the_msdos_open.c

阿基米德操作系统的源代码

////////////////////////////////////////////////////////////////////////////////////////////////
#include "general.h"

#include "hd_info_struct.h"
#include "dir_entry.h"
#include "msdos_dir_entry.h"
#include "d_inode.h"
#include "m_inode.h"
#include "buffer_head.h"
#include "fat_cache.h"
#include "file.h"
#include "hd_request_struct.h"
#include "super_block.h"

#include "common_head.h"
////////////////////////////////////////////////////////////////////////////////////////////////
int the_msdos_open(const char * filename,unsigned long flag,unsigned long mode,unsigned char * buf,unsigned long length)
{
	struct m_inode * temp_inode;
	struct file    * temp_filep;
	int				 temp_fd , temp_retval;
	unsigned char	 temp_flag;
	unsigned char	 temp_mode;

	temp_flag = flag;
	temp_mode = mode;	
	if (temp_flag & (~(O_APPEND | O_TRUNC | O_EXCL | O_CREAT | O_RDWR)))
		return -1;
	if (temp_flag & (O_APPEND | O_TRUNC))
		temp_flag = temp_flag | O_WRONLY;

	for (temp_fd = 0, temp_filep = file_table; temp_fd < NR_FILE; temp_fd++, temp_filep++)
		if (!temp_filep->f_count)
			break;
	if (temp_fd >= NR_FILE)
		return -1;

	if (!(temp_retval = msdos_open_namei(filename,temp_flag,temp_mode,&temp_inode,buf,length))) 
		return -1;

	temp_filep->f_inode = temp_inode;
	temp_filep->f_pos   = 0;
	temp_filep->f_flag  = temp_flag & (O_APPEND | O_RDWR);
	temp_filep->f_count = 1;

	return temp_fd;
}

int msdos_sys_open(const char * filename,unsigned long flag,unsigned long mode)
{
	return the_msdos_open(filename, flag, mode, NULL, 0);
}

int msdos_sys_openEX(const char * filename,unsigned long flag,unsigned long mode,unsigned char * buf,unsigned long length)
{
	return the_msdos_open(filename, flag, mode, buf, length);
}

int msdos_sys_create(const char * pathname, unsigned long mode)
{
	return the_msdos_open(pathname, O_CREAT | O_EXCL, mode, NULL, 0);
}

int msdos_sys_close(int fd)
{	
	if ((fd >= NR_FILE) || (file_table[fd].f_count == 0))
		return -1;
	if (--file_table[fd].f_count)
		return 0;
	msdos_iput(file_table[fd].f_inode);
	return 0;
}