path_server.h

#ifndef PATH_SERVER_H_20131005
#define PATH_SERVER_H_20131005
#include <stddef.h>
#include "task.h"

#define PIPE_BUF   64 /* Size of largest atomic pipe message */
#define PATH_MAX   32 /* Longest absolute path */
#define PIPE_LIMIT (TASK_LIMIT * 2)
#define PATHSERVER_FD (TASK_LIMIT + 3)
/* File descriptor of pipe to pathserver */

#define S_IFIFO 1
#define S_IMSGQ 2

#define O_CREAT 4
#define PATH_SERVER_NAME "/sys/pathserver"

struct pipe_ringbuffer {
    int start;
    int end;
    char data[PIPE_BUF];

    int (*readable) (struct pipe_ringbuffer*, struct task_control_block*);
    int (*writable) (struct pipe_ringbuffer*, struct task_control_block*);
    int (*read) (struct pipe_ringbuffer*, struct task_control_block*);
    int (*write) (struct pipe_ringbuffer*, struct task_control_block*);
};

#define RB_PUSH(rb, size, v) do { \
        (rb).data[(rb).end] = (v); \
        (rb).end++; \
        if ((rb).end >= size) (rb).end = 0; \
    } while (0)

#define RB_POP(rb, size, v) do { \
        (v) = (rb).data[(rb).start]; \
        (rb).start++; \
        if ((rb).start >= size) (rb).start = 0; \
    } while (0)

#define RB_PEEK(rb, size, v, i) do { \
        int _counter = (i); \
        int _src_index = (rb).start; \
        int _dst_index = 0; \
        while (_counter--) { \
            ((char*)&(v))[_dst_index++] = (rb).data[_src_index++]; \
            if (_src_index >= size) _src_index = 0; \
        } \
    } while (0)

#define RB_LEN(rb, size) (((rb).end - (rb).start) + \
    (((rb).end < (rb).start) ? size : 0))

#define PIPE_PUSH(pipe, v) RB_PUSH((pipe), PIPE_BUF, (v))
#define PIPE_POP(pipe, v)  RB_POP((pipe), PIPE_BUF, (v))
#define PIPE_PEEK(pipe, v, i)  RB_PEEK((pipe), PIPE_BUF, (v), (i))
#define PIPE_LEN(pipe)     (RB_LEN((pipe), PIPE_BUF))

void pathserver_task();
int open(const char *pathname, int flags);
void _read(struct task_control_block *task, struct task_control_block *tasks, struct pipe_ringbuffer *pipes);
void _write(struct task_control_block *task, struct task_control_block *tasks, struct pipe_ringbuffer *pipes);
int mq_open(const char *name, int oflag);
int mkfifo(const char *pathname, int mode);
int _mknod(struct pipe_ringbuffer *pipe, int dev);

#endif /* TASK_H_20131005 */