replace libsysfs

We never used any of the libsysfs convenience features. Here we replace
it completely with 300 lines of code, which are much simpler and a bit
faster cause udev(d) does not open any syfs file for a simple event which
does not need any parent device information.

Signed-off-by: Kay Sievers <kay.sievers@suse.de>

1 files changed, 345 insertions, 0 deletions

diff --git a/udev_sysfs.c b/udev_sysfs.c
new file mode 100644
index 00000000..19fd614e
--- /dev/null
+++ b/udev_sysfs.c
@@ -0,0 +1,345 @@
+/*
+ * udev_sysfs.c - sysfs access
+ *
+ * Copyright (C) 2005 Kay Sievers <kay.sievers@vrfy.org>
+ *
+ *	This program is free software; you can redistribute it and/or modify it
+ *	under the terms of the GNU General Public License as published by the
+ *	Free Software Foundation version 2 of the License.
+ * 
+ *	This program is distributed in the hope that it will be useful, but
+ *	WITHOUT ANY WARRANTY; without even the implied warranty of
+ *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *	General Public License for more details.
+ * 
+ *	You should have received a copy of the GNU General Public License along
+ *	with this program; if not, write to the Free Software Foundation, Inc.,
+ *	675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <errno.h>
+
+#include "udev.h"
+
+char sysfs_path[PATH_SIZE];
+
+/* device cache */
+static LIST_HEAD(dev_list);
+
+/* attribute value cache */
+static LIST_HEAD(attr_list);
+struct sysfs_attr {
+	struct list_head node;
+	char path[PATH_SIZE];
+	char value[NAME_SIZE];
+};
+
+int sysfs_init(void)
+{
+	const char *env;
+
+	env = getenv("SYSFS_PATH");
+	if (env) {
+		strlcpy(sysfs_path, env, sizeof(sysfs_path));
+		remove_trailing_chars(sysfs_path, '/');
+	} else
+		strlcpy(sysfs_path, "/sys", sizeof(sysfs_path));
+	dbg("sysfs_path='%s'", sysfs_path);
+
+	INIT_LIST_HEAD(&dev_list);
+	INIT_LIST_HEAD(&attr_list);
+	return 0;
+}
+
+void sysfs_cleanup(void)
+{
+	struct sysfs_attr *attr_loop;
+	struct sysfs_attr *attr_temp;
+	struct sysfs_device *dev_loop;
+	struct sysfs_device *dev_temp;
+
+	list_for_each_entry_safe(attr_loop, attr_temp, &attr_list, node) {
+		list_del(&attr_loop->node);
+		free(attr_loop);
+	}
+
+	list_for_each_entry_safe(dev_loop, dev_temp, &dev_list, node) {
+		list_del(&dev_loop->node);
+		free(dev_loop);
+	}
+}
+
+void sysfs_device_set_values(struct sysfs_device *dev, const char *devpath, const char *subsystem)
+{
+	char *pos;
+
+	strlcpy(dev->devpath, devpath, sizeof(dev->devpath));
+	if (subsystem != NULL)
+		strlcpy(dev->subsystem, subsystem, sizeof(dev->subsystem));
+
+	/* set kernel name */
+	pos = strrchr(dev->devpath, '/');
+	if (pos == NULL)
+		return;
+
+	strlcpy(dev->kernel_name, &pos[1], sizeof(dev->kernel_name));
+	dbg("kernel_name='%s'", dev->kernel_name);
+
+	/* some devices have '!' in their name, change that to '/' */
+	pos = dev->kernel_name;
+	while (pos[0] != '\0') {
+		if (pos[0] == '!')
+			pos[0] = '/';
+		pos++;
+	}
+
+	/* get kernel number */
+	pos = &dev->kernel_name[strlen(dev->kernel_name)];
+	while (isdigit(pos[-1]))
+		pos--;
+	strlcpy(dev->kernel_number, pos, sizeof(dev->kernel_number));
+	dbg("kernel_number='%s'", dev->kernel_number);
+}
+
+struct sysfs_device *sysfs_device_get(const char *devpath)
+{
+	char path[PATH_SIZE];
+	char devpath_real[PATH_SIZE];
+	struct sysfs_device *dev;
+	struct sysfs_device *dev_loop;
+	struct stat statbuf;
+	char link_path[PATH_SIZE];
+	char link_target[PATH_SIZE];
+	int len;
+	char *pos;
+
+	dbg("open '%s'", devpath);
+	strlcpy(devpath_real, devpath, sizeof(devpath_real));
+	remove_trailing_chars(devpath_real, '/');
+
+	strlcpy(path, sysfs_path, sizeof(path));
+	strlcat(path, devpath_real, sizeof(path));
+	if (lstat(path, &statbuf) != 0) {
+		dbg("stat '%s' failed: %s", devpath, strerror(errno));
+		return NULL;
+	}
+
+	/* if we got a link, resolve it to the real device */
+	if (S_ISLNK(statbuf.st_mode)) {
+		int i;
+		int back;
+
+		len = readlink(path, link_target, sizeof(link_target));
+		if (len <= 0)
+			return NULL;
+		link_target[len] = '\0';
+		dbg("devpath link '%s' points to '%s'", path, link_target);
+
+		for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
+			;
+		dbg("base '%s', tail '%s', back %i", devpath_real, &link_target[back * 3], back);
+		for (i = 0; i <= back; i++) {
+			pos = strrchr(devpath_real, '/');
+			if (pos == NULL)
+				return NULL;
+			pos[0] = '\0';
+		}
+		dbg("after moving back '%s'", devpath_real);
+		strlcat(devpath_real, "/", sizeof(devpath_real));
+		strlcat(devpath_real, &link_target[back * 3], sizeof(devpath_real));
+	}
+
+	/* look for device in cache */
+	list_for_each_entry(dev_loop, &dev_list, node) {
+		if (strcmp(dev_loop->devpath, devpath_real) == 0) {
+			dbg("found in cache '%s'", dev_loop->devpath);
+			return dev_loop;
+		}
+	}
+
+	/* new device */
+	dbg("'%s'", devpath_real);
+	dev = malloc(sizeof(struct sysfs_device));
+	if (dev == NULL)
+		return NULL;
+	memset(dev, 0x00, sizeof(struct sysfs_device));
+
+	sysfs_device_set_values(dev, devpath_real, NULL);
+
+	/* get subsystem */
+	if (strncmp(dev->devpath, "/class/", 7) == 0) {
+		strlcpy(dev->subsystem, &dev->devpath[7], sizeof(dev->subsystem));
+		pos = strchr(dev->subsystem, '/');
+		if (pos != NULL)
+			pos[0] = '\0';
+		else
+			dev->subsystem[0] = '\0';
+	} else if (strncmp(devpath, "/block/", 7) == 0) {
+		strlcpy(dev->subsystem, "block", sizeof(dev->subsystem));
+	} else if (strncmp(devpath, "/devices/", 9) == 0) {
+		/* get subsystem from bus name */
+		strlcpy(link_path, sysfs_path, sizeof(link_path));
+		strlcat(link_path, dev->devpath, sizeof(link_path));
+		strlcat(link_path, "/bus", sizeof(link_path));
+		len = readlink(link_path, link_target, sizeof(link_target));
+		if (len > 0) {
+			link_target[len] = '\0';
+			dbg("bus link '%s' points to '%s'", link_path, link_target);
+			pos = strrchr(link_target, '/');
+			if (pos != NULL)
+				strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
+		}
+
+		/* get driver name */
+		strlcpy(link_path, sysfs_path, sizeof(link_path));
+		strlcat(link_path, dev->devpath, sizeof(link_path));
+		strlcat(link_path, "/driver", sizeof(link_path));
+		len = readlink(link_path, link_target, sizeof(link_target));
+		if (len > 0) {
+			link_target[len] = '\0';
+			dbg("driver link '%s' points to '%s'", link_path, link_target);
+			pos = strrchr(link_target, '/');
+			if (pos != NULL)
+				strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
+		}
+	} else if (strncmp(devpath, "/bus/", 5) == 0 && strstr(devpath, "/drivers/")) {
+		strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
+	} else if (strncmp(devpath, "/module/", 8) == 0) {
+		strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
+	}
+
+	dbg("add to cache 'devpath=%s', subsystem='%s', driver='%s'", dev->devpath, dev->subsystem, dev->driver);
+	list_add(&dev->node, &dev_list);
+
+	return dev;
+}
+
+struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
+{
+	char parent_devpath[PATH_SIZE];
+	char device_link[PATH_SIZE];
+	char device_link_target[PATH_SIZE];
+	char *pos;
+	int i;
+	int len;
+	int back;
+
+	/* requesting a parent is only valid for devices */
+	if ((strncmp(dev->devpath, "/devices/", 9) != 0) &&
+	    (strncmp(dev->devpath, "/class/", 7) != 0) &&
+	    (strncmp(dev->devpath, "/block/", 7) != 0))
+		return NULL;
+
+	strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
+	dbg("'%s'", parent_devpath);
+
+	/* strip last element */
+	pos = strrchr(parent_devpath, '/');
+	if (pos == NULL || pos == parent_devpath)
+		return NULL;
+	pos[0] = '\0';
+
+	/* are we at the top level */
+	if (strcmp(parent_devpath, "/devices") == 0) {
+		dbg("/devices top level");
+		return NULL;
+	}
+
+	/* at the top level we may follow the "device" link */
+	if (strcmp(parent_devpath, "/block") == 0) {
+		dbg("/block top level, look for device link");
+		goto device_link;
+	}
+
+	if (strncmp(parent_devpath, "/class", 6) == 0) {
+		pos = strrchr(parent_devpath, '/');
+		if (pos == &parent_devpath[6] || pos == parent_devpath) {
+			dbg("class top level, look for device link");
+			goto device_link;
+		}
+	}
+	return sysfs_device_get(parent_devpath);
+
+device_link:
+	strlcpy(device_link, sysfs_path, sizeof(device_link));
+	strlcat(device_link, dev->devpath, sizeof(device_link));
+	strlcat(device_link, "/device", sizeof(device_link));
+	len = readlink(device_link, device_link_target, sizeof(device_link_target));
+	if (len < 0)
+		return NULL;
+	device_link_target[len] = '\0';
+	dbg("device link '%s' points to '%s'", device_link, device_link_target);
+
+	for (back = 0; strncmp(&device_link_target[back * 3], "../", 3) == 0; back++)
+		;
+	strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
+	dbg("base='%s', tail='%s', back=%i", parent_devpath, &device_link_target[back * 3], back);
+	for (i = 0; i < back; i++) {
+		pos = strrchr(parent_devpath, '/');
+		if (pos == NULL)
+			return NULL;
+		pos[0] = '\0';
+	}
+	dbg("after moving back '%s'", parent_devpath);
+	strlcat(parent_devpath, "/", sizeof(parent_devpath));
+	strlcat(parent_devpath, &device_link_target[back * 3], sizeof(parent_devpath));
+	return sysfs_device_get(parent_devpath);
+}
+
+char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
+{
+	char path_full[PATH_SIZE];
+	const char *path;
+	char value[NAME_SIZE];
+	struct sysfs_attr *attr_loop;
+	struct sysfs_attr *attr;
+	int fd;
+	ssize_t size;
+	size_t sysfs_len;
+
+	sysfs_len = strlcpy(path_full, sysfs_path, sizeof(path_full));
+	path = &path_full[sysfs_len];
+	strlcat(path_full, devpath, sizeof(path_full));
+	strlcat(path_full, "/", sizeof(path_full));
+	strlcat(path_full, attr_name, sizeof(path_full));
+
+	/* look for attribute in cache */
+	list_for_each_entry(attr_loop, &attr_list, node) {
+		if (strcmp(attr_loop->path, path) == 0) {
+			dbg("found in cache '%s'", attr_loop->path);
+			return attr_loop->value;
+		}
+	}
+
+	/* read attribute value */
+	fd = open(path_full, O_RDONLY);
+	if (fd < 0)
+		return NULL;
+	size = read(fd, value, sizeof(value));
+	close(fd);
+	if (size < 0)
+		return NULL;
+	if (size == sizeof(value))
+		return NULL;
+	value[size] = '\0';
+	remove_trailing_chars(value, '\n');
+
+	/* store attribute in cache */
+	attr = malloc(sizeof(struct sysfs_attr));
+	if (attr == NULL)
+		return NULL;
+	strlcpy(attr->path, path, sizeof(attr->path));
+	strlcpy(attr->value, value, sizeof(attr->value));
+	dbg("add to cache '%s' '%s'", attr->path, attr->value);
+	list_add(&attr->node, &attr_list);
+
+	return attr->value;
+}