llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-llvm-support Author: None (llvmbot) <details> <summary>Changes</summary> Backport 85cd3d9 Requested by: @<!-- -->zygoloid --- Full diff: https://github.com/llvm/llvm-project/pull/153486.diff 1 Files Affected: - (modified) llvm/lib/Support/MemoryBuffer.cpp (+8-2) ``````````diff diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp index 601f11f6d23c8..1c4645ad83641 100644 --- a/llvm/lib/Support/MemoryBuffer.cpp +++ b/llvm/lib/Support/MemoryBuffer.cpp @@ -501,8 +501,14 @@ getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize, std::unique_ptr<MB> Result( new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>( RequiresNullTerminator, FD, MapSize, Offset, EC)); - if (!EC) - return std::move(Result); + if (!EC) { + // On at least Linux, and possibly on other systems, mmap may return pages + // from the page cache that are not properly filled with trailing zeroes, + // if some prior user of the page wrote non-zero bytes. Detect this and + // don't use mmap in that case. + if (!RequiresNullTerminator || *Result->getBufferEnd() == '\0') + return std::move(Result); + } } #ifdef __MVS__ `````````` </details> https://github.com/llvm/llvm-project/pull/153486 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
