MappedFile and FileMap should support zero-length mappings.
Bug: http://b/119818070 "app crashes when reading asset of zero length"
Test: ran tests
Change-Id: Idd2ad6f6e72c8e445aff78a460fac96dea41c950
diff --git a/libutils/FileMap.cpp b/libutils/FileMap.cpp
index 5feb2aa..1202c15 100644
--- a/libutils/FileMap.cpp
+++ b/libutils/FileMap.cpp
@@ -174,12 +174,6 @@
return false;
}
#else // !defined(__MINGW32__)
- int prot, flags, adjust;
- off64_t adjOffset;
- size_t adjLength;
-
- void* ptr;
-
assert(fd >= 0);
assert(offset >= 0);
assert(length > 0);
@@ -193,20 +187,23 @@
}
}
- adjust = offset % mPageSize;
- adjOffset = offset - adjust;
- adjLength = length + adjust;
+ int adjust = offset % mPageSize;
+ off64_t adjOffset = offset - adjust;
+ size_t adjLength = length + adjust;
- flags = MAP_SHARED;
- prot = PROT_READ;
- if (!readOnly)
- prot |= PROT_WRITE;
+ int flags = MAP_SHARED;
+ int prot = PROT_READ;
+ if (!readOnly) prot |= PROT_WRITE;
- ptr = mmap(nullptr, adjLength, prot, flags, fd, adjOffset);
+ void* ptr = mmap(nullptr, adjLength, prot, flags, fd, adjOffset);
if (ptr == MAP_FAILED) {
- ALOGE("mmap(%lld,%zu) failed: %s\n",
- (long long)adjOffset, adjLength, strerror(errno));
- return false;
+ if (errno == EINVAL && length == 0) {
+ ptr = nullptr;
+ adjust = 0;
+ } else {
+ ALOGE("mmap(%lld,%zu) failed: %s\n", (long long)adjOffset, adjLength, strerror(errno));
+ return false;
+ }
}
mBasePtr = ptr;
#endif // !defined(__MINGW32__)
@@ -217,8 +214,6 @@
mDataPtr = (char*) mBasePtr + adjust;
mDataLength = length;
- assert(mBasePtr != NULL);
-
ALOGV("MAP: base %p/%zu data %p/%zu\n",
mBasePtr, mBaseLength, mDataPtr, mDataLength);
diff --git a/libutils/tests/Android.bp b/libutils/tests/Android.bp
index 1390552..62f5acb 100644
--- a/libutils/tests/Android.bp
+++ b/libutils/tests/Android.bp
@@ -22,6 +22,7 @@
srcs: [
"BitSet_test.cpp",
+ "FileMap_test.cpp",
"LruCache_test.cpp",
"Mutex_test.cpp",
"Singleton_test.cpp",
diff --git a/libutils/tests/FileMap_test.cpp b/libutils/tests/FileMap_test.cpp
new file mode 100644
index 0000000..576d89b
--- /dev/null
+++ b/libutils/tests/FileMap_test.cpp
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "utils/FileMap.h"
+
+#include <gtest/gtest.h>
+
+#include "android-base/file.h"
+
+TEST(FileMap, zero_length_mapping) {
+ // http://b/119818070 "app crashes when reading asset of zero length".
+ // mmap fails with EINVAL for a zero length region.
+ TemporaryFile tf;
+ ASSERT_TRUE(tf.fd != -1);
+
+ android::FileMap m;
+ ASSERT_TRUE(m.create("test", tf.fd, 4096, 0, true));
+ ASSERT_STREQ("test", m.getFileName());
+ ASSERT_EQ(0u, m.getDataLength());
+ ASSERT_EQ(4096, m.getDataOffset());
+}