实现函数sys_getdents,还有部分有关读的内容稍作调整

read_write.c

@@ -0,0 +1,152 @@
+/*
+ *  linux/fs/read_write.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <sys/stat.h>
+#include <errno.h>
+#include <sys/types.h>
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <asm/segment.h>
+#include <unistd.h>
+extern int rw_char(int rw,int dev, char * buf, int count, off_t * pos);
+extern int read_pipe(struct m_inode * inode, char * buf, int count);
+extern int write_pipe(struct m_inode * inode, char * buf, int count);
+extern int block_read(int dev, off_t * pos, char * buf, int count);
+extern int block_write(int dev, off_t * pos, char * buf, int count);
+extern int file_read(struct m_inode * inode, struct file * filp,
+		char * buf, int count);
+extern int file_write(struct m_inode * inode, struct file * filp,
+		char * buf, int count);
+
+int sys_lseek(unsigned int fd,off_t offset, int origin)
+{
+	struct file * file;
+	int tmp;
+
+	if (fd >= NR_OPEN || !(file=current->filp[fd]) || !(file->f_inode)
+	   || !IS_SEEKABLE(MAJOR(file->f_inode->i_dev)))
+		return -EBADF;
+	if (file->f_inode->i_pipe)
+		return -ESPIPE;
+	switch (origin) {
+		case 0:
+			if (offset<0) return -EINVAL;
+			file->f_pos=offset;
+			break;
+		case 1:
+			if (file->f_pos+offset<0) return -EINVAL;
+			file->f_pos += offset;
+			break;
+		case 2:
+			if ((tmp=file->f_inode->i_size+offset) < 0)
+				return -EINVAL;
+			file->f_pos = tmp;
+			break;
+		default:
+			return -EINVAL;
+	}
+	return file->f_pos;
+}
+
+int sys_read(unsigned int fd,char * buf,int count)
+{
+	struct file * file;
+	struct m_inode * inode;
+
+	if (fd>=NR_OPEN || count<0 || !(file=current->filp[fd]))
+		return -EINVAL;
+	if (!count)
+		return 0;
+	verify_area(buf,count);
+	inode = file->f_inode;
+	if (inode->i_pipe)
+		return (file->f_mode&1)?read_pipe(inode,buf,count):-EIO;
+	if (S_ISCHR(inode->i_mode))
+		return rw_char(READ,inode->i_zone[0],buf,count,&file->f_pos);
+	if (S_ISBLK(inode->i_mode))
+		return block_read(inode->i_zone[0],&file->f_pos,buf,count);
+	if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode)) {
+		if (count+file->f_pos > inode->i_size)
+			count = inode->i_size - file->f_pos;
+		if (count<=0)
+			return 0;
+		return file_read(inode,file,buf,count);
+	}
+	printk("(Read)inode->i_mode=%06o\n\r",inode->i_mode);
+	return -EINVAL;
+}
+int k_read(unsigned int fd,char * buf,int count)
+{
+	struct file * file;
+	struct m_inode * inode;
+
+	if (fd>=NR_OPEN || count<0 || !(file=current->filp[fd]))
+		return -EINVAL;
+	if (!count)
+		return 0;
+	verify_area(buf,count);
+	inode = file->f_inode;
+	if (inode->i_pipe)
+		return (file->f_mode&1)?read_pipe(inode,buf,count):-EIO;
+	if (S_ISCHR(inode->i_mode))
+		return rw_char(READ,inode->i_zone[0],buf,count,&file->f_pos);
+	if (S_ISBLK(inode->i_mode))
+		return block_read(inode->i_zone[0],&file->f_pos,buf,count);
+	if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode)) {
+		if (count+file->f_pos > inode->i_size)
+			count = inode->i_size - file->f_pos;
+		if (count<=0)
+			return 0;
+		return k_file_read(inode,file,buf,count);
+	}
+	printk("(Read)inode->i_mode=%06o\n\r",inode->i_mode);
+	return -EINVAL;
+}
+int sys_write(unsigned int fd,char * buf,int count)
+{
+	struct file * file;
+	struct m_inode * inode;
+	
+	if (fd>=NR_OPEN || count <0 || !(file=current->filp[fd]))
+		return -EINVAL;
+	if (!count)
+		return 0;
+	inode=file->f_inode;
+	if (inode->i_pipe)
+		return (file->f_mode&2)?write_pipe(inode,buf,count):-EIO;
+	if (S_ISCHR(inode->i_mode))
+		return rw_char(WRITE,inode->i_zone[0],buf,count,&file->f_pos);
+	if (S_ISBLK(inode->i_mode))
+		return block_write(inode->i_zone[0],&file->f_pos,buf,count);
+	if (S_ISREG(inode->i_mode))
+		return file_write(inode,file,buf,count);
+	printk("(Write)inode->i_mode=%06o\n\r",inode->i_mode);
+	return -EINVAL;
+}
+int sys_getdents(unsigned int fd, struct linux_dirent *dirp, unsigned long count)
+{
+	char name[16];
+	int i=0,j=0;
+	int rst=count;
+
+	while(k_read(fd,name,16)>0 && name[0] && count-32>0)
+	{
+		put_fs_long(name, &(dirp->d_ino));
+		i++;
+		put_fs_long(i,&(dirp->d_off));
+		put_fs_word(32,&(dirp->d_reclen));
+
+		for(j=0;j<14;j++)
+		{
+			put_fs_byte(name[j+2],dirp->d_name+j);
+		}
+		count-=32;
+		dirp=(struct linux_dirent*)((char *)dirp+32);
+	}
+	return rst-count;
+}
+