util.c

NTFS 磁盘系统 加载源代码

/*
 *  super.c
 *
 *  Copyright (C) 1997 Martin von L鰓is
 *
 *  The utf8 routines are copied from Python wstrop module,
 *  Copyright (C) 1997 Martin von L鰓is
 */
#include <errno.h>
#include "ntfs.h"

/* Converts a single wide character to a sequence of utf8 bytes.
   Returns the number of bytes, or 0 on error. */
static int
to_utf8(ntfs_u16 c,unsigned char* buf)
{
	if(c==0)
		return 0; /* No support for embedded 0 runes */
	if(c<0x80){
		if(buf)buf[0]=c;
		return 1;
	}
	if(c<0x800){
		if(buf){
			buf[0] = 0xc0 | (c>>6);
			buf[1] = 0x80 | (c & 0x3f);
		}
		return 2;
	}
	if(c<0x10000){
		if(buf){
			buf[0] = 0xe0 | (c>>12);
			buf[1] = 0x80 | ((c>>6) & 0x3f);
			buf[2] = 0x80 | (c & 0x3f);
		}
		return 3;
	}
	/* We don't support characters above 0xFFFF in NTFS */
	return 0;
}

/* Decodes a sequence of utf8 bytes into a single wide character.
   Returns the number of bytes consumed, or 0 on error */
static int
from_utf8(const unsigned char* str,ntfs_u16 *c)
{
	int l=0,i;
	if(*str<0x80){
		*c = *str;
		return 1;
	}
	if(*str<0xc0) /* lead byte must not be 10xxxxxx */
		return 0;   /* is c0 a possible lead byte? */
	if(*str<0xe0){         /* 110xxxxx */
		*c = *str & 0x1f;
		l=2;
	}else if(*str<0xf0){   /* 1110xxxx */
		*c = *str & 0xf;
		l=3;
	}else if(*str<0xf8){   /* 11110xxx */
		*c = *str & 7;
		l=4;
	}else /* We don't support characters above 0xFFFF in NTFS */
		return 0;
	 

	for(i=1;i<l;i++){
		/* all other bytes must be 10xxxxxx */
		if((str[i] & 0xc0) != 0x80)
			return 0;
		*c <<= 6;
		*c |= str[i] & 0x3f;
	}
	return l;
}

/* Converts wide string to UTF-8. Expects two in- and two out-parameters.
   Returns 0 on success, or error code. 
   The caller has to free the result string.
   There is no support for UTF-16, yet */
int ntfs_dupuni2utf8(ntfs_u16* in, int in_len,char **out,int *out_len)
{
	int i,tmp;
	int len8;
	unsigned char *result;
	/* count the length of the resulting UTF-8 */
	for(i=len8=0;i<in_len;i++){
		tmp=to_utf8(in[i],0);
		if(!tmp)
			/* invalid character */
			return EILSEQ;
		len8+=tmp;
	}
	*out=result=ntfs_malloc(len8+1); /* allow for zero-termination */
	if(!result)
		return ENOMEM;
	result[len8]='\0';
	*out_len=len8;
	for(i=len8=0;i<in_len;i++)
		len8+=to_utf8(in[i],result+len8);
	return 0;
}

/* Converts an UTF-8 sequence to a wide string. Same conventions as the
   previous function */
int ntfs_duputf82uni(unsigned char* in, int in_len,ntfs_u16** out,int *out_len)
{
	int i,tmp;
	int len16;
	ntfs_u16* result;
	ntfs_u16 wtmp;
	for(i=len16=0;i<in_len;i+=tmp,len16++){
		tmp=from_utf8(in+i,&wtmp);
		if(!tmp)
			return EILSEQ;
	}
	*out=result=ntfs_malloc(2*(len16+1));
	if(!result)
		return ENOMEM;
	result[len16]=0;
	*out_len=len16;
	for(i=len16=0;i<in_len;i+=tmp,len16++)
		tmp=from_utf8(in+i,result+len16);
	return 0;
}

/* See above. Produces ISO-8859-1 from wide strings */
int ntfs_dupuni288591(ntfs_u16* in,int in_len,char** out,int *out_len)
{
	int i;
	char *result;
	/* check for characters out of range */
	for(i=0;i<in_len;i++)
		if(in[i]>=256)
			return EILSEQ;
	*out=result=ntfs_malloc(in_len+1);
	if(!result)
		return ENOMEM;
	result[in_len]='\0';
	*out_len=in_len;
	for(i=0;i<in_len;i++)
		result[i]=in[i];
	return 0;
}

/* See above */
int ntfs_dup885912uni(unsigned char* in,int in_len,ntfs_u16 **out,int *out_len)
{
	int i;
	ntfs_u16* result;
	*out=result=ntfs_malloc(2*in_len);
	if(!result)
		return ENOMEM;
	*out_len=in_len;
	for(i=0;i<in_len;i++)
		result[i]=in[i];
	return 0;
}

/* Encodings dispatcher */
int ntfs_encodeuni(ntfs_volume *vol,ntfs_u16 *in, int in_len,
		   char **out, int *out_len)
{
	switch(vol->nct){
	case nct_utf8: return ntfs_dupuni2utf8(in,in_len,out,out_len);
	case nct_iso8859_1:return ntfs_dupuni288591(in,in_len,out,out_len);
	default:return EINVAL; /* unknown encoding */
	}
}
int ntfs_decodeuni(ntfs_volume *vol,char *in, int in_len,
		   ntfs_u16 **out, int *out_len)
{
	switch(vol->nct){
	case nct_utf8: return ntfs_duputf82uni(in,in_len,out,out_len);
	case nct_iso8859_1:return ntfs_dup885912uni(in,in_len,out,out_len);
	default:return EINVAL;
	}
}

/*
 * Local variables:
 * c-file-style: "linux"
 * End:
 */