Merge "Add fchmodat(AT_SYMLINK_NOFOLLOW) and fchmod O_PATH support"
diff --git a/libc/Android.mk b/libc/Android.mk
index 90f1a12..fe7b116 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -116,6 +116,8 @@
bionic/error.cpp \
bionic/eventfd_read.cpp \
bionic/eventfd_write.cpp \
+ bionic/fchmod.cpp \
+ bionic/fchmodat.cpp \
bionic/ffs.cpp \
bionic/flockfile.cpp \
bionic/fork.cpp \
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 0fa2a1e..d68a00f 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -113,7 +113,7 @@
int __fcntl64:fcntl64(int, int, void*) arm,mips,x86
int fcntl(int, int, void*) arm64,mips64,x86_64
int flock(int, int) all
-int fchmod(int, mode_t) all
+int __fchmod:fchmod(int, mode_t) all
int dup(int) all
int pipe2(int*, int) all
int dup3(int, int, int) all
@@ -131,7 +131,7 @@
int __openat:openat(int, const char*, int, mode_t) all
int faccessat(int, const char*, int, int) all
-int fchmodat(int, const char*, mode_t, int) all
+int __fchmodat:fchmodat(int, const char*, mode_t) all
int fchownat(int, const char*, uid_t, gid_t, int) all
int fstatat64|fstatat:fstatat64(int, const char*, struct stat*, int) arm,mips,x86
int fstatat64|fstatat:newfstatat(int, const char*, struct stat*, int) arm64,x86_64
diff --git a/libc/arch-arm/syscalls/fchmod.S b/libc/arch-arm/syscalls/__fchmod.S
similarity index 89%
rename from libc/arch-arm/syscalls/fchmod.S
rename to libc/arch-arm/syscalls/__fchmod.S
index 5675f0a..ff888a1 100644
--- a/libc/arch-arm/syscalls/fchmod.S
+++ b/libc/arch-arm/syscalls/__fchmod.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmod)
+ENTRY(__fchmod)
mov ip, r7
ldr r7, =__NR_fchmod
swi #0
@@ -11,4 +11,4 @@
bxls lr
neg r0, r0
b __set_errno_internal
-END(fchmod)
+END(__fchmod)
diff --git a/libc/arch-arm/syscalls/fchmodat.S b/libc/arch-arm/syscalls/__fchmodat.S
similarity index 88%
rename from libc/arch-arm/syscalls/fchmodat.S
rename to libc/arch-arm/syscalls/__fchmodat.S
index 3f7e0ee..4d10f00 100644
--- a/libc/arch-arm/syscalls/fchmodat.S
+++ b/libc/arch-arm/syscalls/__fchmodat.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmodat)
+ENTRY(__fchmodat)
mov ip, r7
ldr r7, =__NR_fchmodat
swi #0
@@ -11,4 +11,4 @@
bxls lr
neg r0, r0
b __set_errno_internal
-END(fchmodat)
+END(__fchmodat)
diff --git a/libc/arch-arm64/syscalls/fchmod.S b/libc/arch-arm64/syscalls/__fchmod.S
similarity index 82%
rename from libc/arch-arm64/syscalls/fchmod.S
rename to libc/arch-arm64/syscalls/__fchmod.S
index 83a8060..05c67fc 100644
--- a/libc/arch-arm64/syscalls/fchmod.S
+++ b/libc/arch-arm64/syscalls/__fchmod.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmod)
+ENTRY(__fchmod)
mov x8, __NR_fchmod
svc #0
@@ -11,4 +11,5 @@
b.hi __set_errno_internal
ret
-END(fchmod)
+END(__fchmod)
+.hidden __fchmod
diff --git a/libc/arch-arm64/syscalls/fchmodat.S b/libc/arch-arm64/syscalls/__fchmodat.S
similarity index 81%
rename from libc/arch-arm64/syscalls/fchmodat.S
rename to libc/arch-arm64/syscalls/__fchmodat.S
index 8c5bb0e..2406ea8 100644
--- a/libc/arch-arm64/syscalls/fchmodat.S
+++ b/libc/arch-arm64/syscalls/__fchmodat.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmodat)
+ENTRY(__fchmodat)
mov x8, __NR_fchmodat
svc #0
@@ -11,4 +11,5 @@
b.hi __set_errno_internal
ret
-END(fchmodat)
+END(__fchmodat)
+.hidden __fchmodat
diff --git a/libc/arch-mips/syscalls/fchmod.S b/libc/arch-mips/syscalls/__fchmod.S
similarity index 89%
rename from libc/arch-mips/syscalls/fchmod.S
rename to libc/arch-mips/syscalls/__fchmod.S
index 2a95cc3..9bc491c 100644
--- a/libc/arch-mips/syscalls/fchmod.S
+++ b/libc/arch-mips/syscalls/__fchmod.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmod)
+ENTRY(__fchmod)
.set noreorder
.cpload t9
li v0, __NR_fchmod
@@ -16,4 +16,4 @@
j t9
nop
.set reorder
-END(fchmod)
+END(__fchmod)
diff --git a/libc/arch-mips/syscalls/fchmodat.S b/libc/arch-mips/syscalls/__fchmodat.S
similarity index 88%
rename from libc/arch-mips/syscalls/fchmodat.S
rename to libc/arch-mips/syscalls/__fchmodat.S
index d9de036..07ea8f8 100644
--- a/libc/arch-mips/syscalls/fchmodat.S
+++ b/libc/arch-mips/syscalls/__fchmodat.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmodat)
+ENTRY(__fchmodat)
.set noreorder
.cpload t9
li v0, __NR_fchmodat
@@ -16,4 +16,4 @@
j t9
nop
.set reorder
-END(fchmodat)
+END(__fchmodat)
diff --git a/libc/arch-mips64/syscalls/fchmod.S b/libc/arch-mips64/syscalls/__fchmod.S
similarity index 88%
rename from libc/arch-mips64/syscalls/fchmod.S
rename to libc/arch-mips64/syscalls/__fchmod.S
index a877b78..94dd0a1 100644
--- a/libc/arch-mips64/syscalls/fchmod.S
+++ b/libc/arch-mips64/syscalls/__fchmod.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmod)
+ENTRY(__fchmod)
.set push
.set noreorder
li v0, __NR_fchmod
@@ -22,4 +22,5 @@
j t9
move ra, t0
.set pop
-END(fchmod)
+END(__fchmod)
+.hidden __fchmod
diff --git a/libc/arch-mips64/syscalls/fchmodat.S b/libc/arch-mips64/syscalls/__fchmodat.S
similarity index 86%
rename from libc/arch-mips64/syscalls/fchmodat.S
rename to libc/arch-mips64/syscalls/__fchmodat.S
index 151492a..79f453f 100644
--- a/libc/arch-mips64/syscalls/fchmodat.S
+++ b/libc/arch-mips64/syscalls/__fchmodat.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmodat)
+ENTRY(__fchmodat)
.set push
.set noreorder
li v0, __NR_fchmodat
@@ -22,4 +22,5 @@
j t9
move ra, t0
.set pop
-END(fchmodat)
+END(__fchmodat)
+.hidden __fchmodat
diff --git a/libc/arch-x86/syscalls/fchmod.S b/libc/arch-x86/syscalls/__fchmod.S
similarity index 94%
rename from libc/arch-x86/syscalls/fchmod.S
rename to libc/arch-x86/syscalls/__fchmod.S
index 37851ff..7ad213e 100644
--- a/libc/arch-x86/syscalls/fchmod.S
+++ b/libc/arch-x86/syscalls/__fchmod.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmod)
+ENTRY(__fchmod)
pushl %ebx
.cfi_def_cfa_offset 8
.cfi_rel_offset ebx, 0
@@ -23,4 +23,4 @@
popl %ecx
popl %ebx
ret
-END(fchmod)
+END(__fchmod)
diff --git a/libc/arch-x86/syscalls/fchmodat.S b/libc/arch-x86/syscalls/__fchmodat.S
similarity index 70%
rename from libc/arch-x86/syscalls/fchmodat.S
rename to libc/arch-x86/syscalls/__fchmodat.S
index f515512..f03c03f 100644
--- a/libc/arch-x86/syscalls/fchmodat.S
+++ b/libc/arch-x86/syscalls/__fchmodat.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmodat)
+ENTRY(__fchmodat)
pushl %ebx
.cfi_def_cfa_offset 8
.cfi_rel_offset ebx, 0
@@ -12,13 +12,9 @@
pushl %edx
.cfi_adjust_cfa_offset 4
.cfi_rel_offset edx, 0
- pushl %esi
- .cfi_adjust_cfa_offset 4
- .cfi_rel_offset esi, 0
- mov 20(%esp), %ebx
- mov 24(%esp), %ecx
- mov 28(%esp), %edx
- mov 32(%esp), %esi
+ mov 16(%esp), %ebx
+ mov 20(%esp), %ecx
+ mov 24(%esp), %edx
movl $__NR_fchmodat, %eax
int $0x80
cmpl $-MAX_ERRNO, %eax
@@ -28,9 +24,8 @@
call __set_errno_internal
addl $4, %esp
1:
- popl %esi
popl %edx
popl %ecx
popl %ebx
ret
-END(fchmodat)
+END(__fchmodat)
diff --git a/libc/arch-x86_64/syscalls/fchmod.S b/libc/arch-x86_64/syscalls/__fchmod.S
similarity index 84%
rename from libc/arch-x86_64/syscalls/fchmod.S
rename to libc/arch-x86_64/syscalls/__fchmod.S
index b35bd21..ba75f74 100644
--- a/libc/arch-x86_64/syscalls/fchmod.S
+++ b/libc/arch-x86_64/syscalls/__fchmod.S
@@ -2,7 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmod)
+ENTRY(__fchmod)
movl $__NR_fchmod, %eax
syscall
cmpq $-MAX_ERRNO, %rax
@@ -12,4 +12,5 @@
call __set_errno_internal
1:
ret
-END(fchmod)
+END(__fchmod)
+.hidden __fchmod
diff --git a/libc/arch-x86_64/syscalls/fchmodat.S b/libc/arch-x86_64/syscalls/__fchmodat.S
similarity index 82%
rename from libc/arch-x86_64/syscalls/fchmodat.S
rename to libc/arch-x86_64/syscalls/__fchmodat.S
index 2d78d8e..a8fae95 100644
--- a/libc/arch-x86_64/syscalls/fchmodat.S
+++ b/libc/arch-x86_64/syscalls/__fchmodat.S
@@ -2,8 +2,7 @@
#include <private/bionic_asm.h>
-ENTRY(fchmodat)
- movq %rcx, %r10
+ENTRY(__fchmodat)
movl $__NR_fchmodat, %eax
syscall
cmpq $-MAX_ERRNO, %rax
@@ -13,4 +12,5 @@
call __set_errno_internal
1:
ret
-END(fchmodat)
+END(__fchmodat)
+.hidden __fchmodat
diff --git a/libc/bionic/fchmod.cpp b/libc/bionic/fchmod.cpp
new file mode 100644
index 0000000..6e020b6
--- /dev/null
+++ b/libc/bionic/fchmod.cpp
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdio.h>
+
+extern "C" int __fchmod(int, mode_t);
+
+int fchmod(int fd, mode_t mode) {
+ int saved_errno = errno;
+ int result = __fchmod(fd, mode);
+
+ if ((result == 0) || (errno != EBADF)) {
+ return result;
+ }
+
+ // fd could be an O_PATH file descriptor, and the kernel
+ // may not directly support fchmod() on such a file descriptor.
+ // Use /proc/self/fd instead to emulate this support.
+ // https://sourceware.org/bugzilla/show_bug.cgi?id=14578
+ //
+ // As of February 2015, there are no kernels which support fchmod
+ // on an O_PATH file descriptor, and "man open" documents fchmod
+ // on O_PATH file descriptors as returning EBADF.
+ int fd_flag = fcntl(fd, F_GETFL);
+ if ((fd_flag == -1) || ((fd_flag & O_PATH) == 0)) {
+ errno = EBADF;
+ return -1;
+ }
+
+ char buf[40];
+ snprintf(buf, sizeof(buf), "/proc/self/fd/%d", fd);
+ errno = saved_errno;
+ result = chmod(buf, mode);
+ if ((result == -1) && (errno == ELOOP)) {
+ // Linux does not support changing the mode of a symlink.
+ // For fchmodat(AT_SYMLINK_NOFOLLOW), POSIX requires a return
+ // value of ENOTSUP. Assume that's true here too.
+ errno = ENOTSUP;
+ }
+
+ return result;
+}
diff --git a/libc/bionic/fchmodat.cpp b/libc/bionic/fchmodat.cpp
new file mode 100644
index 0000000..c28e15a
--- /dev/null
+++ b/libc/bionic/fchmodat.cpp
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "private/ErrnoRestorer.h"
+
+extern "C" int __fchmodat(int, const char*, mode_t);
+
+int fchmodat(int dirfd, const char* pathname, mode_t mode, int flags) {
+ if ((flags & ~AT_SYMLINK_NOFOLLOW) != 0) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ if (flags & AT_SYMLINK_NOFOLLOW) {
+ // Emulate AT_SYMLINK_NOFOLLOW using the mechanism described
+ // at https://sourceware.org/bugzilla/show_bug.cgi?id=14578
+ // comment #10
+
+ int fd = openat(dirfd, pathname, O_PATH | O_NOFOLLOW | O_CLOEXEC);
+ if (fd == -1) {
+ return -1; // returns errno from openat
+ }
+
+ // POSIX requires that ENOTSUP be returned when the system
+ // doesn't support setting the mode of a symbolic link.
+ // This is true for all Linux kernels.
+ // We rely on the O_PATH compatibility layer added in the
+ // fchmod() function to get errno correct.
+ int result = fchmod(fd, mode);
+ ErrnoRestorer errno_restorer; // don't let close() clobber errno
+ close(fd);
+ return result;
+ }
+
+ return __fchmodat(dirfd, pathname, mode);
+}
diff --git a/tests/sys_stat_test.cpp b/tests/sys_stat_test.cpp
index e465774..7bbb7c6 100644
--- a/tests/sys_stat_test.cpp
+++ b/tests/sys_stat_test.cpp
@@ -95,3 +95,127 @@
ASSERT_EQ(0, fstat64(fd, &sb));
close(fd);
}
+
+TEST(sys_stat, fchmodat_EFAULT_file) {
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, (char *) 0x1, 0751, 0));
+ ASSERT_EQ(EFAULT, errno);
+}
+
+TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_EFAULT_file) {
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, (char *) 0x1, 0751, AT_SYMLINK_NOFOLLOW));
+#if defined(__BIONIC__)
+ ASSERT_EQ(EFAULT, errno);
+#else
+ // glibc 2.19 does not implement AT_SYMLINK_NOFOLLOW and always
+ // returns ENOTSUP
+ ASSERT_EQ(ENOTSUP, errno);
+#endif
+}
+
+TEST(sys_stat, fchmodat_bad_flags) {
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, ~AT_SYMLINK_NOFOLLOW));
+ ASSERT_EQ(EINVAL, errno);
+}
+
+TEST(sys_stat, fchmodat_bad_flags_ALL) {
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, ~0));
+ ASSERT_EQ(EINVAL, errno);
+}
+
+TEST(sys_stat, fchmodat_nonexistant_file) {
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, 0));
+ ASSERT_EQ(ENOENT, errno);
+}
+
+TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_nonexistant_file) {
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, AT_SYMLINK_NOFOLLOW));
+#if defined(__BIONIC__)
+ ASSERT_EQ(ENOENT, errno);
+#else
+ // glibc 2.19 does not implement AT_SYMLINK_NOFOLLOW and always
+ // returns ENOTSUP
+ ASSERT_EQ(ENOTSUP, errno);
+#endif
+}
+
+TEST(sys_stat, fchmodat_file) {
+ TemporaryFile tf;
+ struct stat sb;
+
+ ASSERT_EQ(0, fchmodat(AT_FDCWD, tf.filename, 0751, 0));
+ ASSERT_EQ(0, fstat(tf.fd, &sb));
+ ASSERT_TRUE(0751 == (sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
+}
+
+TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_file) {
+ TemporaryFile tf;
+ errno = 0;
+ int result = fchmodat(AT_FDCWD, tf.filename, 0751, AT_SYMLINK_NOFOLLOW);
+
+#if defined(__BIONIC__)
+ struct stat sb;
+ ASSERT_EQ(0, result);
+ ASSERT_EQ(0, errno);
+ ASSERT_EQ(0, fstat(tf.fd, &sb));
+ ASSERT_TRUE(0751 == (sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
+#else
+ // glibc 2.19 does not implement AT_SYMLINK_NOFOLLOW and always
+ // returns ENOTSUP
+ ASSERT_EQ(-1, result);
+ ASSERT_EQ(ENOTSUP, errno);
+#endif
+}
+
+TEST(sys_stat, fchmodat_symlink) {
+ TemporaryFile tf;
+ char linkname[255];
+ struct stat sb;
+
+ snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
+
+ ASSERT_EQ(0, symlink(tf.filename, linkname));
+ ASSERT_EQ(0, fchmodat(AT_FDCWD, linkname, 0751, 0));
+ ASSERT_EQ(0, fstat(tf.fd, &sb));
+ ASSERT_TRUE(0751 == (sb.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO)));
+ unlink(linkname);
+}
+
+TEST(sys_stat, fchmodat_dangling_symlink) {
+ TemporaryFile tf;
+ char linkname[255];
+ char target[255];
+
+ snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
+ snprintf(target, sizeof(target), "%s.doesnotexist", tf.filename);
+
+ ASSERT_EQ(0, symlink(target, linkname));
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, linkname, 0751, 0));
+ ASSERT_EQ(ENOENT, errno);
+ unlink(linkname);
+}
+
+TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_with_symlink) {
+ TemporaryFile tf;
+ char linkname[255];
+
+ snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
+
+ ASSERT_EQ(0, symlink(tf.filename, linkname));
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, linkname, 0751, AT_SYMLINK_NOFOLLOW));
+ ASSERT_EQ(ENOTSUP, errno);
+ unlink(linkname);
+}
+
+TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_with_dangling_symlink) {
+ TemporaryFile tf;
+ char linkname[255];
+ char target[255];
+
+ snprintf(linkname, sizeof(linkname), "%s.link", tf.filename);
+ snprintf(target, sizeof(target), "%s.doesnotexist", tf.filename);
+
+ ASSERT_EQ(0, symlink(target, linkname));
+ ASSERT_EQ(-1, fchmodat(AT_FDCWD, linkname, 0751, AT_SYMLINK_NOFOLLOW));
+ ASSERT_EQ(ENOTSUP, errno);
+ unlink(linkname);
+}