#include <linux/seq_file.h>

#define SP_MAX_INPUT_BUF 8192 
#define SP_MAX_PATH_LEN 4096
#define sp_debug_print(format, arg...) // printk(KERN_ERR "[%s/%d] " format, __func__, __LINE__, ##arg)

/*
* add_simple_proc_file creates a simple procfile:
*    path relative to '/proc/': e.g. '{subdir/}my_proc_file'
*    kernel_input: function, which takes two arguments: 
*      - char *buffer: contains data, which was received via proc file, copied from userspace
*      - void *private: pointer to private data, which was setup here via add_simple_proc_file
*    kernel_output: function, which takes two arguments, creates data, which is sent to userspace via proc_file
*      - struct seq_file *seq: you should pass this to seq_printf in your output kernel_output function
*      - void *private: pointer to private data, which was setup here via add_simple_proc_file
*    kernel_output might be called several times, though userspace performs only one read
*    you can improve this behavior by setting simple_proc_file_setup_expected_output_size
*/
int add_simple_proc_file(
   const char* path,
   int (*kernel_input) (char *, void *),
   void (*kernel_output) (struct seq_file *, void *),
   void *priv_data
   );

/*
* removes simple procfile, which was created by add_simple_proc_file():
*/
void remove_simple_proc_file(const char* path);

/*
* in case your kernel_output function writes more than PAGESIZE,
* your kernel_output function will be called several times. On every call, output
* buffer size will be doubled, till everything fits in
* If you want to improve this behavior you can setup output buffers size for the first
* call of your output function
*/
void simple_proc_file_setup_expected_output_size( const char* path, size_t expected_output_size );

/*
* this struct is used in add_simple_proc_file_array and remove_simple_proc_file_array
*/
struct simple_proc_file {
	const char* path;
	int (*kernel_input) (char *, void *);
	void (*kernel_output) (struct seq_file *, void *);
	void *priv_data;
	int enabled;
};

/*
* in case you want to (un-)register a NULL terminated struct simple_proc_file array[]
* you can use these functions for batch processing
*/
int add_simple_proc_file_array(struct simple_proc_file *array);
void remove_simple_proc_file_array(struct simple_proc_file *array);