1 files changed, 96 insertions, 0 deletions
diff --git a/src/basic/chattr-util.c b/src/basic/chattr-util.c
new file mode 100644
index 0000000..235cfb9
--- /dev/null
+++ b/src/basic/chattr-util.c
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <linux/fs.h>
+
+#include "chattr-util.h"
+#include "fd-util.h"
+#include "macro.h"
+
+int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous) {
+        unsigned old_attr, new_attr;
+        struct stat st;
+
+        assert(fd >= 0);
+
+        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 && !previous)
+                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 (previous)
+                        *previous = old_attr;
+                return 0;
+        }
+
+        if (ioctl(fd, FS_IOC_SETFLAGS, &new_attr) < 0)
+                return -errno;
+
+        if (previous)
+                *previous = old_attr;
+
+        return 1;
+}
+
+int chattr_path(const char *p, unsigned value, unsigned mask, unsigned *previous) {
+        _cleanup_close_ int fd = -1;
+
+        assert(p);
+
+        if (mask == 0)
+                return 0;
+
+        fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+        if (fd < 0)
+                return -errno;
+
+        return chattr_fd(fd, value, mask, previous);
+}
+
+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;
+
+        if (ioctl(fd, FS_IOC_GETFLAGS, ret) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int read_attr_path(const char *p, unsigned *ret) {
+        _cleanup_close_ int fd = -1;
+
+        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);
+}