io_dir.h

  1/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
  2/*
  3 * Lightweight directory reading library.
  4 */
  5#ifndef __API_IO_DIR__
  6#define __API_IO_DIR__
  7
  8#include <dirent.h>
  9#include <fcntl.h>
 10#include <stdlib.h>
 11#include <unistd.h>
 12#include <sys/stat.h>
 13#include <sys/syscall.h>
 14#include <linux/limits.h>
 15
 16#if !defined(SYS_getdents64)
 17#if defined(__x86_64__) || defined(__arm__)
 18  #define SYS_getdents64 217
 19#elif defined(__i386__) || defined(__s390x__) || defined(__sh__)
 20  #define SYS_getdents64 220
 21#elif defined(__alpha__)
 22  #define SYS_getdents64 377
 23#elif defined(__mips__)
 24  #define SYS_getdents64 308
 25#elif defined(__powerpc64__) || defined(__powerpc__)
 26  #define SYS_getdents64 202
 27#elif defined(__sparc64__) || defined(__sparc__)
 28  #define SYS_getdents64 154
 29#elif defined(__xtensa__)
 30  #define SYS_getdents64 60
 31#else
 32  #define SYS_getdents64 61
 33#endif
 34#endif /* !defined(SYS_getdents64) */
 35
 36static inline ssize_t perf_getdents64(int fd, void *dirp, size_t count)
 37{
 38#ifdef MEMORY_SANITIZER
 39	memset(dirp, 0, count);
 40#endif
 41	return syscall(SYS_getdents64, fd, dirp, count);
 42}
 43
 44struct io_dirent64 {
 45	ino64_t        d_ino;    /* 64-bit inode number */
 46	off64_t        d_off;    /* 64-bit offset to next structure */
 47	unsigned short d_reclen; /* Size of this dirent */
 48	unsigned char  d_type;   /* File type */
 49	char           d_name[NAME_MAX + 1]; /* Filename (null-terminated) */
 50};
 51
 52struct io_dir {
 53	int dirfd;
 54	ssize_t available_bytes;
 55	struct io_dirent64 *next;
 56	struct io_dirent64 buff[4];
 57};
 58
 59static inline void io_dir__init(struct io_dir *iod, int dirfd)
 60{
 61	iod->dirfd = dirfd;
 62	iod->available_bytes = 0;
 63}
 64
 65static inline void io_dir__rewinddir(struct io_dir *iod)
 66{
 67	lseek(iod->dirfd, 0, SEEK_SET);
 68	iod->available_bytes = 0;
 69}
 70
 71static inline struct io_dirent64 *io_dir__readdir(struct io_dir *iod)
 72{
 73	struct io_dirent64 *entry;
 74
 75	if (iod->available_bytes <= 0) {
 76		ssize_t rc = perf_getdents64(iod->dirfd, iod->buff, sizeof(iod->buff));
 77
 78		if (rc <= 0)
 79			return NULL;
 80		iod->available_bytes = rc;
 81		iod->next = iod->buff;
 82	}
 83	entry = iod->next;
 84	iod->next = (struct io_dirent64 *)((char *)entry + entry->d_reclen);
 85	iod->available_bytes -= entry->d_reclen;
 86	return entry;
 87}
 88
 89static inline bool io_dir__is_dir(const struct io_dir *iod, struct io_dirent64 *dent)
 90{
 91	if (dent->d_type == DT_UNKNOWN) {
 92		struct stat st;
 93
 94		if (fstatat(iod->dirfd, dent->d_name, &st, /*flags=*/0))
 95			return false;
 96
 97		if (S_ISDIR(st.st_mode)) {
 98			dent->d_type = DT_DIR;
 99			return true;
100		}
101	}
102	return dent->d_type == DT_DIR;
103}
104
105#endif  /* __API_IO_DIR__ */