krb5 commit [krb5-1.15]: Fix option parsing on Windows

https://github.com/krb5/krb5/commit/8b8cad8b9ff92e2a2d344fc7c4d77277c9c09829
commit 8b8cad8b9ff92e2a2d344fc7c4d77277c9c09829
Author: Greg Hudson <[email protected]>
Date:   Tue May 15 21:52:08 2018 -0700

    Fix option parsing on Windows
    
    Commit 8f9ade8ec50cde1176411085294f85ecfb2820a4 (ticket 8391) moved
    the built-in getopt() and getopt_long() implementations from a static
    library in util/windows to util/support, where (on Windows) it is
    built into k5sprt32.dll or k5sprt64.dll.  The getopt() interface uses
    global variables opterr, optind, optopt, and optarg, each renamed via
    macro to have a k5_ prefix when we use the built-in implementation.
    Data objects exported from DLLs need special handling in Windows; they
    must be marked as DATA in the DLL .def file, and they must be declared
    with "__declspec(dllimport)" in calling code.  Without this handling,
    optind begins with a garbage value and getopt_long() returns -1
    immediately, so client programs always behave as if they have no
    arguments.
    
    Stop unnecessarily declaring optind and optarg in client programs.
    Declare the getopt() global variables with __declspec(dllimport) on
    Windows, except when compiling getopt.c itself.  When creating
    libkrb5support.exports on Windows (this file is later used by
    lib/Makefile.in to create k5sprt32.def), add a DATA tag to the data
    objects.
    
    (cherry picked from commit 63246cf3513a0e8bdfc734db985af14c8c5170c5)
    
    ticket: 8684
    version_fixed: 1.15.4

 src/clients/kdestroy/kdestroy.c |    3 ---
 src/clients/klist/klist.c       |    2 --
 src/clients/kswitch/kswitch.c   |    3 ---
 src/clients/kvno/kvno.c         |    3 ---
 src/include/k5-platform.h       |   14 ++++++++++----
 src/util/support/Makefile.in    |    4 +++-
 src/util/support/getopt.c       |    2 ++
 7 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/clients/kdestroy/kdestroy.c b/src/clients/kdestroy/kdestroy.c
index f955549..8c12771 100644
--- a/src/clients/kdestroy/kdestroy.c
+++ b/src/clients/kdestroy/kdestroy.c
@@ -37,9 +37,6 @@
 #define BELL_CHAR '\007'
 #endif
 
-extern int optind;
-extern char *optarg;
-
 #ifndef _WIN32
 #define GET_PROGNAME(x) (strrchr((x), '/') ? strrchr((x), '/')+1 : (x))
 #else
diff --git a/src/clients/klist/klist.c b/src/clients/klist/klist.c
index ba19788..a5438df 100644
--- a/src/clients/klist/klist.c
+++ b/src/clients/klist/klist.c
@@ -48,8 +48,6 @@
 #include <netdb.h>
 #endif
 
-extern int optind;
-
 int show_flags = 0, show_time = 0, status_only = 0, show_keys = 0;
 int show_etype = 0, show_addresses = 0, no_resolve = 0, print_version = 0;
 int show_adtype = 0, show_all = 0, list_all = 0, use_client_keytab = 0;
diff --git a/src/clients/kswitch/kswitch.c b/src/clients/kswitch/kswitch.c
index f26ecea..9cba7cb 100644
--- a/src/clients/kswitch/kswitch.c
+++ b/src/clients/kswitch/kswitch.c
@@ -27,9 +27,6 @@
 #include "k5-int.h"
 #include <locale.h>
 
-extern int optind;
-extern char *optarg;
-
 #ifndef _WIN32
 #define GET_PROGNAME(x) (strrchr((x), '/') ? strrchr((x), '/')+1 : (x))
 #else
diff --git a/src/clients/kvno/kvno.c b/src/clients/kvno/kvno.c
index 80bee59..9b402f3 100644
--- a/src/clients/kvno/kvno.c
+++ b/src/clients/kvno/kvno.c
@@ -32,9 +32,6 @@
 #endif
 #include <string.h>
 
-extern int optind;
-extern char *optarg;
-
 static char *prog;
 
 static void xusage()
diff --git a/src/include/k5-platform.h b/src/include/k5-platform.h
index 994f463..1210cc3 100644
--- a/src/include/k5-platform.h
+++ b/src/include/k5-platform.h
@@ -1065,10 +1065,16 @@ int k5_path_isabs(const char *path);
 #define N_(s) s
 
 #if !defined(HAVE_GETOPT) || !defined(HAVE_UNISTD_H)
-extern int k5_opterr;
-extern int k5_optind;
-extern int k5_optopt;
-extern char *k5_optarg;
+/* Data objects imported from DLLs must be declared as such on Windows. */
+#if defined(_WIN32) && !defined(K5_GETOPT_C)
+#define K5_GETOPT_DECL __declspec(dllimport)
+#else
+#define K5_GETOPT_DECL
+#endif
+K5_GETOPT_DECL extern int k5_opterr;
+K5_GETOPT_DECL extern int k5_optind;
+K5_GETOPT_DECL extern int k5_optopt;
+K5_GETOPT_DECL extern char *k5_optarg;
 #define opterr k5_opterr
 #define optind k5_optind
 #define optopt k5_optopt
diff --git a/src/util/support/Makefile.in b/src/util/support/Makefile.in
index 6239e41..30fe154 100644
--- a/src/util/support/Makefile.in
+++ b/src/util/support/Makefile.in
@@ -172,8 +172,9 @@ SHLIB_EXPORT_FILE=libkrb5support.exports
 
 EXTRA_SUPPORT_SYMS= @EXTRA_SUPPORT_SYMS@
 ##DOS##EXTRA_SUPPORT_SYMS= krb5int_mkstemp krb5int_strlcpy krb5int_strlcat \
-##DOS##		k5_optind k5_optarg k5_opterr k5_optopt k5_getopt k5_getopt_long \
+##DOS##		k5_getopt k5_getopt_long \
 ##DOS##		krb5int_vasprintf krb5int_asprintf krb5int_gettimeofday $(IPC_SYMS)
+##DOS##DATA_SUPPORT_SYMS= k5_opterr k5_optind k5_optopt k5_optarg
 
 ##DOS##!if 0
 libkrb5support.exports: $(srcdir)/libkrb5support-fixed.exports Makefile
@@ -186,6 +187,7 @@ libkrb5support.exports: $(srcdir)/libkrb5support-fixed.exports Makefile
 ##DOS##libkrb5support.exports: libkrb5support-fixed.exports Makefile
 ##DOS##	$(CP) libkrb5support-fixed.exports new-exports
 ##DOS##	for %%x in ($(EXTRA_SUPPORT_SYMS) .) do if not %%x==. echo %%x >> new-exports
+##DOS##	for %%x in ($(DATA_SUPPORT_SYMS) .) do if not %x==. echo %%x DATA >> new-exports
 ##DOS##	$(RM) libkrb5support.exports
 ##DOS##	$(MV) new-exports libkrb5support.exports
 
diff --git a/src/util/support/getopt.c b/src/util/support/getopt.c
index 44cda68..ae8cb10 100644
--- a/src/util/support/getopt.c
+++ b/src/util/support/getopt.c
@@ -39,6 +39,8 @@
 static char sccsid[] = "@(#)getopt.c	8.3 (Berkeley) 4/27/95";
 #endif
 
+#define K5_GETOPT_C
+
 #include <assert.h>
 #include <errno.h>
 #include <stdio.h>