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/*
* linux/fs/proc/sysvipc.c
*
* Copyright (c) 1999 Dragos Acostachioaie
*
* This code is derived from linux/fs/proc/generic.c,
* which is Copyright (C) 1991, 1992 Linus Torvalds.
*
* /proc/sysvipc directory handling functions
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#ifndef MIN
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
/* 4K page size but our output routines use some slack for overruns */
#define PROC_BLOCK_SIZE (3*1024)
static ssize_t
proc_sysvipc_read(struct file * file, char * buf, size_t nbytes, loff_t *ppos)
{
struct inode * inode = file->f_dentry->d_inode;
char *page;
ssize_t retval=0;
int eof=0;
ssize_t n, count;
char *start;
struct proc_dir_entry * dp;
dp = (struct proc_dir_entry *) inode->u.generic_ip;
if (!(page = (char*) __get_free_page(GFP_KERNEL)))
return -ENOMEM;
while ((nbytes > 0) && !eof)
{
count = MIN(PROC_BLOCK_SIZE, nbytes);
start = NULL;
if (dp->get_info) {
/*
* Handle backwards compatibility with the old net
* routines.
*
* XXX What gives with the file->f_flags & O_ACCMODE
* test? Seems stupid to me....
*/
n = dp->get_info(page, &start, *ppos, count,
(file->f_flags & O_ACCMODE) == O_RDWR);
if (n < count)
eof = 1;
} else if (dp->read_proc) {
n = dp->read_proc(page, &start, *ppos,
count, &eof, dp->data);
} else
break;
if (!start) {
/*
* For proc files that are less than 4k
*/
start = page + *ppos;
n -= *ppos;
if (n <= 0)
break;
if (n > count)
n = count;
}
if (n == 0)
break; /* End of file */
if (n < 0) {
if (retval == 0)
retval = n;
break;
}
/* This is a hack to allow mangling of file pos independent
* of actual bytes read. Simply place the data at page,
* return the bytes, and set `start' to the desired offset
* as an unsigned int. - Paul.Russell@rustcorp.com.au
*/
n -= copy_to_user(buf, start < page ? page : start, n);
if (n == 0) {
if (retval == 0)
retval = -EFAULT;
break;
}
*ppos += start < page ? (long)start : n; /* Move down the file */
nbytes -= n;
buf += n;
retval += n;
}
free_page((unsigned long) page);
return retval;
}
static struct file_operations proc_sysvipc_operations = {
NULL, /* lseek */
proc_sysvipc_read, /* read */
NULL, /* write */
NULL, /* readdir */
NULL, /* poll */
NULL, /* ioctl */
NULL, /* mmap */
NULL, /* no special open code */
NULL, /* no special release code */
NULL /* can't fsync */
};
/*
* proc directories can do almost nothing..
*/
struct inode_operations proc_sysvipc_inode_operations = {
&proc_sysvipc_operations, /* default net file-ops */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
NULL, /* readlink */
NULL, /* follow_link */
NULL, /* readpage */
NULL, /* writepage */
NULL, /* bmap */
NULL, /* truncate */
NULL /* permission */
};
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