90 lines
2.8 KiB
C++
90 lines
2.8 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Common helper functions/classes used both in the host and device forwarder.
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#ifndef TOOLS_ANDROID_FORWARDER2_COMMON_H_
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#define TOOLS_ANDROID_FORWARDER2_COMMON_H_
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#include <stdarg.h>
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#include <stdio.h>
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#include <errno.h>
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#include "base/basictypes.h"
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#include "base/compiler_specific.h"
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#include "base/logging.h"
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#include "base/posix/eintr_wrapper.h"
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// Preserving errno for Close() is important because the function is very often
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// used in cleanup code, after an error occurred, and it is very easy to pass an
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// invalid file descriptor to close() in this context, or more rarely, a
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// spurious signal might make close() return -1 + setting errno to EINTR,
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// masking the real reason for the original error. This leads to very unpleasant
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// debugging sessions.
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#define PRESERVE_ERRNO_HANDLE_EINTR(Func) \
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do { \
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int local_errno = errno; \
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(void) HANDLE_EINTR(Func); \
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errno = local_errno; \
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} while (false);
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// Wrapper around RAW_LOG() which is signal-safe. The only purpose of this macro
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// is to avoid documenting uses of RawLog().
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#define SIGNAL_SAFE_LOG(Level, Msg) \
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RAW_LOG(Level, Msg);
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namespace forwarder2 {
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// Note that the two following functions are not signal-safe.
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// Chromium logging-aware implementation of libc's perror().
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void PError(const char* msg);
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// Closes the provided file descriptor and logs an error if it failed.
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void CloseFD(int fd);
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// Helps build a formatted C-string allocated in a fixed-size array. This is
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// useful in signal handlers where base::StringPrintf() can't be used safely
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// (due to its use of LOG()).
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template <int BufferSize>
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class FixedSizeStringBuilder {
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public:
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FixedSizeStringBuilder() {
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Reset();
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}
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const char* buffer() const { return buffer_; }
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void Reset() {
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buffer_[0] = 0;
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write_ptr_ = buffer_;
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}
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// Returns the number of bytes appended to the underlying buffer or -1 if it
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// failed.
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int Append(const char* format, ...) PRINTF_FORMAT(/* + 1 for 'this' */ 2, 3) {
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if (write_ptr_ >= buffer_ + BufferSize)
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return -1;
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va_list ap;
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va_start(ap, format);
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const int bytes_written = vsnprintf(
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write_ptr_, BufferSize - (write_ptr_ - buffer_), format, ap);
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va_end(ap);
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if (bytes_written > 0)
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write_ptr_ += bytes_written;
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return bytes_written;
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}
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private:
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char* write_ptr_;
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char buffer_[BufferSize];
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COMPILE_ASSERT(BufferSize >= 1, Size_of_buffer_must_be_at_least_one);
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DISALLOW_COPY_AND_ASSIGN(FixedSizeStringBuilder);
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};
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} // namespace forwarder2
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#endif // TOOLS_ANDROID_FORWARDER2_COMMON_H_
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