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/*
* probe-buffer.c
* Copyright 2010-2013 John Lindgren
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions, and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions, and the following disclaimer in the documentation
* provided with the distribution.
*
* This software is provided "as is" and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising from
* the use of this software.
*/
#include "probe-buffer.h"
#include "runtime.h"
#include <string.h>
static constexpr int MAXBUF = 256 * 1024;
ProbeBuffer::ProbeBuffer (const char * filename, SmartPtr<VFSImpl> && file) :
m_filename (filename),
m_file (std::move (file))
{
AUDINFO ("<%p> buffering enabled for %s\n", this, (const char *) m_filename);
}
ProbeBuffer::~ProbeBuffer ()
{
delete[] m_buffer;
}
void ProbeBuffer::increase_buffer (int64_t size)
{
size = aud::min ((size + 0xFF) & ~0xFF, (int64_t) MAXBUF);
if (m_filled < size)
{
if (! m_buffer)
m_buffer = new char[MAXBUF];
m_filled += m_file->fread (m_buffer + m_filled, 1, size - m_filled);
}
}
void ProbeBuffer::release_buffer ()
{
AUDINFO ("<%p> buffering disabled for %s\n", this, (const char *) m_filename);
delete[] m_buffer;
m_buffer = nullptr;
m_filled = 0;
m_at = -1;
}
int64_t ProbeBuffer::fread (void * buffer, int64_t size, int64_t count)
{
int64_t total = 0;
int64_t remain = size * count;
/* read from buffer if possible */
if (remain && m_at >= 0 && m_at < MAXBUF)
{
increase_buffer (m_at + remain);
int copy = aud::min (remain, (int64_t) (m_filled - m_at));
memcpy (buffer, m_buffer + m_at, copy);
m_at += copy;
buffer = (char *) buffer + copy;
total += copy;
remain -= copy;
}
/* then read from real file if allowed */
if (remain && ! m_limited)
{
/* release buffer if leaving bufferable area */
if (m_at == MAXBUF)
release_buffer ();
if (m_at < 0)
total += m_file->fread (buffer, 1, remain);
}
return (size > 0) ? total / size : 0;
}
int64_t ProbeBuffer::fwrite (const void * data, int64_t size, int64_t count)
{
return 0; /* not allowed */
}
int ProbeBuffer::fseek (int64_t offset, VFSSeekType whence)
{
/* seek within the buffer if possible */
if (m_at >= 0 && whence != VFS_SEEK_END)
{
/* calculate requested position */
if (whence == VFS_SEEK_CUR)
{
offset += m_at;
whence = VFS_SEEK_SET;
}
if (offset < 0)
return -1; /* invalid argument */
if (offset <= MAXBUF)
{
increase_buffer (offset);
if (offset > m_filled)
return -1; /* seek past end of file */
m_at = offset;
return 0;
}
}
/* seek within real file if allowed */
if (m_limited || m_file->fseek (offset, whence) < 0)
return -1;
/* release buffer only if real seek succeeded
* (prevents change of file position if seek failed) */
if (m_at >= 0)
release_buffer ();
/* activate buffering again when seeking to beginning of file */
if (whence == VFS_SEEK_SET && offset == 0)
{
AUDINFO ("<%p> buffering enabled for %s\n", this, (const char *) m_filename);
m_at = 0;
}
return 0;
}
int64_t ProbeBuffer::ftell ()
{
if (m_at >= 0)
return m_at;
return m_file->ftell ();
}
bool ProbeBuffer::feof ()
{
if (m_at >= 0 && m_at < m_filled)
return false;
return m_file->feof ();
}
int ProbeBuffer::ftruncate (int64_t size)
{
return -1; /* not allowed */
}
int ProbeBuffer::fflush ()
{
return 0; /* no-op */
}
int64_t ProbeBuffer::fsize ()
{
return m_file->fsize ();
}
String ProbeBuffer::get_metadata (const char * field)
{
return m_file->get_metadata (field);
}
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