/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
 * Directory access for NOLIBC
 * Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
 */

/* make sure to include all global symbols */
#include "nolibc.h"

#ifndef _NOLIBC_DIRENT_H
#define _NOLIBC_DIRENT_H

#include "compiler.h"
#include "stdint.h"
#include "types.h"
#include "fcntl.h"

#include <linux/limits.h>

struct dirent {
        ino_t   d_ino;
        char    d_name[NAME_MAX + 1];
};

/* See comment of FILE in stdio.h */
typedef struct {
        char dummy[1];
} DIR;

static __attribute__((unused))
DIR *fdopendir(int fd)
{
        if (fd < 0) {
                SET_ERRNO(EBADF);
                return NULL;
        }
        return (DIR *)(intptr_t)~fd;
}

static __attribute__((unused))
DIR *opendir(const char *name)
{
        int fd;

        fd = open(name, O_RDONLY);
        if (fd == -1)
                return NULL;
        return fdopendir(fd);
}

static __attribute__((unused))
int closedir(DIR *dirp)
{
        intptr_t i = (intptr_t)dirp;

        if (i >= 0) {
                SET_ERRNO(EBADF);
                return -1;
        }
        return close(~i);
}

static __attribute__((unused))
int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
{
        char buf[sizeof(struct linux_dirent64) + NAME_MAX + 1] __nolibc_aligned_as(struct linux_dirent64);
        struct linux_dirent64 *ldir = (void *)buf;
        intptr_t i = (intptr_t)dirp;
        int fd, ret;

        if (i >= 0)
                return EBADF;

        fd = ~i;

        ret = _sys_getdents64(fd, ldir, sizeof(buf));
        if (ret < 0)
                return -ret;
        if (ret == 0) {
                *result = NULL;
                return 0;
        }

        /*
         * getdents64() returns as many entries as fit the buffer.
         * readdir() can only return one entry at a time.
         * Make sure the non-returned ones are not skipped.
         */
        ret = _sys_lseek(fd, ldir->d_off, SEEK_SET);
        if (ret < 0)
                return -ret;

        entry->d_ino = ldir->d_ino;
        /* the destination should always be big enough */
        strlcpy(entry->d_name, ldir->d_name, sizeof(entry->d_name));
        *result = entry;
        return 0;
}

#endif /* _NOLIBC_DIRENT_H */