void copy_to_buffer(const char *Ptr, size_t Size);
};
+/// An abstract base class for streams implementations that also support a
+/// 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 {
+public:
+ using raw_ostream::raw_ostream;
+ virtual void pwrite(const char *Ptr, size_t Size, uint64_t Offset) = 0;
+};
+
//===----------------------------------------------------------------------===//
// File Output Streams
//===----------------------------------------------------------------------===//
/// A raw_ostream that writes to a file descriptor.
///
-class raw_fd_ostream : public raw_ostream {
+class raw_fd_ostream : public raw_pwrite_stream {
int FD;
bool ShouldClose;
/// 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.
///
/// A raw_ostream that writes to an SmallVector or SmallString. This is a
/// simple adaptor class. This class does not encounter output errors.
-class raw_svector_ostream : public raw_ostream {
+class raw_svector_ostream : public raw_pwrite_stream {
SmallVectorImpl<char> &OS;
/// See raw_ostream::write_impl.
/// Return the current position within the stream, not counting the bytes
/// currently in the buffer.
uint64_t current_pos() const override;
+
+protected:
+ // Like the regular constructor, but doesn't call init.
+ explicit raw_svector_ostream(SmallVectorImpl<char> &O, unsigned);
+ void init();
+
public:
/// Construct a new raw_svector_ostream.
///
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
/// raw_svector_ostream has previously been flushed.
};
/// A raw_ostream that discards all output.
-class raw_null_ostream : public raw_ostream {
+class raw_null_ostream : public raw_pwrite_stream {
/// See raw_ostream::write_impl.
void write_impl(const char *Ptr, size_t size) override;
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 {
+ raw_ostream &OS;
+ SmallVector<char, 0> Buffer;
+
+public:
+ buffer_ostream(raw_ostream &OS) : raw_svector_ostream(Buffer, 0), OS(OS) {
+ init();
+ }
+ ~buffer_ostream() { OS << str(); }
};
} // end llvm namespace
/// FD is the file descriptor that this writes to. If ShouldClose is true, this
/// closes the file when the stream is destroyed.
raw_fd_ostream::raw_fd_ostream(int fd, bool shouldClose, bool unbuffered)
- : raw_ostream(unbuffered), FD(fd),
- ShouldClose(shouldClose), Error(false), UseAtomicWrites(false) {
+ : raw_pwrite_stream(unbuffered), FD(fd), ShouldClose(shouldClose),
+ Error(false), UseAtomicWrites(false) {
if (FD < 0 ) {
ShouldClose = false;
return;
return pos;
}
+void raw_fd_ostream::pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
+ uint64_t Pos = tell();
+ seek(Offset);
+ write(Ptr, Size);
+ seek(Pos);
+}
+
size_t raw_fd_ostream::preferred_buffer_size() const {
#if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(__minix)
// Windows and Minix have no st_blksize.
// capacity. This allows raw_ostream to write directly into the correct place,
// and we only need to set the vector size when the data is flushed.
+raw_svector_ostream::raw_svector_ostream(SmallVectorImpl<char> &O, unsigned)
+ : OS(O) {}
+
raw_svector_ostream::raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
+ init();
+}
+
+void raw_svector_ostream::init() {
// Set up the initial external buffer. We make sure that the buffer has at
// least 128 bytes free; raw_ostream itself only requires 64, but we want to
// make sure that we don't grow the buffer unnecessarily on destruction (when
flush();
}
+void raw_svector_ostream::pwrite(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);
+}
+
/// resync - 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 raw_svector_ostream has previously been flushed.
uint64_t raw_null_ostream::current_pos() const {
return 0;
}
+
+void raw_null_ostream::pwrite(const char *Ptr, size_t Size, uint64_t Offset) {}
--- /dev/null
+//===- raw_pwrite_stream_test.cpp - raw_pwrite_stream tests ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(raw_pwrite_ostreamTest, TestSVector) {
+ SmallString<64> Buffer;
+ raw_svector_ostream OS(Buffer);
+ StringRef Test = "test";
+ OS.pwrite(Test.data(), Test.size(), 0);
+ EXPECT_EQ(Test, OS.str());
+}
+}
OSDN Git Service
