Refactor code in preparation of merging with the fork in Chromium OS.

This patch is part of a bigger patch that helps merging the breakpad code
with the modified version in Chromium OS.

Specifically, this patch makes the following changes:
1. Add a MemoryRange class for encapsulating and checking read access
   to a contiguous range of memory.
2. Add a MemoryMappedFile class for mapping a file into memory for
   read-only access.
3. Refactor other source code to use MemoryMappedFile.

BUG=455
TEST=Tested the following:
1. Build on 32-bit and 64-bit Linux with gcc 4.4.3 and gcc 4.6.
2. Build on Mac OS X 10.6.8 with gcc 4.2 and clang 3.0 (with latest gmock).
3. All unit tests pass.
4. Run minidump-2-core to covnert a minidump file to a core file.
Review URL: http://breakpad.appspot.com/332001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@895 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 102 insertions, 0 deletions

diff --git a/src/common/linux/memory_mapped_file.cc b/src/common/linux/memory_mapped_file.cc
new file mode 100644
index 00000000..6f450bd3
--- /dev/null
+++ b/src/common/linux/memory_mapped_file.cc
@@ -0,0 +1,102 @@
+// Copyright (c) 2011, 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.
+
+// memory_mapped_file.cc: Implement google_breakpad::MemoryMappedFile.
+// See memory_mapped_file.h for details.
+
+#include "common/linux/memory_mapped_file.h"
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "common/memory_range.h"
+#include "third_party/lss/linux_syscall_support.h"
+
+namespace google_breakpad {
+
+MemoryMappedFile::MemoryMappedFile() {}
+
+MemoryMappedFile::MemoryMappedFile(const char* path) {
+  Map(path);
+}
+
+MemoryMappedFile::~MemoryMappedFile() {
+  Unmap();
+}
+
+bool MemoryMappedFile::Map(const char* path) {
+  Unmap();
+
+  int fd = sys_open(path, O_RDONLY, 0);
+  if (fd == -1) {
+    return false;
+  }
+
+#if defined(__x86_64__)
+  struct kernel_stat st;
+  if (sys_fstat(fd, &st) == -1 || st.st_size < 0) {
+#else
+  struct kernel_stat64 st;
+  if (sys_fstat64(fd, &st) == -1 || st.st_size < 0) {
+#endif
+    sys_close(fd);
+    return false;
+  }
+
+  // If the file size is zero, simply use an empty MemoryRange and return
+  // true. Don't bother to call mmap() even though mmap() can handle an
+  // empty file on some platforms.
+  if (st.st_size == 0) {
+    sys_close(fd);
+    return true;
+  }
+
+#if defined(__x86_64__)
+  void* data = sys_mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+#else
+  void* data = sys_mmap2(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+#endif
+  sys_close(fd);
+  if (data == MAP_FAILED) {
+    return false;
+  }
+
+  content_.Set(data, st.st_size);
+  return true;
+}
+
+void MemoryMappedFile::Unmap() {
+  if (content_.data()) {
+    sys_munmap(const_cast<u_int8_t*>(content_.data()), content_.length());
+    content_.Set(NULL, 0);
+  }
+}
+
+}  // namespace google_breakpad