win32: use lazy loading for certain DLLs

Only a handful of functions are used from shell32.dll, userenv.dll
and psapi.dll.  Mostly these functions are in out of the way places.

By loading the functions only when required we can avoid the startup
cost of linking the three DLLs in the common case that they aren't
needed.

1 files changed, 6 insertions, 1 deletions

diff --git a/loginutils/suw32.c b/loginutils/suw32.c
index de29f423a..3500c08db 100644
--- a/loginutils/suw32.c
+++ b/loginutils/suw32.c
@@ -22,6 +22,7 @@
 //usage:     "\n    -c CMD  Command to pass to 'sh -c'"
 
 #include "libbb.h"
+#include "lazyload.h"
 
 int suw32_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int suw32_main(int argc UNUSED_PARAM, char **argv)
@@ -29,6 +30,7 @@ int suw32_main(int argc UNUSED_PARAM, char **argv)
         char *opt_command = NULL;
         SHELLEXECUTEINFO info;
         char *bb_path, *cwd;
+        DECLARE_PROC_ADDR(BOOL, ShellExecuteExA, SHELLEXECUTEINFOA *);
 
         getopt32(argv, "c:", &opt_command);
         if (argv[optind])
@@ -63,5 +65,8 @@ int suw32_main(int argc UNUSED_PARAM, char **argv)
         /* info.lpDirectory = NULL; */
         info.nShow = SW_SHOWNORMAL;
 
-        return !ShellExecuteEx(&info);
+        if (!INIT_PROC_ADDR(shell32.dll, ShellExecuteExA))
+                return -1;
+
+        return !ShellExecuteExA(&info);
 }