106 lines
2.1 KiB
C
106 lines
2.1 KiB
C
/*
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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/minix_fs.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 minix_file_read(struct inode * inode, struct file * filp, char * buf, int count)
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{
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int read,left,chars,nr;
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struct buffer_head * bh;
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if (filp->f_pos > inode->i_size)
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left = 0;
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else
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left = inode->i_size - filp->f_pos;
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if (left > count)
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left = count;
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read = 0;
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while (left > 0) {
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if (nr = bmap(inode,(filp->f_pos)>>BLOCK_SIZE_BITS)) {
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if (!(bh=bread(inode->i_dev,nr)))
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return read?read:-EIO;
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} else
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bh = NULL;
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nr = filp->f_pos & (BLOCK_SIZE-1);
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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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read += 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 read;
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}
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int minix_file_write(struct 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 written,block,c;
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struct buffer_head * bh;
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char * p;
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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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written = 0;
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while (written<count) {
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if (!(block = minix_create_block(inode,pos/BLOCK_SIZE))) {
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if (!written)
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written = -ENOSPC;
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break;
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}
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if (!(bh=bread(inode->i_dev,block))) {
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if (!written)
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written = -EIO;
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break;
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}
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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-written)
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c = count-written;
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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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written += 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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inode->i_dirt = 1;
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}
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return written;
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}
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