Add LaTeX script and sample code

examples/procfs3.c

@@ -0,0 +1,85 @@
+/*
+    procfs3.c
+*/
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+
+#define PROCFS_MAX_SIZE         2048
+#define PROCFS_ENTRY_FILENAME   "buffer2k"
+
+struct proc_dir_entry *Our_Proc_File;
+static char procfs_buffer[PROCFS_MAX_SIZE];
+static unsigned long procfs_buffer_size = 0;
+
+static ssize_t procfs_read(struct file *filp, char *buffer,
+                           size_t length, loff_t *offset)
+{
+    static int finished = 0;
+    if(finished)
+    {
+        pr_debug("procfs_read: END\n");
+        finished = 0;
+        return 0;
+    }
+    finished = 1;
+    if(copy_to_user(buffer, procfs_buffer, procfs_buffer_size))
+        return -EFAULT;
+    pr_debug("procfs_read: read %lu bytes\n", procfs_buffer_size);
+    return procfs_buffer_size;
+}
+static ssize_t procfs_write(struct file *file,  const char *buffer,
+                            size_t len, loff_t *off)
+{
+    if(len>PROCFS_MAX_SIZE)
+        procfs_buffer_size = PROCFS_MAX_SIZE;
+    else
+        procfs_buffer_size = len;
+    if(copy_from_user(procfs_buffer, buffer, procfs_buffer_size))
+        return -EFAULT;
+    pr_debug("procfs_write: write %lu bytes\n", procfs_buffer_size);
+    return procfs_buffer_size;
+}
+int procfs_open(struct inode *inode, struct file *file)
+{
+    try_module_get(THIS_MODULE);
+    return 0;
+}
+int procfs_close(struct inode *inode, struct file *file)
+{
+    module_put(THIS_MODULE);
+    return 0;
+}
+
+static struct proc_ops File_Ops_4_Our_Proc_File = {
+    .proc_read       = procfs_read,
+    .proc_write      = procfs_write,
+    .proc_open       = procfs_open,
+    .proc_release    = procfs_close,
+};
+
+int init_module()
+{
+    Our_Proc_File = proc_create(PROCFS_ENTRY_FILENAME, 0644, NULL,&File_Ops_4_Our_Proc_File);
+    if(Our_Proc_File == NULL)
+    {
+        remove_proc_entry(PROCFS_ENTRY_FILENAME, NULL);
+        pr_debug("Error: Could not initialize /proc/%s\n", PROCFS_ENTRY_FILENAME);
+        return -ENOMEM;
+    }
+    proc_set_size(Our_Proc_File, 80);
+    proc_set_user(Our_Proc_File,  GLOBAL_ROOT_UID, GLOBAL_ROOT_GID);
+
+    pr_debug("/proc/%s created\n", PROCFS_ENTRY_FILENAME);
+    return 0;
+}
+void cleanup_module()
+{
+    remove_proc_entry(PROCFS_ENTRY_FILENAME, NULL);
+    pr_debug("/proc/%s removed\n", PROCFS_ENTRY_FILENAME);
+}
+
+MODULE_LICENSE("GPL");