From 7bf0cc02ed3323224e0cfc19cfe9118990bae729 Mon Sep 17 00:00:00 2001
From: Scott Anderson <scott@anderso.nz>
Date: Fri, 17 May 2019 13:43:10 +1200
Subject: Allow explicitly selecting DRM devices

---
 drm_info.h |  2 +-
 json.c     | 28 ++++++++++++++++++++--------
 main.c     |  4 ++--
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/drm_info.h b/drm_info.h
index 7c7fa98..654440a 100644
--- a/drm_info.h
+++ b/drm_info.h
@@ -3,7 +3,7 @@
 
 struct json_object;
 
-struct json_object *drm_info(void);
+struct json_object *drm_info(char *paths[]);
 void print_drm(struct json_object *obj);
 
 #endif
diff --git a/json.c b/json.c
index ee82aaf..5960dae 100644
--- a/json.c
+++ b/json.c
@@ -603,18 +603,30 @@ static struct json_object *node_info(const char *path)
 	return obj;
 }
 
-struct json_object *drm_info(void)
+/* paths is a NULL terminated argv array */
+struct json_object *drm_info(char *paths[])
 {
 	struct json_object *obj = json_object_new_object();
 
-	char path[PATH_MAX];
-	for (int i = 0;; ++i) {
-		snprintf(path, sizeof path, DRM_DEV_NAME, DRM_DIR_NAME, i);
-		if (access(path, R_OK) < 0)
-			break;
+	/* Print everything by default */
+	if (!paths[0]) {
+		char path[PATH_MAX];
+		for (int i = 0;; ++i) {
+			snprintf(path, sizeof path, DRM_DEV_NAME, DRM_DIR_NAME, i);
+			if (access(path, R_OK) < 0)
+				break;
 
-		struct json_object *dev = node_info(path);
-		json_object_object_add(obj, path, dev);
+			struct json_object *dev = node_info(path);
+			json_object_object_add(obj, path, dev);
+		}
+	} else {
+		for (char **path = paths; *path; ++path) {
+			struct json_object *dev = node_info(*path);
+			if (!dev)
+				continue;
+
+			json_object_object_add(obj, *path, dev);
+		}
 	}
 
 	return obj;
diff --git a/main.c b/main.c
index b404192..1b2650e 100644
--- a/main.c
+++ b/main.c
@@ -19,12 +19,12 @@ int main(int argc, char *argv[])
 			json = true;
 			break;
 		default:
-			fprintf(stderr, "usage: drm_info [-j]\n");
+			fprintf(stderr, "usage: drm_info [-j] [--] [path]...\n");
 			exit(opt == '?' ? EXIT_SUCCESS : EXIT_FAILURE);
 		}
 	}
 
-	struct json_object *obj = drm_info();
+	struct json_object *obj = drm_info(&argv[optind]);
 	if (json) {
 		json_object_to_fd(STDOUT_FILENO, obj,
 			JSON_C_TO_STRING_PRETTY | JSON_C_TO_STRING_SPACED);
-- 
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