file-syscall.c

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

#include "../hos.h"
// file system calls
int do_creat(char *fname){
   struct Inode *ldir_inode;
   struct DirBlock *ldir;
   int x, new_ino,new_bno;
   char leaf_name[EXT2_NAME_LEN]; // for leaf file name
   // compute the inode for last directory, and leaf file name 
   ldir_inode = ITable_compute_inode_for_last_directory(fname, leaf_name);
   printk("last dir ino %d : ",ldir_inode->ino);
   // get the directory block for this dir
   ldir = Inode_get_block(ldir_inode);
   printk("its blk is "); FB_dump((char *)ldir);
   // alloc new inode
   new_ino = BitVect_get_free_bit(d_ibm);
   printk("new ino %d : ",new_ino);
   // alloc a block
   new_bno = BitVect_get_free_bit(d_dbm);
   printk("new blk %d : ", new_bno);
   // make inode
   ITable_make_inode(new_ino, new_bno);
   // report this in the last directory
   DirBlk_report_new_entry(ldir, new_ino, leaf_name);
   // flush file system
   flush_to_disk();
   // now perform open for this file
   x = do_open(fname);
   return x;
}

int do_open(char *fname){
   struct Inode *inode;
   struct FilePtr *fptr;
   int x;

   inode = ITable_compute_inode(fname);
   // report it in file table
   fptr = FPTable_report_new_file(inode);
   // report it in current->fd
   x = FDTable_report_new_fd(current->fd, fptr);
   return x;
}

void do_read(int x, char *buf, int n){
// read n bytes from file x. put it in buf
   struct Inode *in;
   char *blk;
   int pos;
   
   pos = current->fd[x]->pos; // current file pointer
   in = current->fd[x]->iptr;
   // get it
   if ((pos+n) >= BLKSIZE) panic("can't read past block, yet\n");
   blk = FBTable_get_block(in->inode->i_block[0]);
   substr(blk, buf, pos, pos+n-1);
   current->fd[x]->pos += n; // move the file pointer
}

void do_write(int x, char *buf, int n){
// write n bytes in buf to file x
   struct Inode *in;
   char *blk;
   int pos;
   
   pos = current->fd[x]->pos; // current file pointer
   in = current->fd[x]->iptr;
   // assume all files are 1 block for now. get it
   blk = FBTable_get_block(in->inode->i_block[0]);
   write_substr(buf, blk, pos, pos+n-1);
   current->fd[x]->pos += n; // move the file pointer
   flush_to_disk();
}