Update our FreeBSD realpath(3) to upstream head.

Change-Id: I8c89728184ecd2c1a28a05cefa84a5037d28b552

libc/upstream-freebsd/lib/libc/stdlib/realpath.c

@@ -132,26 +132,7 @@ realpath(const char * __restrict path, char * __restrict resolved)
 			resolved[resolved_len] = '\0';
 		}
 		if (next_token[0] == '\0') {
-			/*
+			/* Handle consequential slashes. */
-			 * Handle consequential slashes.  The path
-			 * before slash shall point to a directory.
-			 *
-			 * Only the trailing slashes are not covered
-			 * by other checks in the loop, but we verify
-			 * the prefix for any (rare) "//" or "/\0"
-			 * occurence to not implement lookahead.
-			 */
-			if (lstat(resolved, &sb) != 0) {
-				if (m)
-					free(resolved);
-				return (NULL);
-			}
-			if (!S_ISDIR(sb.st_mode)) {
-				if (m)
-					free(resolved);
-				errno = ENOTDIR;
-				return (NULL);
-			}
 			continue;
 		}
 		else if (strcmp(next_token, ".") == 0)
@@ -236,6 +217,11 @@ realpath(const char * __restrict path, char * __restrict resolved)
 				}
 			}
 			left_len = strlcpy(left, symlink, sizeof(left));
+		} else if (!S_ISDIR(sb.st_mode) && p != NULL) {
+			if (m)
+				free(resolved);
+			errno = ENOTDIR;
+			return (NULL);
 		}
 	}
 

tests/stdlib_test.cpp

@@ -99,6 +99,18 @@ TEST(stdlib, realpath__ENOENT) {
   ASSERT_EQ(ENOENT, errno);
 }
 
+TEST(stdlib, realpath__component_after_non_directory) {
+  errno = 0;
+  char* p = realpath("/dev/null/.", NULL);
+  ASSERT_TRUE(p == NULL);
+  ASSERT_EQ(ENOTDIR, errno);
+
+  errno = 0;
+  p = realpath("/dev/null/..", NULL);
+  ASSERT_TRUE(p == NULL);
+  ASSERT_EQ(ENOTDIR, errno);
+}
+
 TEST(stdlib, realpath) {
   // Get the name of this executable.
   char executable_path[PATH_MAX];