Add ZipReader::ExtractCurrentEntry with a delegate interface.

This change gives consumers of ZipReader a way to have the current entry
streamed to them via a Delegate interface. It also:

- Reduces duplication in the ExtractCurrentEntry* functions.
- Uses the heap rather than the stack for intermediate buffers.
- Changes ExtractCurrentEntryToFd to ExtractCurrentEntryToFile, making
  it cross-platform in the process.

BUG=462584

Committed: https://crrev.com/2919be01ff758875fc7161f6b41f4461518c1213
Cr-Commit-Position: refs/heads/master@{#320948}

Review URL: https://codereview.chromium.org/1014653002

Cr-Original-Commit-Position: refs/heads/master@{#321205}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 98e6db00a6cc9cf6df682240d61f1b535b564cb8

1 files changed, 48 insertions, 7 deletions

diff --git a/google/zip_reader.h b/google/zip_reader.h
index 9280f23..da6cc93 100644
--- a/google/zip_reader.h
+++ b/google/zip_reader.h
@@ -23,6 +23,21 @@
 
 namespace zip {
 
+// A delegate interface used to stream out an entry; see
+// ZipReader::ExtractCurrentEntry.
+class WriterDelegate {
+ public:
+  virtual ~WriterDelegate() {}
+
+  // Invoked once before any data is streamed out to pave the way (e.g., to open
+  // the output file). Return false on failure to cancel extraction.
+  virtual bool PrepareOutput() = 0;
+
+  // Invoked to write the next chunk of data. Return false on failure to cancel
+  // extraction.
+  virtual bool WriteBytes(const char* data, int num_bytes) = 0;
+};
+
 // This class is used for reading zip files. A typical use case of this
 // class is to scan entries in a zip file and extract them. The code will
 // look like:
@@ -141,6 +156,9 @@ class ZipReader {
   // success. On failure, current_entry_info() becomes NULL.
   bool LocateAndOpenEntry(const base::FilePath& path_in_zip);
 
+  // Extracts the current entry in chunks to |delegate|.
+  bool ExtractCurrentEntry(WriterDelegate* delegate) const;
+
   // Extracts the current entry to the given output file path. If the
   // current file is a directory, just creates a directory
   // instead. Returns true on success. OpenCurrentEntryInZip() must be
@@ -148,7 +166,8 @@ class ZipReader {
   //
   // This function preserves the timestamp of the original entry. If that
   // timestamp is not valid, the timestamp will be set to the current time.
-  bool ExtractCurrentEntryToFilePath(const base::FilePath& output_file_path);
+  bool ExtractCurrentEntryToFilePath(
+      const base::FilePath& output_file_path) const;
 
   // Asynchronously extracts the current entry to the given output file path.
   // If the current entry is a directory it just creates the directory
@@ -174,13 +193,11 @@ class ZipReader {
   // This function preserves the timestamp of the original entry. If that
   // timestamp is not valid, the timestamp will be set to the current time.
   bool ExtractCurrentEntryIntoDirectory(
-      const base::FilePath& output_directory_path);
+      const base::FilePath& output_directory_path) const;
 
-#if defined(OS_POSIX)
-  // Extracts the current entry by writing directly to a file descriptor.
-  // Does not close the file descriptor. Returns true on success.
-  bool ExtractCurrentEntryToFd(int fd);
-#endif
+  // Extracts the current entry by writing directly to a platform file.
+  // Does not close the file. Returns true on success.
+  bool ExtractCurrentEntryToFile(base::File* file) const;
 
   // Extracts the current entry into memory. If the current entry is a directory
   // the |output| parameter is set to the empty string. If the current entry is
@@ -232,6 +249,30 @@ class ZipReader {
   DISALLOW_COPY_AND_ASSIGN(ZipReader);
 };
 
+// A writer delegate that writes to a given File.
+class FileWriterDelegate : public WriterDelegate {
+ public:
+  explicit FileWriterDelegate(base::File* file);
+
+  // Truncates the file to the number of bytes written.
+  ~FileWriterDelegate() override;
+
+  // WriterDelegate methods:
+
+  // Seeks to the beginning of the file, returning false if the seek fails.
+  bool PrepareOutput() override;
+
+  // Writes |num_bytes| bytes of |data| to the file, returning false on error or
+  // if not all bytes could be written.
+  bool WriteBytes(const char* data, int num_bytes) override;
+
+ private:
+  base::File* file_;
+  int64_t file_length_;
+
+  DISALLOW_COPY_AND_ASSIGN(FileWriterDelegate);
+};
+
 }  // namespace zip
 
 #endif  // THIRD_PARTY_ZLIB_GOOGLE_ZIP_READER_H_