From 4722274ca048e245fe017b8ca6f776b45cfc4ead Mon Sep 17 00:00:00 2001
From: Kay Sievers <kay.sievers@vrfy.org>
Date: Sat, 2 Jun 2007 09:43:57 +0200
Subject: [PATCH] sysfs: add device lookup by $SUBSYSYTEM:$KERNEL

---
 udev_sysfs.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/udev_sysfs.c b/udev_sysfs.c
index 1846a42f6..8525620a0 100644
--- a/udev_sysfs.c
+++ b/udev_sysfs.c
@@ -429,3 +429,95 @@ char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 out:
 	return attr->value;
 }
+
+int sysfs_lookup_devpath_by_subsys_id(char *devpath_full, size_t len, const char *subsystem, const char *id)
+{
+	size_t sysfs_len;
+	char path_full[PATH_SIZE];
+	char *path;
+	struct stat statbuf;
+
+	sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
+	path = &path_full[sysfs_len];
+
+	if (strcmp(subsystem, "subsystem") == 0) {
+		strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
+		strlcat(path, id, sizeof(path_full) - sysfs_len);
+		if (stat(path_full, &statbuf) == 0)
+			goto found;
+
+		strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
+		strlcat(path, id, sizeof(path_full) - sysfs_len);
+		if (stat(path_full, &statbuf) == 0)
+			goto found;
+
+		strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
+		strlcat(path, id, sizeof(path_full) - sysfs_len);
+		if (stat(path_full, &statbuf) == 0)
+			goto found;
+		goto out;
+	}
+
+	if (strcmp(subsystem, "module") == 0) {
+		strlcpy(path, "/module/", sizeof(path_full) - sysfs_len);
+		strlcat(path, id, sizeof(path_full) - sysfs_len);
+		if (stat(path_full, &statbuf) == 0)
+			goto found;
+		goto out;
+	}
+
+	if (strcmp(subsystem, "drivers") == 0) {
+		char subsys[NAME_SIZE];
+		char *driver;
+
+		strlcpy(subsys, id, sizeof(subsys));
+		driver = strchr(subsys, ':');
+		if (driver != NULL) {
+			driver[0] = '\0';
+			driver = &driver[1];
+			strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
+			strlcat(path, subsys, sizeof(path_full) - sysfs_len);
+			strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
+			strlcat(path, driver, sizeof(path_full) - sysfs_len);
+			if (stat(path_full, &statbuf) == 0)
+				goto found;
+
+			strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
+			strlcat(path, subsys, sizeof(path_full) - sysfs_len);
+			strlcat(path, "/drivers/", sizeof(path_full) - sysfs_len);
+			strlcat(path, driver, sizeof(path_full) - sysfs_len);
+			if (stat(path_full, &statbuf) == 0)
+				goto found;
+		}
+		goto out;
+	}
+
+	strlcpy(path, "/subsystem/", sizeof(path_full) - sysfs_len);
+	strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
+	strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
+	strlcat(path, id, sizeof(path_full) - sysfs_len);
+	if (stat(path_full, &statbuf) == 0)
+		goto found;
+
+	strlcpy(path, "/class/", sizeof(path_full) - sysfs_len);
+	strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
+	strlcat(path, "/", sizeof(path_full) - sysfs_len);
+	strlcat(path, id, sizeof(path_full) - sysfs_len);
+	if (stat(path_full, &statbuf) == 0)
+		goto found;
+
+	strlcpy(path, "/bus/", sizeof(path_full) - sysfs_len);
+	strlcat(path, subsystem, sizeof(path_full) - sysfs_len);
+	strlcat(path, "/devices/", sizeof(path_full) - sysfs_len);
+	strlcat(path, id, sizeof(path_full) - sysfs_len);
+	if (stat(path_full, &statbuf) == 0)
+		goto found;
+out:
+	return 0;
+
+found:
+	if (S_ISLNK(statbuf.st_mode))
+		sysfs_resolve_link(path, sizeof(path_full) - sysfs_len);
+	strlcpy(devpath_full, path, len);
+	return 1;
+}
-- 
2.30.2