Reinhard Tartler discovered a corner case of calling xfwrite() where the
length of the string is zero.

Arnaud Lacombe suggested to use assertion for the corner case, as
fwrite(3) is currently used:

 1) in comment printers. Empty comment are not allowed.
 2) in a callback passed to expr_print(), where the string printed is
    either NULL OR non-empty.
 3) in the lexer, auto-generated, and unused.

I feel using assertion is a good solution:

 1) It cleanly takes care of the above-mentioned corner case.
 2) It can be easily disabled by defining NDEBUG.
 3) It asserts xfwrite() is simply a wrapper for fwrite().

Reported-by: Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

* 'kconfig' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6: (25 commits)
  kconfig: Introduce IS_ENABLED(), IS_BUILTIN() and IS_MODULE()
  xconfig: Abort close if configuration cannot be saved
  kconfig: fix missing "0x" prefix from S_HEX symbol in autoconf.h
  kconfig/nconf: remove useless conditionnal
  kconfig/nconf: prevent segfault on empty menu
  kconfig/nconf: use the generic menu_get_ext_help()
  nconfig: Avoid Wunused-but-set warning
  kconfig/conf: mark xfgets() private
  kconfig: remove pending prototypes for kconfig_load()
  kconfig/conf: add command line options' description
  kconfig/conf: reduce the scope of `defconfig_file'
  kconfig: use calloc() for expr allocation
  kconfig: introduce specialized printer
  kconfig: do not overwrite symbol direct dependency in assignment
  kconfig/gconf: silent missing prototype warnings
  kconfig/gconf: kill deadcode
  kconfig: nuke LKC_DIRECT_LINK cruft
  kconfig: nuke reference to SWIG
  kconfig: add missing <stdlib.h> inclusion
  kconfig: add missing <ctype.h> inclusion
  ...

Fix up conflicts in scripts/kconfig/Makefile

This function has not much reason to be public. In the mean time, convert
declaration from K&R C to ISO C.

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>

Commit 5a6f8d2bd9e3392569ed6f29ea4d7210652f929b removed `kconfig_load()',
however, it missed an hidden prototypes in `lkc.h'. Fix this.

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>

Make conf_write_symbol() grammar agnostic to be able to use it from different
code path. These path pass a printer callback which will print a symbol's name
and its value in different format.

conf_write_symbol()'s job become mostly only to prepare a string for the
printer. This avoid to have to pass specialized flag to generic
functions

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
[mmarek: rebased on top of de12518 (kconfig: autogenerated config_is_xxx
macro)]
Signed-off-by: Michal Marek <mmarek@suse.cz>

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>

This interface is not (and has never been ?) used by any frontend, just get rid
of it.

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>

* 'kconfig' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6:
  nconf: handle comment entries within choice/endchoice
  kconfig: fix warning
  kconfig: Make expr_copy() take a const argument
  kconfig: simplify select-with-unmet-direct-dependency warning
  kconfig: add more S_INT and S_HEX consistency checks
  kconfig: fix `zconfdebug' extern declaration
  kconfig/conf: merge duplicate switch's case
  kconfig: fix typos
  kbuild/gconf: add dummy inline for bind_textdomain_codeset()
  kbuild/nconf: fix spaces damage
  kconfig: nuke second argument of conf_write_symbol()
  kconfig: do not define AUTOCONF_INCLUDED
  kconfig: the day kconfig warns about "select"-abuse has come

This symbol is only exist if YYDEBUG is defined.

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>