From: Thomas Weißschuh thomas.weissschuh@linutronix.de

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 Signed-off-by: Thomas Weißschuh linux@weissschuh.net --- tools/include/nolibc/Makefile | 1 + tools/include/nolibc/dirent.h | 98 ++++++++++++++++++++++++++++ tools/include/nolibc/nolibc.h | 1 + tools/testing/selftests/nolibc/nolibc-test.c | 39 +++++++++++ 4 files changed, 139 insertions(+)

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile index a1f55fb24bb38c1f49c653af5825e8bcc569a56d..dceec0e1a135119108d6f4dcb3d2ec57c002ffd3 100644 --- a/tools/include/nolibc/Makefile +++ b/tools/include/nolibc/Makefile @@ -29,6 +29,7 @@ all_files := \ compiler.h \ crt.h \ ctype.h \ + dirent.h \ errno.h \ nolibc.h \ signal.h \ diff --git a/tools/include/nolibc/dirent.h b/tools/include/nolibc/dirent.h new file mode 100644 index 0000000000000000000000000000000000000000..c5c30d0dd6806b1bec2fa8120a3df29aaa201393 --- /dev/null +++ b/tools/include/nolibc/dirent.h @@ -0,0 +1,98 @@ +/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ +/* + * Directory access for NOLIBC + * Copyright (C) 2025 Thomas Weißschuh linux@weissschuh.net + */ + +#ifndef _NOLIBC_DIRENT_H +#define _NOLIBC_DIRENT_H + +#include "stdint.h" +#include "types.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]; + 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 = lseek(fd, ldir->d_off, SEEK_SET); + if (ret == -1) + return errno; + + 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; +} + +/* make sure to include all global symbols */ +#include "nolibc.h" + +#endif /* _NOLIBC_DIRENT_H */ diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h index 92436b1e44413e659b3cca592930aad8b458cb74..05d92afedb7258f0e3c311bf6f12be68b25d6e9a 100644 --- a/tools/include/nolibc/nolibc.h +++ b/tools/include/nolibc/nolibc.h @@ -105,6 +105,7 @@ #include "string.h" #include "time.h" #include "stackprotector.h" +#include "dirent.h"

/* Used by programs to avoid std includes */ #define NOLIBC diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index f162793b162f9b1ec687098b9094a6d247a53e99..798fbdcd3ff8c36b514feb3fa1c7b8d7701cccd7 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -769,6 +769,44 @@ int test_getdents64(const char *dir) return ret; }

+static int test_dirent(void) +{ + int comm = 0, cmdline = 0; + struct dirent dirent, *result; + DIR *dir; + int ret; + + dir = opendir("/proc/self"); + if (!dir) + return 1; + + while (1) { + errno = 0; + ret = readdir_r(dir, &dirent, &result); + if (ret != 0) + return 1; + if (!result) + break; + + if (strcmp(dirent.d_name, "comm") == 0) + comm++; + else if (strcmp(dirent.d_name, "cmdline") == 0) + cmdline++; + } + + if (errno) + return 1; + + ret = closedir(dir); + if (ret) + return 1; + + if (comm != 1 || cmdline != 1) + return 1; + + return 0; +} + int test_getpagesize(void) { int x = getpagesize(); @@ -1061,6 +1099,7 @@ int run_syscall(int min, int max) CASE_TEST(fork); EXPECT_SYSZR(1, test_fork()); break; CASE_TEST(getdents64_root); EXPECT_SYSNE(1, test_getdents64("/"), -1); break; CASE_TEST(getdents64_null); EXPECT_SYSER(1, test_getdents64("/dev/null"), -1, ENOTDIR); break; + CASE_TEST(directories); EXPECT_SYSZR(proc, test_dirent()); break; CASE_TEST(gettimeofday_tv); EXPECT_SYSZR(1, gettimeofday(&tv, NULL)); break; CASE_TEST(gettimeofday_tv_tz);EXPECT_SYSZR(1, gettimeofday(&tv, &tz)); break; CASE_TEST(getpagesize); EXPECT_SYSZR(1, test_getpagesize()); break;