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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <fcntl.h>
#include <linux/stat.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/xattr.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "macro.h"
#include "missing.h"
#include "sparse-endian.h"
#include "stdio-util.h"
#include "string-util.h"
#include "time-util.h"
#include "xattr-util.h"
int getxattr_malloc(const char *path, const char *name, char **value, bool allow_symlink) {
char *v;
size_t l;
ssize_t n;
assert(path);
assert(name);
assert(value);
for (l = 100; ; l = (size_t) n + 1) {
v = new0(char, l);
if (!v)
return -ENOMEM;
if (allow_symlink)
n = lgetxattr(path, name, v, l);
else
n = getxattr(path, name, v, l);
if (n >= 0 && (size_t) n < l) {
*value = v;
return n;
}
free(v);
if (n < 0 && errno != ERANGE)
return -errno;
if (allow_symlink)
n = lgetxattr(path, name, NULL, 0);
else
n = getxattr(path, name, NULL, 0);
if (n < 0)
return -errno;
}
}
int fgetxattr_malloc(int fd, const char *name, char **value) {
char *v;
size_t l;
ssize_t n;
assert(fd >= 0);
assert(name);
assert(value);
for (l = 100; ; l = (size_t) n + 1) {
v = new0(char, l);
if (!v)
return -ENOMEM;
n = fgetxattr(fd, name, v, l);
if (n >= 0 && (size_t) n < l) {
*value = v;
return n;
}
free(v);
if (n < 0 && errno != ERANGE)
return -errno;
n = fgetxattr(fd, name, NULL, 0);
if (n < 0)
return -errno;
}
}
int fgetxattrat_fake(
int dirfd,
const char *filename,
const char *attribute,
void *value, size_t size,
int flags,
size_t *ret_size) {
char fn[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
_cleanup_close_ int fd = -1;
ssize_t l;
/* The kernel doesn't have a fgetxattrat() command, hence let's emulate one */
if (flags & ~(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH))
return -EINVAL;
if (isempty(filename)) {
if (!(flags & AT_EMPTY_PATH))
return -EINVAL;
xsprintf(fn, "/proc/self/fd/%i", dirfd);
} else {
fd = openat(dirfd, filename, O_CLOEXEC|O_PATH|(flags & AT_SYMLINK_NOFOLLOW ? O_NOFOLLOW : 0));
if (fd < 0)
return -errno;
xsprintf(fn, "/proc/self/fd/%i", fd);
}
l = getxattr(fn, attribute, value, size);
if (l < 0)
return -errno;
*ret_size = l;
return 0;
}
static int parse_crtime(le64_t le, usec_t *usec) {
uint64_t u;
assert(usec);
u = le64toh(le);
if (IN_SET(u, 0, (uint64_t) -1))
return -EIO;
*usec = (usec_t) u;
return 0;
}
int fd_getcrtime_at(int dirfd, const char *name, usec_t *ret, int flags) {
struct_statx sx;
usec_t a, b;
le64_t le;
size_t n;
int r;
assert(ret);
if (flags & ~(AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW))
return -EINVAL;
/* So here's the deal: the creation/birth time (crtime/btime) of a file is a relatively newly supported concept
* on Linux (or more strictly speaking: a concept that only recently got supported in the API, it was
* implemented on various file systems on the lower level since a while, but never was accessible). However, we
* needed a concept like that for vaccuuming algorithms and such, hence we emulated it via a user xattr for a
* long time. Starting with Linux 4.11 there's statx() which exposes the timestamp to userspace for the first
* time, where it is available. Thius function will read it, but it tries to keep some compatibility with older
* systems: we try to read both the crtime/btime and the xattr, and then use whatever is older. After all the
* concept is useful for determining how "old" a file really is, and hence using the older of the two makes
* most sense. */
if (statx(dirfd, strempty(name), flags|AT_STATX_DONT_SYNC, STATX_BTIME, &sx) >= 0 &&
(sx.stx_mask & STATX_BTIME) &&
sx.stx_btime.tv_sec != 0)
a = (usec_t) sx.stx_btime.tv_sec * USEC_PER_SEC +
(usec_t) sx.stx_btime.tv_nsec / NSEC_PER_USEC;
else
a = USEC_INFINITY;
r = fgetxattrat_fake(dirfd, name, "user.crtime_usec", &le, sizeof(le), flags, &n);
if (r >= 0) {
if (n != sizeof(le))
r = -EIO;
else
r = parse_crtime(le, &b);
}
if (r < 0) {
if (a != USEC_INFINITY) {
*ret = a;
return 0;
}
return r;
}
if (a != USEC_INFINITY)
*ret = MIN(a, b);
else
*ret = b;
return 0;
}
int fd_getcrtime(int fd, usec_t *ret) {
return fd_getcrtime_at(fd, NULL, ret, AT_EMPTY_PATH);
}
int path_getcrtime(const char *p, usec_t *ret) {
return fd_getcrtime_at(AT_FDCWD, p, ret, 0);
}
int fd_setcrtime(int fd, usec_t usec) {
le64_t le;
assert(fd >= 0);
if (IN_SET(usec, 0, USEC_INFINITY))
usec = now(CLOCK_REALTIME);
le = htole64((uint64_t) usec);
if (fsetxattr(fd, "user.crtime_usec", &le, sizeof(le), 0) < 0)
return -errno;
return 0;
}
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