/*  util.c -  Miscellaneous support
 *
 *  Copyright (C) 1997,1999 Martin von Löwis
 *  Copyright (C) 1997 Régis Duchesne
 *  Copyright (C) 2001 Anton Altaparmakov (AIA)
 *
 *  The utf8 routines are copied from Python wstrop module.
 */

#include "ntfstypes.h"
#include "struct.h"
#include "util.h"

#include <linux/string.h>
#include <linux/errno.h>
#include "support.h"

/* Converts a single wide character to a sequence of utf8 bytes.
 * The character is represented in host byte order.
 * 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] = (unsigned char)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.
 * The character is returned in host byte order.
 * 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. */
static int ntfs_dupuni2utf8(ntfs_u16* in, int in_len, char **out, int *out_len)
{
	int i, tmp;
	int len8;
	unsigned char *result;

	ntfs_debug(DEBUG_NAME1, "converting l = %d\n", in_len);
	/* Count the length of the resulting UTF-8. */
	for (i = len8 = 0; i < in_len; i++){
		tmp = to_utf8(NTFS_GETU16(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(NTFS_GETU16(in + i), result + len8);
	ntfs_debug(DEBUG_NAME1, "result %p:%s\n", result, result);
	return 0;
}

/* Converts an UTF-8 sequence to a wide string. Same conventions as the
 * previous function. */
static 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, &wtmp);
		NTFS_PUTU16(result + len16, wtmp);
	}
	return 0;
}

/* See above. Produces ISO-8859-1 from wide strings. */
static 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 (NTFS_GETU16(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] = (unsigned char)NTFS_GETU16(in + i);
	return 0;
}

/* See above. */
static 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++)
		NTFS_PUTU16(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)
{
	if (vol->nct & nct_utf8)
		return ntfs_dupuni2utf8(in, in_len, out, out_len);
	else if (vol->nct & nct_iso8859_1)
		return ntfs_dupuni288591(in, in_len, out, out_len);
	else if(vol->nct & (nct_map | nct_uni_xlate))
		/* uni_xlate is handled inside map. */
		return ntfs_dupuni2map(vol, in, in_len, out, out_len);
	else
		return -EINVAL; /* unknown encoding */
}

int ntfs_decodeuni(ntfs_volume *vol, char *in, int in_len, ntfs_u16 **out,
		   int *out_len)
{
	if (vol->nct & nct_utf8)
		return ntfs_duputf82uni(in, in_len, out, out_len);
	else if (vol->nct & nct_iso8859_1)
		return ntfs_dup885912uni(in, in_len, out, out_len);
	else if (vol->nct & (nct_map | nct_uni_xlate))
		return ntfs_dupmap2uni(vol, in, in_len, out, out_len);
	else
		return -EINVAL;
}

/* Same address space copies. */
void ntfs_put(ntfs_io *dest, void *src, ntfs_size_t n)
{
	ntfs_memcpy(dest->param, src, n);
	((char*)dest->param) += n;
}

void ntfs_get(void* dest, ntfs_io *src, ntfs_size_t n)
{
	ntfs_memcpy(dest, src->param, n);
	((char*)src->param) += n;
}

void *ntfs_calloc(int size)
{
	void *result = ntfs_malloc(size);
	if (result)
		ntfs_bzero(result, size);
	return result;
}

#if 0
/* Copy len unicode characters from from to to. :) */
void ntfs_uni2ascii(char *to, short int *from, int len)
{
	int i;

	for (i = 0; i < len; i++)
		to[i] = NTFS_GETU16(from + i);
	to[i] = '\0';
}
#endif

/* Copy len ascii characters from from to to. :) */
void ntfs_ascii2uni(short int *to, char *from, int len)
{
	int i;

	for (i = 0; i < len; i++)
		NTFS_PUTU16(to + i, from[i]);
	to[i] = 0;
}

/* strncmp for Unicode strings. */
int ntfs_uni_strncmp(short int* a, short int *b, int n)
{
	int i;

	for(i = 0; i < n; i++)
	{
		if (NTFS_GETU16(a + i) < NTFS_GETU16(b + i))
			return -1;
		if (NTFS_GETU16(b + i) < NTFS_GETU16(a + i))
			return 1;
		if (NTFS_GETU16(a + i) == 0)
			return 0;
	}
	return 0;
}

/* strncmp between Unicode and ASCII strings. */
int ntfs_ua_strncmp(short int* a, char* b, int n)
{
	int i;

	for (i = 0; i < n; i++)	{
		if(NTFS_GETU16(a + i) < b[i])
			return -1;
		if(b[i] < NTFS_GETU16(a + i))
			return 1;
		if (b[i] == 0)
			return 0;
	}
	return 0;
}

/* Convert the NT UTC (based 1.1.1601, in hundred nanosecond units)
 * into Unix UTC (based 1.1.1970, in seconds). */
ntfs_time_t ntfs_ntutc2unixutc(ntfs_time64_t ntutc)
{
/* This is very gross because:
 * 1: We must do 64-bit division on a 32-bit machine.
 * 2: We can't use libgcc for long long operations in the kernel.
 * 3: Floating point math in the kernel would corrupt user data. */
	const unsigned int D = 10000000;
	unsigned int H = (unsigned int)(ntutc >> 32);
	unsigned int L = (unsigned int)ntutc;
	unsigned int numerator2;
	unsigned int lowseconds;
	unsigned int result;

	/* It is best to subtract 0x019db1ded53e8000 first. */
	/* Then the 1601-based date becomes a 1970-based date. */
	if (L < (unsigned)0xd53e8000)
		H--;
	L -= (unsigned)0xd53e8000;
	H -= (unsigned)0x019db1de;

	/* Now divide 64-bit numbers on a 32-bit machine. :-)
	 * With the subtraction already done, the result fits in 32 bits.
	 * The numerator fits in 56 bits and the denominator fits
	 * in 24 bits, so we can shift by 8 bits to make this work. */

	numerator2  = (H << 8) | (L >> 24);
	result      = (numerator2 / D);   /* shifted 24 right!! */
	lowseconds  = result << 24;

	numerator2  = ((numerator2 - result * D) << 8) | ((L >> 16) & 0xff);
	result      = (numerator2 / D);   /* shifted 16 right!! */
	lowseconds |= result << 16;

	numerator2  = ((numerator2 - result * D) << 8) | ((L >> 8) & 0xff);
	result      = (numerator2 / D);   /* shifted 8 right!! */
	lowseconds |= result << 8;

	numerator2  = ((numerator2 - result * D) << 8) | (L & 0xff);
	result      = (numerator2 / D);   /* not shifted */
	lowseconds |= result;

	return lowseconds;
}

/* Convert the Unix UTC into NT UTC. */
ntfs_time64_t ntfs_unixutc2ntutc(ntfs_time_t t)
{
	return ((t + (ntfs_time64_t)(369 * 365 + 89) * 24 * 3600) * 10000000);
}

/* Fill index name. */
void ntfs_indexname(char *buf, int type)
{
	char hex[] = "0123456789ABCDEF";
	int index;
	*buf++ = '$';
	*buf++ = 'I';
	for (index = 24; index > 0; index -= 4)
		if ((0xF << index) & type)
			break;
	while (index >= 0) {
		*buf++ = hex[(type >> index) & 0xF];
		index -= 4;
	}
	*buf = '\0';
}