sortix--sortix/libc/dirent/readdir.c

/*
 * Copyright (c) 2011, 2014, 2015 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * dirent/readdir.c
 * Reads a directory entry from a directory stream into a DIR-specific buffer.
 */

#include <sys/readdirents.h>

#include <dirent.h>
#include <errno.h>
#include <stdlib.h>

struct dirent* readdir(DIR* dir)
{
	int old_errno = errno;
	struct dirent fallback;
	struct dirent* entry = dir->entry ? dir->entry : &fallback;
	size_t size = dir->entry ? dir->size : sizeof(fallback);
	ssize_t amount;
	while ( (amount = readdirents(dir->fd, entry, size)) < 0 )
	{
		if ( errno != ERANGE )
			return NULL;
		errno = old_errno;
		size_t needed = entry->d_reclen;
		free(dir->entry);
		dir->entry = NULL;
		struct dirent* new_dirent = (struct dirent*) malloc(needed);
		if ( !new_dirent )
			return NULL;
		entry = dir->entry = new_dirent;
		size = dir->size = needed;
	}
	if ( amount == 0 )
		return NULL;
	return dir->entry;
}