* Added breakpad support for Linux.

thirdparty/breakpad/common/byte_cursor.h

@@ -0,0 +1,263 @@
+// -*- mode: c++ -*-
+
+// Copyright (c) 2010, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
+
+// byte_cursor.h: Classes for parsing values from a buffer of bytes.
+// The ByteCursor class provides a convenient interface for reading
+// fixed-size integers of arbitrary endianness, being thorough about
+// checking for buffer overruns.
+
+#ifndef COMMON_BYTE_CURSOR_H_
+#define COMMON_BYTE_CURSOR_H_
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <string>
+
+namespace google_breakpad {
+
+// A buffer holding a series of bytes.
+struct ByteBuffer {
+  ByteBuffer() : start(0), end(0) { }
+  ByteBuffer(const uint8_t *set_start, size_t set_size)
+      : start(set_start), end(set_start + set_size) { }
+  ~ByteBuffer() { };
+
+  // Equality operators. Useful in unit tests, and when we're using
+  // ByteBuffers to refer to regions of a larger buffer.
+  bool operator==(const ByteBuffer &that) const {
+    return start == that.start && end == that.end;
+  }
+  bool operator!=(const ByteBuffer &that) const {
+    return start != that.start || end != that.end;
+  }
+
+  // Not C++ style guide compliant, but this definitely belongs here.
+  size_t Size() const {
+    assert(start <= end);
+    return end - start;
+  }
+
+  const uint8_t *start, *end;
+};
+
+// A cursor pointing into a ByteBuffer that can parse numbers of various
+// widths and representations, strings, and data blocks, advancing through
+// the buffer as it goes. All ByteCursor operations check that accesses
+// haven't gone beyond the end of the enclosing ByteBuffer.
+class ByteCursor {
+ public:
+  // Create a cursor reading bytes from the start of BUFFER. By default, the
+  // cursor reads multi-byte values in little-endian form.
+  ByteCursor(const ByteBuffer *buffer, bool big_endian = false)
+      : buffer_(buffer), here_(buffer->start), 
+        big_endian_(big_endian), complete_(true) { }
+
+  // Accessor and setter for this cursor's endianness flag.
+  bool big_endian() const { return big_endian_; }
+  void set_big_endian(bool big_endian) { big_endian_ = big_endian; }
+
+  // Accessor and setter for this cursor's current position. The setter
+  // returns a reference to this cursor.
+  const uint8_t *here() const { return here_; }
+  ByteCursor &set_here(const uint8_t *here) {
+    assert(buffer_->start <= here && here <= buffer_->end);
+    here_ = here;
+    return *this;
+  }
+
+  // Return the number of bytes available to read at the cursor.
+  size_t Available() const { return size_t(buffer_->end - here_); }
+
+  // Return true if this cursor is at the end of its buffer.
+  bool AtEnd() const { return Available() == 0; }
+
+  // When used as a boolean value this cursor converts to true if all
+  // prior reads have been completed, or false if we ran off the end
+  // of the buffer.
+  operator bool() const { return complete_; }
+
+  // Read a SIZE-byte integer at this cursor, signed if IS_SIGNED is true,
+  // unsigned otherwise, using the cursor's established endianness, and set
+  // *RESULT to the number. If we read off the end of our buffer, clear
+  // this cursor's complete_ flag, and store a dummy value in *RESULT.
+  // Return a reference to this cursor.
+  template<typename T>
+  ByteCursor &Read(size_t size, bool is_signed, T *result) {
+    if (CheckAvailable(size)) {
+      T v = 0;
+      if (big_endian_) {
+        for (size_t i = 0; i < size; i++)
+          v = (v << 8) + here_[i];
+      } else {
+        // This loop condition looks weird, but size_t is unsigned, so
+        // decrementing i after it is zero yields the largest size_t value.
+        for (size_t i = size - 1; i < size; i--)
+          v = (v << 8) + here_[i];
+      }
+      if (is_signed && size < sizeof(T)) {
+        size_t sign_bit = (T)1 << (size * 8 - 1);
+        v = (v ^ sign_bit) - sign_bit;
+      }
+      here_ += size;
+      *result = v;
+    } else {
+      *result = (T) 0xdeadbeef;
+    }
+    return *this;
+  }
+
+  // Read an integer, using the cursor's established endianness and
+  // *RESULT's size and signedness, and set *RESULT to the number. If we
+  // read off the end of our buffer, clear this cursor's complete_ flag.
+  // Return a reference to this cursor.
+  template<typename T>
+  ByteCursor &operator>>(T &result) {
+    bool T_is_signed = (T)-1 < 0;
+    return Read(sizeof(T), T_is_signed, &result); 
+  }
+
+  // Copy the SIZE bytes at the cursor to BUFFER, and advance this
+  // cursor to the end of them. If we read off the end of our buffer,
+  // clear this cursor's complete_ flag, and set *POINTER to NULL.
+  // Return a reference to this cursor.
+  ByteCursor &Read(uint8_t *buffer, size_t size) {
+    if (CheckAvailable(size)) {
+      memcpy(buffer, here_, size);
+      here_ += size;
+    }
+    return *this;
+  }
+
+  // Set STR to a copy of the '\0'-terminated string at the cursor. If the
+  // byte buffer does not contain a terminating zero, clear this cursor's
+  // complete_ flag, and set STR to the empty string. Return a reference to
+  // this cursor.
+  ByteCursor &CString(std::string *str) {
+    const uint8_t *end
+      = static_cast<const uint8_t *>(memchr(here_, '\0', Available()));
+    if (end) {
+      str->assign(reinterpret_cast<const char *>(here_), end - here_);
+      here_ = end + 1;
+    } else {
+      str->clear();
+      here_ = buffer_->end;
+      complete_ = false;
+    }
+    return *this;
+  }
+
+  // Like CString(STR), but extract the string from a fixed-width buffer
+  // LIMIT bytes long, which may or may not contain a terminating '\0'
+  // byte. Specifically:
+  //
+  // - If there are not LIMIT bytes available at the cursor, clear the
+  //   cursor's complete_ flag and set STR to the empty string.
+  //
+  // - Otherwise, if the LIMIT bytes at the cursor contain any '\0'
+  //   characters, set *STR to a copy of the bytes before the first '\0',
+  //   and advance the cursor by LIMIT bytes.
+  //   
+  // - Otherwise, set *STR to a copy of those LIMIT bytes, and advance the
+  //   cursor by LIMIT bytes.
+  ByteCursor &CString(std::string *str, size_t limit) {
+    if (CheckAvailable(limit)) {
+      const uint8_t *end
+        = static_cast<const uint8_t *>(memchr(here_, '\0', limit));
+      if (end)
+        str->assign(reinterpret_cast<const char *>(here_), end - here_);
+      else
+        str->assign(reinterpret_cast<const char *>(here_), limit);
+      here_ += limit;
+    } else {
+      str->clear();
+    }
+    return *this;
+  }
+
+  // Set *POINTER to point to the SIZE bytes at the cursor, and advance
+  // this cursor to the end of them. If SIZE is omitted, don't move the
+  // cursor. If we read off the end of our buffer, clear this cursor's
+  // complete_ flag, and set *POINTER to NULL. Return a reference to this
+  // cursor.
+  ByteCursor &PointTo(const uint8_t **pointer, size_t size = 0) {
+    if (CheckAvailable(size)) {
+      *pointer = here_;
+      here_ += size;
+    } else {
+      *pointer = NULL;
+    }
+    return *this;
+  }
+
+  // Skip SIZE bytes at the cursor. If doing so would advance us off
+  // the end of our buffer, clear this cursor's complete_ flag, and
+  // set *POINTER to NULL. Return a reference to this cursor.
+  ByteCursor &Skip(size_t size) {
+    if (CheckAvailable(size))
+      here_ += size;
+    return *this;
+  }
+
+ private:
+  // If there are at least SIZE bytes available to read from the buffer,
+  // return true. Otherwise, set here_ to the end of the buffer, set
+  // complete_ to false, and return false.
+  bool CheckAvailable(size_t size) {
+    if (Available() >= size) {
+      return true;
+    } else {
+      here_ = buffer_->end;
+      complete_ = false;
+      return false;
+    }
+  }
+
+  // The buffer we're reading bytes from.
+  const ByteBuffer *buffer_;
+
+  // The next byte within buffer_ that we'll read.
+  const uint8_t *here_;
+
+  // True if we should read numbers in big-endian form; false if we
+  // should read in little-endian form.
+  bool big_endian_;
+
+  // True if we've been able to read all we've been asked to.
+  bool complete_;
+};
+
+}  // namespace google_breakpad
+
+#endif  // COMMON_BYTE_CURSOR_H_