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665fa8dea9
Add an implementation for directory access operations. To keep nolibc itself allocation-free, a "DIR *" does not point to any data, but directly encodes a filedescriptor number, equivalent to "FILE *". Without any per-directory storage it is not possible to implement readdir() POSIX confirming. Instead only readdir_r() is provided. While readdir_r() is deprecated in glibc, the reasons for that are not applicable to nolibc. Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Link: https://lore.kernel.org/r/20250209-nolibc-dir-v2-2-57cc1da8558b@weissschuh.net Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
99 lines
1.8 KiB
C
99 lines
1.8 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* Directory access for NOLIBC
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* Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
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*/
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#ifndef _NOLIBC_DIRENT_H
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#define _NOLIBC_DIRENT_H
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#include "stdint.h"
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#include "types.h"
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#include <linux/limits.h>
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struct dirent {
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ino_t d_ino;
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char d_name[NAME_MAX + 1];
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};
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/* See comment of FILE in stdio.h */
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typedef struct {
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char dummy[1];
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} DIR;
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static __attribute__((unused))
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DIR *fdopendir(int fd)
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{
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if (fd < 0) {
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SET_ERRNO(EBADF);
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return NULL;
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}
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return (DIR *)(intptr_t)~fd;
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}
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static __attribute__((unused))
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DIR *opendir(const char *name)
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{
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int fd;
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fd = open(name, O_RDONLY);
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if (fd == -1)
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return NULL;
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return fdopendir(fd);
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}
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static __attribute__((unused))
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int closedir(DIR *dirp)
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{
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intptr_t i = (intptr_t)dirp;
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if (i >= 0) {
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SET_ERRNO(EBADF);
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return -1;
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}
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return close(~i);
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}
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static __attribute__((unused))
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int readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
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{
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char buf[sizeof(struct linux_dirent64) + NAME_MAX + 1];
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struct linux_dirent64 *ldir = (void *)buf;
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intptr_t i = (intptr_t)dirp;
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int fd, ret;
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if (i >= 0)
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return EBADF;
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fd = ~i;
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ret = sys_getdents64(fd, ldir, sizeof(buf));
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if (ret < 0)
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return -ret;
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if (ret == 0) {
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*result = NULL;
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return 0;
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}
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/*
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* getdents64() returns as many entries as fit the buffer.
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* readdir() can only return one entry at a time.
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* Make sure the non-returned ones are not skipped.
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*/
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ret = lseek(fd, ldir->d_off, SEEK_SET);
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if (ret == -1)
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return errno;
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entry->d_ino = ldir->d_ino;
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/* the destination should always be big enough */
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strlcpy(entry->d_name, ldir->d_name, sizeof(entry->d_name));
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*result = entry;
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return 0;
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}
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/* make sure to include all global symbols */
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#include "nolibc.h"
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#endif /* _NOLIBC_DIRENT_H */
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