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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#include "dir.h"
#include "bfstd.h"
#include "config.h"
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#if __has_feature(memory_sanitizer)
# include <sanitizer/msan_interface.h>
#endif
#if __linux__
# include <sys/syscall.h>
/** Directory entry type for bfs_getdents() */
typedef struct dirent64 sys_dirent;
#else
typedef struct dirent sys_dirent;
#endif
#define BFS_GETDENTS (__linux__ || __FreeBSD__)
#if BFS_GETDENTS
/** getdents() syscall wrapper. */
static ssize_t bfs_getdents(int fd, void *buf, size_t size) {
#if __has_feature(memory_sanitizer)
__msan_allocated_memory(buf, size);
#endif
#if __linux__ && __GLIBC__ && !__GLIBC_PREREQ(2, 30)
ssize_t ret = syscall(__NR_getdents64, fd, buf, size);
#elif __linux__
ssize_t ret = getdents64(fd, buf, size);
#else
ssize_t ret = getdents(fd, buf, size);
#endif
#if __has_feature(memory_sanitizer)
if (ret > 0) {
__msan_unpoison(buf, ret);
}
#endif
return ret;
}
#endif // BFS_GETDENTS
enum bfs_type bfs_mode_to_type(mode_t mode) {
switch (mode & S_IFMT) {
#ifdef S_IFBLK
case S_IFBLK:
return BFS_BLK;
#endif
#ifdef S_IFCHR
case S_IFCHR:
return BFS_CHR;
#endif
#ifdef S_IFDIR
case S_IFDIR:
return BFS_DIR;
#endif
#ifdef S_IFDOOR
case S_IFDOOR:
return BFS_DOOR;
#endif
#ifdef S_IFIFO
case S_IFIFO:
return BFS_FIFO;
#endif
#ifdef S_IFLNK
case S_IFLNK:
return BFS_LNK;
#endif
#ifdef S_IFPORT
case S_IFPORT:
return BFS_PORT;
#endif
#ifdef S_IFREG
case S_IFREG:
return BFS_REG;
#endif
#ifdef S_IFSOCK
case S_IFSOCK:
return BFS_SOCK;
#endif
#ifdef S_IFWHT
case S_IFWHT:
return BFS_WHT;
#endif
default:
return BFS_UNKNOWN;
}
}
struct bfs_dir {
#if BFS_GETDENTS
int fd;
unsigned short pos;
unsigned short size;
#else
DIR *dir;
struct dirent *de;
#endif
};
#if BFS_GETDENTS
# define DIR_SIZE (64 << 10)
# define BUF_SIZE (DIR_SIZE - sizeof(struct bfs_dir))
#else
# define DIR_SIZE sizeof(struct bfs_dir)
#endif
struct bfs_dir *bfs_opendir(int at_fd, const char *at_path) {
struct bfs_dir *dir = malloc(DIR_SIZE);
if (!dir) {
return NULL;
}
int fd;
if (at_path) {
fd = openat(at_fd, at_path, O_RDONLY | O_CLOEXEC | O_DIRECTORY);
} else if (at_fd >= 0) {
fd = at_fd;
} else {
free(dir);
errno = EBADF;
return NULL;
}
if (fd < 0) {
free(dir);
return NULL;
}
#if BFS_GETDENTS
dir->fd = fd;
dir->pos = 0;
dir->size = 0;
#else
dir->dir = fdopendir(fd);
if (!dir->dir) {
if (at_path) {
close_quietly(fd);
}
free(dir);
return NULL;
}
dir->de = NULL;
#endif
return dir;
}
int bfs_dirfd(const struct bfs_dir *dir) {
#if BFS_GETDENTS
return dir->fd;
#else
return dirfd(dir->dir);
#endif
}
/** Convert de->d_type to a bfs_type, if it exists. */
static enum bfs_type bfs_d_type(const sys_dirent *de) {
#ifdef DTTOIF
return bfs_mode_to_type(DTTOIF(de->d_type));
#else
return BFS_UNKNOWN;
#endif
}
/** Read a single directory entry. */
static int bfs_getdent(struct bfs_dir *dir, const sys_dirent **de) {
#if BFS_GETDENTS
char *buf = (char *)(dir + 1);
if (dir->pos >= dir->size) {
ssize_t ret = bfs_getdents(dir->fd, buf, BUF_SIZE);
if (ret <= 0) {
return ret;
}
dir->pos = 0;
dir->size = ret;
}
*de = (void *)(buf + dir->pos);
dir->pos += (*de)->d_reclen;
return 1;
#else
errno = 0;
*de = readdir(dir->dir);
if (*de) {
return 1;
} else if (errno == 0) {
return 0;
} else {
return -1;
}
#endif
}
/** Skip ".", "..", and deleted/empty dirents. */
static bool skip_dirent(const sys_dirent *de) {
#if __FreeBSD__
// NFS mounts on FreeBSD can return empty dirents with inode number 0
if (de->d_fileno == 0) {
return true;
}
#endif
const char *name = de->d_name;
return name[0] == '.' && (name[1] == '\0' || (name[1] == '.' && name[2] == '\0'));
}
int bfs_readdir(struct bfs_dir *dir, struct bfs_dirent *de) {
while (true) {
const sys_dirent *sysde;
int ret = bfs_getdent(dir, &sysde);
if (ret <= 0) {
return ret;
}
if (skip_dirent(sysde)) {
continue;
}
if (de) {
de->type = bfs_d_type(sysde);
de->name = sysde->d_name;
}
return 1;
}
}
int bfs_closedir(struct bfs_dir *dir) {
#if BFS_GETDENTS
int ret = xclose(dir->fd);
#else
int ret = closedir(dir->dir);
#endif
free(dir);
return ret;
}
int bfs_freedir(struct bfs_dir *dir) {
#if BFS_GETDENTS
int ret = dir->fd;
free(dir);
return ret;
#else
int ret = dup_cloexec(dirfd(dir->dir));
bfs_closedir(dir);
return ret;
#endif
}
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