Support HTTP test-server based net unit tests on Android.

tools/android/forwarder2/common.h

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