* Initialize an expandable text buffer.

#include "less.h"
#include "xbuf.h"

/*
* Initialize an expandable text buffer.
*/
public void xbuf_init(struct xbuffer *xbuf)
{
xbuf->data = NULL;
xbuf->size = xbuf->end = 0;
}

public void xbuf_deinit(struct xbuffer *xbuf)
{
if (xbuf->data != NULL)
free(xbuf->data);
xbuf_init(xbuf);
}

public void xbuf_reset(struct xbuffer *xbuf)
{
xbuf->end = 0;
}

/*
* Add a byte to an expandable text buffer.
*/
public void xbuf_add_byte(struct xbuffer *xbuf, unsigned char b)
{
if (xbuf->end >= xbuf->size)
{
unsigned char *data;
if (ckd_add(&xbuf->size, xbuf->size, xbuf->size ? xbuf->size : 16))
out_of_memory();
data = (unsigned char *) ecalloc(xbuf->size, sizeof(unsigned char));
if (xbuf->data != NULL)
{
memcpy(data, xbuf->data, xbuf->end);
free(xbuf->data);
}
xbuf->data = data;
}
xbuf->data[xbuf->end++] = (unsigned char) b;
}

public void xbuf_add_data(struct xbuffer *xbuf, unsigned char *data, int len)
{
int i;
for (i = 0; i < len; i++)
xbuf_add_byte(xbuf, data[i]);
}

public int xbuf_pop(struct xbuffer *buf)
{
if (buf->end == 0)
return -1;
return (int) buf->data[--(buf->end)];
}

public void xbuf_set(struct xbuffer *dst, struct xbuffer *src)
{
xbuf_reset(dst);
xbuf_add_data(dst, src->data, src->end);
}

public char * xbuf_char_data(struct xbuffer *xbuf)
{
return (char *)(xbuf->data);
}

/*
* Helper functions for the ckd_add and ckd_mul macro substitutes.
* These helper functions do not set *R on overflow, and assume that
* arguments are nonnegative, that INTMAX_MAX <= UINTMAX_MAX, and that
* sizeof is a reliable way to distinguish integer representations.
* Despite these limitations they are good enough for 'less' on all
* known practical platforms. For more-complicated substitutes
* without most of these limitations, see Gnulib's stdckdint module.
*/
#if !HAVE_STDCKDINT_H
/*
* If the integer *R can represent VAL, store the value and return FALSE.
* Otherwise, possibly set *R to an indeterminate value and return TRUE.
* R has size RSIZE, and is signed if and only if RSIGNED is nonzero.
*/
static int help_fixup(void *r, uintmax val, int rsize, int rsigned)
{
if (rsigned)
{
if (rsize == sizeof (int))
{
int *pr = r;
if (INT_MAX < val)
return TRUE;
*pr = (int) val;
#ifdef LLONG_MAX
} else if (rsize == sizeof (long long))
{
long long *pr = r;
if (LLONG_MAX < val)
return TRUE;
*pr = val;
#endif
#ifdef INTMAX_MAX
} else if (rsize == sizeof (intmax_t)) {
intmax_t *pr = r;
if (INTMAX_MAX < val)
return TRUE;
*pr = val;
#endif
} else /* rsize == sizeof (long) */
{
long *pr = r;
if (LONG_MAX < val)
return TRUE;
*pr = (long) val;
}
} else {
if (rsize == sizeof (unsigned)) {
unsigned *pr = r;
if (UINT_MAX < val)
return TRUE;
*pr = (unsigned) val;
} else if (rsize == sizeof (unsigned long)) {
unsigned long *pr = r;
if (ULONG_MAX < val)
return TRUE;
*pr = (unsigned long) val;
#ifdef ULLONG_MAX
} else if (rsize == sizeof (unsigned long long)) {
long long *pr = r;
if (ULLONG_MAX < val)
return TRUE;
*pr = val;
#endif
} else /* rsize == sizeof (uintmax) */
{
uintmax *pr = r;
*pr = val;
}
}
return FALSE;
}
/*
* If *R can represent the mathematical sum of A and B, store the sum
* and return FALSE. Otherwise, possibly set *R to an indeterminate
* value and return TRUE. R has size RSIZE, and is signed if and only
* if RSIGNED is nonzero.
*/
public int help_ckd_add(void *r, uintmax a, uintmax b, int rsize, int rsigned)
{
uintmax sum = a + b;
return sum < a || help_fixup(r, sum, rsize, rsigned);
}
/* Likewise, but for the product of A and B. */
public int help_ckd_mul(void *r, uintmax a, uintmax b, int rsize, int rsigned)
{
uintmax product = a * b;
return ((b != 0 && a != product / b)
|| help_fixup(r, product, rsize, rsigned));
}
#endif