+---
+Switch CONFIG_SYMBOLS to ENABLE_SYMBOLS
+
+ In busybox 1.0 and earlier, configuration was done by CONFIG_SYMBOLS
+ that were either defined or undefined to indicate whether the symbol was
+ selected in the .config file. They were used with #ifdefs, ala:
+
+ #ifdef CONFIG_SYMBOL
+ if (other_test) {
+ do_code();
+ }
+ #endif
+
+ In 1.1, we have new ENABLE_SYMBOLS which are always defined (as 0 or 1),
+ meaning you can still use them for preprocessor tests by replacing
+ "#ifdef CONFIG_SYMBOL" with "#if ENABLE_SYMBOL". But more importantly, we
+ can use them as a true or false test in normal C code:
+
+ if (ENABLE_SYMBOL && other_test) {
+ do_code();
+ }
+
+ (Optimizing away if() statements that resolve to a constant value
+ is known as "dead code elimination", an optimization so old and simple that
+ Turbo Pascal for DOS did it twenty years ago. Even modern mini-compilers
+ like the Tiny C Compiler (tcc) and the Small Device C Compiler (SDCC)
+ perform dead code elimination.)
+
+ Right now, busybox.h is #including both "config.h" (defining the
+ CONFIG_SYMBOLS) and "bb_config.h" (defining the ENABLE_SYMBOLS). At some
+ point in the future, it would be nice to wean ourselves off of the
+ CONFIG versions. (Among other things, some defective build environments
+ leak the Linux kernel's CONFIG_SYMBOLS into the system's standard #include
+ files. We've experienced collisions before.)
+---
+FEATURE_CLEAN_UP
+ This is more an unresolved issue than a to-do item. More thought is needed.
+
+ Normally we rely on exit() to free memory, close files and unmap segments
+ for us. This makes most calls to free(), close(), and unmap() optional in
+ busybox applets that don't intend to run for very long, and optional stuff
+ can be omitted to save size.
+
+ The idea was raised that we could simulate fork/exit with setjmp/longjmp
+ for _really_ brainless embedded systems, or speed up the standalone shell
+ by not forking. Doing so would require a reliable FEATURE_CLEAN_UP.
+ Unfortunately, this isn't as easy as it sounds.
+
+ The problem is, lots of things exit(), sometimes unexpectedly (xmalloc())
+ and sometimes reliably (bb_perror_msg_and_die() or show_usage()). This
+ jumps out of the normal flow control and bypasses any cleanup code we
+ put at the end of our applets.
+
+ It's possible to add hooks to libbb functions like xmalloc() and xopen()
+ to add their entries to a linked list, which could be traversed and
+ freed/closed automatically. (This would need to be able to free just the
+ entries after a checkpoint to be usable for a forkless standalone shell.
+ You don't want to free the shell's own resources.)
+
+ Right now, FEATURE_CLEAN_UP is more or less a debugging aid, to make things
+ like valgrind happy. It's also documentation of _what_ we're trusting
+ exit() to clean up for us. But new infrastructure to auto-free stuff would
+ render the existing FEATURE_CLEAN_UP code redundant.
+
+ For right now, exit() handles it just fine.
+
+
+Minor stuff:
+ watchdog.c could autodetect the timer duration via:
+ if(!ioctl (fd, WDIOC_GETTIMEOUT, &tmo)) timer_duration = 1 + (tmo / 2);
+ Unfortunately, that needs linux/watchdog.h and that contains unfiltered
+ kernel types on some distros, which breaks the build.
+---
+ use bb_error_msg where appropriate: See
+ egrep "(printf.*\([[:space:]]*(stderr|2)|[^_]write.*\([[:space:]]*(stderr|2))"
+---
+ use bb_perror_msg where appropriate: See
+ egrep "[^_]perror"
+---
+ possible code duplication ingroup() and is_a_group_member()
+---
+ Move __get_hz() to a better place and (re)use it in route.c, ash.c
+---
+ See grep -r strtod
+ Alot of duplication that wants cleanup.
+---
+ in_ether duplicated in network/{interface,ifconfig}.c
+---
+ unify progress_meter. wget, flash_eraseall, pipe_progress, fbsplash, setfiles.
+---
+ support start-stop-daemon -d <chdir-path>
+
+Code cleanup:
+
+Replace deprecated functions.
+
+---
+vdprintf() -> similar sized functionality
+---
+
+(TODO list after discussion 11.05.2009)
+
+* shrink tc/brctl/ip
+ tc/brctl seem like fairly large things to try and tackle in your timeframe,
+ and i think people have posted attempts in the past. Adding additional
+ options to ip though seems reasonable.
+
+* add tests for some applets
+
+* implement POSIX utilities and audit them for POSIX conformance. then
+ audit them for GNU conformance. then document all your findings in a new
+ doc/conformance.txt file while perhaps implementing some of the missing
+ features.
+ you can find the latest POSIX documentation (1003.1-2008) here:
+ http://www.opengroup.org/onlinepubs/9699919799/
+ and the complete list of all utilities that POSIX covers:
+ http://www.opengroup.org/onlinepubs/9699919799/idx/utilities.html
+ The first step would to generate a file/matrix what is already archived
+ (also IPV6)
+
+* ntpdate/ntpd (see ntpclient and openntp for examples)
+
+* implement 'at'
+
+* rpcbind (former portmap) or equivalent
+ so that we don't have to use -o nolock on nfs mounts
+
+* check IPV6 compliance
+
+* generate a mini example using kernel+busybox only (+libc) for example
+
+* more support for advanced linux 2.6.x features, see: iotop
+ most likely there is more
+
+* even more support for statistics: mpstat, iostat, powertop....
+
+
+Unicode work needed:
+
+Unicode support uses libc multibyte functions if LOCALE_SUPPORT is on
+(in this case, the code will also support many more encodings),
+or uses a limited subset of re-implemented multibyte functions
+which only understand "one byte == one char" and unicode.
+This is useful if you build against uclibc with locale support disabled.
+
+Unicode-dependent applets must call check_unicode_in_env() when they
+begin executing.
+
+Applet code may conditionalize on FEATURE_ASSUME_UNICODE
+in order to use more efficient code if unicode support is not requested.
+
+Available functions (if you need more, implement them in libbb/unicode.c
+so that they work without LOCALE_SUPPORT too):
+
+int bb_mbstrlen(str) - multibyte-aware strlen
+size_t mbstowcs(wdest, src, n)
+size_t wcstombs(dest, wsrc, n)
+size_t wcrtomb(str, wc, wstate)
+int iswspace(wc)
+int iswalnum(wc)
+int iswpunct(wc)
+
+Applets which only need to align columns on screen correctly:
+
+ls - already done, use source as an example
+df
+dumpleases
+lsmod
+
+Applets which need to account for Unicode chars
+while processing the output:
+
+[un]expand
+fold
+man
+watch
+cut (-b and -c are currently the same, needs fixing)
+
+These applets need to ensure that unicode input
+is handled correctly (say, <unicode><backspace> sequence):
+
+getty, login
+rm -i
+unzip (overwrite prompt)
+
+Viewers/editors are more difficult (many cases to get right).
+libbb/lineedit.c is an example how to do it:
+
+less, most, ed, vi
+awk
+[ef]grep
+sed
+
+Probably needs some specialized work:
+
+loadkeys