[821] | 1 | Busybox TODO
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| 2 |
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| 3 | Stuff that needs to be done. This is organized by who plans to get around to
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| 4 | doing it eventually, but that doesn't mean they "own" the item. If you want to
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| 5 | do one of these bounce an email off the person it's listed under to see if they
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| 6 | have any suggestions how they plan to go about it, and to minimize conflicts
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| 7 | between your work and theirs. But otherwise, all of these are fair game.
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| 8 |
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| 9 | Rob Landley <rob@landley.net>:
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| 10 | Add BB_NOMMU to platform.h and migrate __uClinux__ tests to that.
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| 11 | #if defined __UCLIBC__ && !defined __ARCH_USE_MMU__
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| 12 | Add a libbb/platform.c
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| 13 | Implement fdprintf() for platforms that haven't got one.
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| 14 | Implement bb_realpath() that can handle NULL on non-glibc.
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| 15 | Cleanup bb_asprintf()
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| 16 |
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| 17 | Migrate calloc() and bb_calloc() occurrences to bb_xzalloc().
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| 18 | Remove obsolete _() wrapper crud for internationalization we don't do.
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| 19 | Figure out where we need utf8 support, and add it.
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| 20 |
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| 21 | sh
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| 22 | The command shell situation is a big mess. We have three or four different
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| 23 | shells that don't really share any code, and the "standalone shell" doesn't
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| 24 | work all that well (especially not in a chroot environment), due to apps not
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| 25 | being reentrant. I'm writing a new shell (bbsh) to unify the various
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| 26 | shells and configurably add the minimal set of bash features people
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| 27 | actually use. The hardest part is it has to configure down as small as
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| 28 | lash while providing lash's features. The rest is easy in comparison.
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| 29 | bzip2
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| 30 | Compression-side support.
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| 31 | init
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| 32 | General cleanup (should use ENABLE_FEATURE_INIT_SYSLOG and ENABLE_FEATURE_INIT_DEBUG).
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| 33 | depmod
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| 34 | busybox lacks a way to update module deps when running from firmware without the
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| 35 | use of the depmod.pl (perl is to bloated for most embedded setups) and or orig
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| 36 | modutils. The orig depmod is rather pointless to have to add to a firmware image
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| 37 | in when we already have a insmod/rmmod and friends.
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| 38 | Unify base64 handling.
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| 39 | There's base64 encoding and decoding going on in:
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| 40 | networking/wget.c:base64enc()
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| 41 | coreutils/uudecode.c:read_base64()
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| 42 | coreutils/uuencode.c:tbl_base64[]
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| 43 | networking/httpd.c:decodeBase64()
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| 44 | And probably elsewhere. That needs to be unified into libbb functions.
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| 45 | Do a SUSv3 audit
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| 46 | Look at the full Single Unix Specification version 3 (available online at
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| 47 | "http://www.opengroup.org/onlinepubs/009695399/nfindex.html") and
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| 48 | figure out which of our apps are compliant, and what we're missing that
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| 49 | we might actually care about.
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| 50 |
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| 51 | Even better would be some kind of automated compliance test harness that
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| 52 | exercises each command line option and the various corner cases.
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| 53 | Internationalization
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| 54 | How much internationalization should we do?
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| 55 |
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| 56 | The low hanging fruit is UTF-8 character set support. We should do this.
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| 57 | (Vodz pointed out the shell's cmdedit as needing work here. What else?)
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| 58 |
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| 59 | We also have lots of hardwired english text messages. Consolidating this
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| 60 | into some kind of message table not only makes translation easier, but
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| 61 | also allows us to consolidate redundant (or close) strings.
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| 62 |
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| 63 | We probably don't want to be bloated with locale support. (Not unless we
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| 64 | can cleanly export it from our underlying C library without having to
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| 65 | concern ourselves with it directly. Perhaps a few specific things like a
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| 66 | config option for "date" are low hanging fruit here?)
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| 67 |
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| 68 | What level should things happen at? How much do we care about
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| 69 | internationalizing the text console when X11 and xterms are so much better
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| 70 | at it? (There's some infrastructure here we don't implement: The
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| 71 | "unicode_start" and "unicode_stop" shell scripts need "vt-is-UTF8" and a
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| 72 | --unicode option to loadkeys. That implies a real loadkeys/dumpkeys
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| 73 | implementation to replace loadkmap/dumpkmap. Plus messing with console font
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| 74 | loading. Is it worth it, or do we just say "use X"?)
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| 75 |
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| 76 | Individual compilation of applets.
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| 77 | It would be nice if busybox had the option to compile to individual applets,
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| 78 | for people who want an alternate implementation less bloated than the gnu
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| 79 | utils (or simply with less political baggage), but without it being one big
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| 80 | executable.
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| 81 |
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| 82 | Turning libbb into a real dll is another possibility, especially if libbb
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| 83 | could export some of the other library interfaces we've already more or less
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| 84 | got the code for (like zlib).
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| 85 | buildroot - Make a "dogfood" option
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| 86 | Busybox 1.1 will be capable of replacing most gnu packages for real world
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| 87 | use, such as developing software or in a live CD. It needs wider testing.
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| 88 |
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| 89 | Busybox should now be able to replace bzip2, coreutils, e2fsprogs, file,
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| 90 | findutils, gawk, grep, inetutils, less, modutils, net-tools, patch, procps,
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| 91 | sed, shadow, sysklogd, sysvinit, tar, util-linux, and vim. The resulting
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| 92 | system should be self-hosting (I.E. able to rebuild itself from source
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| 93 | code). This means it would need (at least) binutils, gcc, and make, or
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| 94 | equivalents.
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| 95 |
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| 96 | It would be a good "eating our own dogfood" test if buildroot had the option
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| 97 | of using a "make allyesconfig" busybox instead of the all of the above
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| 98 | packages. Anything that's wrong with the resulting system, we can fix. (It
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| 99 | would be nice to be able to upgrade busybox to be able to replace bash and
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| 100 | diffutils as well, but we're not there yet.)
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| 101 |
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| 102 | One example of an existing system that does this already is Firmware Linux:
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| 103 | http://www.landley.net/code/firmware
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| 104 | initramfs
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| 105 | Busybox should have a sample initramfs build script. This depends on
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| 106 | bbsh, mdev, and switch_root.
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| 107 | mkdep
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| 108 | Write a mkdep that doesn't segfault if there's a directory it doesn't
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| 109 | have permission to read, isn't based on manually editing the output of
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| 110 | lexx and yacc, doesn't make such a mess under include/config, etc.
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| 111 | Group globals into unions of structures.
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| 112 | Go through and turn all the global and static variables into structures,
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| 113 | and have all those structures be in a big union shared between processes,
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| 114 | so busybox uses less bss. (This is a big win on nommu machines.) See
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| 115 | sed.c and mdev.c for examples.
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| 116 | Go through bugs.busybox.net and close out all of that somehow.
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| 117 | This one's open to everybody, but I'll wind up doing it...
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| 118 |
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| 119 |
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| 120 | Bernhard Fischer <rep.nop@anon.at>:
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| 121 | Makefile stuff:
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| 122 | make -j is broken, -j1 is forced atm
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| 123 | New debug options:
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| 124 | -Wlarger-than-127
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| 125 | Collate BUFSIZ IOBUF_SIZE MY_BUF_SIZE PIPE_PROGRESS_SIZE BUFSIZE PIPESIZE
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| 126 | Use bb_common_bufsiz1?
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| 127 |
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| 128 | As yet unclaimed:
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| 129 |
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| 130 | ----
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| 131 | find
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| 132 | doesn't understand (), lots of susv3 stuff.
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| 133 | ----
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| 134 | diff
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| 135 | Make sure we handle empty files properly:
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| 136 | From the patch man page:
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| 137 |
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| 138 | you can remove a file by sending out a context diff that compares
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| 139 | the file to be deleted with an empty file dated the Epoch. The
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| 140 | file will be removed unless patch is conforming to POSIX and the
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| 141 | -E or --remove-empty-files option is not given.
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| 142 | ---
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| 143 | patch
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| 144 | Should have simple fuzz factor support to apply patches at an offset which
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| 145 | shouldn't take up too much space.
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| 146 |
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| 147 | And while we're at it, a new patch filename quoting format is apparently
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| 148 | coming soon: http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2
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| 149 | ---
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| 150 | man
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| 151 | It would be nice to have a man command. Not one that handles troff or
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| 152 | anything, just one that can handle preformatted ascii man pages, possibly
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| 153 | compressed. This could probably be a script in the extras directory that
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| 154 | calls cat/zcat/bzcat | less
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| 155 |
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| 156 | (How doclifter might work into this is anybody's guess.)
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| 157 | ---
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| 158 | ar
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| 159 | Write support?
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| 160 | ---
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| 161 | crond
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| 162 | turn FEATURE_DEBUG_OPT into ENABLE_FEATURE_CROND_DEBUG_OPT
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| 163 |
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| 164 | Architectural issues:
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| 165 |
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| 166 | bb_close() with fsync()
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| 167 | We should have a bb_close() in place of normal close, with a CONFIG_ option
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| 168 | to not just check the return value of close() for an error, but fsync().
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| 169 | Close can't reliably report anything useful because if write() accepted the
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| 170 | data then it either went out to the network or it's in cache or a pipe
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| 171 | buffer. Either way, there's no guarantee it'll make it to its final
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| 172 | destination before close() gets called, so there's no guarantee that any
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| 173 | error will be reported.
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| 174 |
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| 175 | You need to call fsync() if you care about errors that occur after write(),
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| 176 | but that can have a big performance impact. So make it a config option.
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| 177 | ---
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| 178 | Unify archivers
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| 179 | Lots of archivers have the same general infrastructure. The directory
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| 180 | traversal code should be factored out, and the guts of each archiver could
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| 181 | be some setup code and a series of callbacks for "add this file",
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| 182 | "add this directory", "add this symlink" and so on.
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| 183 |
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| 184 | This could clean up tar and zip, and make it cheaper to add cpio and ar
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| 185 | write support, and possibly even cheaply add things like mkisofs or
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| 186 | mksquashfs someday, if they become relevant.
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| 187 | ---
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| 188 | Text buffer support.
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| 189 | Several existing applets (sort, vi, less...) read
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| 190 | a whole file into memory and act on it. There might be an opportunity
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| 191 | for shared code in there that could be moved into libbb...
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| 192 | ---
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| 193 | Memory Allocation
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| 194 | We have a CONFIG_BUFFER mechanism that lets us select whether to do memory
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| 195 | allocation on the stack or the heap. Unfortunately, we're not using it much.
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| 196 | We need to audit our memory allocations and turn a lot of malloc/free calls
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| 197 | into RESERVE_CONFIG_BUFFER/RELEASE_CONFIG_BUFFER.
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| 198 | For a start, see e.g. make EXTRA_CFLAGS=-Wlarger-than-64
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| 199 |
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| 200 | And while we're at it, many of the CONFIG_FEATURE_CLEAN_UP #ifdefs will be
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| 201 | optimized out by the compiler in the stack allocation case (since there's no
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| 202 | free for an alloca()), and this means that various cleanup loops that just
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| 203 | call free might also be optimized out by the compiler if written right, so
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| 204 | we can yank those #ifdefs too, and generally clean up the code.
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| 205 | ---
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| 206 | Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS
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| 207 |
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| 208 | In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS
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| 209 | that were either defined or undefined to indicate whether the symbol was
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| 210 | selected in the .config file. They were used with #ifdefs, ala:
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| 211 |
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| 212 | #ifdef CONFIG_SYMBOL
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| 213 | if (other_test) {
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| 214 | do_code();
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| 215 | }
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| 216 | #endif
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| 217 |
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| 218 | In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1),
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| 219 | meaning you can still use them for preprocessor tests by replacing
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| 220 | "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we
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| 221 | can use them as a true or false test in normal C code:
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| 222 |
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| 223 | if (ENABLE_SYMBOL && other_test) {
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| 224 | do_code();
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| 225 | }
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| 226 |
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| 227 | (Optimizing away if() statements that resolve to a constant value
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| 228 | is known as "dead code elimination", an optimization so old and simple that
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| 229 | Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers
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| 230 | like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC)
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| 231 | perform dead code elimination.)
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| 232 |
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| 233 | Right now, busybox.h is #including both "config.h" (defining the
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| 234 | CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some
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| 235 | point in the future, it would be nice to wean ourselves off of the
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| 236 | CONFIG versions. (Among other things, some defective build environments
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| 237 | leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include
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| 238 | files. We've experienced collisions before.)
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| 239 | ---
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| 240 | FEATURE_CLEAN_UP
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| 241 | This is more an unresolved issue than a to-do item. More thought is needed.
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| 242 |
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| 243 | Normally we rely on exit() to free memory, close files, and unmap segments
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| 244 | for us. This makes most calls to free(), close(), and unmap() optional in
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| 245 | busybox applets that don't intend to run for very long, and optional stuff
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| 246 | can be omitted to save size.
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| 247 |
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| 248 | The idea was raised that we could simulate fork/exit with setjmp/longjmp
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| 249 | for _really_ brainless embedded systems, or speed up the standalone shell
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| 250 | by not forking. Doing so would require a reliable FEATURE_CLEAN_UP.
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| 251 | Unfortunately, this isn't as easy as it sounds.
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| 252 |
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| 253 | The problem is, lots of things exit(), sometimes unexpectedly (xmalloc())
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| 254 | and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This
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| 255 | jumps out of the normal flow control and bypasses any cleanup code we
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| 256 | put at the end of our applets.
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| 257 |
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| 258 | It's possible to add hooks to libbb functions like xmalloc() and bb_xopen()
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| 259 | to add their entries to a linked list, which could be traversed and
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| 260 | freed/closed automatically. (This would need to be able to free just the
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| 261 | entries after a checkpoint to be usable for a forkless standalone shell.
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| 262 | You don't want to free the shell's own resources.)
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| 263 |
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| 264 | Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things
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| 265 | like valgrind happy. It's also documentation of _what_ we're trusting
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| 266 | exit() to clean up for us. But new infrastructure to auto-free stuff would
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| 267 | render the existing FEATURE_CLEAN_UP code redundant.
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| 268 |
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| 269 | For right now, exit() handles it just fine.
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| 270 |
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| 271 |
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| 272 |
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| 273 | Minor stuff:
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| 274 | watchdog.c could autodetect the timer duration via:
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| 275 | if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2);
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| 276 | Unfortunately, that needs linux/watchdog.h and that contains unfiltered
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| 277 | kernel types on some distros, which breaks the build.
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| 278 | ---
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| 279 | use bb_error_msg where appropriate: See
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| 280 | egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))"
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| 281 | ---
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| 282 | use bb_perror_msg where appropriate: See
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| 283 | egrep "[^_]perror"
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| 284 | ---
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| 285 | Remove superfluous fmt occurances: e.g.
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| 286 | fprintf(stderr, "%s: %s not found\n", "unalias", *argptr);
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| 287 | -> fprintf(stderr, "unalias: %s not found\n", *argptr);
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| 288 | ---
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| 289 | possible code duplication ingroup() and is_a_group_member()
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| 290 | ---
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| 291 | unify itoa: netstat.c, hush.c, lash.c, msh.c
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| 292 | Put one single, robust version into e.g. safe_strtol.c
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| 293 | ---
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| 294 |
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| 295 |
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| 296 | Code cleanup:
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| 297 |
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| 298 | Replace deprecated functions.
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| 299 |
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| 300 | bzero() -> memset()
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| 301 | ---
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| 302 | sigblock(), siggetmask(), sigsetmask(), sigmask() -> sigprocmask et al
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| 303 | ---
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| 304 | vdprintf() -> similar sized functionality
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| 305 | ---
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| 306 |
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