finish the getdent

mysystem_call.c

@@ -0,0 +1,78 @@
+#define __LIBRARY__
+#include <unistd.h>
+#include <stdarg.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <asm/segment.h>
+#include <sys/stat.h>
+
+#include <fcntl.h>
+
+#define BUF_MAX 4096
+#define	DIRBUF		8192
+#define NAME_MAX          14
+
+struct dirent {
+    long           d_ino;
+    off_t          d_off;
+    unsigned short d_reclen;
+    char           d_name[NAME_MAX+1];
+};
+
+/*参数count指定该缓冲区的大小*/
+int sys_getdents(unsigned int fd,struct linux_dirent *dirp,unsigned int count);
+{
+    if(!count)return -1;/*count is zero*/
+    if(fd>=NR_OPEN)return -EINVAL;/*fd is over range*/
+    
+    struct file *file;
+    struct m_inode * inode;
+    int ret;
+    struct buffer_head *hd;
+    struct dir_entry *de;
+    struct dirent * temp;
+    char * buf;
+    int desize,ldsize,i,ldi;
+
+    file=current->filp[fd];
+    if(!file)return ENOTDIR;/*the file is not exist or not file*/
+    ldsize = sizeof(struct dirent);
+    desize = sizeof(struct dir_entry);
+    inode = file ->f_inode;
+    temp = (struct dirent *)malloc(ldsize);/* //the inter veriable */
+    buf = (char*)malloc(ldsize); 
+
+    /*get the inode's bread*/
+    hd = bread(inode->i_dev , inode->i_zone[0]);
+
+    ldi=0;
+    ret=0;
+
+    for (;ret<inode->i_size;ret += desize){
+        if (ldi >= count-ldsize)
+            break; /* full */
+        de = (struct dir_entry *)(hd->b_data + ret);/* de is set to the current dir_entry */
+        if (!de -> inode )/* to skip if there is no data in de */
+            continue;            
+        /*To  write, copying  current  dirent,  */
+        temp->d_ino = de->inode;
+        temp->d_off = 0; 
+        temp->d_reclen = ldsize;
+        strcpy(temp->d_name,de->name);
+
+        
+        /* by put_fs_byte to write back data to the usr */
+        memcpy(buf, temp, ldsize);
+        for (i=0;i < ldsize;i++){
+            put_fs_byte(*(buf+i), ((char*)dirp)+i+ldi); 
+        }
+        /* memcpy(temp, buf, ldsize); */
+        ldi += ldsize;
+    }
+    return ldi;
+}
+