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/*
* Copyright (C) 2001 - 2004 Mike Wray <mike.wray@hp.com>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/** @file
* An IOStream implementation using printk() for output.
* Input is not implemented.
*/
#ifdef __KERNEL__
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include "kernel_stream.h"
#include "allocate.h"
/** Number of characters in the output buffer.
* The kernel uses 1024 for printk, so that should suffice.
*/
#define BUF_N 1024
/** State for a kernel stream. */
typedef struct KernelData {
/** Stream lock. We need a lock to serialize access to the stream. */
spinlock_t lock;
/** Saved flags for locking. */
unsigned long flags;
/** Size of the output buffer. */
int buf_n;
/** Output buffer. */
char buf[BUF_N];
} KernelData;
static int kernel_write(IOStream *s, const char *msg, int n);
static void kernel_free(IOStream *s);
static void kernel_stream_lock(IOStream *s);
static void kernel_stream_unlock(IOStream *s);
/** Methods for a kernel stream. Output only. */
static const IOMethods kernel_methods = {
write: kernel_write,
free: kernel_free,
lock: kernel_stream_lock,
unlock: kernel_stream_unlock,
};
/** Shared state for kernel streams.
* All implementations write using printk, so we can use
* shared state and avoid allocating it.
*/
static const KernelData kernel_data = {
lock: SPIN_LOCK_UNLOCKED,
flags: 0,
buf_n: BUF_N,
};
/** Stream for kernel printk. */
static IOStream iokernel = {
methods: &kernel_methods,
data: &kernel_data,
};
/** Stream for kernel printk. */
IOStream *iostdout = &iokernel;
/** Stream for kernel printk. */
IOStream *iostdin = &iokernel;
/** Stream for kernel printk. */
IOStream *iostderr = &iokernel;
/** Get an output-only stream implementation using
* printk(). The stream uses static storage, and must not be freed.
*
* @return kernel stream
*/
IOStream get_stream_kernel(void){
return iokernel;
}
/** Obtain the lock on the stream state.
*
* @param kdata stream state
*/
static inline void KernelData_lock(KernelData *kdata){
spin_lock_irqsave(&kdata->lock, kdata->flags);
}
/** Release the lock on the stream state.
*
* @param kdata stream state
*/
static inline void KernelData_unlock(KernelData *kdata){
spin_unlock_irqrestore(&kdata->lock, kdata->flags);
}
/** Get the stream state.
*
* @param s kernel stream
* @return stream state
*/
static inline KernelData *get_kernel_data(IOStream *s){
return (KernelData*)s->data;
}
/** Obtain the lock on the stream state.
*
* @param s stream
*/
void kernel_stream_lock(IOStream *s){
KernelData_lock(get_kernel_data(s));
}
/** Release the lock on the stream state.
*
* @param s stream
*/
void kernel_stream_unlock(IOStream *s){
KernelData_unlock(get_kernel_data(s));
}
/** Write to a kernel stream.
*
* @param stream kernel stream
* @param format print format
* @param args print arguments
* @return result of the print
*/
static int kernel_write(IOStream *stream, const char *buf, int n){
KernelData *kdata = get_kernel_data(stream);
int k;
k = kdata->buf_n - 1;
if(n < k) k = n;
memcpy(kdata->buf, buf, k);
kdata->buf[k] = '\0'
printk(kdata->buf);
return k;
}
/** Free a kernel stream.
* Frees the internal state of the stream.
* Do not call this unless the stream was dynamically allocated.
* Do not call this on a stream returned from get_stream_kernel().
*
* @param io stream to free
*/
static void kernel_free(IOStream *io){
KernelData *kdata;
if(io == &iokernel) return;
kdata = get_kernel_data(io);
zero(kdata, sizeof(*kdata));
deallocate(kdata);
}
#endif /* __KERNEL__ */
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