diff options
| -rw-r--r-- | src/backup.c | 163 |
1 files changed, 93 insertions, 70 deletions
diff --git a/src/backup.c b/src/backup.c index 5f57ecd..40e00dc 100644 --- a/src/backup.c +++ b/src/backup.c @@ -8,8 +8,17 @@ #include <stdlib.h> #include <string.h> -int -backup(const options_t *const opts, resources_t *const res) +static int check_files(const options_t *const opts, + const resources_t *const res); +static int allocate_buffers(const options_t *const opts, size_t out_buffer_size, + resources_t *const res); +static int read_sector(FILE *const file, char *const buffer, + uint32_t buffer_size, uint32_t sector_size); +static int write_out_buffer(const char *const buffer, size_t size, + FILE *const file); + +static int +check_files(const options_t *const opts, const resources_t *const res) { const long in_size = file_size(res->in_file); @@ -36,11 +45,13 @@ backup(const options_t *const opts, resources_t *const res) return 1; } - /* Allocate the buffers */ - /* The output buffer contains also the offsets */ - const size_t out_buffer_size = - ((opts->buffer_size / opts->sector_size) * sizeof(uint64_t)) + - opts->buffer_size; + return 0; +} + +static int +allocate_buffers(const options_t *const opts, size_t out_buffer_size, + resources_t *const res) +{ if ((res->in_buffer = (char *)malloc(opts->buffer_size)) == NULL) { print_error("cannot allocate buffer for input file data"); @@ -53,97 +64,109 @@ backup(const options_t *const opts, resources_t *const res) return 1; } - size_t out_buffer_index = 0; - uint64_t offset = 0; + return 0; +} - for (;;) { - /* Read the sectors from the input file to the buffer */ - const size_t in_read = - fread(res->in_buffer, 1U, opts->buffer_size, res->in_file); +static int +read_sector(FILE *const file, char *const buffer, uint32_t buffer_size, + uint32_t sector_size) +{ + const size_t bytes_read = fread(buffer, 1U, buffer_size, file); - if ((in_read % opts->sector_size) != 0) { - print_error( - "data read from input file is not multiple of sector size"); - return 1; - } else if (ferror(res->in_file)) { - print_error("cannot read from input file: %s", strerror(errno)); - return 1; - } + if (ferror(file)) { + print_error("cannot read from input file: %s", strerror(errno)); + return 1; + } else if ((bytes_read % sector_size) != 0) { + print_error("data read from input file is not multiple of sector size"); + return 1; + } else if (bytes_read != buffer_size) { + print_error("cannot read enough data from input file"); + return 1; + } - /* Read sectors from the reference file to the buffer */ - const size_t ref_read = - fread(res->ref_buffer, 1U, opts->buffer_size, res->ref_file); + return 0; +} - if ((ref_read % opts->sector_size) != 0) { - print_error( - "data read from reference file is not multiple of sector size"); - return 1; - } else if (ferror(res->ref_file)) { - print_error("%s", strerror(errno)); +static int +write_out_buffer(const char *const buffer, size_t size, FILE *const file) +{ + const size_t bytes_written = fwrite(buffer, 1U, size, file); + + if (bytes_written != size) { + print_error("cannot write to output file: %s", strerror(errno)); + return 1; + } + + return 0; +} + +int +backup(const options_t *const opts, resources_t *const res) +{ + if (check_files(opts, res) != 0) { + return 1; + } + + /* The output buffer contains also the offsets */ + const size_t out_buffer_size = + ((opts->buffer_size / opts->sector_size) * sizeof(uint64_t)) + + opts->buffer_size; + + if (allocate_buffers(opts, out_buffer_size, res) != 0) { + return 1; + } + + size_t out_buffer_index = 0; + uint64_t input_file_offset = 0; + + while (!feof(res->in_file)) { + /* Read the sectors from the input file to the buffer */ + if (read_sector(res->in_file, res->in_buffer, opts->buffer_size, + opts->sector_size) != 0) { return 1; } - if (in_read != ref_read) { - print_error( - "data read from input file and reference file differ in size"); + /* Read sectors from the reference file to the buffer */ + if (read_sector(res->ref_file, res->ref_buffer, opts->buffer_size, + opts->sector_size) != 0) { return 1; } /* Process sectors in the buffer */ - for (size_t i = 0; i < in_read; i += opts->sector_size) { - /* Compare the sectors */ - int changed = 0; - const size_t j_end = i + opts->sector_size; - for (size_t j = i; j < j_end; ++j) { - if (res->in_buffer[j] != res->ref_buffer[j]) { - changed = 1; - break; - } - } - - if (changed) { - /* Write changed sector */ + for (size_t buffer_offset = 0; buffer_offset < opts->buffer_size; + buffer_offset += opts->sector_size) { + if (memcmp(res->in_buffer + buffer_offset, + res->ref_buffer + buffer_offset, + opts->sector_size) != 0) { + /* Backup the changed sector */ if (out_buffer_index >= out_buffer_size) { - /* The output buffer is full. Write it to the - * output file. + /* The output buffer is full. Write it to the output file. */ - const size_t x = fwrite(res->out_buffer, 1U, - out_buffer_index, res->out_file); - - if (x != out_buffer_index) { - print_error("cannot write to output file: %s", - strerror(errno)); + if (write_out_buffer(res->out_buffer, out_buffer_index, + res->out_file) != 1) { return 1; } - out_buffer_index = 0; } - - const uint64_t o = htole64(offset); - + /* Write the next backup record */ + const uint64_t o = htole64(input_file_offset); memcpy(res->out_buffer + out_buffer_index, (void *)&o, sizeof(o)); out_buffer_index += sizeof(o); - memcpy(res->out_buffer + out_buffer_index, &(res->in_buffer[i]), - opts->sector_size); + + memcpy(res->out_buffer + out_buffer_index, + res->in_buffer + buffer_offset, opts->sector_size); out_buffer_index += opts->sector_size; } - offset += opts->sector_size; - } - - if (feof(res->in_file)) { - break; + input_file_offset += opts->sector_size; } } /* Write out the output buffer */ if (out_buffer_index >= 0) { - const size_t x = - fwrite(res->out_buffer, 1U, out_buffer_index, res->out_file); - - if (x != out_buffer_index) { - print_error("cannot write to output file: %s", strerror(errno)); + if (write_out_buffer(res->out_buffer, out_buffer_index, + res->out_file) != 1) { return 1; } } |