crashpad_database_util: Accept --new-report=- to read a new report from standard input

util/file/file_reader.h

 // Copyright 2015 The Crashpad 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 CRASHPAD_UTIL_FILE_FILE_READER_H_
 #define CRASHPAD_UTIL_FILE_FILE_READER_H_
 
+#include <stdio.h>
 #include <sys/types.h>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "util/file/file_io.h"
 #include "util/file/file_seeker.h"
 
 namespace crashpad {
 
 //! \brief An interface to read to files and other file-like objects with
 //!     semantics matching the underlying platform (POSIX or Windows).
 class FileReaderInterface : public virtual FileSeekerInterface {
  public:
+  virtual ~FileReaderInterface() {}
+
   //! \brief Wraps ReadFile(), or provides an implementation with identical
   //!     semantics.
   //!
   //! \return The number of bytes actually read if the operation succeeded,
   //!     which may be `0` or any positive value less than or equal to \a size.
   //!     `-1` if the operation failed, with an error message logged.
   virtual ssize_t Read(void* data, size_t size) = 0;
 
   //! \brief Wraps Read(), ensuring that the read succeeded and exactly \a size
   //!     bytes were read.
   //!
   //! Semantically, this behaves as LoggingReadFile().
   //!
   //! \return `true` if the operation succeeded, `false` if it failed, with an
   //!     error message logged. Short reads are treated as failures.
   bool ReadExactly(void* data, size_t size);
-
- protected:
-  ~FileReaderInterface() {}
 };
 
 //! \brief A file reader backed by a FileHandle.
 //!
 //! FileReader requires users to provide a FilePath to open, but this class
 //! accepts an already-open FileHandle instead. Like FileReader, this class may
 //! read from a filesystem-based file, but unlike FileReader, this class is not
 //! responsible for opening or closing the file. Users of this class must ensure
 //! that the file handle is closed appropriately elsewhere. Objects of this
 //! class may be used to read from file handles not associated with
 //! filesystem-based files, although special attention should be paid to the
 //! Seek() method, which may not function on file handles that do not refer to
 //! disk-based files.
 //!
 //! This class is expected to be used when other code is responsible for
 //! opening files and already provides file handles.
 class WeakFileHandleFileReader : public FileReaderInterface {
  public:
   explicit WeakFileHandleFileReader(FileHandle file_handle);
-  ~WeakFileHandleFileReader();
+  ~WeakFileHandleFileReader() override;
 
   // FileReaderInterface:
   ssize_t Read(void* data, size_t size) override;
 
   // FileSeekerInterface:
 
   //! \copydoc FileReaderInterface::Seek()
   //!
   //! \note This method is only guaranteed to function on file handles referring
   //!     to disk-based files.
@@ skipping 12 matching lines @@
   friend class FileReader;
 
   DISALLOW_COPY_AND_ASSIGN(WeakFileHandleFileReader);
 };
 
 //! \brief A file reader implementation that wraps traditional system file
 //!     operations on files accessed through the filesystem.
 class FileReader : public FileReaderInterface {
  public:
   FileReader();
-  ~FileReader();
+  ~FileReader() override;
 
   // FileReaderInterface:
 
   //! \brief Wraps LoggingOpenFileForRead().
   //!
   //! \return `true` if the operation succeeded, `false` if it failed, with an
   //!     error message logged.
   //!
   //! \note After a successful call, this method cannot be called again until
   //!     after Close().
@@ skipping 22 matching lines @@
   //!     a Close().
   FileOffset Seek(FileOffset offset, int whence) override;
 
  private:
   ScopedFileHandle file_;
   WeakFileHandleFileReader weak_file_handle_file_reader_;
 
   DISALLOW_COPY_AND_ASSIGN(FileReader);
 };
 
+//! \brief A file reader backed by a standard input/output `FILE*`.
+//!
+//! This class accepts an already-open `FILE*`. It is not responsible for
+//! opening or closing this `FILE*`. Users of this class must ensure that the
+//! `FILE*` is closed appropriately elsewhere. Objects of this class may be used
+//! to read from `FILE*` objects not associated with filesystem-based files,
+//! although special attention should be paid to the Seek() method, which may
+//! not function on `FILE*` objects that do not refer to disk-based files.
+//!
+//! This class is expected to be used when other code is responsible for
+//! opening `FILE*` objects and already provides `FILE*` objects. A good use
+//! would be a WeakStdioFileReader for `stdin`.
+class WeakStdioFileReader : public FileReaderInterface {

[Robert Sesek, 2015/04/23 13:40:13]

Why use this instead of WeakFileHandleReader(STDIN_FILENO) ? 

[Mark Mentovai, 2015/08/06 14:30:08]

Robert Sesek wrote:
I did try WeakFileHandleReader(fileno(stdin)) first, but it didn’t work as well.
It totally misses the EOF when stdin is a terminal:

mark@mela zsh% out/Debug/crashpad_database_util -d /tmp/z --new-report=-  
crash report
^D
[…wait…]

It only hears it when you press ^D twice in a row. Weird. The loop in ReadFile()
gets the whole string on the first attempt, but then goes back to block even
though the ^D should have closed it and the next read should immediately return
0.

+ public:
+  explicit WeakStdioFileReader(FILE* file);
+  ~WeakStdioFileReader() override;
+
+  // FileReaderInterface:
+  ssize_t Read(void* data, size_t size) override;
+
+  // FileSeekerInterface:
+
+  //! \copydoc FileReaderInterface::Seek()
+  //!
+  //! \note This method is only guaranteed to function on `FILE*` objects
+  //!     referring to disk-based files.
+  FileOffset Seek(FileOffset offset, int whence) override;
+
+ private:
+  FILE* file_;  // weak
+
+  DISALLOW_COPY_AND_ASSIGN(WeakStdioFileReader);
+};
+
 }  // namespace crashpad
 
 #endif  // CRASHPAD_UTIL_FILE_FILE_READER_H_