Encapsulate file mapping in preparation for providing a Windows imple…

…mentation.

Progress on #276.

--
MOS_MIGRATED_REVID=114740700

third_party/ijar/BUILD

@@ -15,9 +15,13 @@ filegroup(
 
 cc_library(
     name = "zip",
-    srcs = ["zip.cc"],
+    srcs = [
+        "mapped_file_unix.cc",
+        "zip.cc",
+    ],
     hdrs = [
         "common.h",
+        "mapped_file.h",
         "zip.h",
     ],
     # TODO(bazel-team): we should replace the -lz flag, it is non-hermetic.

third_party/ijar/mapped_file.h

@@ -0,0 +1,82 @@
+// Copyright 2015 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDED_THIRD_PARTY_IJAR_MAPPED_FILE_H
+#define INCLUDED_THIRD_PARTY_IJAR_MAPPED_FILE_H
+
+#include "third_party/ijar/common.h"
+
+namespace devtools_ijar {
+
+class MappedInputFileImpl;
+class MappedOutputFileImpl;
+
+// A memory mapped input file.
+class MappedInputFile {
+ private:
+  MappedInputFileImpl *impl_;
+
+ protected:
+  const char* errmsg_;
+  bool opened_;
+  u1* buffer_;
+  size_t length_;
+
+ public:
+  MappedInputFile(const char* name);
+  virtual ~MappedInputFile();
+
+  // If opening the file succeeded or not.
+  bool Opened() const { return opened_; }
+
+  // Description of the last error that happened.
+  const char* Error() const { return errmsg_; }
+
+  // The mapped contents of the file.
+  u1* Buffer() const { return buffer_ ; }
+
+  // The length of the file.
+  size_t Length() const { return length_; }
+
+  // Unmap a given number of bytes from the beginning of the file.
+  void Discard(size_t bytes);
+  int Close();
+};
+
+class MappedOutputFile {
+ private:
+  MappedOutputFileImpl *impl_;
+
+ protected:
+  const char* errmsg_;
+  bool opened_;
+  u1* buffer_;
+
+ public:
+  MappedOutputFile(const char* name, u8 estimated_size);
+  virtual ~MappedOutputFile();
+
+  // If opening the file succeeded or not.
+  bool Opened() const { return opened_; }
+
+  // Description of the last error that happened.
+  const char* Error() const { return errmsg_; }
+
+  // The mapped contents of the file.
+  u1* Buffer() const { return buffer_; }
+  int Close(int size);
+};
+
+}  // namespace devtools_ijar
+#endif

third_party/ijar/mapped_file_unix.cc

@@ -0,0 +1,147 @@
+// Copyright 2015 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include <algorithm>
+
+#include "third_party/ijar/mapped_file.h"
+
+#define MAX_ERROR 2048
+
+namespace devtools_ijar {
+
+static char errmsg[MAX_ERROR];
+
+struct MappedInputFileImpl {
+  size_t discarded_;
+  int fd_;
+};
+
+MappedInputFile::MappedInputFile(const char* name) {
+  impl_ = NULL;
+  opened_ = false;
+
+  int fd = open(name, O_RDONLY);
+  if (fd < 0) {
+    snprintf(errmsg, MAX_ERROR, "open(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return;
+  }
+
+  off_t length = lseek(fd, 0, SEEK_END);
+  if (length < 0) {
+    snprintf(errmsg, MAX_ERROR, "lseek(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return;
+  }
+
+  void* buffer = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
+  if (buffer == MAP_FAILED) {
+    snprintf(errmsg, MAX_ERROR, "mmap(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return;
+  }
+
+  impl_ = new MappedInputFileImpl();
+  impl_->fd_ = fd;
+  impl_->discarded_ = 0;
+  buffer_ = reinterpret_cast<u1*>(buffer);
+  length_ = length;
+  opened_ = true;
+}
+
+MappedInputFile::~MappedInputFile() {
+  delete impl_;
+}
+
+void MappedInputFile::Discard(size_t bytes) {
+  munmap(buffer_ + impl_->discarded_, bytes);
+  impl_->discarded_ += bytes;
+}
+
+int MappedInputFile::Close() {
+  if (close(impl_->fd_) < 0) {
+    snprintf(errmsg, MAX_ERROR, "close(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return -1;
+  }
+
+  return 0;
+}
+
+struct MappedOutputFileImpl {
+  int fd_;
+};
+
+MappedOutputFile::MappedOutputFile(const char* name, u8 estimated_size) {
+  impl_ = NULL;
+  opened_ = false;
+  int fd = open(name, O_CREAT|O_RDWR|O_TRUNC, 0644);
+  if (fd < 0) {
+    snprintf(errmsg, MAX_ERROR, "open(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return;
+  }
+
+  // Create mmap-able sparse file
+  if (ftruncate(fd, estimated_size) < 0) {
+    snprintf(errmsg, MAX_ERROR, "ftruncate(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return;
+  }
+
+  // Ensure that any buffer overflow in JarStripper will result in
+  // SIGSEGV or SIGBUS by over-allocating beyond the end of the file.
+  size_t mmap_length = std::min(estimated_size + sysconf(_SC_PAGESIZE),
+                                (u8) std::numeric_limits<size_t>::max());
+  void* mapped = mmap(NULL, mmap_length, PROT_WRITE, MAP_SHARED, fd, 0);
+  if (mapped == MAP_FAILED) {
+    snprintf(errmsg, MAX_ERROR, "mmap(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return;
+  }
+
+  impl_ = new MappedOutputFileImpl();
+  impl_->fd_ = fd;
+  buffer_ = reinterpret_cast<u1*>(mapped);
+  opened_ = true;
+}
+
+
+MappedOutputFile::~MappedOutputFile() {
+  delete impl_;
+}
+
+int MappedOutputFile::Close(int size) {
+  if (ftruncate(impl_->fd_, size) < 0) {
+    snprintf(errmsg, MAX_ERROR, "ftruncate(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return -1;
+  }
+
+  if (close(impl_->fd_) < 0) {
+    snprintf(errmsg, MAX_ERROR, "close(): %s", strerror(errno));
+    errmsg_ = errmsg;
+    return -1;
+  }
+
+  return 0;
+}
+
+}  // namespace devtools_ijar