Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 162 insertions, 0 deletions

diff --git a/src/basic/chattr-util.c b/src/basic/chattr-util.c
new file mode 100644
index 0000000..fe8b9ab
--- /dev/null
+++ b/src/basic/chattr-util.c
@@ -0,0 +1,162 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <linux/fs.h>
+
+#include "chattr-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "macro.h"
+#include "string-util.h"
+
+int chattr_full(
+              int dir_fd,
+              const char *path,
+              unsigned value,
+              unsigned mask,
+              unsigned *ret_previous,
+              unsigned *ret_final,
+              ChattrApplyFlags flags) {
+
+        _cleanup_close_ int fd = -EBADF;
+        unsigned old_attr, new_attr;
+        int set_flags_errno = 0;
+        struct stat st;
+
+        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+
+        fd = xopenat(dir_fd, path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, /* xopen_flags = */ 0, /* mode = */ 0);
+        if (fd < 0)
+                return fd;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        /* Explicitly check whether this is a regular file or directory. If it is anything else (such
+         * as a device node or fifo), then the ioctl will not hit the file systems but possibly
+         * drivers, where the ioctl might have different effects. Notably, DRM is using the same
+         * ioctl() number. */
+
+        if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
+                return -ENOTTY;
+
+        if (mask == 0 && !ret_previous && !ret_final)
+                return 0;
+
+        if (ioctl(fd, FS_IOC_GETFLAGS, &old_attr) < 0)
+                return -errno;
+
+        new_attr = (old_attr & ~mask) | (value & mask);
+        if (new_attr == old_attr) {
+                if (ret_previous)
+                        *ret_previous = old_attr;
+                if (ret_final)
+                        *ret_final = old_attr;
+                return 0;
+        }
+
+        if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) >= 0) {
+                unsigned attr;
+
+                /* Some filesystems (BTRFS) silently fail when a flag cannot be set. Let's make sure our
+                 * changes actually went through by querying the flags again and verifying they're equal to
+                 * the flags we tried to configure. */
+
+                if (ioctl(fd, FS_IOC_GETFLAGS, &attr) < 0)
+                        return -errno;
+
+                if (new_attr == attr) {
+                        if (ret_previous)
+                                *ret_previous = old_attr;
+                        if (ret_final)
+                                *ret_final = new_attr;
+                        return 1;
+                }
+
+                /* Trigger the fallback logic. */
+                errno = EINVAL;
+        }
+
+        if ((errno != EINVAL && !ERRNO_IS_NOT_SUPPORTED(errno)) ||
+            !FLAGS_SET(flags, CHATTR_FALLBACK_BITWISE))
+                return -errno;
+
+        /* When -EINVAL is returned, we assume that incompatible attributes are simultaneously
+         * specified. E.g., compress(c) and nocow(C) attributes cannot be set to files on btrfs.
+         * As a fallback, let's try to set attributes one by one.
+         *
+         * Also, when we get EOPNOTSUPP (or a similar error code) we assume a flag might just not be
+         * supported, and we can ignore it too */
+
+        unsigned current_attr = old_attr;
+        for (unsigned i = 0; i < sizeof(unsigned) * 8; i++) {
+                unsigned new_one, mask_one = 1u << i;
+
+                if (!FLAGS_SET(mask, mask_one))
+                        continue;
+
+                new_one = UPDATE_FLAG(current_attr, mask_one, FLAGS_SET(value, mask_one));
+                if (new_one == current_attr)
+                        continue;
+
+                if (ioctl(fd, FS_IOC_SETFLAGS, &new_one) < 0) {
+                        if (errno != EINVAL && !ERRNO_IS_NOT_SUPPORTED(errno))
+                                return -errno;
+
+                        log_full_errno(FLAGS_SET(flags, CHATTR_WARN_UNSUPPORTED_FLAGS) ? LOG_WARNING : LOG_DEBUG,
+                                       errno,
+                                       "Unable to set file attribute 0x%x on %s, ignoring: %m", mask_one, strna(path));
+
+                        /* Ensures that we record whether only EOPNOTSUPP&friends are encountered, or if a more serious
+                         * error (thus worth logging at a different level, etc) was seen too. */
+                        if (set_flags_errno == 0 || !ERRNO_IS_NOT_SUPPORTED(errno))
+                                set_flags_errno = -errno;
+
+                        continue;
+                }
+
+                if (ioctl(fd, FS_IOC_GETFLAGS, &current_attr) < 0)
+                        return -errno;
+        }
+
+        if (ret_previous)
+                *ret_previous = old_attr;
+        if (ret_final)
+                *ret_final = current_attr;
+
+        /* -ENOANO indicates that some attributes cannot be set. ERRNO_IS_NOT_SUPPORTED indicates that all
+         * encountered failures were due to flags not supported by the FS, so return a specific error in
+         * that case, so callers can handle it properly (e.g.: tmpfiles.d can use debug level logging). */
+        return current_attr == new_attr ? 1 : ERRNO_IS_NOT_SUPPORTED(set_flags_errno) ? set_flags_errno : -ENOANO;
+}
+
+int read_attr_fd(int fd, unsigned *ret) {
+        struct stat st;
+
+        assert(fd >= 0);
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
+                return -ENOTTY;
+
+        return RET_NERRNO(ioctl(fd, FS_IOC_GETFLAGS, ret));
+}
+
+int read_attr_path(const char *p, unsigned *ret) {
+        _cleanup_close_ int fd = -EBADF;
+
+        assert(p);
+        assert(ret);
+
+        fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+        if (fd < 0)
+                return -errno;
+
+        return read_attr_fd(fd, ret);
+}