[thirdparty/systemd.git] / src / basic / xattr-util.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/xattr.h>

#include "alloc-util.h"
#include "fd-util.h"
#include "macro.h"
#include "missing_syscall.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 **ret,
                bool allow_symlink) {

        size_t l = 100;

        assert(path);
        assert(name);
        assert(ret);

        for(;;) {
                _cleanup_free_ char *v = NULL;
                ssize_t n;

                v = new0(char, l+1);
                if (!v)
                        return -ENOMEM;

                if (allow_symlink)
                        n = lgetxattr(path, name, v, l);
                else
                        n = getxattr(path, name, v, l);
                if (n < 0) {
                        if (errno != ERANGE)
                                return -errno;
                } else {
                        v[n] = 0; /* NUL terminate */
                        *ret = TAKE_PTR(v);
                        return (int) n;
                }

                if (allow_symlink)
                        n = lgetxattr(path, name, NULL, 0);
                else
                        n = getxattr(path, name, NULL, 0);
                if (n < 0)
                        return -errno;
                if (n > INT_MAX) /* We couldn't return this as 'int' anymore */
                        return -E2BIG;

                l = (size_t) n;
        }
}

int fgetxattr_malloc(
                int fd,
                const char *name,
                char **ret) {

        size_t l = 100;

        assert(fd >= 0);
        assert(name);
        assert(ret);

        for (;;) {
                _cleanup_free_ char *v = NULL;
                ssize_t n;

                v = new(char, l+1);
                if (!v)
                        return -ENOMEM;

                n = fgetxattr(fd, name, v, l);
                if (n < 0) {
                        if (errno != ERANGE)
                                return -errno;
                } else {
                        v[n] = 0; /* NUL terminate */
                        *ret = TAKE_PTR(v);
                        return (int) n;
                }

                n = fgetxattr(fd, name, NULL, 0);
                if (n < 0)
                        return -errno;
                if (n > INT_MAX) /* We couldn't return this as 'int' anymore */
                        return -E2BIG;

                l = (size_t) n;
        }
}

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
#if HAS_FEATURE_MEMORY_SANITIZER
                = {}
#  warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
#endif
                ;
        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;
}

int flistxattr_malloc(int fd, char **ret) {
        size_t l = 100;

        assert(fd >= 0);
        assert(ret);

        for (;;) {
                _cleanup_free_ char *v = NULL;
                ssize_t n;

                v = new(char, l+1);
                if (!v)
                        return -ENOMEM;

                n = flistxattr(fd, v, l);
                if (n < 0) {
                        if (errno != ERANGE)
                                return -errno;
                } else {
                        v[n] = 0; /* NUL terminate */
                        *ret = TAKE_PTR(v);
                        return (int) n;
                }

                n = flistxattr(fd, NULL, 0);
                if (n < 0)
                        return -errno;
                if (n > INT_MAX) /* We couldn't return this as 'int' anymore */
                        return -E2BIG;

                l = (size_t) n;
        }
}
Commit	Line	Data
	1	/* SPDX-License-Identifier: LGPL-2.1+ */
	2
	3	#include <errno.h>
	4	#include <fcntl.h>
	5	#include <stdint.h>
	6	#include <stdlib.h>
	7	#include <sys/time.h>
	8	#include <sys/xattr.h>
	9
	10	#include "alloc-util.h"
	11	#include "fd-util.h"
	12	#include "macro.h"
	13	#include "missing_syscall.h"
	14	#include "sparse-endian.h"
	15	#include "stdio-util.h"
	16	#include "string-util.h"
	17	#include "time-util.h"
	18	#include "xattr-util.h"
	19
	20	int getxattr_malloc(
	21	const char *path,
	22	const char *name,
	23	char **ret,
	24	bool allow_symlink) {
	25
	26	size_t l = 100;
	27
	28	assert(path);
	29	assert(name);
	30	assert(ret);
	31
	32	for(;;) {
	33	_cleanup_free_ char *v = NULL;
	34	ssize_t n;
	35
	36	v = new0(char, l+1);
	37	if (!v)
	38	return -ENOMEM;
	39
	40	if (allow_symlink)
	41	n = lgetxattr(path, name, v, l);
	42	else
	43	n = getxattr(path, name, v, l);
	44	if (n < 0) {
	45	if (errno != ERANGE)
	46	return -errno;
	47	} else {
	48	v[n] = 0; /* NUL terminate */
	49	*ret = TAKE_PTR(v);
	50	return (int) n;
	51	}
	52
	53	if (allow_symlink)
	54	n = lgetxattr(path, name, NULL, 0);
	55	else
	56	n = getxattr(path, name, NULL, 0);
	57	if (n < 0)
	58	return -errno;
	59	if (n > INT_MAX) /* We couldn't return this as 'int' anymore */
	60	return -E2BIG;
	61
	62	l = (size_t) n;
	63	}
	64	}
	65
	66	int fgetxattr_malloc(
	67	int fd,
	68	const char *name,
	69	char **ret) {
	70
	71	size_t l = 100;
	72
	73	assert(fd >= 0);
	74	assert(name);
	75	assert(ret);
	76
	77	for (;;) {
	78	_cleanup_free_ char *v = NULL;
	79	ssize_t n;
	80
	81	v = new(char, l+1);
	82	if (!v)
	83	return -ENOMEM;
	84
	85	n = fgetxattr(fd, name, v, l);
	86	if (n < 0) {
	87	if (errno != ERANGE)
	88	return -errno;
	89	} else {
	90	v[n] = 0; /* NUL terminate */
	91	*ret = TAKE_PTR(v);
	92	return (int) n;
	93	}
	94
	95	n = fgetxattr(fd, name, NULL, 0);
	96	if (n < 0)
	97	return -errno;
	98	if (n > INT_MAX) /* We couldn't return this as 'int' anymore */
	99	return -E2BIG;
	100
	101	l = (size_t) n;
	102	}
	103	}
	104
	105	int fgetxattrat_fake(
	106	int dirfd,
	107	const char *filename,
	108	const char *attribute,
	109	void *value, size_t size,
	110	int flags,
	111	size_t *ret_size) {
	112
	113	char fn[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
	114	_cleanup_close_ int fd = -1;
	115	ssize_t l;
	116
	117	/* The kernel doesn't have a fgetxattrat() command, hence let's emulate one */
	118
	119	if (flags & ~(AT_SYMLINK_NOFOLLOW\|AT_EMPTY_PATH))
	120	return -EINVAL;
	121
	122	if (isempty(filename)) {
	123	if (!(flags & AT_EMPTY_PATH))
	124	return -EINVAL;
	125
	126	xsprintf(fn, "/proc/self/fd/%i", dirfd);
	127	} else {
	128	fd = openat(dirfd, filename, O_CLOEXEC\|O_PATH\|(flags & AT_SYMLINK_NOFOLLOW ? O_NOFOLLOW : 0));
	129	if (fd < 0)
	130	return -errno;
	131
	132	xsprintf(fn, "/proc/self/fd/%i", fd);
	133	}
	134
	135	l = getxattr(fn, attribute, value, size);
	136	if (l < 0)
	137	return -errno;
	138
	139	*ret_size = l;
	140	return 0;
	141	}
	142
	143	static int parse_crtime(le64_t le, usec_t *usec) {
	144	uint64_t u;
	145
	146	assert(usec);
	147
	148	u = le64toh(le);
	149	if (IN_SET(u, 0, (uint64_t) -1))
	150	return -EIO;
	151
	152	*usec = (usec_t) u;
	153	return 0;
	154	}
	155
	156	int fd_getcrtime_at(int dirfd, const char name, usec_t ret, int flags) {
	157	struct_statx sx
	158	#if HAS_FEATURE_MEMORY_SANITIZER
	159	= {}
	160	# warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
	161	#endif
	162	;
	163	usec_t a, b;
	164	le64_t le;
	165	size_t n;
	166	int r;
	167
	168	assert(ret);
	169
	170	if (flags & ~(AT_EMPTY_PATH\|AT_SYMLINK_NOFOLLOW))
	171	return -EINVAL;
	172
	173	/* So here's the deal: the creation/birth time (crtime/btime) of a file is a relatively newly supported concept
	174	* on Linux (or more strictly speaking: a concept that only recently got supported in the API, it was
	175	* implemented on various file systems on the lower level since a while, but never was accessible). However, we
	176	* needed a concept like that for vaccuuming algorithms and such, hence we emulated it via a user xattr for a
	177	* long time. Starting with Linux 4.11 there's statx() which exposes the timestamp to userspace for the first
	178	* time, where it is available. Thius function will read it, but it tries to keep some compatibility with older
	179	* systems: we try to read both the crtime/btime and the xattr, and then use whatever is older. After all the
	180	* concept is useful for determining how "old" a file really is, and hence using the older of the two makes
	181	* most sense. */
	182
	183	if (statx(dirfd, strempty(name), flags\|AT_STATX_DONT_SYNC, STATX_BTIME, &sx) >= 0 &&
	184	(sx.stx_mask & STATX_BTIME) &&
	185	sx.stx_btime.tv_sec != 0)
	186	a = (usec_t) sx.stx_btime.tv_sec * USEC_PER_SEC +
	187	(usec_t) sx.stx_btime.tv_nsec / NSEC_PER_USEC;
	188	else
	189	a = USEC_INFINITY;
	190
	191	r = fgetxattrat_fake(dirfd, name, "user.crtime_usec", &le, sizeof(le), flags, &n);
	192	if (r >= 0) {
	193	if (n != sizeof(le))
	194	r = -EIO;
	195	else
	196	r = parse_crtime(le, &b);
	197	}
	198	if (r < 0) {
	199	if (a != USEC_INFINITY) {
	200	*ret = a;
	201	return 0;
	202	}
	203
	204	return r;
	205	}
	206
	207	if (a != USEC_INFINITY)
	208	*ret = MIN(a, b);
	209	else
	210	*ret = b;
	211
	212	return 0;
	213	}
	214
	215	int fd_getcrtime(int fd, usec_t *ret) {
	216	return fd_getcrtime_at(fd, NULL, ret, AT_EMPTY_PATH);
	217	}
	218
	219	int path_getcrtime(const char p, usec_t ret) {
	220	return fd_getcrtime_at(AT_FDCWD, p, ret, 0);
	221	}
	222
	223	int fd_setcrtime(int fd, usec_t usec) {
	224	le64_t le;
	225
	226	assert(fd >= 0);
	227
	228	if (IN_SET(usec, 0, USEC_INFINITY))
	229	usec = now(CLOCK_REALTIME);
	230
	231	le = htole64((uint64_t) usec);
	232	if (fsetxattr(fd, "user.crtime_usec", &le, sizeof(le), 0) < 0)
	233	return -errno;
	234
	235	return 0;
	236	}
	237
	238	int flistxattr_malloc(int fd, char **ret) {
	239	size_t l = 100;
	240
	241	assert(fd >= 0);
	242	assert(ret);
	243
	244	for (;;) {
	245	_cleanup_free_ char *v = NULL;
	246	ssize_t n;
	247
	248	v = new(char, l+1);
	249	if (!v)
	250	return -ENOMEM;
	251
	252	n = flistxattr(fd, v, l);
	253	if (n < 0) {
	254	if (errno != ERANGE)
	255	return -errno;
	256	} else {
	257	v[n] = 0; /* NUL terminate */
	258	*ret = TAKE_PTR(v);
	259	return (int) n;
	260	}
	261
	262	n = flistxattr(fd, NULL, 0);
	263	if (n < 0)
	264	return -errno;
	265	if (n > INT_MAX) /* We couldn't return this as 'int' anymore */
	266	return -E2BIG;
	267
	268	l = (size_t) n;
	269	}
	270	}