reverse string using libunistring routines

rev.c

#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <uniconv.h>
#include <unigbrk.h>
#include <unistr.h>

int
reverse(uint8_t *str) {
	size_t len;
	size_t glen;
	uint8_t *temp;
	const uint8_t *src;
	uint8_t *dest;
	const uint8_t *next;
	const uint8_t *end;

	temp = u8_strdup(str);
	if (!temp)
		return 0;

	len = u8_strlen(str);
	end = str + len;

	src = str;
	dest = temp + len;

	while ((next = u8_grapheme_next(src, end))) {
		glen = next - src;
		dest -= glen;
		u8_cpy(dest, src, glen);
		src = next;
	}

	u8_cpy(str, temp, len);
	free(temp);

	return 1;
}

int
main(int argc, char *argv[]) {
	int i;
	uint8_t *str;
	char *rstr;

	setlocale(LC_ALL, "");

	for (i = 1; i < argc; i++) {
		str = u8_strconv_from_locale(argv[i]);
		if (!str) {
			perror(argv[i]);
			continue;
		}

		if (!reverse(str)) {
			perror(argv[i]);
			goto end;
		}

		rstr = u8_strconv_to_locale(str);
		if (!rstr) {
			perror(argv[i]);
			goto end;
		}

		printf("%s\n", rstr);

		free(rstr);
end:
		free(str);
	}
}

strwrev.c

void
strwrev(char *p) {
  char *a, *b;

  while (*p) {
    for (a = p; isspace(*a); a++);
    for (p = a; *p && !isspace(*p); p++);
    for (b = p - 1; a < b; a++, b--) {
      *a ^= *b;
      *b ^= *a;
      *a ^= *b;
    }
  }
}

wrev.c

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* reverse substring between A and B in-place */
void
ssrev(char *a, char *b) {
	for (; a < b; a++, b--) {
		*a ^= *b;
		*b ^= *a;
		*a ^= *b;
	}
}

/* reverse string S in-place */
void
srev(char *s) {
	ssrev(s, s + strlen(s) - 1);
}

/* reverse words in string S in-place */
void
swrev(char *s) {
	char *w;

	while (*s) {
		for (w = s; isspace(*w); w++);
		for (s = w; *s && !isspace(*s); s++);
		ssrev(w, s - 1);
	}
}

int
main(int argc, char *argv[]) {
	char *s;

	s = strdup(argv[1]);
	srev(s);
	swrev(s);
	puts(s);
	free(s);
}