utils-std

yes.c (948B)

// utils-std: Collection of commonly available Unix tools
// SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>  // fwrite, perror, ferror
#include <string.h> // strlen
int
main(int argc, char *argv[])
{
	size_t arg_len = 0;
	assert(argc >= 1);
	if(argc == 1)
	{
		argv[0][0] = 'y';
		argv[0][1] = '\n';
		argv[0][2] = '\0';
		arg_len = 2;
	}
	else
	{
		argv++;
		argc--;
		for(int i = 0; i < argc; i++)
		{
			size_t len = strlen(argv[i]);
			argv[i][len] = ' ';
			arg_len += len + 1; // str + space
		}
		if(arg_len == 0)
		{
			argv[0][0] = '\n';
			argv[0][1] = '\0';
			arg_len = 1;
		}
		else
			argv[0][arg_len - 1] = '\n';
	}
	while(fwrite(*argv, arg_len, 1, stdout) == 1)
		;
	if(ferror(stdout))
	{
		perror("yes: error: Failed writing");
		return 1;
	}
	return 0;
}