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/*
* COPYRIGHT (c) 2012 Chris Johns <chrisj@rtems.org>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
/**
* @file
*
* @ingroup rtems_rtl
*
* @brief RTEMS Run-Time Linker Object File cache buffers a section of the
* object file in a buffer to localise read performance.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <rtl-allocator.h>
#include <rtl-obj-cache.h>
#include <rtl-error.h>
bool
rtems_rtl_obj_cache_open (rtems_rtl_obj_cache_t* cache, size_t size)
{
cache->fd = -1;
cache->file_size = 0;
cache->offset = 0;
cache->size = size;
cache->level = 0;
cache->buffer = rtems_rtl_alloc_new (RTEMS_RTL_ALLOC_OBJECT, size, false);
if (!cache->buffer)
{
rtems_rtl_set_error (ENOMEM, "no memory for cache buffer");
return false;
}
return true;
}
void
rtems_rtl_obj_cache_close (rtems_rtl_obj_cache_t* cache)
{
rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_OBJECT, cache->buffer);
cache->fd = -1;
cache->file_size = 0;
cache->level = 0;
}
void
rtems_rtl_obj_cache_flush (rtems_rtl_obj_cache_t* cache)
{
cache->fd = -1;
cache->file_size = 0;
cache->level = 0;
}
bool
rtems_rtl_obj_cache_read (rtems_rtl_obj_cache_t* cache,
int fd,
off_t offset,
void** buffer,
size_t* length)
{
struct stat sb;
if (*length > cache->size)
{
rtems_rtl_set_error (EINVAL, "read size larger than cache size");
return false;
}
if (cache->fd == fd)
{
if (offset > cache->file_size)
{
rtems_rtl_set_error (EINVAL, "offset past end of file: offset=%i size=%i",
(int) offset, (int) cache->file_size);
return false;
}
if ((offset + *length) > cache->file_size)
*length = cache->file_size - offset;
}
while (true)
{
size_t buffer_offset = 0;
size_t buffer_read = cache->size;
/*
* Is the data in the cache for this file ?
*/
if (fd == cache->fd)
{
/*
* Is any part of the data in the cache ?
*/
if ((offset >= cache->offset) &&
(offset < (cache->offset + cache->level)))
{
buffer_offset = offset - cache->offset;
/*
* Return the location of the data in the cache.
*/
*buffer = cache->buffer + buffer_offset;
/*
* Is all the data in the cache or just a part ?
*/
if (*length <= (cache->level - buffer_offset))
{
return true;
}
/*
* Copy down the data in the buffer and then fill the remaining
* space with as much data we are able to read.
*/
memmove (cache->buffer,
cache->buffer + buffer_offset,
cache->size - buffer_offset);
buffer_read = buffer_offset;
buffer_offset = cache->size - buffer_offset;
}
}
if (lseek (fd, offset + buffer_offset, SEEK_SET) < 0)
{
rtems_rtl_set_error (errno, "file seek failed");
return false;
}
/*
* Loop reading the data from the file until either an error or 0 is
* returned and if data has been read check if the amount is what we
* want. If not it is an error. A POSIX read can read data in fragments.
*/
cache->level = buffer_read;
while (buffer_read)
{
int r = read (fd, cache->buffer + buffer_offset, buffer_read);
if (r < 0)
{
rtems_rtl_set_error (errno, "file read failed");
return false;
}
if ((r == 0) && buffer_read)
{
cache->level = cache->level - buffer_read;
buffer_read = 0;
}
else
{
buffer_read -= r;
buffer_offset += r;
}
}
cache->fd = fd;
cache->offset = offset;
if (fstat (cache->fd, &sb) < 0)
{
rtems_rtl_set_error (errno, "file stat failed");
return false;
}
cache->file_size = sb.st_size;
}
return false;
}
bool
rtems_rtl_obj_cache_read_byval (rtems_rtl_obj_cache_t* cache,
int fd,
off_t offset,
void* buffer,
size_t length)
{
void* cbuffer = 0;
size_t len = length;
bool ok = rtems_rtl_obj_cache_read (cache, fd, offset, &cbuffer, &len);
if (ok && (len != length))
ok = false;
if (ok)
memcpy (buffer, cbuffer, length);
return ok;
}
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