[PATCH] D79338: [Support] Allow FileOutputBuffer::create to create an empty file
Fangrui Song via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon May 4 10:10:27 PDT 2020
MaskRay created this revision.
MaskRay added reviewers: dblaikie, jhenderson.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a reviewer: alexshap.
Herald added a project: LLVM.
Size==0 triggers `assert(Size != 0)` in mapped_file_region::init.
I plan to use an empty file in an llvm-objcopy --dump-section patch.
According to POSIX, "If len is zero, mmap() shall fail and no mapping
shall be established." Just specialize case Size=0 to use
createInMemoryBuffer.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D79338
Files:
llvm/lib/Support/FileOutputBuffer.cpp
llvm/unittests/Support/FileOutputBufferTest.cpp
Index: llvm/unittests/Support/FileOutputBufferTest.cpp
===================================================================
--- llvm/unittests/Support/FileOutputBufferTest.cpp
+++ llvm/unittests/Support/FileOutputBufferTest.cpp
@@ -140,6 +140,21 @@
ASSERT_NO_ERROR(fs::file_size(Twine(File5), File5Size));
ASSERT_EQ(File5Size, 8000ULL);
ASSERT_NO_ERROR(fs::remove(File5.str()));
+
+ // TEST 6: Create an empty file.
+ SmallString<128> File6(TestDirectory);
+ File6.append("/file6");
+ {
+ Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
+ FileOutputBuffer::create(File6, 0);
+ ASSERT_NO_ERROR(errorToErrorCode(BufferOrErr.takeError()));
+ ASSERT_NO_ERROR(errorToErrorCode((*BufferOrErr)->commit()));
+ }
+ uint64_t File6Size;
+ ASSERT_NO_ERROR(fs::file_size(Twine(File6), File6Size));
+ ASSERT_EQ(File6Size, 0ULL);
+ ASSERT_NO_ERROR(fs::remove(File6.str()));
+
// Clean up.
ASSERT_NO_ERROR(fs::remove(TestDirectory.str()));
}
Index: llvm/lib/Support/FileOutputBuffer.cpp
===================================================================
--- llvm/lib/Support/FileOutputBuffer.cpp
+++ llvm/lib/Support/FileOutputBuffer.cpp
@@ -172,6 +172,10 @@
if (Flags & F_executable)
Mode |= fs::all_exe;
+ // If Size is zero, don't use mmap which will fail with EINVAL.
+ if (Size == 0)
+ return createInMemoryBuffer(Path, Size, Mode);
+
fs::file_status Stat;
fs::status(Path, Stat);
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