133 lines
4.6 KiB
C++
133 lines
4.6 KiB
C++
#include "ext2_file.h"
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#include <cstring>
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#include "delog/delog.h"
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using namespace EXT2;
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EXT2_File::EXT2_File(EXT2_DEntry *d, EXT2_Inode *i) {
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ext2_dentry = d;
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ext2_inode = i;
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ext2_fs = i->ext2_fs;
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type = d->type;
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pos = 0;
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size = i->i->size;
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_dbg_log("打开文件");
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_si(size);
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}
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EXT2_File::EXT2_File(EXT2_DEntry *d) {
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if (d->ext2_inode == nullptr)
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d->inflate();
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ext2_dentry = d;
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ext2_inode = d->ext2_inode;
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ext2_fs = d->ext2_inode->ext2_fs;
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type = d->type;
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pos = 0;
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size = d->ext2_inode->i->size;
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_dbg_log("打开文件");
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_si(size);
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}
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_u32 EXT2_File::tell() {
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return pos;
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}
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_u32 EXT2_File::seek(int pos, int whence) {
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switch (whence) {
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case VFS::SEEK::CUR:
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this->pos += pos;
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break;
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case VFS::SEEK::END:
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this->pos = std::min(this->size + pos, this->size);
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break;
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case VFS::SEEK::SET:
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this->pos = pos;
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break;
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default:
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_error_s(whence, "Unknow whence");
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}
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return this->pos;
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}
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_u32 EXT2_File::read(_u8 *buf, _u32 len) {
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if (pos + len > size)
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return 0;
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_u32 read_len = 0, this_read_len;
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_u32 block_size = ext2_fs->block_size; // 块大小
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_u32 byte_in_block = pos % block_size; // 第一个字节在块中的位置
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_u32 nth_block = pos / block_size; // 第一个字节在第n个块，pos以0开始计数，不需要加1
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auto it = ext2_inode->iter_at(nth_block);
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_u32 block_n = *it; // 第一个字节的块号
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_si(block_n);
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_u32 pos_in_fs = ext2_fs->block_to_pos(block_n); // 第一个块在文件系统中的位置
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MM::Buf buff(block_size);
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ext2_fs->dev->read(buff, pos_in_fs, block_size); // 从第一个块读入数据，每次都读出一整块
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memcpy(buf, buff.data + byte_in_block, std::min(len, block_size - byte_in_block));
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read_len = std::min(len, block_size - byte_in_block);
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while (read_len < len && pos + read_len < size) {
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it++; // 指向下一个块
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block_n = *it; // 下一个块号
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pos_in_fs = ext2_fs->block_to_pos(block_n); // 下一个块的位置
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this_read_len = ext2_fs->dev->read(buff, pos_in_fs, block_size); // 读入
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memcpy(buf + read_len, buff.data, std::min(block_size, len - read_len));
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read_len += this_read_len;
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}
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pos += read_len;
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return read_len;
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}
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_u32 EXT2_File::write(_u8 *buf, _u32 len) {
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_u32 write_len = 0, this_write_len;
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_u32 block_size = ext2_fs->block_size; // 块大小
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_u32 byte_in_block = pos % block_size; // 第一个字节在块中的位置
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_u32 nth_block = pos / block_size; // 第一个字节在第n个块，pos以0开始计数，不需要加1
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auto it = ext2_inode->iter_at(nth_block);
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_u32 block_n = *it; // 第一个字节的块号
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_u32 pos_in_fs = ext2_fs->block_to_pos(block_n); // 第一个块在文件系统中的位置
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//_si(pos + len);
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MM::Buf buff(block_size);
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this_write_len = std::min(block_size - byte_in_block, len);
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memcpy(buff.data, buf, this_write_len);
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ext2_fs->dev->write(buff, pos_in_fs + byte_in_block, this_write_len); // 向第一个块写数据
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write_len = this_write_len;
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while (write_len < len) {
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it++; // 指向下一个块
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block_n = *it; // 下一个块号
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pos_in_fs = ext2_fs->block_to_pos(block_n); // 下一个块的位置
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this_write_len = std::min(block_size, len - write_len);
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memcpy(buff.data, buf + write_len, this_write_len);
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ext2_fs->dev->write(buff, pos_in_fs, this_write_len); // 写
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write_len += this_write_len;
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}
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pos += write_len;
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//_si(pos);
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if (pos > size)
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size = pos;
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return write_len;
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}
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void EXT2_File::resize(_u32 new_size) {
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if (size == new_size)
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return;
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if (ext2_inode->i->blocks >= 13)
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_error_s(ext2_inode->i->blocks, "not support big file yet");
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_u32 current_blocks = ext2_inode->i->blocks;
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_u32 target_blocks = new_size / ext2_fs->block_size + ((new_size % ext2_fs->block_size) > 0);
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if (new_size < size) {
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while (target_blocks < current_blocks) {
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current_blocks--;
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if (ext2_inode->i->block[current_blocks] == 0)
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continue;
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ext2_fs->release_block(ext2_inode->i->block[current_blocks]); // 循环释放当前块
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ext2_inode->i->block[current_blocks] = 0;
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}
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} else {
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while (target_blocks > current_blocks) {
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ext2_inode->i->block[current_blocks - 1] = ext2_fs->alloc_block();
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current_blocks++;
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}
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}
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ext2_inode->i->blocks = current_blocks;
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} |