Reimplement realpath.
Use O_PATH like musl to let the kernel do the hard work, rather than the
traditional BSD manual scheme.
Also add the most obvious missing tests from reading the man page, plus
a non-obvious test for deleted files.
Bug: http://b/131435126
Test: treehugger
Change-Id: Ie8a8986fea55f045952a81afee377ce8288a49d5
diff --git a/libc/Android.bp b/libc/Android.bp
index c764cb9..f1cca49 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -359,7 +359,6 @@
defaults: ["libc_defaults"],
srcs: [
"upstream-freebsd/lib/libc/gen/glob.c",
- "upstream-freebsd/lib/libc/stdlib/realpath.c",
],
cflags: [
@@ -1179,6 +1178,7 @@
"bionic/raise.cpp",
"bionic/rand.cpp",
"bionic/readlink.cpp",
+ "bionic/realpath.cpp",
"bionic/reboot.cpp",
"bionic/recv.cpp",
"bionic/rename.cpp",
diff --git a/libc/NOTICE b/libc/NOTICE
index e2afdbf..fd2fd32 100644
--- a/libc/NOTICE
+++ b/libc/NOTICE
@@ -3781,34 +3781,6 @@
-------------------------------------------------------------------
-Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
-1. Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
-2. 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.
-3. The names of the authors may not be used to endorse or promote
- products derived from this software without specific prior written
- permission.
-
-THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
-
--------------------------------------------------------------------
-
Copyright (c) 2003 Dag-Erling Smørgrav
All rights reserved.
diff --git a/libc/bionic/realpath.cpp b/libc/bionic/realpath.cpp
new file mode 100644
index 0000000..e43d8e2
--- /dev/null
+++ b/libc/bionic/realpath.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2019 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 <stdlib.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include "private/FdPath.h"
+#include "private/ScopedFd.h"
+
+// This function needs a 4KiB (PATH_MAX) buffer.
+// The alternative is to heap allocate and then trim, but that's 2x the code.
+// (Remember that readlink(2) won't tell you the needed size, so the multi-pass
+// algorithm isn't even an option unless you want to just guess, in which case
+// you're back needing to trim again.)
+#pragma GCC diagnostic ignored "-Wframe-larger-than="
+
+char* realpath(const char* path, char* result) {
+ // Weird special case.
+ if (!path) {
+ errno = EINVAL;
+ return nullptr;
+ }
+
+ // Get an O_PATH fd, and...
+ ScopedFd fd(open(path, O_PATH | O_CLOEXEC));
+ if (fd.get() == -1) return nullptr;
+
+ // (...remember the device/inode that we're talking about and...)
+ struct stat sb;
+ if (fstat(fd.get(), &sb) == -1) return nullptr;
+ dev_t st_dev = sb.st_dev;
+ ino_t st_ino = sb.st_ino;
+
+ // ...ask the kernel to do the hard work for us.
+ FdPath fd_path(fd.get());
+ char dst[PATH_MAX];
+ ssize_t l = readlink(fd_path.c_str(), dst, sizeof(dst) - 1);
+ if (l == -1) return nullptr;
+ dst[l] = '\0';
+
+ // What if the file was removed in the meantime? readlink(2) will have
+ // returned "/a/b/c (deleted)", and we want to return ENOENT instead.
+ if (stat(dst, &sb) == -1 || st_dev != sb.st_dev || st_ino != sb.st_ino) {
+ errno = ENOENT;
+ return nullptr;
+ }
+
+ return result ? strcpy(result, dst) : strdup(dst);
+}
diff --git a/libc/upstream-freebsd/lib/libc/stdlib/realpath.c b/libc/upstream-freebsd/lib/libc/stdlib/realpath.c
deleted file mode 100644
index c4bd953..0000000
--- a/libc/upstream-freebsd/lib/libc/stdlib/realpath.c
+++ /dev/null
@@ -1,235 +0,0 @@
-/*
- * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. 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.
- * 3. The names of the authors may not be used to endorse or promote
- * products derived from this software without specific prior written
- * permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94";
-#endif /* LIBC_SCCS and not lint */
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
-
-#include "namespace.h"
-#include <sys/param.h>
-#include <sys/stat.h>
-
-#include <errno.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include "un-namespace.h"
-
-/*
- * Find the real name of path, by removing all ".", ".." and symlink
- * components. Returns (resolved) on success, or (NULL) on failure,
- * in which case the path which caused trouble is left in (resolved).
- */
-char *
-realpath(const char * __restrict path, char * __restrict resolved)
-{
- struct stat sb;
- char *p, *q, *s;
- size_t left_len, resolved_len;
- unsigned symlinks;
- int m, slen;
- char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
-
- if (path == NULL) {
- errno = EINVAL;
- return (NULL);
- }
- if (path[0] == '\0') {
- errno = ENOENT;
- return (NULL);
- }
- if (resolved == NULL) {
- resolved = malloc(PATH_MAX);
- if (resolved == NULL)
- return (NULL);
- m = 1;
- } else
- m = 0;
- symlinks = 0;
- if (path[0] == '/') {
- resolved[0] = '/';
- resolved[1] = '\0';
- if (path[1] == '\0')
- return (resolved);
- resolved_len = 1;
- left_len = strlcpy(left, path + 1, sizeof(left));
- } else {
- if (getcwd(resolved, PATH_MAX) == NULL) {
- if (m)
- free(resolved);
- else {
- resolved[0] = '.';
- resolved[1] = '\0';
- }
- return (NULL);
- }
- resolved_len = strlen(resolved);
- left_len = strlcpy(left, path, sizeof(left));
- }
- if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
- if (m)
- free(resolved);
- errno = ENAMETOOLONG;
- return (NULL);
- }
-
- /*
- * Iterate over path components in `left'.
- */
- while (left_len != 0) {
- /*
- * Extract the next path component and adjust `left'
- * and its length.
- */
- p = strchr(left, '/');
- s = p ? p : left + left_len;
- if (s - left >= sizeof(next_token)) {
- if (m)
- free(resolved);
- errno = ENAMETOOLONG;
- return (NULL);
- }
- memcpy(next_token, left, s - left);
- next_token[s - left] = '\0';
- left_len -= s - left;
- if (p != NULL)
- memmove(left, s + 1, left_len + 1);
- if (resolved[resolved_len - 1] != '/') {
- if (resolved_len + 1 >= PATH_MAX) {
- if (m)
- free(resolved);
- errno = ENAMETOOLONG;
- return (NULL);
- }
- resolved[resolved_len++] = '/';
- resolved[resolved_len] = '\0';
- }
- if (next_token[0] == '\0') {
- /* Handle consequential slashes. */
- continue;
- }
- else if (strcmp(next_token, ".") == 0)
- continue;
- else if (strcmp(next_token, "..") == 0) {
- /*
- * Strip the last path component except when we have
- * single "/"
- */
- if (resolved_len > 1) {
- resolved[resolved_len - 1] = '\0';
- q = strrchr(resolved, '/') + 1;
- *q = '\0';
- resolved_len = q - resolved;
- }
- continue;
- }
-
- /*
- * Append the next path component and lstat() it.
- */
- resolved_len = strlcat(resolved, next_token, PATH_MAX);
- if (resolved_len >= PATH_MAX) {
- if (m)
- free(resolved);
- errno = ENAMETOOLONG;
- return (NULL);
- }
- if (lstat(resolved, &sb) != 0) {
- if (m)
- free(resolved);
- return (NULL);
- }
- if (S_ISLNK(sb.st_mode)) {
- if (symlinks++ > MAXSYMLINKS) {
- if (m)
- free(resolved);
- errno = ELOOP;
- return (NULL);
- }
- slen = readlink(resolved, symlink, sizeof(symlink) - 1);
- if (slen < 0) {
- if (m)
- free(resolved);
- return (NULL);
- }
- symlink[slen] = '\0';
- if (symlink[0] == '/') {
- resolved[1] = 0;
- resolved_len = 1;
- } else if (resolved_len > 1) {
- /* Strip the last path component. */
- resolved[resolved_len - 1] = '\0';
- q = strrchr(resolved, '/') + 1;
- *q = '\0';
- resolved_len = q - resolved;
- }
-
- /*
- * If there are any path components left, then
- * append them to symlink. The result is placed
- * in `left'.
- */
- if (p != NULL) {
- if (symlink[slen - 1] != '/') {
- if (slen + 1 >= sizeof(symlink)) {
- if (m)
- free(resolved);
- errno = ENAMETOOLONG;
- return (NULL);
- }
- symlink[slen] = '/';
- symlink[slen + 1] = 0;
- }
- left_len = strlcat(symlink, left,
- sizeof(symlink));
- if (left_len >= sizeof(left)) {
- if (m)
- free(resolved);
- errno = ENAMETOOLONG;
- return (NULL);
- }
- }
- left_len = strlcpy(left, symlink, sizeof(left));
- } else if (!S_ISDIR(sb.st_mode) && p != NULL) {
- if (m)
- free(resolved);
- errno = ENOTDIR;
- return (NULL);
- }
- }
-
- /*
- * Remove trailing slash except when the resolved pathname
- * is a single "/".
- */
- if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
- resolved[resolved_len - 1] = '\0';
- return (resolved);
-}