[llvm] r235303 - Don't allow pwrite to resize a stream.
Rafael Espindola
rafael.espindola at gmail.com
Mon Apr 20 06:04:30 PDT 2015
Author: rafael
Date: Mon Apr 20 08:04:30 2015
New Revision: 235303
URL: http://llvm.org/viewvc/llvm-project?rev=235303&view=rev
Log:
Don't allow pwrite to resize a stream.
The current implementations could exhibit some behavior differences:
raw_fd_ostream: Whatever the underlying fd does with seek+write. In a normal
file, the write position would be back to the old offset.
raw_svector_ostream: The write position is always the end of the stream, so
after pwrite the write position would be the new end. This matches what OS_X
(all BSD?) do with a pwrite in a O_APPEND fd.
Given that we don't need that feature and don't use O_APPEND a lot in LLVM,
just disallow it.
I am open to suggestions on renaming pwrite to something else, but this fixes
the issue for now.
Thanks to Yaron Keren for reporting it.
Modified:
llvm/trunk/include/llvm/Support/raw_ostream.h
llvm/trunk/lib/Support/raw_ostream.cpp
llvm/trunk/unittests/Support/raw_pwrite_stream_test.cpp
Modified: llvm/trunk/include/llvm/Support/raw_ostream.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/raw_ostream.h?rev=235303&r1=235302&r2=235303&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/raw_ostream.h (original)
+++ llvm/trunk/include/llvm/Support/raw_ostream.h Mon Apr 20 08:04:30 2015
@@ -317,10 +317,15 @@ private:
/// pwrite operation. This is usefull for code that can mostly stream out data,
/// but needs to patch in a header that needs to know the output size.
class raw_pwrite_stream : public raw_ostream {
+ virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0;
+
public:
explicit raw_pwrite_stream(bool Unbuffered = false)
: raw_ostream(Unbuffered) {}
- virtual void pwrite(const char *Ptr, size_t Size, uint64_t Offset) = 0;
+ void pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
+ assert(Size + Offset <= tell() && "We don't support extending the stream");
+ pwrite_impl(Ptr, Size, Offset);
+ }
};
//===----------------------------------------------------------------------===//
@@ -348,6 +353,8 @@ class raw_fd_ostream : public raw_pwrite
/// See raw_ostream::write_impl.
void write_impl(const char *Ptr, size_t Size) override;
+ void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
+
/// Return the current position within the stream, not counting the bytes
/// currently in the buffer.
uint64_t current_pos() const override { return pos; }
@@ -388,8 +395,6 @@ public:
/// to the offset specified from the beginning of the file.
uint64_t seek(uint64_t off);
- void pwrite(const char *Ptr, size_t Size, uint64_t Offset) override;
-
/// Set the stream to attempt to use atomic writes for individual output
/// routines where possible.
///
@@ -478,6 +483,8 @@ class raw_svector_ostream : public raw_p
/// See raw_ostream::write_impl.
void write_impl(const char *Ptr, size_t Size) override;
+ void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
+
/// Return the current position within the stream, not counting the bytes
/// currently in the buffer.
uint64_t current_pos() const override;
@@ -495,7 +502,6 @@ public:
explicit raw_svector_ostream(SmallVectorImpl<char> &O);
~raw_svector_ostream() override;
- void pwrite(const char *Ptr, size_t Size, uint64_t Offset) override;
/// This is called when the SmallVector we're appending to is changed outside
/// of the raw_svector_ostream's control. It is only safe to do this if the
@@ -511,6 +517,7 @@ public:
class raw_null_ostream : public raw_pwrite_stream {
/// See raw_ostream::write_impl.
void write_impl(const char *Ptr, size_t size) override;
+ void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
/// Return the current position within the stream, not counting the bytes
/// currently in the buffer.
@@ -519,7 +526,6 @@ class raw_null_ostream : public raw_pwri
public:
explicit raw_null_ostream() {}
~raw_null_ostream() override;
- void pwrite(const char *Ptr, size_t Size, uint64_t Offset) override;
};
class buffer_ostream : public raw_svector_ostream {
Modified: llvm/trunk/lib/Support/raw_ostream.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=235303&r1=235302&r2=235303&view=diff
==============================================================================
--- llvm/trunk/lib/Support/raw_ostream.cpp (original)
+++ llvm/trunk/lib/Support/raw_ostream.cpp Mon Apr 20 08:04:30 2015
@@ -630,7 +630,8 @@ uint64_t raw_fd_ostream::seek(uint64_t o
return pos;
}
-void raw_fd_ostream::pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
+void raw_fd_ostream::pwrite_impl(const char *Ptr, size_t Size,
+ uint64_t Offset) {
uint64_t Pos = tell();
seek(Offset);
write(Ptr, Size);
@@ -781,14 +782,9 @@ raw_svector_ostream::~raw_svector_ostrea
flush();
}
-void raw_svector_ostream::pwrite(const char *Ptr, size_t Size,
- uint64_t Offset) {
+void raw_svector_ostream::pwrite_impl(const char *Ptr, size_t Size,
+ uint64_t Offset) {
flush();
-
- uint64_t End = Offset + Size;
- if (End > OS.size())
- OS.resize(End);
-
memcpy(OS.begin() + Offset, Ptr, Size);
}
@@ -847,4 +843,5 @@ uint64_t raw_null_ostream::current_pos()
return 0;
}
-void raw_null_ostream::pwrite(const char *Ptr, size_t Size, uint64_t Offset) {}
+void raw_null_ostream::pwrite_impl(const char *Ptr, size_t Size,
+ uint64_t Offset) {}
Modified: llvm/trunk/unittests/Support/raw_pwrite_stream_test.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/raw_pwrite_stream_test.cpp?rev=235303&r1=235302&r2=235303&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/raw_pwrite_stream_test.cpp (original)
+++ llvm/trunk/unittests/Support/raw_pwrite_stream_test.cpp Mon Apr 20 08:04:30 2015
@@ -16,10 +16,18 @@ using namespace llvm;
namespace {
TEST(raw_pwrite_ostreamTest, TestSVector) {
- SmallString<64> Buffer;
+ SmallVector<char, 0> Buffer;
raw_svector_ostream OS(Buffer);
+ OS << "abcd";
StringRef Test = "test";
OS.pwrite(Test.data(), Test.size(), 0);
EXPECT_EQ(Test, OS.str());
+
+#ifdef GTEST_HAS_DEATH_TEST
+#ifndef NDEBUG
+ EXPECT_DEATH(OS.pwrite("12345", 5, 0),
+ "We don't support extending the stream");
+#endif
+#endif
}
}
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