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-rw-r--r--src/basic/xattr-util.c266
1 files changed, 266 insertions, 0 deletions
diff --git a/src/basic/xattr-util.c b/src/basic/xattr-util.c
new file mode 100644
index 0000000..b9a0dc5
--- /dev/null
+++ b/src/basic/xattr-util.c
@@ -0,0 +1,266 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#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 "stat-util.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_DEFINE(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;
+}
+
+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;
+ }
+}
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