/* $Id: symlink.c,v 1.7 2026/02/08 01:42:12 kostik Exp kostik $ */

#include <sys/stat.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

static void
onelink(const char *name)
{
	struct stat st;
	long plen;
	ssize_t llen;
	int fd;

	fd = open(name, O_PATH | O_NOFOLLOW);
	if (fd == -1) {
		warn("open \"%s\"", name);
		return;
	}
	if (fstatat(fd, "", &st, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW) == -1) {
		warn("fstatat \"%s\"", name);
		goto ret;
	}
	if (!S_ISLNK(st.st_mode)) {
		warnx("%s: not a symlink", name);
		goto ret;
	}
#if defined __FreeBSD__
	plen = fpathconf(fd, _PC_SYMLINK_MAX);
	if (plen == -1) {
		warn("fpathconf \"%s\"", name);
		goto ret;
	}
#elif defined __linux__
	/* On Linux, fpathconf() does not work on O_PATH-fd. */
	plen = 2048;
#endif

	{
		char path[plen + 1];

		llen = readlinkat(fd, "", path, plen);
		if (llen == -1) {
			warn("readlinkat \"%s\"", name);
			goto ret;
		}
		path[llen] = '\0';
		printf("%s => %s\n", name, path);
	}

ret:
	close(fd);
}

int
main(int argc, char *argv[])
{
	for (int i = 1; i < argc; i++)
		onelink(argv[i]);
}