[PATCH wayland 1/4] scanner: introduce "public-code" and "private-code"

[Emil Velikov]

From: Emil Velikov <emil.velikov at collabora.com>

The options are used to indicate how the code will be used - will it be
public, as part of a DSO or private.

In nearly every instance, people want to use the latter. One noticeable
exception is the wayland libraries. They provide the base marshalling
protocol that everyone uses.

The option "code" was deprecated in favour of "public-code" with a
warning message produced to guide people.

Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
 src/scanner.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 44 insertions(+), 6 deletions(-)

diff --git a/src/scanner.c b/src/scanner.c
index 1308fc7..679e006 100644
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -57,15 +57,23 @@ enum side {
 	SERVER,
 };
 
+enum visibility {
+	PRIVATE,
+	PUBLIC,
+};
+
 static int
 usage(int ret)
 {
-	fprintf(stderr, "usage: %s [OPTION] [client-header|server-header|code]"
+	fprintf(stderr, "usage: %s [OPTION] [client-header|server-header|private-code|public-code]"
 		" [input_file output_file]\n", PROGRAM_NAME);
 	fprintf(stderr, "\n");
 	fprintf(stderr, "Converts XML protocol descriptions supplied on "
 			"stdin or input file to client\n"
-			"headers, server headers, or protocol marshalling code.\n\n");
+			"headers, server headers, or protocol marshalling code.\n\n"
+			"Use \"public-code\" only if the marshalling code will be public - "
+			"aka DSO will export it while other components will be using it.\n"
+			"Using \"private-code\" is strongly recommended.\n\n");
 	fprintf(stderr, "options:\n");
 	fprintf(stderr, "    -h,  --help                  display this help and exit.\n"
 			"    -v,  --version               print the wayland library version that\n"
@@ -1714,9 +1722,11 @@ emit_messages(struct wl_list *message_list,
 	printf("};\n\n");
 }
 
+
 static void
-emit_code(struct protocol *protocol)
+emit_code(struct protocol *protocol, enum visibility vis)
 {
+	const char *symbol_visibility;
 	struct interface *i, *next;
 	struct wl_array types;
 	char **p, *prev;
@@ -1730,6 +1740,19 @@ emit_code(struct protocol *protocol)
 	       "#include <stdint.h>\n"
 	       "#include \"wayland-util.h\"\n\n");
 
+	/* When building a shared library symbols must be exported, otherwise
+	 * we want to have the symbols hidden. */
+	if (vis == PRIVATE) {
+		symbol_visibility = "WL_PRIVATE";
+		printf("#if defined(__GNUC__) && __GNUC__ >= 4\n"
+		       "#define WL_PRIVATE __attribute__ ((visibility(\"hidden\")))\n"
+		       "#else\n"
+		       "#define WL_PRIVATE\n"
+		       "#endif\n\n");
+	} else {
+		symbol_visibility = "WL_EXPORT";
+	}
+
 	wl_array_init(&types);
 	wl_list_for_each(i, &protocol->interface_list, link) {
 		emit_types_forward_declarations(protocol, &i->request_list, &types);
@@ -1759,10 +1782,10 @@ emit_code(struct protocol *protocol)
 		emit_messages(&i->request_list, i, "requests");
 		emit_messages(&i->event_list, i, "events");
 
-		printf("WL_EXPORT const struct wl_interface "
+		printf("%s const struct wl_interface "
 		       "%s_interface = {\n"
 		       "\t\"%s\", %d,\n",
-		       i->name, i->name, i->version);
+		       symbol_visibility, i->name, i->name, i->version);
 
 		if (!wl_list_empty(&i->request_list))
 			printf("\t%d, %s_requests,\n",
@@ -1809,6 +1832,8 @@ int main(int argc, char *argv[])
 	enum {
 		CLIENT_HEADER,
 		SERVER_HEADER,
+		PRIVATE_CODE,
+		PUBLIC_CODE,
 		CODE,
 	} mode;
 
@@ -1860,6 +1885,10 @@ int main(int argc, char *argv[])
 		mode = CLIENT_HEADER;
 	else if (strcmp(argv[0], "server-header") == 0)
 		mode = SERVER_HEADER;
+	else if (strcmp(argv[0], "private-code") == 0)
+		mode = PRIVATE_CODE;
+	else if (strcmp(argv[0], "public-code") == 0)
+		mode = PUBLIC_CODE;
 	else if (strcmp(argv[0], "code") == 0)
 		mode = CODE;
 	else
@@ -1947,8 +1976,17 @@ int main(int argc, char *argv[])
 		case SERVER_HEADER:
 			emit_header(&protocol, SERVER);
 			break;
+		case PRIVATE_CODE:
+			emit_code(&protocol, PRIVATE);
+			break;
 		case CODE:
-			emit_code(&protocol);
+			fprintf(stderr,
+				"Using \"code\" is deprecated - use "
+				"private-code or public-code.\n"
+				"See the help page for details.\n");
+			/* fallthrough */
+		case PUBLIC_CODE:
+			emit_code(&protocol, PUBLIC);
 			break;
 	}
 
-- 
2.16.0