<sys/stat.h>: add lchmod().

Bug: http://b/361334945
Change-Id: I6a76db7bd2f657ad9b058c2672bf7a4e687017f9
diff --git a/tests/sys_stat_test.cpp b/tests/sys_stat_test.cpp
index 126f469..50c50df 100644
--- a/tests/sys_stat_test.cpp
+++ b/tests/sys_stat_test.cpp
@@ -151,12 +151,12 @@
   ASSERT_ERRNO(EINVAL);
 }
 
-TEST(sys_stat, fchmodat_nonexistant_file) {
+TEST(sys_stat, fchmodat_nonexistent_file) {
   ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, 0));
   ASSERT_ERRNO(ENOENT);
 }
 
-TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_nonexistant_file) {
+TEST(sys_stat, fchmodat_AT_SYMLINK_NOFOLLOW_nonexistent_file) {
   ASSERT_EQ(-1, fchmodat(AT_FDCWD, "/blah", 0751, AT_SYMLINK_NOFOLLOW));
 #if defined(__BIONIC__)
   ASSERT_ERRNO(ENOENT);
@@ -305,7 +305,7 @@
   ASSERT_EQ(0, faccessat(AT_FDCWD, "/dev/null", R_OK|W_OK, 0));
 }
 
-TEST(sys_stat, faccessat_nonexistant) {
+TEST(sys_stat, faccessat_nonexistent) {
   ASSERT_EQ(-1, faccessat(AT_FDCWD, "/blah", F_OK, AT_SYMLINK_NOFOLLOW));
 #if defined(__BIONIC__)
   // Android doesn't support AT_SYMLINK_NOFOLLOW
@@ -314,3 +314,26 @@
   ASSERT_ERRNO(ENOENT);
 #endif
 }
+
+TEST(sys_stat, lchmod) {
+  TemporaryFile tf;
+  struct stat tf_sb;
+  ASSERT_EQ(0, stat(tf.path, &tf_sb));
+
+  char linkname[255];
+  snprintf(linkname, sizeof(linkname), "%s.link", tf.path);
+
+  ASSERT_EQ(0, symlink(tf.path, linkname));
+  int result = lchmod(linkname, 0751);
+  // Whether or not chmod is allowed on a symlink depends on the kernel.
+  if (result == 0) {
+    AssertSymlinkModeEquals(0751, linkname);
+  } else {
+    ASSERT_EQ(-1, result);
+    ASSERT_ERRNO(ENOTSUP);
+  }
+
+  // The target file mode shouldn't be modified.
+  AssertFileModeEquals(tf_sb.st_mode, tf.path);
+  unlink(linkname);
+}