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/base/mapped_file.cpp b/base/mapped_file.cpp
index f7901af..faa845d 100644
--- a/base/mapped_file.cpp
+++ b/base/mapped_file.cpp
@@ -16,6 +16,8 @@
#include "android-base/mapped_file.h"
+#include <errno.h>
+
namespace android {
namespace base {
@@ -50,7 +52,14 @@
new MappedFile{static_cast<char*>(base), length, slop, handle});
#else
void* base = mmap(nullptr, file_length, prot, MAP_SHARED, fd, file_offset);
- if (base == MAP_FAILED) return nullptr;
+ if (base == MAP_FAILED) {
+ // http://b/119818070 "app crashes when reading asset of zero length".
+ // mmap fails with EINVAL for a zero length region.
+ if (errno == EINVAL && length == 0) {
+ return std::unique_ptr<MappedFile>(new MappedFile{nullptr, 0, 0});
+ }
+ return nullptr;
+ }
return std::unique_ptr<MappedFile>(new MappedFile{static_cast<char*>(base), length, slop});
#endif
}
diff --git a/base/mapped_file_test.cpp b/base/mapped_file_test.cpp
index 7e89723..cfde73c 100644
--- a/base/mapped_file_test.cpp
+++ b/base/mapped_file_test.cpp
@@ -25,7 +25,6 @@
#include <string>
#include "android-base/file.h"
-#include "android-base/unique_fd.h"
TEST(mapped_file, smoke) {
TemporaryFile tf;
@@ -37,3 +36,13 @@
ASSERT_EQ('l', m->data()[0]);
ASSERT_EQ('o', m->data()[1]);
}
+
+TEST(mapped_file, 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);
+
+ auto m = android::base::MappedFile::FromFd(tf.fd, 4096, 0, PROT_READ);
+ ASSERT_EQ(0u, m->size());
+}