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91 lines
1.8 KiB
91 lines
1.8 KiB
2 years ago
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/*
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* linux/fs/file_dev.c
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*
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* (C) 1991 Linus Torvalds
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <asm/segment.h>
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#define MIN(a,b) (((a)<(b))?(a):(b))
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#define MAX(a,b) (((a)>(b))?(a):(b))
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int file_read(struct m_inode * inode, struct file * filp, char * buf, int count)
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{
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int left,chars,nr;
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struct buffer_head * bh;
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if ((left=count)<=0)
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return 0;
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while (left) {
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if (nr = bmap(inode,(filp->f_pos)/BLOCK_SIZE)) {
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if (!(bh=bread(inode->i_dev,nr)))
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break;
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} else
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bh = NULL;
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nr = filp->f_pos % BLOCK_SIZE;
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chars = MIN( BLOCK_SIZE-nr , left );
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filp->f_pos += chars;
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left -= chars;
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if (bh) {
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char * p = nr + bh->b_data;
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while (chars-->0)
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put_fs_byte(*(p++),buf++);
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brelse(bh);
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} else {
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while (chars-->0)
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put_fs_byte(0,buf++);
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}
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}
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inode->i_atime = CURRENT_TIME;
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return (count-left)?(count-left):-ERROR;
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}
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int file_write(struct m_inode * inode, struct file * filp, char * buf, int count)
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{
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off_t pos;
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int block,c;
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struct buffer_head * bh;
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char * p;
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int i=0;
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/*
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* ok, append may not work when many processes are writing at the same time
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* but so what. That way leads to madness anyway.
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*/
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if (filp->f_flags & O_APPEND)
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pos = inode->i_size;
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else
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pos = filp->f_pos;
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while (i<count) {
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if (!(block = create_block(inode,pos/BLOCK_SIZE)))
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break;
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if (!(bh=bread(inode->i_dev,block)))
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break;
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c = pos % BLOCK_SIZE;
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p = c + bh->b_data;
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bh->b_dirt = 1;
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c = BLOCK_SIZE-c;
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if (c > count-i) c = count-i;
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pos += c;
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if (pos > inode->i_size) {
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inode->i_size = pos;
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inode->i_dirt = 1;
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}
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i += c;
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while (c-->0)
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*(p++) = get_fs_byte(buf++);
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brelse(bh);
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}
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inode->i_mtime = CURRENT_TIME;
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if (!(filp->f_flags & O_APPEND)) {
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filp->f_pos = pos;
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inode->i_ctime = CURRENT_TIME;
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}
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return (i?i:-1);
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}
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