1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/libfsserver/lib/files/block_file_accessor.cc Thu Apr 15 23:15:17 2021 +0200
1.3 @@ -0,0 +1,127 @@
1.4 +/*
1.5 + * A file accessor employing a rewritable memory area.
1.6 + *
1.7 + * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk>
1.8 + *
1.9 + * This program is free software; you can redistribute it and/or
1.10 + * modify it under the terms of the GNU General Public License as
1.11 + * published by the Free Software Foundation; either version 2 of
1.12 + * the License, or (at your option) any later version.
1.13 + *
1.14 + * This program is distributed in the hope that it will be useful,
1.15 + * but WITHOUT ANY WARRANTY; without even the implied warranty of
1.16 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
1.17 + * GNU General Public License for more details.
1.18 + *
1.19 + * You should have received a copy of the GNU General Public License
1.20 + * along with this program; if not, write to the Free Software
1.21 + * Foundation, Inc., 51 Franklin Street, Fifth Floor,
1.22 + * Boston, MA 02110-1301, USA
1.23 + */
1.24 +
1.25 +#include <stdio.h>
1.26 +#include <string.h>
1.27 +#include <sys/types.h>
1.28 +#include <sys/stat.h>
1.29 +
1.30 +#include <algorithm>
1.31 +
1.32 +#include "block_file_accessor.h"
1.33 +
1.34 +
1.35 +
1.36 +BlockFileAccessor::BlockFileAccessor(const char *path, fileid_t fileid)
1.37 +: Accessor(fileid)
1.38 +{
1.39 + /* Obtain the size of the file. */
1.40 +
1.41 + struct stat buf;
1.42 +
1.43 + if (stat(path, &buf))
1.44 + {
1.45 + _size = 0;
1.46 + return;
1.47 + }
1.48 +
1.49 + /* Allocate memory. */
1.50 +
1.51 + _size = buf.st_size;
1.52 + _data = (char *) malloc(_size);
1.53 +
1.54 + if (_data == NULL)
1.55 + return;
1.56 +
1.57 + /* Load the file into memory and initialise the size. */
1.58 +
1.59 + FILE *fp = fopen(path, "r");
1.60 +
1.61 + if (fp == NULL)
1.62 + {
1.63 + free(_data);
1.64 + return;
1.65 + }
1.66 +
1.67 + _size = fread(_data, sizeof(char), _size, fp);
1.68 +
1.69 + fclose(fp);
1.70 +}
1.71 +
1.72 +/* Update the size of the file. */
1.73 +
1.74 +void BlockFileAccessor::set_size(offset_t size)
1.75 +{
1.76 + void *new_data = realloc(_data, size);
1.77 +
1.78 + if (new_data != NULL)
1.79 + {
1.80 + _data = (char *) new_data;
1.81 +
1.82 + if (size > _size)
1.83 + memset(_data + _size, 0, size - _size);
1.84 +
1.85 + Accessor::set_size(size);
1.86 + }
1.87 +}
1.88 +
1.89 +/* Data transfer helper methods. */
1.90 +
1.91 +/* Fill the populated portion of a flexpage. */
1.92 +
1.93 +void BlockFileAccessor::fill_populated(Flexpage *flexpage)
1.94 +{
1.95 + offset_t filepos = flexpage->base_offset;
1.96 + offset_t addr = flexpage->base_addr;
1.97 + offset_t populated_size = std::min(flexpage->size, _size - filepos);
1.98 +
1.99 + /* Tag the region with file state. */
1.100 +
1.101 + flexpage->region->fill(fileid, filepos);
1.102 +
1.103 + /* Fill the region with file content. */
1.104 +
1.105 + memcpy((void *) addr, _data + filepos, populated_size);
1.106 +
1.107 + /* Pad the flexpage with zero. */
1.108 +
1.109 + if (populated_size < flexpage->size)
1.110 + memset((void *) (addr + populated_size), 0, flexpage->size - populated_size);
1.111 +}
1.112 +
1.113 +/* Flush the populated portion of a flexpage. */
1.114 +
1.115 +void BlockFileAccessor::flush_populated(Flexpage *flexpage)
1.116 +{
1.117 + offset_t filepos = flexpage->base_offset;
1.118 + offset_t addr = flexpage->base_addr;
1.119 + offset_t populated_size = std::min(flexpage->size, _size - filepos);
1.120 +
1.121 + /* Remove the file state tag from the region. */
1.122 +
1.123 + flexpage->region->flush();
1.124 +
1.125 + /* Copy the populated region to the block memory. */
1.126 +
1.127 + memcpy((void *) (_data + filepos), (const void *) addr, populated_size);
1.128 +}
1.129 +
1.130 +// vim: tabstop=4 expandtab shiftwidth=4