libgamma_gamma_rampsd_initialise.c


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/* See LICENSE file for copyright and license details. */
#include "common.h"


/**
 * Initialise a gamma ramp in the proper way that allows all adjustment
 * methods to read from and write to it without causing segmentation violation
 * 
 * The input must have `red_size`, `green_size`, and `blue_size` set to the
 * sizes of the gamma ramps that should be allocated
 * 
 * @param   this  The gamma ramps
 * @return        Zero on success, -1 on allocation error, `errno` will be set accordingly
 */
int
libgamma_gamma_rampsd_initialise(struct libgamma_gamma_rampsd *restrict this)
{
	size_t n = this->red_size + this->green_size + this->blue_size;
	if (!n) {
		this->red = this->green = this->blue = NULL;
		return 0;
	}
	if (n > SIZE_MAX / sizeof(*this->red)) {
		errno = ENOMEM;
		return -1;
	}
	this->red   = malloc(n * sizeof(*this->red));
	this->green = &this->  red[this->  red_size];
	this->blue  = &this->green[this->green_size];
	return this->red ? 0 : -1;
}