utils-extra

lolcat.c (1879B)

// utils-extra: Collection of extra tools for Unixes
// SPDX-FileCopyrightText: 2017-2022 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include <errno.h>  /* errno */
#include <math.h>   /* sin() */
#include <stdio.h>  /* fgetc(), fputc(), printf(), fopen(), fclose() */
#include <string.h> /* strerror() */
void
rainbow(double freq, int i)
{
	double red, green, blue;
	double pi = 3.14159;
	red   = sin(freq * i + 0) * 127 + 128;
	green = sin(freq * i + 2 * pi / 3) * 127 + 128;
	blue  = sin(freq * i + 4 * pi / 3) * 127 + 128;
	printf("[38;2;%02d;%02d;%02dm", (int)red, (int)green, (int)blue);
}
int
concat(FILE *stream)
{
	double freq = 0.1;
	int i       = 0;
	int c;
	errno = 0;
	while((c = fgetc(stream)) != EOF)
	{
		rainbow(freq, i);
		i++;
		if(c == '')
		{
			printf("^[");
			continue;
		}
		if(fputc(c, stdout) == EOF)
		{
			fprintf(stderr, "\nlolcat: Write error: %s\n", strerror(errno));
			return 1;
		}
	}
	if(c == EOF && errno != 0)
	{
		fprintf(stderr, "\nlolcat: Read error: %s\n", strerror(errno));
		return 1;
	}
	return 0;
}
int
main(int argc, char *argv[])
{
	int ret = 0;
	if(argc <= 1)
	{
		ret = concat(stdin);
		goto end;
	}
	for(int argi = 1; argi < argc; argi++)
	{
		if(strncmp(argv[argi], "-", 2) == 0)
		{
			ret = concat(stdin);
			if(ret != 0)
			{
				goto end;
			}
		}
		else if(strncmp(argv[argi], "--", 3) == 0)
		{
			continue;
		}
		else
		{
			FILE *file = fopen(argv[argi], "r");
			if(!file)
			{
				fprintf(stderr, "\nlolcat: Error opening ‘%s’: %s\n", argv[argi], strerror(errno));
				ret = 1;
				goto end;
			}
			else
			{
				ret = concat(file);
				if(ret != 0)
				{
					goto end;
				}
				ret = fclose(file);
				if(ret != 0)
				{
					goto end;
				}
			}
		}
	}
end:
	printf("");
	return ret;
}