/* SPDX-License-Identifier: BSD-2-Clause */
/**
* @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.
*/
/*
* COPYRIGHT (c) 2012, 2018 Chris Johns <chrisj@rtems.org>
*
* 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 and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include <rtems/inttypes.h>
#include <rtems/rtl/rtl-allocator.h>
#include <rtems/rtl/rtl-obj-cache.h>
#include "rtl-error.h"
#include <rtems/rtl/rtl-trace.h>
bool
rtems_rtl_obj_cache_open (rtems_rtl_obj_cache* 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* cache)
{
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: close\n", cache->fd);
rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_OBJECT, cache->buffer);
cache->buffer = NULL;
cache->fd = -1;
cache->file_size = 0;
cache->level = 0;
}
void
rtems_rtl_obj_cache_flush (rtems_rtl_obj_cache* cache)
{
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: flush\n", cache->fd);
cache->fd = -1;
cache->file_size = 0;
cache->offset = 0;
cache->level = 0;
}
bool
rtems_rtl_obj_cache_read (rtems_rtl_obj_cache* cache,
int fd,
off_t offset,
void** buffer,
size_t* length)
{
struct stat sb;
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: fd=%d offset=%" PRIdoff_t " length=%zu area=[%"
PRIdoff_t ",%" PRIdoff_t "] cache=[%" PRIdoff_t ",%" PRIdoff_t "] size=%zu\n",
fd, cache->fd, offset, *length,
offset, offset + *length,
cache->offset, cache->offset + cache->level,
cache->file_size);
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;
}
/*
* We sometimes are asked to read strings of a length we do not know.
*/
if ((offset + *length) > cache->file_size)
{
*length = cache->file_size - offset;
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: truncate length=%d\n", fd, (int) *length);
}
}
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)
{
/*
* Do not read past the end of the file.
*/
if ((offset + buffer_read) > cache->file_size)
buffer_read = cache->file_size - offset;
/*
* Is any part of the data in the cache ?
*/
if ((offset >= cache->offset) &&
(offset < (cache->offset + cache->level)))
{
size_t size;
buffer_offset = offset - cache->offset;
size = cache->level - buffer_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 <= size)
return true;
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: copy-down: buffer_offset=%d size=%d level=%d\n",
fd, (int) buffer_offset, (int) size, (int) cache->level);
/*
* 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, size);
cache->offset = offset;
cache->level = size;
buffer_read = cache->size - cache->level;
buffer_offset = size;
/*
* Do not read past the end of the file.
*/
if ((offset + buffer_offset + buffer_read) > cache->file_size)
buffer_read = cache->file_size - (offset + buffer_offset);
}
}
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: seek: offset=%" PRIdoff_t " buffer_offset=%zu"
" read=%zu cache=[%" PRIdoff_t ",%" PRIdoff_t "] "
"dist=%" PRIdoff_t "\n",
fd, offset + buffer_offset, buffer_offset, buffer_read,
offset, offset + buffer_read,
(cache->file_size - 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_offset + 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)
{
if (rtems_rtl_trace (RTEMS_RTL_TRACE_CACHE))
printf ("rtl: cache: %2d: read: past end by=%d\n", fd, (int) buffer_read);
cache->level = cache->level - buffer_read;
buffer_read = 0;
}
else
{
buffer_read -= r;
buffer_offset += r;
}
}
cache->offset = offset;
if (cache->fd != fd)
{
cache->fd = fd;
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* 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;
}
