Энциклопедия разработчика модулей ядра Linux

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)

static ssize_t module_output(

 struct file *file, /* The file read */

 char *buf, /* The buffer to put data to (in the user segment) */

 size_t len, /* The length of the buffer */

 loff_t *offset) /* Offset in the file - ignore */

#else

static int module_output(

 struct inode *inode, /* The inode read */

 struct file *file, /* The file read */

 char *buf, /* The buffer to put data to (in the user segment) */

 int len) /* The length of the buffer */

#endif

{

 static int finished = 0;

 int i;

 char message[MESSAGE_LENGTH+30];

 /* We return 0 to indicate end of file, that we have

 * no more information. Otherwise, processes will

 * continue to read from us in an endless loop. */

 if (finished) {

  finished = 0;

  return 0;

 }

 /* We use put_user to copy the string from the kernel's

 * memory segment to the memory segment of the process

 * that called us. get_user, BTW, is

 * used for the reverse. */

 sprintf(message, "Last input:%s", Message);

 for(i=0; i

 /* Notice, we assume here that the size of the message

 * is below len, or it will be received cut. In a real

 * life situation, if the size of the message is less

 * than len then we'd return len and on the second call

 * start filling the buffer with the len+1'th byte of the message. */

 finished = 1;

 return i; /* Return the number of bytes "read" */

}

/* This function receives input from the user when the

* user writes to the /proc file. */

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)

static ssize_t module_input(

 struct file *file, /* The file itself */

 const char *buf, /* The buffer with input */

 size_t length, /* The buffer's length */

 loff_t *offset) /* offset to file - ignore */

#else

static int module_input(

 struct inode *inode, /* The file's inode */

 struct file *file, /* The file itself */

 const char *buf, /* The buffer with the input */

 int length) /* The buffer's length */

#endif

{

 int i;

 /* Put the input into Message, where module_output will later be able to use it */

 for (i=0; i

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)

  get_user(Message[i], buf+i);

  /* In version 2.2 the semantics of get_user changed,

  * it not longer returns a character, but expects a

  * variable to fill up as its first argument and a

  * user segment pointer to fill it from as the its  second.

  *

  * The reason for this change is that the version 2.2

  * get_user can also read an short or an int. The way

  * it knows the type of the variable it should read

  * is by using sizeof, and for that it needs the

  * variable itself. */

#else

  Message[i] = get_user(buf+i);

#endif