[llvm] r297624 - Fix crash when multiple raw_fd_ostreams to stdout are created.
Rafael Espindola via llvm-commits
llvm-commits at lists.llvm.org
Mon Mar 13 07:45:07 PDT 2017
Author: rafael
Date: Mon Mar 13 09:45:06 2017
New Revision: 297624
URL: http://llvm.org/viewvc/llvm-project?rev=297624&view=rev
Log:
Fix crash when multiple raw_fd_ostreams to stdout are created.
If raw_fd_ostream is constructed with the path of "-", it claims
ownership of the stdout file descriptor. This means that it closes
stdout when it is destroyed. If there are multiple users of
raw_fd_ostream wrapped around stdout, then a crash can occur because
of operations on a closed stream.
An example of this would be running something like "clang -S -o - -MD
-MF - test.cpp". Alternatively, using outs() (which creates a local
version of raw_fd_stream to stdout) anywhere combined with such a
stream usage would cause the crash.
The fix duplicates the stdout file descriptor when used within
raw_fd_ostream, so that only that particular descriptor is closed when
the stream is destroyed.
Patch by James Henderson!
Added:
llvm/trunk/test/Other/writing-to-stdout.ll
Modified:
llvm/trunk/lib/Support/raw_ostream.cpp
llvm/trunk/unittests/Support/raw_ostream_test.cpp
Modified: llvm/trunk/lib/Support/raw_ostream.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=297624&r1=297623&r2=297624&view=diff
==============================================================================
--- llvm/trunk/lib/Support/raw_ostream.cpp (original)
+++ llvm/trunk/lib/Support/raw_ostream.cpp Mon Mar 13 09:45:06 2017
@@ -473,7 +473,7 @@ static int getFD(StringRef Filename, std
// possible.
if (!(Flags & sys::fs::F_Text))
sys::ChangeStdoutToBinary();
- return STDOUT_FILENO;
+ return dup(STDOUT_FILENO);
}
int FD;
Added: llvm/trunk/test/Other/writing-to-stdout.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Other/writing-to-stdout.ll?rev=297624&view=auto
==============================================================================
--- llvm/trunk/test/Other/writing-to-stdout.ll (added)
+++ llvm/trunk/test/Other/writing-to-stdout.ll Mon Mar 13 09:45:06 2017
@@ -0,0 +1,14 @@
+; Often LLVM tools use "-" to indicate that output should be written to stdout
+; instead of a file. This behaviour is implemented by the raw_fd_ostream class.
+; This test verifies that when doing so multiple times we don't try to access a
+; closed STDOUT_FILENO. The exact options used in this test are unimportant, as
+; long as they write to stdout using raw_fd_ostream.
+; RUN: llc %s -o=- -pass-remarks-output=- -filetype=asm | FileCheck %s
+; foobar should appear as a function somewhere in the assembly file.
+; CHECK: foobar
+; !Analysis appears at the start of pass-remarks-output.
+; CHECK: !Analysis
+
+define void @foobar() {
+ ret void
+}
Modified: llvm/trunk/unittests/Support/raw_ostream_test.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/raw_ostream_test.cpp?rev=297624&r1=297623&r2=297624&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/raw_ostream_test.cpp (original)
+++ llvm/trunk/unittests/Support/raw_ostream_test.cpp Mon Mar 13 09:45:06 2017
@@ -9,6 +9,7 @@
#include "gtest/gtest.h"
#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
@@ -330,4 +331,11 @@ TEST(raw_ostreamTest, FormattedHexBytes)
"0007: 68 69 6a 6b 6c |hijkl|",
format_bytes_with_ascii_str(B.take_front(12), 0, 7, 1));
}
+
+TEST(raw_fd_ostreamTest, multiple_raw_fd_ostream_to_stdout) {
+ std::error_code EC;
+
+ { raw_fd_ostream("-", EC, sys::fs::OpenFlags::F_None); }
+ { raw_fd_ostream("-", EC, sys::fs::OpenFlags::F_None); }
+}
}
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