rock.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

/*
 *  linux/fs/isofs/rock.c
 *
 *  (C) 1992, 1993  Eric Youngdale
 *
 *  Rock Ridge Extensions to iso9660
 */

#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/iso_fs.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>

#include "rock.h"

/* These functions are designed to read the system areas of a directory record
 * and extract relevant information.  There are different functions provided
 * depending upon what information we need at the time.  One function fills
 * out an inode structure, a second one extracts a filename, a third one
 * returns a symbolic link name, and a fourth one returns the extent number
 * for the file. */

#define SIG(A,B) ((A) | ((B) << 8)) /* isonum_721() */


/* This is a way of ensuring that we have something in the system
   use fields that is compatible with Rock Ridge */
#define CHECK_SP(FAIL)	       			\
      if(rr->u.SP.magic[0] != 0xbe) FAIL;	\
      if(rr->u.SP.magic[1] != 0xef) FAIL;       \
      inode->i_sb->u.isofs_sb.s_rock_offset=rr->u.SP.skip;
/* We define a series of macros because each function must do exactly the
   same thing in certain places.  We use the macros to ensure that everything
   is done correctly */

#define CONTINUE_DECLS \
  int cont_extent = 0, cont_offset = 0, cont_size = 0;   \
  void * buffer = 0

#define CHECK_CE	       			\
      {cont_extent = isonum_733(rr->u.CE.extent); \
      cont_offset = isonum_733(rr->u.CE.offset); \
      cont_size = isonum_733(rr->u.CE.size);}

#define SETUP_ROCK_RIDGE(DE,CHR,LEN)	      		      	\
  {LEN= sizeof(struct iso_directory_record) + DE->name_len[0];	\
  if(LEN & 1) LEN++;						\
  CHR = ((unsigned char *) DE) + LEN;				\
  LEN = *((unsigned char *) DE) - LEN;                          \
  if (inode->i_sb->u.isofs_sb.s_rock_offset!=-1)                \
  {                                                             \
     LEN-=inode->i_sb->u.isofs_sb.s_rock_offset;                \
     CHR+=inode->i_sb->u.isofs_sb.s_rock_offset;                \
     if (LEN<0) LEN=0;                                          \
  }                                                             \
}                                     

#define MAYBE_CONTINUE(LABEL,DEV) \
  {if (buffer) kfree(buffer); \
  if (cont_extent){ \
    int block, offset, offset1; \
    struct buffer_head * pbh; \
    buffer = kmalloc(cont_size,GFP_KERNEL); \
    if (!buffer) goto out; \
    block = cont_extent; \
    offset = cont_offset; \
    offset1 = 0; \
    pbh = sb_bread(DEV->i_sb, block); \
    if(pbh){       \
      memcpy(buffer + offset1, pbh->b_data + offset, cont_size - offset1); \
      brelse(pbh); \
      chr = (unsigned char *) buffer; \
      len = cont_size; \
      cont_extent = 0; \
      cont_size = 0; \
      cont_offset = 0; \
      goto LABEL; \
    }    \
    printk("Unable to read rock-ridge attributes\n");    \
  }}

/* This is the inner layer of the get filename routine, and is called
   for each system area and continuation record related to the file */

int find_rock_ridge_relocation(struct iso_directory_record * de, 
			       struct inode * inode) {
  int flag;
  int len;
  int retval;
  unsigned char * chr;
  CONTINUE_DECLS;
  flag = 0;
  
  /* If this is a '..' then we are looking for the parent, otherwise we
     are looking for the child */
  
  if (de->name[0]==1 && de->name_len[0]==1) flag = 1;
  /* Return value if we do not find appropriate record. */
  retval = isonum_733 (de->extent);
  
  if (!inode->i_sb->u.isofs_sb.s_rock) return retval;

  SETUP_ROCK_RIDGE(de, chr, len);
 repeat:
  {
    int rrflag, sig;
    struct rock_ridge * rr;
    
    while (len > 1){ /* There may be one byte for padding somewhere */
      rr = (struct rock_ridge *) chr;
      if (rr->len == 0) goto out; /* Something got screwed up here */
      sig = isonum_721(chr);
      chr += rr->len; 
      len -= rr->len;

      switch(sig){
      case SIG('R','R'):
	rrflag = rr->u.RR.flags[0];
	if (flag && !(rrflag & RR_PL)) goto out;
	if (!flag && !(rrflag & RR_CL)) goto out;
	break;
      case SIG('S','P'):
	CHECK_SP(goto out);
	break;
      case SIG('C','L'):
	if (flag == 0) {
	  retval = isonum_733(rr->u.CL.location);
	  goto out;
	}
	break;
      case SIG('P','L'):
	if (flag != 0) {
	  retval = isonum_733(rr->u.PL.location);
	  goto out;
	}
	break;
      case SIG('C','E'):
	CHECK_CE; /* This tells is if there is a continuation record */
	break;
      default:
	break;
      }
    }
  }
  MAYBE_CONTINUE(repeat, inode);
  return retval;
 out:
  if(buffer) kfree(buffer);
  return retval;
}

/* return length of name field; 0: not found, -1: to be ignored */
int get_rock_ridge_filename(struct iso_directory_record * de,
			    char * retname, struct inode * inode)
{
  int len;
  unsigned char * chr;
  CONTINUE_DECLS;
  int retnamlen = 0, truncate=0;
 
  if (!inode->i_sb->u.isofs_sb.s_rock) return 0;
  *retname = 0;

  SETUP_ROCK_RIDGE(de, chr, len);
 repeat:
  {
    struct rock_ridge * rr;
    int sig;
    
    while (len > 1){ /* There may be one byte for padding somewhere */
      rr = (struct rock_ridge *) chr;
      if (rr->len == 0) goto out; /* Something got screwed up here */
      sig = isonum_721(chr);
      chr += rr->len; 
      len -= rr->len;

      switch(sig){
      case SIG('R','R'):
	if((rr->u.RR.flags[0] & RR_NM) == 0) goto out;
	break;
      case SIG('S','P'):
	CHECK_SP(goto out);
	break;
      case SIG('C','E'):
	CHECK_CE;
	break;
      case SIG('N','M'):
	if (truncate) break;
        /*
	 * If the flags are 2 or 4, this indicates '.' or '..'.
	 * We don't want to do anything with this, because it
	 * screws up the code that calls us.  We don't really
	 * care anyways, since we can just use the non-RR
	 * name.
	 */
	if (rr->u.NM.flags & 6) {
	  break;
	}

	if (rr->u.NM.flags & ~1) {
	  printk("Unsupported NM flag settings (%d)\n",rr->u.NM.flags);
	  break;
	}
	if((strlen(retname) + rr->len - 5) >= 254) {
	  truncate = 1;
	  break;
	}
	strncat(retname, rr->u.NM.name, rr->len - 5);
	retnamlen += rr->len - 5;
	break;
      case SIG('R','E'):
	if (buffer) kfree(buffer);
	return -1;
      default:
	break;
      }
    }
  }
  MAYBE_CONTINUE(repeat,inode);
  return retnamlen; /* If 0, this file did not have a NM field */
 out:
  if(buffer) kfree(buffer);
  return 0;
}

int parse_rock_ridge_inode_internal(struct iso_directory_record * de,
			            struct inode * inode,int regard_xa){
  int len;
  unsigned char * chr;
  int symlink_len = 0;
  CONTINUE_DECLS;

  if (!inode->i_sb->u.isofs_sb.s_rock) return 0;

  SETUP_ROCK_RIDGE(de, chr, len);
  if (regard_xa)
   {
     chr+=14;
     len-=14;
     if (len<0) len=0;
   };
   
 repeat:
  {
    int cnt, sig;
    struct inode * reloc;
    struct rock_ridge * rr;
    int rootflag;
    
    while (len > 1){ /* There may be one byte for padding somewhere */
      rr = (struct rock_ridge *) chr;
      if (rr->len == 0) goto out; /* Something got screwed up here */
      sig = isonum_721(chr);
      chr += rr->len; 
      len -= rr->len;
      
      switch(sig){
#ifndef CONFIG_ZISOFS		/* No flag for SF or ZF */
      case SIG('R','R'):
	if((rr->u.RR.flags[0] & 
 	    (RR_PX | RR_TF | RR_SL | RR_CL)) == 0) goto out;
	break;
#endif
      case SIG('S','P'):
	CHECK_SP(goto out);
	break;
      case SIG('C','E'):
	CHECK_CE;
	break;
      case SIG('E','R'):
	inode->i_sb->u.isofs_sb.s_rock = 1;
	printk(KERN_DEBUG "ISO 9660 Extensions: ");
	{ int p;
	  for(p=0;p<rr->u.ER.len_id;p++) printk("%c",rr->u.ER.data[p]);
	}
	  printk("\n");
	break;
      case SIG('P','X'):
	inode->i_mode  = isonum_733(rr->u.PX.mode);
	inode->i_nlink = isonum_733(rr->u.PX.n_links);
	inode->i_uid   = isonum_733(rr->u.PX.uid);
	inode->i_gid   = isonum_733(rr->u.PX.gid);
	break;
      case SIG('P','N'):
	{ int high, low;
	  high = isonum_733(rr->u.PN.dev_high);
	  low = isonum_733(rr->u.PN.dev_low);
	  /*
	   * The Rock Ridge standard specifies that if sizeof(dev_t) <= 4,
	   * then the high field is unused, and the device number is completely
	   * stored in the low field.  Some writers may ignore this subtlety,
	   * and as a result we test to see if the entire device number is
	   * stored in the low field, and use that.