better prefix guessing on Windows

see https://github.com/tumagonx/pygi-mingw-patches/issues/5

ChangeLog

@@ -7,6 +7,7 @@
 - vips_conv(), vips_compass(), vips_convsep() default to FLOAT precision
 - add FORCE resize mode to break aspect ratio
 - add vips_thumbnail_image()
+- better prefix guessing on Windows, thanks tumagonx
 
 23/4/17 started 8.5.5
 - doc polishing

libvips/include/vips/util.h

@@ -332,7 +332,7 @@ guint32 vips__random( guint32 seed );
 guint32 vips__random_add( guint32 seed, int value );
 
 const char *vips__icc_dir( void );
-const char *vips__locale_dir( void );
+const char *vips__windows_prefix( void );
 
 #ifdef __cplusplus
 }

libvips/iofuncs/init.c

@@ -267,6 +267,7 @@ vips_init( const char *argv0 )
 	char *prgname;
 	const char *prefix;
 	const char *libdir;
+	char *locale;
 
 	/* Two stage done handling: 'done' means we've completed, 'started'
 	 * means we're currently initialising. Use this to prevent recursive
@@ -341,7 +342,9 @@ vips_init( const char *argv0 )
 
 	/* Get i18n .mo files from $VIPSHOME/share/locale/.
 	 */
-	bindtextdomain( GETTEXT_PACKAGE, vips__locale_dir() );
+	locale = g_build_filename( prefix, "share", "locale", NULL );
+	bindtextdomain( GETTEXT_PACKAGE, locale );
+	g_free( locale );
 	bind_textdomain_codeset( GETTEXT_PACKAGE, "UTF-8" );
 
 	/* Deprecated, this is just for compat.
@@ -953,8 +956,6 @@ const char *
 vips_guess_prefix( const char *argv0, const char *env_name )
 {
         const char *prefix;
-        char *basename;
-        char name[VIPS_PATH_MAX];
 
 	/* Already set?
 	 */
@@ -966,29 +967,18 @@ vips_guess_prefix( const char *argv0, const char *env_name )
                 return( prefix );
 	}
 
-	/* Get the program name from argv0.
-	 */
+#ifdef OS_WIN32
+	prefix = vips__windows_prefix();
+#else
+{
+        char *basename;
+
 	basename = g_path_get_basename( argv0 );
-
-	/* Add the exe suffix, if it's missing.
-	 */
-	if( strlen( VIPS_EXEEXT ) > 0 ) {
-		const char *olds[] = { VIPS_EXEEXT };
-
-		vips__change_suffix( basename, name, 
-			VIPS_PATH_MAX, VIPS_EXEEXT, olds, 1 );
-	}
-	else
-		vips_strncpy( name, basename, VIPS_PATH_MAX );
-
+	prefix = guess_prefix( argv0, basename );
 	g_free( basename ); 
+}
+#endif
 
-#ifdef DEBUG
-	printf( "vips_guess_prefix: argv0 = %s\n", argv0 );
-	printf( "vips_guess_prefix: name = %s\n", name );
-#endif /*DEBUG*/
-
-	prefix = guess_prefix( argv0, name );
 	g_setenv( env_name, prefix, TRUE );
 
 	return( prefix );

libvips/iofuncs/util.c

@@ -1970,13 +1970,13 @@ vips__icc_dir( void )
 }
 
 #ifdef OS_WIN32
-static HMODULE vips_dll = NULL;
+static HMODULE vips__dll = NULL;
 #ifdef DLL_EXPORT
 BOOL WINAPI
 DllMain( HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved )
 {
 	if( fdwReason == DLL_PROCESS_ATTACH )
-		vips_dll = hinstDLL;
+		vips__dll = hinstDLL;
 
 	return( TRUE );
 }
@@ -1984,25 +1984,25 @@ DllMain( HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved )
 #endif
 
 static void *
-vips_locale_dir_once( void *null )
+vips__windows_prefix_once( void *null )
 {
 	char *prefix;
 
 #ifdef OS_WIN32
 	prefix = g_win32_get_package_installation_directory_of_module( 
-		vips_dll ),
+		vips__dll ),
 #else
         prefix = (char *) g_getenv( "VIPSHOME" );
 #endif
 
-	return( (void *) g_build_filename( prefix, "share", "locale", NULL ) );
+	return( (void *) prefix ); 
 }
 
 const char *
-vips__locale_dir( void )
+vips__windows_prefix( void )
 {
 	static GOnce once = G_ONCE_INIT;
 
 	return( (const char *) g_once( &once, 
-		(GThreadFunc) vips_locale_dir_once, NULL ) );
+		(GThreadFunc) vips__windows_prefix_once, NULL ) );
 }