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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 <string.h>
#include <glib.h>
#include "debug.h"
#include "probe-buffer.h"
#define BUFSIZE (256 * 1024)
typedef struct
{
VFSFile * file;
int filled, at;
unsigned char buffer[BUFSIZE];
}
ProbeBuffer;
static int probe_buffer_fclose (VFSFile * file)
{
ProbeBuffer * p = vfs_get_handle (file);
int ret = vfs_fclose (p->file);
g_free (p);
return ret;
}
static void increase_buffer (ProbeBuffer * p, int64_t size)
{
size = (size + 0xFF) & ~0xFF;
if (size > sizeof p->buffer)
size = sizeof p->buffer;
if (p->filled < size)
p->filled += vfs_fread (p->buffer + p->filled, 1, size - p->filled,
p->file);
}
static int64_t probe_buffer_fread (void * buffer, int64_t size, int64_t count,
VFSFile * file)
{
ProbeBuffer * p = vfs_get_handle (file);
increase_buffer (p, p->at + size * count);
int readed = (size > 0) ? MIN (count, (p->filled - p->at) / size) : 0;
memcpy (buffer, p->buffer + p->at, size * readed);
p->at += size * readed;
return readed;
}
static int64_t probe_buffer_fwrite (const void * data, int64_t size, int64_t count,
VFSFile * file)
{
return 0; /* not allowed */
}
static int probe_buffer_fseek (VFSFile * file, int64_t offset, int whence)
{
ProbeBuffer * p = vfs_get_handle (file);
if (whence == SEEK_END)
return -1; /* not allowed */
if (whence == SEEK_CUR)
offset += p->at;
if (offset < 0 || offset > sizeof p->buffer)
return -1;
increase_buffer (p, offset);
if (offset > p->filled)
return -1;
p->at = offset;
return 0;
}
static int64_t probe_buffer_ftell (VFSFile * file)
{
return ((ProbeBuffer *) vfs_get_handle (file))->at;
}
static bool_t probe_buffer_feof (VFSFile * file)
{
ProbeBuffer * p = vfs_get_handle (file);
if (p->at < p->filled)
return FALSE;
if (p->at == sizeof p->buffer)
return TRUE;
return vfs_feof (p->file);
}
static int probe_buffer_ftruncate (VFSFile * file, int64_t size)
{
return -1; /* not allowed */
}
static int64_t probe_buffer_fsize (VFSFile * file)
{
ProbeBuffer * p = vfs_get_handle (file);
int64_t size = vfs_fsize (p->file);
return MIN (size, sizeof p->buffer);
}
static char * probe_buffer_get_metadata (VFSFile * file, const char * field)
{
return vfs_get_metadata (((ProbeBuffer *) vfs_get_handle (file))->file, field);
}
static VFSConstructor probe_buffer_table =
{
.vfs_fopen_impl = NULL,
.vfs_fclose_impl = probe_buffer_fclose,
.vfs_fread_impl = probe_buffer_fread,
.vfs_fwrite_impl = probe_buffer_fwrite,
.vfs_fseek_impl = probe_buffer_fseek,
.vfs_ftell_impl = probe_buffer_ftell,
.vfs_feof_impl = probe_buffer_feof,
.vfs_ftruncate_impl = probe_buffer_ftruncate,
.vfs_fsize_impl = probe_buffer_fsize,
.vfs_get_metadata_impl = probe_buffer_get_metadata,
};
VFSFile * probe_buffer_new (const char * filename)
{
VFSFile * file = vfs_fopen (filename, "r");
if (! file)
return NULL;
ProbeBuffer * p = g_new (ProbeBuffer, 1);
p->file = file;
p->filled = 0;
p->at = 0;
return vfs_new (filename, & probe_buffer_table, p);
}
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