Clean up warnings

Eliminate compiler warnings due to various issues (listed below).  This
allows Zephyr to build cleanly under GCC versions ranging from 4.1.0 to
4.7.2 with all of the options shown below:

  -g -O2 -Wall -Werror
  -Wno-deprecated-declarations
  -Wmissing-declarations
  -Wpointer-arith
  -Wstrict-prototypes
  -Wshadow
  -Wextra
  -Wno-missing-field-initializers
  -Wno-unused-parameter

  and, on recent versions, -Wunreachable-code

Test builds were done
  - On Ubuntu 12.10 (Quantal Quetzal) using both MIT Kerberos 1.10.1 and
    Heimdal 1.6, without krb4 and both with and without C-Ares and Hesiod
  - On Fedora 14 using Heimdal 0.6, without C-Ares or Hesiod and both
    with and without krb4 (KTH Kerberos 1.3rc2)
  - On Fedora Core 3, Fedora Core 5, Fedora 7, and Fedora 10, using
    Heimdal 0.6 and without C-Ares, Hesiod, or krb4

It also allows clean builds  on Solaris 10 under the Sun Studio 12 (9/07)
C compiler with the following options:

  -g -fd -v -errfmt -errhdr=%user -errtags=yes -errwarn=%all
  -erroff=E_OLD_STYLE_FUNC_DECL,E_ENUM_TYPE_MISMATCH_ARG,E_ARG_INCOMPATIBLE_WITH_ARG

... and under Solaris 9 with the Sun Forte 7 (3/02) C compiler with the above
options and -erroff=E_FUNC_HAS_NO_RETURN_STMT.  Solaris builds were done
with Heimdal 0.6 and without C-Ares, Hesiod, or krb4.

The following types of issues are addressed in this change:

- Parameters and local variables with the same names as library functions
- Parameters and local variables with the same names as globals
- Declarations for exported global variables missing from headers
- Prototypes for exported functions missing from headers
- Missing 'static' on functions that shouldn't be exported
- Old-style function declarations
- Duplicate declarations
- Type mismatches
- Unused variables and functions
- Uninitialized variables
- Forward references to enums
- Necessary header files not included
- Violations of the aliasing rules, where GCC was able to detect them
- Missing braces on if blocks that might be empty
- Attempts to do pointer arithmetic on pointers of type void *, which
  is not permitted in standard C.
- An attempt to pass a function pointer via a void * parameter, which is
  not permitted in standard C.  Instead, we now pass a pointer to a
  structure, which then contains the required function pointer.
- Unnecessary inclusion of <krb5_err.h>, which is already included by
  <krb5.h> when the former exists, and might not be protected against
  double inclusion, depending on which com_err was used.
- Missing include of <com_err.h>, which was masked by the fact that it is
  included by headers generated by e2fsprogs compile_et
- Use of com_err() with a non-constant value in place of the format string,
  which in every case was a fixed-size buffer in which a message was built
  using sprintf(!).  Both the calls to sprintf and the fixed-size buffers
  have been removed, in favor of just letting com_err() do the formatting.
- Various cases where X library functions expecting a parameter of type
  wchar_t * were instead passed a parameter of type XChar2b *.  The two
  types look similar, but are not the same and are _not_ interchangeable.
- An overly-simplistic configure test which failed to detect existence of
  <term.h> on Solaris, due to not including <curses.h>.
- Using the wrong type for the flags output of krb5_auth_con_getflags()
  when building against Heimdal.  A configure test is added to detect
  the correct type.

1 files changed, 27 insertions, 1 deletions

diff --git a/configure.ac b/configure.ac
index 77524a3..7ea77dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,10 +36,15 @@ dnl Checks for header files.
 AC_PATH_XTRA
 AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
-AC_CHECK_HEADERS(fcntl.h paths.h sgtty.h unistd.h malloc.h term.h)
+AC_CHECK_HEADERS(fcntl.h paths.h sgtty.h unistd.h malloc.h)
 AC_CHECK_HEADERS(sys/filio.h sys/ioctl.h sys/time.h sys/file.h sys/utsname.h)
 AC_CHECK_HEADERS(sys/select.h sys/msgbuf.h sys/cdefs.h krb5_err.h termcap.h)
 AC_CHECK_HEADERS(arpa/nameser_compat.h stdbool.h termio.h curses.h)
+AC_CHECK_HEADERS([term.h], [], [],
+[#ifdef HAVE_CURSES_H
+#include <curses.h>
+#endif
+])
 
 if test "$no_x" != "yes"; then
 	ZWGC_LIBX11=-lX11
@@ -301,6 +306,27 @@ if test "$ac_cv_krb5_auth_con_getauthenticator_takes_double_pointer" = yes; then
 fi
 AC_MSG_RESULT($krb5_authent_type)
 
+AC_CACHE_CHECK([krb5_auth_con_getflags out argument type],
+	       [ac_cv_krb5_auth_con_flags_type], [
+local_save_CPPFLAGS="$CPPFLAGS"
+CPPFLAGS="${CPPFLAGS} ${KRB5_INC_FLAGS}"
+for t in krb5_flags int32_t ; do
+   AC_TRY_COMPILE(
+      [#include <krb5.h>
+       extern krb5_error_code
+       krb5_auth_con_getflags(krb5_context, krb5_auth_context, $t *);],
+       [krb5_error_code foo = krb5_auth_con_getflags(0, 0, 0);],
+       [ac_cv_krb5_auth_con_flags_type=$t; break])
+done
+CPPFLAGS="${local_save_CPPFLAGS}"
+if test "x$ac_cv_krb5_auth_con_flags_type" = x ; then
+   AC_MSG_ERROR([Cannot identify krb5_auth_con_getflags function signature])
+fi
+])
+AC_DEFINE_UNQUOTED([KRB5_AUTH_CON_FLAGS_TYPE],
+		   [$ac_cv_krb5_auth_con_flags_type],
+		   [krb5_auth_con_getflags() output arg type])
+
 AC_MSG_CHECKING(for enc_part2 in struct krb5_ticket)
 AC_CACHE_VAL(ac_cv_have_krb5_ticket_enc_part2, [
 local_save_CPPFLAGS="$CPPFLAGS"