Lesson05: Interfaces (procfs, sysfs)

05-Interfaces/procfs/Makefile

@@ -0,0 +1,6 @@
+obj-m+=procfs.o
+all:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
+clean:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean
+

05-Interfaces/procfs/procfs.c

@@ -0,0 +1,190 @@
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/proc_fs.h>
+#include <linux/uaccess.h>
+#include <linux/ctype.h>
+
+#define DIR_NAME	"uppercase"
+#define ENT1_NAME	"converter"
+#define ENT2_NAME	"statistic"
+
+static struct proc_dir_entry *dir;
+static struct proc_dir_entry *ent1, *ent2;
+
+static struct
+{
+	uint32_t nread;
+	uint32_t nwrite;
+	uint32_t charprocessed;
+	uint32_t charconverted;
+} stat;
+
+static char buf[PAGE_SIZE];
+static ssize_t len;
+
+static char bufstat[PAGE_SIZE];
+static ssize_t lenstat;
+
+static ssize_t readconv(struct file *file,
+					char __user *pbuf,
+					size_t count,
+					loff_t *ppos)
+{
+	char *path;
+	ssize_t nreaded;
+
+	path = dentry_path_raw(file->f_path.dentry, buf, sizeof(buf));
+	pr_info("uppercase:\n"
+			"\tread file path: %s\n"
+			"\tread file full path: %s\n"
+			"\tpbuf: %p\n"
+			"\tcount: %zu\n",
+			file->f_path.dentry->d_iname,
+			path,
+			pbuf,
+			count
+	);
+
+	if (copy_to_user(pbuf, buf, len))
+		return -EFAULT;
+
+	nreaded = len;
+	len -= len;
+	if (len != 0)
+		stat.nread++;
+
+	return nreaded;
+}
+
+static ssize_t readstat(struct file *file,
+					char __user *pbuf,
+					size_t count,
+					loff_t *ppos)
+{
+	char *path;
+
+	path = dentry_path_raw(file->f_path.dentry, buf, sizeof(buf));
+	pr_info("uppercase:\n"
+			"\tread file path: %s\n"
+			"\tread file full path: %s\n"
+			"\tpbuf: %p\n"
+			"\tcount: %zu\n",
+			file->f_path.dentry->d_iname,
+			path,
+			pbuf,
+			count
+	);
+
+	if (lenstat == 0) {
+		lenstat = snprintf(bufstat, sizeof(bufstat),
+							"read: %u\n"
+							"write: %u\n"
+							"char processed: %u\n"
+							"char converted: %u\n",
+							stat.nread,
+							stat.nwrite,
+							stat.charprocessed,
+							stat.charconverted
+		);
+		lenstat++; // '\0'
+	} else {
+		lenstat = 0;
+	}
+
+	if (copy_to_user(pbuf, bufstat, lenstat))
+		return -EFAULT;
+	return lenstat;
+}
+
+static ssize_t writeconv(struct file *file,
+					const char __user *pbuf,
+					size_t count,
+					loff_t *ppos)
+{
+	char *path, *s, c;
+
+	path = dentry_path_raw(file->f_path.dentry, buf, sizeof(buf));
+	pr_info("uppercase:\n"
+			"\twrite file path: %s\n"
+			"\twrite file full path: %s\n"
+			"\tpbuf: %p\n"
+			"\tcount: %zu\n",
+			file->f_path.dentry->d_iname,
+			path,
+			pbuf,
+			count
+	);
+	stat.nwrite++;
+
+	if (copy_from_user(buf, pbuf, count))
+		return -EFAULT;
+	buf[count] = 0;
+
+	// Convert
+	s = buf;
+	while (*s != 0) {
+		c = toupper(*s);
+		if (c != *s)
+			stat.charconverted++;
+		*s++ = c;
+	}
+	len = s - buf;
+	stat.charprocessed += len;
+
+	return count;
+}
+
+static int mymodule_init(void)
+{
+	static const struct file_operations ops_conv = {
+		.owner = THIS_MODULE,
+		.read = readconv,
+		.write = writeconv
+	};
+
+	static const struct file_operations ops_stat = {
+		.owner = THIS_MODULE,
+		.read = readstat,
+	};
+
+	dir = proc_mkdir(DIR_NAME, NULL);
+	if (dir == NULL) {
+		pr_err("uppercase: error creating procfs directory\n");
+		return -ENOMEM;
+	}
+
+	ent1 = proc_create(ENT1_NAME, 0666, dir, &ops_conv);
+	if (ent1 == NULL) {
+		pr_err("caseconv: error creating procfs entry 1\n");
+		remove_proc_entry(DIR_NAME, NULL);
+		return -ENOMEM;
+	}
+
+	ent2 = proc_create(ENT2_NAME, 0444, dir, &ops_stat);
+	if (ent2 == NULL) {
+		pr_err("uppercase: error creating procfs entry 2\n");
+		remove_proc_entry(ENT1_NAME, dir);
+		remove_proc_entry(DIR_NAME, NULL);
+		return -ENOMEM;
+	}
+
+	pr_info("uppercase: module loaded\n");
+	return 0;
+}
+
+static void mymodule_exit(void)
+{
+	proc_remove(dir);
+	pr_info("uppercase: module exited\n");
+}
+
+module_init(mymodule_init);
+module_exit(mymodule_exit);
+
+MODULE_AUTHOR("Roman.Storozhenko <[email protected]>");
+MODULE_DESCRIPTION("Simple string uppercase converter using procfs");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.1");
+

05-Interfaces/sysfs/Makefile

@@ -0,0 +1,6 @@
+obj-m+=sysfsm.o
+all:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
+clean:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean
+

05-Interfaces/sysfs/sysfsm.c

@@ -0,0 +1,131 @@
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/ctype.h>
+
+static char buf[PAGE_SIZE];
+static ssize_t len;
+
+static char bufstat[PAGE_SIZE];
+static ssize_t lenstat;
+
+static struct
+{
+	uint32_t nread;
+	uint32_t nwrite;
+	uint32_t charprocessed;
+	uint32_t charconverted;
+} stat;
+
+static ssize_t show_converter(struct class *class, struct class_attribute *attr, char *pbuf)
+{
+	size_t nreaded;
+
+	pr_info("lowercase: %s\n", __func__);
+
+	nreaded = len;
+	memcpy(pbuf, buf, len);
+	len = len - len;
+	return nreaded;
+}
+
+static ssize_t show_statistic(struct class *class, struct class_attribute *attr, char *pbuf)
+{
+	pr_info("lowercase: %s\n", __func__);
+
+	lenstat = snprintf(bufstat, sizeof(bufstat),
+						"read: %u\n"
+						"write: %u\n"
+						"char processed: %u\n"
+						"char converted: %u\n",
+						stat.nread,
+						stat.nwrite,
+						stat.charprocessed,
+						stat.charconverted
+	);
+	lenstat++; // '\0'
+	memcpy(pbuf, bufstat, lenstat);
+	return lenstat;
+}
+
+static ssize_t store_converter(struct class *class, struct class_attribute *attr, const char *pbuf, size_t count)
+{
+	char *s, c;
+
+	pr_info("lowercase: %s\n", __func__);
+
+	// Copy and convert
+	s = buf;
+	while (*pbuf != 0) {
+		c = tolower(*pbuf);
+		if (c != *pbuf)
+			stat.charconverted++;
+		*s++ = c;
+		pbuf++;
+	}
+	len = s - buf;
+	stat.charprocessed += len;
+
+	return count;
+}
+
+struct class_attribute class_attr_converter = {
+	.attr = { .name = "converter", .mode = 0666 },
+	.show	= show_converter,
+	.store	= store_converter
+};
+
+struct class_attribute class_attr_statistic = {
+	.attr = { .name = "statistic", .mode = 0444 },
+	.show	= show_statistic,
+};
+
+static struct class *attr_class;
+
+static int mymodule_init(void)
+{
+	int ret;
+
+	attr_class = class_create(THIS_MODULE, "lowercase");
+	if (attr_class == NULL) {
+		pr_err("lowercase: error creating sysfs class\n");
+		return -ENOMEM;
+	}
+
+	ret = class_create_file(attr_class, &class_attr_converter);
+	if (ret) {
+		pr_err("lowercase: error creating sysfs class attribute\n");
+		class_destroy(attr_class);
+		return ret;
+	}
+
+	ret = class_create_file(attr_class, &class_attr_statistic);
+	if (ret) {
+		class_remove_file(attr_class, &class_attr_converter);
+		pr_err("lowercase: error creating sysfs class attribute\n");
+		class_destroy(attr_class);
+		return ret;
+	}
+
+	pr_info("lowercase: module loaded\n");
+	return 0;
+}
+
+static void mymodule_exit(void)
+{
+	class_remove_file(attr_class, &class_attr_statistic);
+	class_remove_file(attr_class, &class_attr_converter);
+	class_destroy(attr_class);
+
+	pr_info("lowercase: module exited\n");
+}
+
+module_init(mymodule_init);
+module_exit(mymodule_exit);
+
+MODULE_AUTHOR("Roman.Storozhenko <[email protected]>");
+MODULE_DESCRIPTION("Simple string lowercase converter using sysfs");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.1");
+