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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#include "stat.h"
#include "atomic.h"
#include "bfstd.h"
#include "config.h"
#include "diag.h"
#include "sanity.h"
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#if defined(STATX_BASIC_STATS) && (!__ANDROID__ || __ANDROID_API__ >= 30)
# define BFS_HAS_LIBC_STATX true
#elif __linux__
# include <linux/stat.h>
# include <sys/syscall.h>
# include <unistd.h>
#endif
#ifndef BFS_USE_STATX
# if BFS_HAS_LIBC_STATX || defined(SYS_statx)
# define BFS_USE_STATX true
# endif
#endif
const char *bfs_stat_field_name(enum bfs_stat_field field) {
switch (field) {
case BFS_STAT_DEV:
return "device number";
case BFS_STAT_INO:
return "inode nunmber";
case BFS_STAT_TYPE:
return "type";
case BFS_STAT_MODE:
return "mode";
case BFS_STAT_NLINK:
return "link count";
case BFS_STAT_GID:
return "group ID";
case BFS_STAT_UID:
return "user ID";
case BFS_STAT_SIZE:
return "size";
case BFS_STAT_BLOCKS:
return "block count";
case BFS_STAT_RDEV:
return "underlying device";
case BFS_STAT_ATTRS:
return "attributes";
case BFS_STAT_ATIME:
return "access time";
case BFS_STAT_BTIME:
return "birth time";
case BFS_STAT_CTIME:
return "change time";
case BFS_STAT_MTIME:
return "modification time";
}
bfs_bug("Unrecognized stat field");
return "???";
}
/**
* Convert a struct stat to a struct bfs_stat.
*/
static void bfs_stat_convert(const struct stat *statbuf, struct bfs_stat *buf) {
buf->mask = 0;
buf->dev = statbuf->st_dev;
buf->mask |= BFS_STAT_DEV;
buf->ino = statbuf->st_ino;
buf->mask |= BFS_STAT_INO;
buf->mode = statbuf->st_mode;
buf->mask |= BFS_STAT_TYPE | BFS_STAT_MODE;
buf->nlink = statbuf->st_nlink;
buf->mask |= BFS_STAT_NLINK;
buf->gid = statbuf->st_gid;
buf->mask |= BFS_STAT_GID;
buf->uid = statbuf->st_uid;
buf->mask |= BFS_STAT_UID;
buf->size = statbuf->st_size;
buf->mask |= BFS_STAT_SIZE;
buf->blocks = statbuf->st_blocks;
buf->mask |= BFS_STAT_BLOCKS;
buf->rdev = statbuf->st_rdev;
buf->mask |= BFS_STAT_RDEV;
#if BSD
buf->attrs = statbuf->st_flags;
buf->mask |= BFS_STAT_ATTRS;
#endif
buf->atime = statbuf->st_atim;
buf->mask |= BFS_STAT_ATIME;
buf->ctime = statbuf->st_ctim;
buf->mask |= BFS_STAT_CTIME;
buf->mtime = statbuf->st_mtim;
buf->mask |= BFS_STAT_MTIME;
#if __APPLE__ || __FreeBSD__ || __NetBSD__
buf->btime = statbuf->st_birthtim;
buf->mask |= BFS_STAT_BTIME;
#endif
}
/**
* bfs_stat() implementation backed by stat().
*/
static int bfs_stat_impl(int at_fd, const char *at_path, int at_flags, struct bfs_stat *buf) {
struct stat statbuf;
int ret = fstatat(at_fd, at_path, &statbuf, at_flags);
if (ret == 0) {
bfs_stat_convert(&statbuf, buf);
}
return ret;
}
#if BFS_USE_STATX
/**
* Wrapper for the statx() system call, which had no glibc wrapper prior to 2.28.
*/
static int bfs_statx(int at_fd, const char *at_path, int at_flags, unsigned int mask, struct statx *buf) {
#if BFS_HAS_LIBC_STATX
int ret = statx(at_fd, at_path, at_flags, mask, buf);
#else
int ret = syscall(SYS_statx, at_fd, at_path, at_flags, mask, buf);
#endif
if (ret == 0) {
// -fsanitize=memory doesn't know about statx()
sanitize_init(buf);
}
return ret;
}
/**
* bfs_stat() implementation backed by statx().
*/
static int bfs_statx_impl(int at_fd, const char *at_path, int at_flags, struct bfs_stat *buf) {
unsigned int mask = STATX_BASIC_STATS | STATX_BTIME;
struct statx xbuf;
int ret = bfs_statx(at_fd, at_path, at_flags, mask, &xbuf);
if (ret != 0) {
return ret;
}
// Callers shouldn't have to check anything except the times
const unsigned int guaranteed = STATX_BASIC_STATS & ~(STATX_ATIME | STATX_CTIME | STATX_MTIME);
if ((xbuf.stx_mask & guaranteed) != guaranteed) {
errno = ENOTSUP;
return -1;
}
buf->mask = 0;
buf->dev = xmakedev(xbuf.stx_dev_major, xbuf.stx_dev_minor);
buf->mask |= BFS_STAT_DEV;
buf->ino = xbuf.stx_ino;
buf->mask |= BFS_STAT_INO;
buf->mode = xbuf.stx_mode;
buf->mask |= BFS_STAT_TYPE;
buf->mask |= BFS_STAT_MODE;
buf->nlink = xbuf.stx_nlink;
buf->mask |= BFS_STAT_NLINK;
buf->gid = xbuf.stx_gid;
buf->mask |= BFS_STAT_GID;
buf->uid = xbuf.stx_uid;
buf->mask |= BFS_STAT_UID;
buf->size = xbuf.stx_size;
buf->mask |= BFS_STAT_SIZE;
buf->blocks = xbuf.stx_blocks;
buf->mask |= BFS_STAT_BLOCKS;
buf->rdev = xmakedev(xbuf.stx_rdev_major, xbuf.stx_rdev_minor);
buf->mask |= BFS_STAT_RDEV;
buf->attrs = xbuf.stx_attributes;
buf->mask |= BFS_STAT_ATTRS;
if (xbuf.stx_mask & STATX_ATIME) {
buf->atime.tv_sec = xbuf.stx_atime.tv_sec;
buf->atime.tv_nsec = xbuf.stx_atime.tv_nsec;
buf->mask |= BFS_STAT_ATIME;
}
if (xbuf.stx_mask & STATX_BTIME) {
buf->btime.tv_sec = xbuf.stx_btime.tv_sec;
buf->btime.tv_nsec = xbuf.stx_btime.tv_nsec;
buf->mask |= BFS_STAT_BTIME;
}
if (xbuf.stx_mask & STATX_CTIME) {
buf->ctime.tv_sec = xbuf.stx_ctime.tv_sec;
buf->ctime.tv_nsec = xbuf.stx_ctime.tv_nsec;
buf->mask |= BFS_STAT_CTIME;
}
if (xbuf.stx_mask & STATX_MTIME) {
buf->mtime.tv_sec = xbuf.stx_mtime.tv_sec;
buf->mtime.tv_nsec = xbuf.stx_mtime.tv_nsec;
buf->mask |= BFS_STAT_MTIME;
}
return ret;
}
#endif // BFS_USE_STATX
/**
* Calls the stat() implementation with explicit flags.
*/
static int bfs_stat_explicit(int at_fd, const char *at_path, int at_flags, int x_flags, struct bfs_stat *buf) {
#if BFS_USE_STATX
static atomic bool has_statx = true;
if (load(&has_statx, relaxed)) {
int ret = bfs_statx_impl(at_fd, at_path, at_flags | x_flags, buf);
// EPERM is commonly returned in a seccomp() sandbox that does
// not allow statx()
if (ret != 0 && (errno == ENOSYS || errno == EPERM)) {
store(&has_statx, false, relaxed);
} else {
return ret;
}
}
#endif
return bfs_stat_impl(at_fd, at_path, at_flags, buf);
}
/**
* Implements the BFS_STAT_TRYFOLLOW retry logic.
*/
static int bfs_stat_tryfollow(int at_fd, const char *at_path, int at_flags, int x_flags, enum bfs_stat_flags bfs_flags, struct bfs_stat *buf) {
int ret = bfs_stat_explicit(at_fd, at_path, at_flags, x_flags, buf);
if (ret != 0
&& (bfs_flags & (BFS_STAT_NOFOLLOW
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