Enhance getcwd(3) to handle NULL like glibc.
Bug: http://code.google.com/p/android/issues/detail?id=36085
Change-Id: I960a1b585887eb66176c61d29c5c61c239a4003f
diff --git a/libc/bionic/getcwd.cpp b/libc/bionic/getcwd.cpp
new file mode 100644
index 0000000..e06f52e
--- /dev/null
+++ b/libc/bionic/getcwd.cpp
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2008 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 <unistd.h>
+#include <errno.h>
+
+extern "C" int __getcwd(char* buf, size_t size);
+
+char* getcwd(char* buf, size_t size) {
+ // You can't specify size 0 unless you're asking us to allocate for you.
+ if (buf != NULL && size == 0) {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ // Allocate a buffer if necessary.
+ char* allocated_buf = NULL;
+ if (buf == NULL) {
+ size_t allocated_size = size;
+ if (size == 0) {
+ // The Linux kernel won't return more than a page, so translate size 0 to 4KiB.
+ // TODO: if we need to support paths longer than that, we'll have to walk the tree ourselves.
+ size = getpagesize();
+ }
+ buf = allocated_buf = reinterpret_cast<char*>(malloc(allocated_size));
+ if (buf == NULL) {
+ // malloc set errno.
+ return NULL;
+ }
+ }
+
+ // Ask the kernel to fill our buffer.
+ int rc = __getcwd(buf, size);
+ if (rc == -1) {
+ free(allocated_buf);
+ // __getcwd set errno.
+ return NULL;
+ }
+
+ // If we allocated a whole page, only return as large an allocation as necessary.
+ if (allocated_buf != NULL) {
+ if (size == 0) {
+ buf = strdup(allocated_buf);
+ free(allocated_buf);
+ } else {
+ buf = allocated_buf;
+ }
+ }
+
+ return buf;
+}