diff options
Diffstat (limited to 'src/restore.cpp')
| -rw-r--r-- | src/restore.cpp | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/src/restore.cpp b/src/restore.cpp new file mode 100644 index 0000000..e73e42e --- /dev/null +++ b/src/restore.cpp @@ -0,0 +1,182 @@ +/* Copyright 2021 Ján Sučan <jan@jansucan.com> + * + * 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 + * HOLDER 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. + */ + +#include "restore.h" + +#include "file.h" +#include "print.h" + +#include <errno.h> +#include <stdbool.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +static bool +is_input_file_valid(const resources_restore_t *const res, uint32_t sector_size) +{ + bool in_size_ok = false; + const size_t in_size = file_size(res->in_file, &in_size_ok); + + if (!in_size_ok) { + print_error("cannot get size of input file: %s", strerror(errno)); + return false; + } else if (in_size == 0) { + print_error("input file is empty"); + return false; + } else if ((in_size % (sizeof(uint64_t) + sector_size)) != 0) { + /* The input file must hold equally sized sectors and the + * offset of each of them + */ + print_error("input file has size that cannot contain valid diff data"); + return false; + } + + bool out_size_ok = false; + const size_t out_size = file_size(res->out_file, &out_size_ok); + + if (!out_size_ok) { + print_error("cannot get size of output file: %s", strerror(errno)); + return 1; + } + + uint64_t prev_out_offset = 0; + bool is_first_reading = true; + + /* Scan the input file and check */ + for (;;) { + uint64_t out_offset; + /* Read the next offset */ + const size_t in_read = + fread(&out_offset, sizeof(out_offset), 1U, res->in_file); + out_offset = le64toh(out_offset); + + if (feof(res->in_file)) { + break; + } else if ((in_read != 1U) || ferror(res->in_file)) { + print_error("cannot read from input file: %s", strerror(errno)); + return false; + } else if (!is_first_reading && (out_offset <= prev_out_offset)) { + print_error("a sector offset points behind the previous offset"); + return false; + } else if ((out_offset + sector_size) > out_size) { + print_error( + "a sector offset points past the end of the output file"); + return false; + } else if (fseek(res->in_file, sector_size, SEEK_CUR) != 0) { + print_error("cannot seek in input file: %s", strerror(errno)); + return false; + } + + is_first_reading = false; + prev_out_offset = out_offset; + } + + bool pos_ok = false; + const size_t pos = file_tell(res->in_file, &pos_ok); + + if (!pos_ok) { + print_error("cannot get position in the input file"); + return false; + } else if (pos != in_size) { + /* The input file must be read completely */ + print_error("input file is not valid"); + return false; + } else if (fseek(res->in_file, 0L, SEEK_SET) != 0) { + /* The file must be prepared for the restoring */ + print_error("cannot seek in input file: %s", strerror(errno)); + return false; + } + + return true; +} + +int +restore(const options_restore_t *const opts, + const resources_restore_t *const res) +{ + /* Check validity of the input file */ + if (!is_input_file_valid(res, opts->sector_size)) { + return 1; + } + + bool in_size_ok = false; + const size_t in_size = file_size(res->in_file, &in_size_ok); + + if (!in_size_ok) { + print_error("cannot get size of input file: %s", strerror(errno)); + return 1; + } + + /* Restore data from the differential image */ + for (;;) { + + /* Read data of the offset and the next sector */ + const size_t in_sectors_read = + file_read_sectors(res->in_file, res->in_buffer, res->in_buffer_size, + res->in_sector_size); + + if (in_sectors_read == 0) { + break; + } + + char *in_buffer = res->in_buffer; + + for (size_t s = 0; s < in_sectors_read; ++s) { + const uint64_t out_offset = le64toh(*((uint64_t *)in_buffer)); + in_buffer += sizeof(uint64_t); + + if (fseek(res->out_file, out_offset, SEEK_SET) != 0) { + print_error("cannot seek in output file: %s", strerror(errno)); + return 1; + } + + const size_t out_written = + fwrite(in_buffer, opts->sector_size, 1U, res->out_file); + in_buffer += opts->sector_size; + + if (out_written != 1U) { + print_error("cannot write to output file: %s", strerror(errno)); + return 1; + } + } + } + + /* The input file must be read completely */ + bool pos_ok = false; + const size_t pos = file_tell(res->in_file, &pos_ok); + + if (!pos_ok) { + print_error("cannot get position in the input file"); + return 1; + } else if (pos != in_size) { + print_error("input file is not valid"); + return 1; + } + + return 0; +} |