diff --git a/fs/file_dev.c b/fs/file_dev.c new file mode 100644 index 0000000..0c50eaa --- /dev/null +++ b/fs/file_dev.c @@ -0,0 +1,90 @@ +/* + * linux/fs/file_dev.c + * + * (C) 1991 Linus Torvalds + */ + +#include +#include + +#include +#include +#include + +#define MIN(a,b) (((a)<(b))?(a):(b)) +#define MAX(a,b) (((a)>(b))?(a):(b)) + +int file_read(struct m_inode * inode, struct file * filp, char * buf, int count) +{ + int left,chars,nr; + struct buffer_head * bh; + + if ((left=count)<=0) + return 0; + while (left) { + if (nr = bmap(inode,(filp->f_pos)/BLOCK_SIZE)) { + if (!(bh=bread(inode->i_dev,nr))) + break; + } else + bh = NULL; + nr = filp->f_pos % BLOCK_SIZE; + chars = MIN( BLOCK_SIZE-nr , left ); + filp->f_pos += chars; + left -= chars; + if (bh) { + char * p = nr + bh->b_data; + while (chars-->0) + put_fs_byte(*(p++),buf++); + brelse(bh); + } else { + while (chars-->0) + put_fs_byte(0,buf++); + } + } + inode->i_atime = CURRENT_TIME; + return (count-left)?(count-left):-ERROR; +} + +int file_write(struct m_inode * inode, struct file * filp, char * buf, int count) +{ + off_t pos; + int block,c; + struct buffer_head * bh; + char * p; + int i=0; + +/* + * ok, append may not work when many processes are writing at the same time + * but so what. That way leads to madness anyway. + */ + if (filp->f_flags & O_APPEND) + pos = inode->i_size; + else + pos = filp->f_pos; + while (ii_dev,block))) + break; + c = pos % BLOCK_SIZE; + p = c + bh->b_data; + bh->b_dirt = 1; + c = BLOCK_SIZE-c; + if (c > count-i) c = count-i; + pos += c; + if (pos > inode->i_size) { + inode->i_size = pos; + inode->i_dirt = 1; + } + i += c; + while (c-->0) + *(p++) = get_fs_byte(buf++); + brelse(bh); + } + inode->i_mtime = CURRENT_TIME; + if (!(filp->f_flags & O_APPEND)) { + filp->f_pos = pos; + inode->i_ctime = CURRENT_TIME; + } + return (i?i:-1); +}