0000 | [diff] [blame] | 69 | You need to call fsync() if you care about errors that occur after write(), |
| 70 | but that can have a big performance impact. So make it a config option. |
| 71 | --- |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 72 | Do a SUSv3 audit |
| 73 | Look at the full Single Unix Specification version 3 (available online at |
| 74 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and |
| 75 | figure out which of our apps are compliant, and what we're missing that |
| 76 | we might actually care about. |
| 77 | |
| 78 | Even better would be some kind of automated compliance test harness that |
| 79 | exercises each command line option and the various corner cases. |
Rob Landley | dbc608b | 2005-10-31 23:52:02 +0000 | [diff] [blame] | 80 | --- |
| 81 | Internationalization |
| 82 | How much internationalization should we do? |
| 83 | |
| 84 | The low hanging fruit is UTF-8 character set support. We should do this. |
| 85 | (Vodz pointed out the shell's cmdedit as needing work here. What else?) |
| 86 | |
| 87 | We also have lots of hardwired english text messages. Consolidating this |
| 88 | into some kind of message table not only makes translation easier, but |
| 89 | also allows us to consolidate redundant (or close) strings. |
| 90 | |
| 91 | We probably don't want to be bloated with locale support. (Not unless we can |
| 92 | cleanly export it from our underlying C library without having to concern |
| 93 | ourselves with it directly. Perhaps a few specific things like a config |
| 94 | option for "date" are low hanging fruit here?) |
| 95 | |
| 96 | What level should things happen at? How much do we care about |
| 97 | internationalizing the text console when X11 and xterms are so much better |
| 98 | at it? (There's some infrastructure here we don't implement: The |
| 99 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a |
| 100 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys |
| 101 | implementation to replace loadkmap/dumpkmap. Plus messing with console font |
| 102 | loading. Is it worth it, or do we just say "use X"?) |
| 103 | --- |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 104 | Unify archivers |
| 105 | Lots of archivers have the same general infrastructure. The directory |
| 106 | traversal code should be factored out, and the guts of each archiver could |
| 107 | be some setup code and a series of callbacks for "add this file", |
| 108 | "add this directory", "add this symlink" and so on. |
| 109 | |
| 110 | This could clean up tar and zip, and make it cheaper to add cpio and ar |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 111 | write support, and possibly even cheaply add things like mkisofs or |
| 112 | mksquashfs someday, if they become relevant. |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 113 | --- |
| 114 | Text buffer support. |
Rob Landley | c58fd15 | 2005-10-25 20:22:50 +0000 | [diff] [blame] | 115 | Several existing applets (sort, vi, less...) read |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 116 | a whole file into memory and act on it. There might be an opportunity |
| 117 | for shared code in there that could be moved into libbb... |
| 118 | --- |
| 119 | Individual compilation of applets. |
| 120 | It would be nice if busybox had the option to compile to individual applets, |
| 121 | for people who want an alternate implementation less bloated than the gnu |
| 122 | utils (or simply with less political baggage), but without it being one big |
| 123 | executable. |
| 124 | |
| 125 | Turning libbb into a real dll is another possibility, especially if libbb |
| 126 | could export some of the other library interfaces we've already more or less |
| 127 | got the code for (like zlib). |
| 128 | --- |
| 129 | buildroot - Make a "dogfood" option |
Rob Landley | c58fd15 | 2005-10-25 20:22:50 +0000 | [diff] [blame] | 130 | Busybox 1.1 will be capable of replacing most gnu packages for real world use, |
| 131 | such as developing software or in a live CD. It needs wider testing. |
| 132 | |
| 133 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file, |
| 134 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps, |
| 135 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting |
| 136 | system should be self-hosting (I.E. able to rebuild itself from source code). |
| 137 | This means it would need (at least) binutils, gcc, and make, or equivalents. |
Rob Landley | f4bb212 | 2005-01-24 06:56:24 +0000 | [diff] [blame] | 138 | |
| 139 | It would be a good "eating our own dogfood" test if buildroot had the option |
Rob Landley | c58fd15 | 2005-10-25 20:22:50 +0000 | [diff] [blame] | 140 | of using a "make allyesconfig" busybox instead of the all of the above |
| 141 | packages. Anything that's wrong with the resulting system, we can fix. (It |
| 142 | would be nice to be able to upgrade busybox to be able to replace bash and |
| 143 | diffutils as well, but we're not there yet.) |
| 144 | |
| 145 | One example of an existing system that does this already is Firmware Linux: |
| 146 | http://www.landley.net/code/firmware |
Rob Landley | 958fa2a | 2005-06-11 22:10:42 +0000 | [diff] [blame] | 147 | --- |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 148 | initramfs |
| 149 | Busybox should have a sample initramfs build script. This depends on |
| 150 | involves bbsh, mdev, and switch_root. |
| 151 | --- |
Rob Landley | 958fa2a | 2005-06-11 22:10:42 +0000 | [diff] [blame] | 152 | Memory Allocation |
| 153 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory |
| 154 | allocation on the stack or the heap. Unfortunately, we're not using it much. |
| 155 | We need to audit our memory allocations and turn a lot of malloc/free calls |
| 156 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER. |
Rob Landley | a882126 | 2005-09-16 14:58:55 +0000 | [diff] [blame] | 157 | |
Rob Landley | 958fa2a | 2005-06-11 22:10:42 +0000 | [diff] [blame] | 158 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be |
| 159 | optimized out by the compiler in the stack allocation case (since there's no |
| 160 | free for an alloca()), and this means that various cleanup loops that just |
| 161 | call free might also be optimized out by the compiler if written right, so |
| 162 | we can yank those #ifdefs too, and generally clean up the code. |
Rob Landley | a882126 | 2005-09-16 14:58:55 +0000 | [diff] [blame] | 163 | --- |
| 164 | Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS |
| 165 | |
| 166 | In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS |
| 167 | that were either defined or undefined to indicate whether the symbol was |
| 168 | selected in the .config file. They were used with #ifdefs, ala: |
| 169 | |
| 170 | #ifdef CONFIG_SYMBOL |
| 171 | if (other_test) { |
| 172 | do_code(); |
| 173 | } |
| 174 | #endif |
| 175 | |
| 176 | In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1), |
| 177 | meaning you can still use them for preprocessor tests by replacing |
| 178 | "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we |
| 179 | can use them as a true or false test in normal C code: |
| 180 | |
| 181 | if (ENABLE_SYMBOL && other_test) { |
| 182 | do_code(); |
| 183 | } |
| 184 | |
| 185 | (Optimizing away if() statements that resolve to a constant value |
| 186 | is known as "dead code elimination", an optimization so old and simple that |
| 187 | Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers |
| 188 | like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC) |
| 189 | perform dead code elimination.) |
| 190 | |
| 191 | Right now, busybox.h is #including both "config.h" (defining the |
| 192 | CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some |
| 193 | point in the future, it would be nice to wean ourselves off of the |
| 194 | CONFIG versions. (Among other things, some defective build environments |
| 195 | leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include |
| 196 | files. We've experienced collisions before.) |
| 197 | --- |
| 198 | FEATURE_CLEAN_UP |
| 199 | This is more an unresolved issue than a to-do item. More thought is needed. |
| 200 | |
| 201 | Normally we rely on exit() to free memory, close files, and unmap segments |
| 202 | for us. This makes most calls to free(), close(), and unmap() optional in |
| 203 | busybox applets that don't intend to run for very long, and optional stuff |
| 204 | can be omitted to save size. |
| 205 | |
| 206 | The idea was raised that we could simulate fork/exit with setjmp/longjmp |
| 207 | for _really_ brainless embedded systems, or speed up the standalone shell |
| 208 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP. |
| 209 | Unfortunately, this isn't as easy as it sounds. |
| 210 | |
| 211 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc()) |
| 212 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This |
| 213 | jumps out of the normal flow control and bypasses any cleanup code we |
| 214 | put at the end of our applets. |
| 215 | |
| 216 | It's possible to add hooks to libbb functions like xmalloc() and bb_xopen() |
| 217 | to add their entries to a linked list, which could be traversed and |
| 218 | freed/closed automatically. (This would need to be able to free just the |
| 219 | entries after a checkpoint to be usable for a forkless standalone shell. |
| 220 | You don't want to free the shell's own resources.) |
| 221 | |
| 222 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things |
| 223 | like valgrind happy. It's also documentation of _what_ we're trusting |
| 224 | exit() to clean up for us. But new infrastructure to auto-free stuff would |
| 225 | render the existing FEATURE_CLEAN_UP code redundant. |
| 226 | |
| 227 | For right now, exit() handles it just fine. |
Rob Landley | 8bcc6e9 | 2006-01-09 00:54:46 +0000 | [diff] [blame^] | 228 | |
| 229 | |
| 230 | |
| 231 | Minor stuff: |
| 232 | watchdog.c could autodetect the timer duration via: |
| 233 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2); |
| 234 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered |
| 235 | kernel types on some distros, which breaks the build. |