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-rw-r--r--src/basic/chattr-util.c96
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);
+}