我有一个二进制文件,在其中写入带有以下字段的结构
typedef struct super_bloque{
size_t s_filesystem_type;
size_t s_inodes_count;
size_t s_blocks_count;
size_t s_free_blocks_count;
size_t s_free_inodes_count;
time_t s_mtime;
time_t s_umtime;
size_t s_mnt_count;
size_t s_magic;
size_t s_inode_size;
size_t s_block_size;
size_t s_first_ino;
size_t s_first_blo;
size_t s_bm_inode_start;
size_t s_bm_block_start;
size_t s_inode_start;
size_t s_block_start;
}SUPER_BLOQUE;
我有以下方法在文件内写入结构
void Operacion::formatear_ext2(char type, size_t part_start, size_t part_size, FILE *disco){
MBR mbr;
fseek(disco, 0, SEEK_SET);
fread(&mbr, sizeof(mbr), 1, disco);
size_t n = (size_t)floor((part_size - sizeof(SUPER_BLOQUE)) / (sizeof(I_NODO) + 3 * sizeof(BLOQUE_ARCHIVO) + 4));
printf("n = %zu\n", n);
SUPER_BLOQUE super_block;
memset(&super_block, 0, sizeof(SUPER_BLOQUE));
super_block.s_filesystem_type = (size_t)2;
super_block.s_inodes_count = n;
super_block.s_blocks_count = (size_t)3 * n;
super_block.s_free_blocks_count = (size_t)3 * n;
super_block.s_free_inodes_count = n;
super_block.s_mtime = time(0);
super_block.s_umtime = time(0);
super_block.s_mnt_count = 1;
super_block.s_magic = 0xEF53;
super_block.s_inode_size = sizeof(I_NODO);
super_block.s_block_size = sizeof(BLOQUE_ARCHIVO);
super_block.s_first_ino = 0;
super_block.s_first_blo = 0;
super_block.s_bm_inode_start = part_start + sizeof(SUPER_BLOQUE);
super_block.s_bm_block_start = part_start + sizeof(SUPER_BLOQUE) + n;
super_block.s_inode_start = part_start + sizeof(SUPER_BLOQUE) + n + 3 * n;
super_block.s_block_start = part_start + sizeof(SUPER_BLOQUE) + n + 3 * n + n * sizeof(I_NODO);
fseek(disco, part_start, SEEK_SET);
fwrite(&super_block, sizeof(SUPER_BLOQUE), 1, disco);
for(size_t i = 0; i < super_block.s_inodes_count; i++){
fseek(disco, super_block.s_first_ino + i, SEEK_SET);
fwrite("0", 1, 1, disco);
}
for(size_t i = 0; i < super_block.s_blocks_count; i++){
fseek(disco, super_block.s_first_blo + i, SEEK_SET);
fwrite("0", 1, 1, disco);
}
if(type == '1'){
size_t tam_ino_bloq = super_block.s_block_start + n * sizeof(BLOQUE_ARCHIVO);
for(size_t i = super_block.s_inode_start; i < tam_ino_bloq; i++){
fseek(disco, i, SEEK_SET);
fwrite("\0", 1, 1, disco);
}
}
然后我读取了磁盘内部的结构以检查数据是否正确存储
fseek(disco, part_start, SEEK_SET);
fread(&tmp_sb, sizeof(SUPER_BLOQUE), 1, disco);
printf("**************************** SUPERBLOQUE ****************************\n");
printf("fs: %zu\n", tmp_sb.s_filesystem_type);
printf("i-nodes count : %zu\n", tmp_sb.s_inodes_count);
printf("blocks count : %zu\n", tmp_sb.s_blocks_count);
printf("free blocks count: %zu\n", tmp_sb.s_free_blocks_count);
printf("free i-nodes count: %zu\n", tmp_sb.s_free_inodes_count);
printf("i-nodes size: %zu\n", tmp_sb.s_inode_size);
printf("blocks size: %zu\n", tmp_sb.s_block_size);
printf("first ino: %zu\n", tmp_sb.s_first_ino);
printf("first blo: %zu\n", tmp_sb.s_first_blo);
printf("bm i-node start: %zu\n", tmp_sb.s_bm_inode_start);
printf("bm block start: %zu\n", tmp_sb.s_bm_block_start);
printf("i-node start: %zu\n", tmp_sb.s_inode_start);
printf("block start: %zu\n", tmp_sb.s_block_start);
printf("***********************************************************************");
} // Finish the method
该结构在编写时具有以下信息
fs: 2
i-nodes count : 64
blocks count : 192
free blocks count: 192
free i-nodes count: 64
i-nodes size: 120
blocks size: 64
first ino: 0
first blo: 0
bm i-node start: 272
bm block start: 336
i-node start: 528
block start: 8208
但是当我阅读信息时,得到以下结果,信息已丢失
fs: 3472328296227680304
i-nodes count : 3472328296227680304
blocks count : 3472328296227680304
free blocks count: 3472328296227680304
free i-nodes count: 3472328296227680304
i-nodes size: 120
blocks size: 64
first ino: 0
first blo: 0
bm i-node start: 272
bm block start: 336
i-node start: 528
block start: 8208
前五个字段包含垃圾。为什么会这样?感谢您的帮助
注意:我已经添加了该方法的所有行。我正在使用Ubuntu发行版。要打开文件,请按照以下说明操作
FILE *disco;
disco = fopen(path, "r+b");
if(disco){
if(cmd.fs == '2'){
formatear_ext2(cmd.type, meta->part_start, meta->part_size, disco);
}else if(cmd.fs == '3'){
formatear_ext3(cmd.type, meta->part_start, meta->part_size, disco);
}else{
printf("ERROR\n");
}
}else{
printf("ERROR: No se pudo acceder al dispositivo.\n");
}
添加一些代码后,我仍然不知道什么是cmd
,meta
,I_NODO
,BLOQUE_ARCHIVO
...以及它们的值是什么。我试图从日志中推测值,以便可以编译和运行,我发现了值3472328296227680304
,就像@Scheff所说的,0x3030303030303030由以下代码编写:
for(size_t i = 0; i < super_block.s_inodes_count; i++){
fseek(disco, super_block.s_first_ino + i, SEEK_SET);
fwrite("0", 1, 1, disco);
}
for(size_t i = 0; i < super_block.s_blocks_count; i++){
fseek(disco, super_block.s_first_blo + i, SEEK_SET);
fwrite("0", 1, 1, disco);
}
如果我注释掉部分代码,则不会出现奇数值由于信息丢失,我无法准确指出该错误,但是我认为这会有所帮助我建议您添加一些调试代码,例如打印出super_block.s_first_ino
值,以查找错误。