1 | Busybox TODO
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2 |
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3 | Harvest patches from
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4 | http://git.openembedded.org/cgit.cgi/openembedded/tree/recipes/busybox/
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5 | https://dev.openwrt.org/browser/trunk/package/busybox/patches/
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6 |
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7 |
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8 | Stuff that needs to be done. This is organized by who plans to get around to
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9 | doing it eventually, but that doesn't mean they "own" the item. If you want to
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10 | do one of these bounce an email off the person it's listed under to see if they
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11 | have any suggestions how they plan to go about it, and to minimize conflicts
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12 | between your work and theirs. But otherwise, all of these are fair game.
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13 |
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14 | Rob Landley suggested this:
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15 | Implement bb_realpath() that can handle NULL on non-glibc.
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16 |
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17 | sh
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18 | The command shell situation is a mess. We have two different
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19 | shells that don't really share any code, and the "standalone shell" doesn't
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20 | work all that well (especially not in a chroot environment), due to apps not
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21 | being reentrant.
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22 |
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23 | Do a SUSv3 audit
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24 | Look at the full Single Unix Specification version 3 (available online at
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25 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and
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26 | figure out which of our apps are compliant, and what we're missing that
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27 | we might actually care about.
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28 |
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29 | Even better would be some kind of automated compliance test harness that
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30 | exercises each command line option and the various corner cases.
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31 |
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32 | Internationalization
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33 | How much internationalization should we do?
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34 |
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35 | The low hanging fruit is UTF-8 character set support. We should do this.
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36 | See TODO_unicode file.
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37 |
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38 | We also have lots of hardwired english text messages. Consolidating this
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39 | into some kind of message table not only makes translation easier, but
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40 | also allows us to consolidate redundant (or close) strings.
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41 |
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42 | We probably don't want to be bloated with locale support. (Not unless we
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43 | can cleanly export it from our underlying C library without having to
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44 | concern ourselves with it directly. Perhaps a few specific things like a
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45 | config option for "date" are low hanging fruit here?)
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46 |
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47 | What level should things happen at? How much do we care about
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48 | internationalizing the text console when X11 and xterms are so much better
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49 | at it? (There's some infrastructure here we don't implement: The
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50 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a
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51 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys
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52 | implementation to replace loadkmap/dumpkmap. Plus messing with console font
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53 | loading. Is it worth it, or do we just say "use X"?)
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54 |
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55 | Individual compilation of applets.
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56 | It would be nice if busybox had the option to compile to individual applets,
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57 | for people who want an alternate implementation less bloated than the gnu
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58 | utils (or simply with less political baggage), but without it being one big
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59 | executable.
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60 |
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61 | Turning libbb into a real dll is another possibility, especially if libbb
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62 | could export some of the other library interfaces we've already more or less
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63 | got the code for (like zlib).
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64 |
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65 | buildroot - Make a "dogfood" option
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66 | Busybox 1.1 will be capable of replacing most gnu packages for real world
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67 | use, such as developing software or in a live CD. It needs wider testing.
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68 |
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69 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file,
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70 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps,
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71 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting
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72 | system should be self-hosting (I.E. able to rebuild itself from source
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73 | code). This means it would need (at least) binutils, gcc, and make, or
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74 | equivalents.
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75 |
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76 | It would be a good "eating our own dogfood" test if buildroot had the option
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77 | of using a "make allyesconfig" busybox instead of the all of the above
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78 | packages. Anything that's wrong with the resulting system, we can fix. (It
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79 | would be nice to be able to upgrade busybox to be able to replace bash and
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80 | diffutils as well, but we're not there yet.)
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81 |
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82 | One example of an existing system that does this already is Firmware Linux:
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83 | http://www.landley.net/code/firmware
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84 |
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85 | initramfs
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86 | Busybox should have a sample initramfs build script. This depends on
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87 | shell, mdev, and switch_root.
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88 |
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89 | mkdep
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90 | Write a mkdep that doesn't segfault if there's a directory it doesn't
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91 | have permission to read, isn't based on manually editing the output of
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92 | lexx and yacc, doesn't make such a mess under include/config, etc.
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93 |
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94 | Group globals into unions of structures.
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95 | Go through and turn all the global and static variables into structures,
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96 | and have all those structures be in a big union shared between processes,
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97 | so busybox uses less bss. (This is a big win on nommu machines.) See
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98 | sed.c and mdev.c for examples.
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99 |
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100 | Go through bugs.busybox.net and close out all of that somehow.
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101 | This one's open to everybody, but I'll wind up doing it...
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102 |
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103 | Bernhard Reutner-Fischer <busybox@busybox.net> suggests to look at these:
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104 | New debug options:
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105 | -Wlarger-than-127
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106 | Cleanup any big users
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107 | Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE
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108 | make bb_common_bufsiz1 configurable, size wise.
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109 | make pipesize configurable, size wise.
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110 | Use bb_common_bufsiz1 throughout applets!
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111 |
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112 | As yet unclaimed:
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113 |
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114 | ----
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115 | diff
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116 | Make sure we handle empty files properly:
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117 | From the patch man page:
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118 |
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119 | you can remove a file by sending out a context diff that compares
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120 | the file to be deleted with an empty file dated the Epoch. The
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121 | file will be removed unless patch is conforming to POSIX and the
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122 | -E or --remove-empty-files option is not given.
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123 | ---
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124 | patch
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125 | Should have simple fuzz factor support to apply patches at an offset which
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126 | shouldn't take up too much space.
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127 |
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128 | And while we're at it, a new patch filename quoting format is apparently
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129 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2
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130 |
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131 | Architectural issues:
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132 |
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133 | bb_close() with fsync()
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134 | We should have a bb_close() in place of normal close, with a CONFIG_ option
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135 | to not just check the return value of close() for an error, but fsync().
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136 | Close can't reliably report anything useful because if write() accepted the
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137 | data then it either went out to the network or it's in cache or a pipe
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138 | buffer. Either way, there's no guarantee it'll make it to its final
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139 | destination before close() gets called, so there's no guarantee that any
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140 | error will be reported.
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141 |
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142 | You need to call fsync() if you care about errors that occur after write(),
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143 | but that can have a big performance impact. So make it a config option.
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144 | ---
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145 | Unify archivers
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146 | Lots of archivers have the same general infrastructure. The directory
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147 | traversal code should be factored out, and the guts of each archiver could
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148 | be some setup code and a series of callbacks for "add this file",
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149 | "add this directory", "add this symlink" and so on.
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150 |
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151 | This could clean up tar and zip, and make it cheaper to add cpio and ar
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152 | write support, and possibly even cheaply add things like mkisofs or
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153 | mksquashfs someday, if they become relevant.
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154 | ---
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155 | Text buffer support.
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156 | Several existing applets (sort, vi, less...) read
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157 | a whole file into memory and act on it. Use open_read_close().
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158 | ---
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159 | Memory Allocation
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160 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory
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161 | allocation on the stack or the heap. Unfortunately, we're not using it much.
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162 | We need to audit our memory allocations and turn a lot of malloc/free calls
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163 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER.
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164 | For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64
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165 |
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166 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be
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167 | optimized out by the compiler in the stack allocation case (since there's no
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168 | free for an alloca()), and this means that various cleanup loops that just
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169 | call free might also be optimized out by the compiler if written right, so
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170 | we can yank those #ifdefs too, and generally clean up the code.
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171 | ---
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172 | FEATURE_CLEAN_UP
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173 | This is more an unresolved issue than a to-do item. More thought is needed.
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174 |
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175 | Normally we rely on exit() to free memory, close files and unmap segments
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176 | for us. This makes most calls to free(), close(), and unmap() optional in
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177 | busybox applets that don't intend to run for very long, and optional stuff
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178 | can be omitted to save size.
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179 |
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180 | The idea was raised that we could simulate fork/exit with setjmp/longjmp
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181 | for _really_ brainless embedded systems, or speed up the standalone shell
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182 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP.
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183 | Unfortunately, this isn't as easy as it sounds.
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184 |
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185 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc())
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186 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This
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187 | jumps out of the normal flow control and bypasses any cleanup code we
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188 | put at the end of our applets.
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189 |
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190 | It's possible to add hooks to libbb functions like xmalloc() and xopen()
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191 | to add their entries to a linked list, which could be traversed and
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192 | freed/closed automatically. (This would need to be able to free just the
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193 | entries after a checkpoint to be usable for a forkless standalone shell.
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194 | You don't want to free the shell's own resources.)
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195 |
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196 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things
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197 | like valgrind happy. It's also documentation of _what_ we're trusting
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198 | exit() to clean up for us. But new infrastructure to auto-free stuff would
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199 | render the existing FEATURE_CLEAN_UP code redundant.
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200 |
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201 | For right now, exit() handles it just fine.
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202 |
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203 |
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204 | Minor stuff:
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205 | watchdog.c could autodetect the timer duration via:
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206 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2);
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207 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered
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208 | kernel types on some distros, which breaks the build.
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209 | ---
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210 | use bb_error_msg where appropriate: See
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211 | egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))"
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212 | ---
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213 | use bb_perror_msg where appropriate: See
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214 | egrep "[^_]perror"
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215 | ---
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216 | possible code duplication ingroup() and is_a_group_member()
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217 | ---
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218 | Move __get_hz() to a better place and (re)use it in route.c, ash.c
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219 | ---
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220 | See grep -r strtod
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221 | Alot of duplication that wants cleanup.
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222 | ---
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223 | unify progress_meter. wget, flash_eraseall, pipe_progress, fbsplash, setfiles.
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224 | ---
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225 | support start-stop-daemon -d <chdir-path>
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226 | ---
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227 | vdprintf() -> similar sized functionality
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228 | ---
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229 |
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230 | (TODO list after discussion 11.05.2009)
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231 |
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232 | * shrink tc/brctl/ip
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233 | tc/brctl seem like fairly large things to try and tackle in your timeframe,
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234 | and i think people have posted attempts in the past. Adding additional
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235 | options to ip though seems reasonable.
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236 |
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237 | * add tests for some applets
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238 |
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239 | * implement POSIX utilities and audit them for POSIX conformance. then
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240 | audit them for GNU conformance. then document all your findings in a new
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241 | doc/conformance.txt file while perhaps implementing some of the missing
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242 | features.
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243 | you can find the latest POSIX documentation (1003.1-2008) here:
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244 | http://www.opengroup.org/onlinepubs/9699919799/
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245 | and the complete list of all utilities that POSIX covers:
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246 | http://www.opengroup.org/onlinepubs/9699919799/idx/utilities.html
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247 | The first step would to generate a file/matrix what is already archived
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248 | (also IPV6)
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249 |
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250 | * implement 'at'
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251 |
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252 | * rpcbind (former portmap) or equivalent
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253 | so that we don't have to use -o nolock on nfs mounts
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254 |
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255 | * check IPV6 compliance
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256 |
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257 | * generate a mini example using kernel+busybox only (+libc) for example
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258 |
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259 | * more support for advanced linux 2.6.x features, see: iotop
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260 | most likely there is more
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