utils

echo.c (1350B)

// Collection of Unix tools, comparable to coreutils
// SPDX-FileCopyrightText: 2017-2023 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include <stdbool.h> /* bool */
#include <stdio.h>   /* perror */
#include <stdlib.h>  /* malloc */
#include <string.h>  /* strlen */
#include <unistd.h>  /* write */
int
main(int argc, char *argv[])
{
	size_t arg_len = 0;
	char *buffer, *buffer_p;
	int err    = 0;
	bool opt_n = false;
	if((argc >= 2) && (strncmp(argv[1], "-n", 3) == 0))
	{
		opt_n = true;
		argc--;
		argv++;
	}
	for(int i = 1; i < argc; i++)
	{
		arg_len += strlen(argv[i]) + 1; // str + space|newline
	}
	if(arg_len == 0)
	{
		if(opt_n) return 0;
		if(write(1, "\n", 1) < 1)
		{
			perror("echo: write(1, \"\n\", 1)");
			return 1;
		}
		return 0;
	}
	if(opt_n) arg_len--; // no newline
	buffer = malloc(arg_len);
	if(buffer == NULL)
	{
		perror("echo: malloc(arg_len)");
		return 1;
	}
	buffer_p = buffer;
	for(int i = 1; i < argc; i++)
	{
		size_t len = strlen(argv[i]);
		memcpy(buffer_p, argv[i], len);
		buffer_p += len;
		if(i < argc - 1)
		{
			*buffer_p++ = ' ';
		}
	}
	if(!opt_n) *buffer_p++ = '\n';
	if(write(1, buffer, arg_len) < (ssize_t)arg_len)
	{
		perror("echo: write(1, buffer, arg_len)");
		err++;
	}
	free(buffer);
	return err;
}