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-x86_64/syscalls/fgetxattr.S b/libc/arch-x86_64/syscalls/___fgetxattr.S
similarity index 82%
rename from libc/arch-x86_64/syscalls/fgetxattr.S
rename to libc/arch-x86_64/syscalls/___fgetxattr.S
index 7762474..302fd77 100644
--- a/libc/arch-x86_64/syscalls/fgetxattr.S
+++ b/libc/arch-x86_64/syscalls/___fgetxattr.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fgetxattr)
+ENTRY(___fgetxattr)
movq %rcx, %r10
movl $__NR_fgetxattr, %eax
syscall
@@ -13,4 +13,5 @@
call __set_errno_internal
1:
ret
-END(fgetxattr)
+END(___fgetxattr)
+.hidden ___fgetxattr
diff --git a/libc/arch-x86_64/syscalls/fsetxattr.S b/libc/arch-x86_64/syscalls/___fsetxattr.S
similarity index 82%
rename from libc/arch-x86_64/syscalls/fsetxattr.S
rename to libc/arch-x86_64/syscalls/___fsetxattr.S
index 97822c4..125ef20 100644
--- a/libc/arch-x86_64/syscalls/fsetxattr.S
+++ b/libc/arch-x86_64/syscalls/___fsetxattr.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fsetxattr)
+ENTRY(___fsetxattr)
movq %rcx, %r10
movl $__NR_fsetxattr, %eax
syscall
@@ -13,4 +13,5 @@
call __set_errno_internal
1:
ret
-END(fsetxattr)
+END(___fsetxattr)
+.hidden ___fsetxattr