/*
* Copyright (C) 2003-2014 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_INPUT_STREAM_HXX
#define MPD_INPUT_STREAM_HXX
#include "check.h"
#include "thread/Mutex.hxx"
#include "Compiler.h"
#include <string>
#include <assert.h>
#include <stdint.h>
class Cond;
class Error;
struct Tag;
class InputStream {
public:
typedef uint64_t offset_type;
private:
/**
* The absolute URI which was used to open this stream.
*/
std::string uri;
public:
/**
* A mutex that protects the mutable attributes of this object
* and its implementation. It must be locked before calling
* any of the public methods.
*
* This object is allocated by the client, and the client is
* responsible for freeing it.
*/
Mutex &mutex;
/**
* A cond that gets signalled when the state of this object
* changes from the I/O thread. The client of this object may
* wait on it. Optional, may be nullptr.
*
* This object is allocated by the client, and the client is
* responsible for freeing it.
*/
Cond &cond;
protected:
/**
* indicates whether the stream is ready for reading and
* whether the other attributes in this struct are valid
*/
bool ready;
/**
* if true, then the stream is fully seekable
*/
bool seekable;
static constexpr offset_type UNKNOWN_SIZE = -1;
/**
* the size of the resource, or #UNKNOWN_SIZE if unknown
*/
offset_type size;
/**
* the current offset within the stream
*/
offset_type offset;
private:
/**
* the MIME content type of the resource, or empty if unknown.
*/
std::string mime;
public:
InputStream(const char *_uri, Mutex &_mutex, Cond &_cond)
:uri(_uri),
mutex(_mutex), cond(_cond),
ready(false), seekable(false),
size(UNKNOWN_SIZE), offset(0) {
assert(_uri != nullptr);
}
/**
* Close the input stream and free resources.
*
* The caller must not lock the mutex.
*/
virtual ~InputStream();
/**
* Opens a new input stream. You may not access it until the "ready"
* flag is set.
*
* @param mutex a mutex that is used to protect this object; must be
* locked before calling any of the public methods
* @param cond a cond that gets signalled when the state of
* this object changes; may be nullptr if the caller doesn't want to get
* notifications
* @return an #InputStream object on success, nullptr on error
*/
gcc_nonnull_all
gcc_malloc
static InputStream *Open(const char *uri, Mutex &mutex, Cond &cond,
Error &error);
/**
* Just like Open(), but waits for the stream to become ready.
* It is a wrapper for Open(), WaitReady() and Check().
*/
gcc_malloc gcc_nonnull_all
static InputStream *OpenReady(const char *uri,
Mutex &mutex, Cond &cond,
Error &error);
/**
* The absolute URI which was used to open this stream.
*
* No lock necessary for this method.
*/
const char *GetURI() const {
return uri.c_str();
}
void Lock() {
mutex.lock();
}
void Unlock() {
mutex.unlock();
}
/**
* Check for errors that may have occurred in the I/O thread.
*
* @return false on error
*/
virtual bool Check(Error &error);
/**
* Update the public attributes. Call before accessing attributes
* such as "ready" or "offset".
*/
virtual void Update();
void SetReady();
/**
* Return whether the stream is ready for reading and whether
* the other attributes in this struct are valid.
*
* The caller must lock the mutex.
*/
bool IsReady() const {
return ready;
}
void WaitReady();
/**
* Wrapper for WaitReady() which locks and unlocks the mutex;
* the caller must not be holding it already.
*/
void LockWaitReady();
gcc_pure
bool HasMimeType() const {
assert(ready);
return !mime.empty();
}
gcc_pure
const char *GetMimeType() const {
assert(ready);
return mime.empty() ? nullptr : mime.c_str();
}
gcc_nonnull_all
void SetMimeType(const char *_mime) {
assert(!ready);
mime = _mime;
}
void SetMimeType(std::string &&_mime) {
assert(!ready);
mime = std::move(_mime);
}
gcc_nonnull_all
void OverrideMimeType(const char *_mime) {
assert(ready);
mime = _mime;
}
gcc_pure
bool KnownSize() const {
assert(ready);
return size != UNKNOWN_SIZE;
}
gcc_pure
offset_type GetSize() const {
assert(ready);
assert(KnownSize());
return size;
}
void AddOffset(offset_type delta) {
assert(ready);
offset += delta;
}
gcc_pure
offset_type GetOffset() const {
assert(ready);
return offset;
}
gcc_pure
offset_type GetRest() const {
assert(ready);
assert(KnownSize());
return size - offset;
}
gcc_pure
bool IsSeekable() const {
assert(ready);
return seekable;
}
/**
* Determines whether seeking is cheap. This is true for local files.
*/
gcc_pure
bool CheapSeeking() const;
/**
* Seeks to the specified position in the stream. This will most
* likely fail if the "seekable" flag is false.
*
* The caller must lock the mutex.
*
* @param offset the relative offset
*/
virtual bool Seek(offset_type offset, Error &error);
/**
* Wrapper for Seek() which locks and unlocks the mutex; the
* caller must not be holding it already.
*/
bool LockSeek(offset_type offset, Error &error);
/**
* Rewind to the beginning of the stream. This is a wrapper
* for Seek(0, error).
*/
bool Rewind(Error &error) {
return Seek(0, error);
}
bool LockRewind(Error &error) {
return LockSeek(0, error);
}
/**
* Returns true if the stream has reached end-of-file.
*
* The caller must lock the mutex.
*/
gcc_pure
virtual bool IsEOF() = 0;
/**
* Wrapper for IsEOF() which locks and unlocks the mutex; the
* caller must not be holding it already.
*/
gcc_pure
bool LockIsEOF();
/**
* Reads the tag from the stream.
*
* The caller must lock the mutex.
*
* @return a tag object which must be freed by the caller, or
* nullptr if the tag has not changed since the last call
*/
gcc_malloc
virtual Tag *ReadTag();
/**
* Wrapper for ReadTag() which locks and unlocks the mutex;
* the caller must not be holding it already.
*/
gcc_malloc
Tag *LockReadTag();
/**
* Returns true if the next read operation will not block: either data
* is available, or end-of-stream has been reached, or an error has
* occurred.
*
* The caller must lock the mutex.
*/
gcc_pure
virtual bool IsAvailable();
/**
* Reads data from the stream into the caller-supplied buffer.
* Returns 0 on error or eof (check with IsEOF()).
*
* The caller must lock the mutex.
*
* @param is the InputStream object
* @param ptr the buffer to read into
* @param size the maximum number of bytes to read
* @return the number of bytes read
*/
gcc_nonnull_all
virtual size_t Read(void *ptr, size_t size, Error &error) = 0;
/**
* Wrapper for Read() which locks and unlocks the mutex;
* the caller must not be holding it already.
*/
gcc_nonnull_all
size_t LockRead(void *ptr, size_t size, Error &error);
};
#endif
