libc: Add O_PATH support for fgetxattr / fsetxattr
Support O_PATH file descriptors when handling fgetxattr and fsetxattr.
This avoids requiring file read access to pull extended attributes.
This is needed to support O_PATH file descriptors when calling
SELinux's fgetfilecon() call. In particular, this allows the querying
and setting of SELinux file context by using something like the following
code:
int dirfd = open("/path/to/dir", O_DIRECTORY);
int fd = openat(dirfd, "file", O_PATH | O_NOFOLLOW);
char *context;
fgetfilecon(fd, &context);
This change was motivated by a comment in
https://android-review.googlesource.com/#/c/152680/1/toys/posix/ls.c
Change-Id: Ic0cdf9f9dd0e35a63b44a4c4a08400020041eddf
diff --git a/libc/arch-arm64/syscalls/___fsetxattr.S b/libc/arch-arm64/syscalls/___fsetxattr.S
new file mode 100644
index 0000000..92be8de
--- /dev/null
+++ b/libc/arch-arm64/syscalls/___fsetxattr.S
@@ -0,0 +1,15 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(___fsetxattr)
+ mov x8, __NR_fsetxattr
+ svc #0
+
+ cmn x0, #(MAX_ERRNO + 1)
+ cneg x0, x0, hi
+ b.hi __set_errno_internal
+
+ ret
+END(___fsetxattr)
+.hidden ___fsetxattr