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104 lines
2.7 KiB
104 lines
2.7 KiB
3 years ago
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/*
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* linux/fs/read_write.c
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*
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* (C) 1991 Linus Torvalds
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*/
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#include <sys/stat.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <asm/segment.h>
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extern int rw_char(int rw,int dev, char * buf, int count, off_t * pos);
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extern int read_pipe(struct m_inode * inode, char * buf, int count);
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extern int write_pipe(struct m_inode * inode, char * buf, int count);
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extern int block_read(int dev, off_t * pos, char * buf, int count);
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extern int block_write(int dev, off_t * pos, char * buf, int count);
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extern int file_read(struct m_inode * inode, struct file * filp,
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char * buf, int count);
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extern int file_write(struct m_inode * inode, struct file * filp,
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char * buf, int count);
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int sys_lseek(unsigned int fd,off_t offset, int origin)
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{
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struct file * file;
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int tmp;
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if (fd >= NR_OPEN || !(file=current->filp[fd]) || !(file->f_inode)
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|| !IS_SEEKABLE(MAJOR(file->f_inode->i_dev)))
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return -EBADF;
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if (file->f_inode->i_pipe)
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return -ESPIPE;
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switch (origin) {
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case 0:
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if (offset<0) return -EINVAL;
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file->f_pos=offset;
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break;
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case 1:
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if (file->f_pos+offset<0) return -EINVAL;
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file->f_pos += offset;
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break;
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case 2:
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if ((tmp=file->f_inode->i_size+offset) < 0)
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return -EINVAL;
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file->f_pos = tmp;
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break;
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default:
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return -EINVAL;
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}
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return file->f_pos;
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}
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int sys_read(unsigned int fd,char * buf,int count)
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{
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struct file * file;
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struct m_inode * inode;
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if (fd>=NR_OPEN || count<0 || !(file=current->filp[fd]))
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return -EINVAL;
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if (!count)
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return 0;
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verify_area(buf,count);
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inode = file->f_inode;
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if (inode->i_pipe)
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return (file->f_mode&1)?read_pipe(inode,buf,count):-EIO;
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if (S_ISCHR(inode->i_mode))
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return rw_char(READ,inode->i_zone[0],buf,count,&file->f_pos);
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if (S_ISBLK(inode->i_mode))
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return block_read(inode->i_zone[0],&file->f_pos,buf,count);
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if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode)) {
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if (count+file->f_pos > inode->i_size)
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count = inode->i_size - file->f_pos;
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if (count<=0)
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return 0;
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return file_read(inode,file,buf,count);
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}
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printk("(Read)inode->i_mode=%06o\n\r",inode->i_mode);
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return -EINVAL;
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}
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int sys_write(unsigned int fd,char * buf,int count)
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{
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struct file * file;
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struct m_inode * inode;
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if (fd>=NR_OPEN || count <0 || !(file=current->filp[fd]))
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return -EINVAL;
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if (!count)
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return 0;
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inode=file->f_inode;
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if (inode->i_pipe)
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return (file->f_mode&2)?write_pipe(inode,buf,count):-EIO;
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if (S_ISCHR(inode->i_mode))
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return rw_char(WRITE,inode->i_zone[0],buf,count,&file->f_pos);
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if (S_ISBLK(inode->i_mode))
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return block_write(inode->i_zone[0],&file->f_pos,buf,count);
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if (S_ISREG(inode->i_mode))
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return file_write(inode,file,buf,count);
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printk("(Write)inode->i_mode=%06o\n\r",inode->i_mode);
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return -EINVAL;
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}
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