RE: [ANNOUNCE] udev 0.2 release

["Guo, Min" <min.guo@intel.com>]

How to write value to sysfs? now sysfs is only readable.

Thanks
Guo Min
-----Original Message-----
From: Guo, Min 
Sent: Tuesday, August 12, 2003 3:19 PM
To: 'Daniel Stekloff'
Cc: linux-hotplug-devel@lists.sourceforge.net; Greg KH
Subject: RE: [ANNOUNCE] udev 0.2 release 


Thanks!The revised path!
----------------------------------------------------------------------------------------------------------
diff -Nuar /udev/libsysfs/libsysfs.h /root/udev-0.2/libsysfs/libsysfs.h
--- /udev/libsysfs/libsysfs.h	2003-07-19 03:06:48.000000000 +0800
+++ /root/udev-0.2/libsysfs/libsysfs.h	2003-08-12 16:05:36.483706096 +0800
@@ -124,6 +124,9 @@
 extern int sysfs_read_attribute(struct sysfs_attribute *sysattr);
 extern int sysfs_read_attribute_value(const char *attrpath, char *value, 
 								size_t vsize);
+extern int sysfs_write_attribute(struct sysfs_attribute *sysattr);
+extern int sysfs_write_attribute_value(const char *attrpath, char *value);
+
 extern char *sysfs_get_value_from_attributes(struct sysfs_attribute *attr, 
 							const char * name);
 extern void sysfs_close_directory(struct sysfs_directory *sysdir);
diff -Nuar /udev/libsysfs/sysfs_dir.c /root/udev-0.2/libsysfs/sysfs_dir.c
--- /udev/libsysfs/sysfs_dir.c	2003-07-19 03:06:34.000000000 +0800
+++ /root/udev-0.2/libsysfs/sysfs_dir.c	2003-08-12 16:07:45.000168624 +0800
@@ -78,6 +78,43 @@
 
 	return sysattr;
 }
+/**
+ * sysfs_write_attribute: write value to the attribute
+ * @sysattr: attribute to write
+ * returns 0 with success and -1 with error.
+ */
+int sysfs_write_attribute(struct sysfs_attribute *sysattr)
+{
+	int fd;
+	int length;
+	
+	if (sysattr = NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	
+	if (!(sysattr->method & SYSFS_METHOD_STORE)) {
+		dprintf (stderr, "Store method not supported for attribute %s\n",
+			sysattr->path);
+		return -1;
+	}
+		
+	if ((fd = open(sysattr->path, O_RDWR)) < 0) {
+		dprintf (stderr, "Error reading attribute %s\n", sysattr->path);
+		return -1;
+	}
+
+	length = write(fd,sysattr->value,sizeof(sysattr->value));
+	if (length < 0) {
+		dprintf (stderr, "Error write to the attribute %s\n",
+			sysattr->path);
+		close(fd);
+		return -1;
+	}
+	close(fd);	
+	return 0;
+}
+
 
 /**
  * sysfs_read_attribute: reads value from attribute
@@ -134,6 +171,41 @@
 }
 
 /**
+ * sysfs_write_attribute_value: given path to attribute, 
+ * value will be saved to the attribute.
+ * @attrpath: sysfs path to attribute
+ * @value: value to give to attribute
+ * returns 0 with success and -1 with error.
+ */
+int sysfs_write_attribute_value(const char *attrpath, char *value)
+{
+	struct sysfs_attribute *attr = NULL;
+	
+	if (attrpath = NULL || value = NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	attr = sysfs_open_attribute(attrpath);
+	if (attr = NULL) {
+		dprintf(stderr, "Invalid attribute path %s\n", attrpath);
+		errno = EINVAL;
+		return -1;
+	}
+	strncpy(attr->value,value,sizeof(value));
+	if((sysfs_write_attribute(attr) != 0 )){
+		dprintf(stderr, "Error write to attribute %s\n", attrpath);
+		sysfs_close_attribute(attr);
+		return -1;
+	}
+
+	sysfs_close_attribute(attr);
+
+	return 0;
+}
+
+
+/**
  * sysfs_read_attribute_value: given path to attribute, return its value.
  *	values can be up to a pagesize, if buffer is smaller the value will 
  *	be truncated. 
-----Original Message-----
From: Daniel Stekloff [mailto:dsteklof@us.ibm.com]
Sent: Tuesday, August 05, 2003 6:09 PM
To: Guo, Min
Cc: linux-hotplug-devel@lists.sourceforge.net; Greg KH
Subject: RE: [ANNOUNCE] udev 0.2 release 



Hi Guo Min,

Thank you very much for the patch. It's a good start. Some ideas:

- sysfs_write_attribute needs to actually write the value out to the 
file/attribute. Use the path in sysfs_attribute.

 - sysfs_write_attribute should probably only need the sysfs_attribute 
*sysattr as an argument, the value being already assigned to the 
sysfs_attribute.

- sysfs_write_attribute_value could assign the value to the included 
sysfs_attribute and then call sysfs_write_attribute like you have it now.

- Please look at sysfs_read_attribute as a guide.

Thanks,

Dan



-------------------------------------------------------
This SF.Net email sponsored by: Free pre-built ASP.NET sites including
Data Reports, E-commerce, Portals, and Forums are available now.
Download today and enter to win an XBOX or Visual Studio .NET.
http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet_072303_01/01
_______________________________________________
Linux-hotplug-devel mailing list  http://linux-hotplug.sourceforge.net
Linux-hotplug-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel