August 2022 Archives

对于特定的函数或者变量属性检测一个特定的参数类：

#include <iostream>
#include <boost/smart_ptr.hpp>
​
#include <type_traits>
using namespace boost;
using namespace std;
​
#define _CAT(A, B) A##B
#define STR(s) #s
#define CAT(A,B) _CAT(A,B)
#define CHECKER_PREFIX __has_member_function_
#define HAS_MEMBER_FUNC_CHECKER_NAME(FUNC) CAT(CHECKER_PREFIX, FUNC)
​
#define HAS_MEMBER_FUNC_CHECKER(FUNC) template <typename T> \
 struct HAS_MEMBER_FUNC_CHECKER_NAME(FUNC){ \
 template <typename C> static std::true_type test(decltype(&C::FUNC)); \
 template <typename C> static std::false_type test(...); \
 static constexpr bool value = std::is_same<decltype(test<T>(nullptr)),std::true_type>::value; \
};
​
#define HAS_MEMBER_FUNC(TYPE, FUNC) (HAS_MEMBER_FUNC_CHECKER_NAME(FUNC)<TYPE>::value)
​
​
class TestA{
public:
    int* foo(){
​
        int* a =new int(1);
        return a;
​
    }
​
    static int foo2(){
        return  1;
    }
​
    static const int foo3;
};
​
HAS_MEMBER_FUNC_CHECKER(foo);
HAS_MEMBER_FUNC_CHECKER(foo2);
HAS_MEMBER_FUNC_CHECKER(foo3);
int main() {
​
    static_assert(HAS_MEMBER_FUNC(TestA, foo));
    std::cout<<HAS_MEMBER_FUNC(TestA, foo) <<std::endl;
​
    return 0;
}

对于确定参数类型的泛型成员函数：

#include <iostream>
#include <boost/smart_ptr.hpp>
​
#include <type_traits>
using namespace boost;
using namespace std;
​
#define _CAT(A, B) A##B
#define STR(s) #s
#define CAT(A,B) _CAT(A,B)
// 对于固定个数的模版类，检测某一个属性或者函数是否存在
#define CHECKER_PREFIX2 _has_member_fcuntoin2_
#define HAS_MEMBER_FUNC_CHECK_NAME2_(FUNC) CAT(CHECKER_PREFIX2,FUNC)
​
#define HAS_MEMBER_FUNC_CEHCKER2(FUNC) template<typename T, typename R> \
    struct HAS_MEMBER_FUNC_CHECK_NAME2_(FUNC){ \
    template<typename C> static std::true_type test(decltype(&C::template FUNC<R>)); \
    template<typename C> static std::false_type test(...); \
    static constexpr bool value = std::is_same<decltype(test<T>(nullptr)),std::true_type>::value; \
}
​
// #define IF_HAS_MEMBER_FUNC2(FUNC,CLASS_,CLASS_F_T) (HAS_MEMBER_FUNC_CEHCK_NAME2_(FUNC)<CLASS_ ,CLASS_F_T>::value)
​
​
class TestA{
public:
    int* foo(){
​
        int* a =new int(1);
        return a;
​
    }
​
    static int foo2(){
        return  1;
    }
​
    template <typename T>
    static  int foo4(){
        return 1;
    }
​
    static const int foo3;
};
​
​
//含有固定类型的模版类
HAS_MEMBER_FUNC_CEHCKER2(foo4);
​
int main() {
    // 输出 1
    std::cout<< HAS_MEMBER_FUNC_CHECK_NAME2_(foo4)<TestA,char>::value << std::endl;
    // 输出 1
    std::cout<< HAS_MEMBER_FUNC_CHECK_NAME2_(foo4)<TestA,int>::value << std::endl;
 
    return 0;
}

See also:

https://blog.csdn.net/TH_NUM/article/details/90968219

https://harrychen.xyz/2019/06/04/cpp-17-mock-concept/

当前fdisk查看的磁盘分区比实际df出来的磁盘分区大，实际磁盘分区不可用。

[SME@search-10 ~]$ df -Th
Filesystem     Type      Size  Used Avail Use% Mounted on
devtmpfs       devtmpfs   94G     0   94G   0% /dev
tmpfs          tmpfs      94G     0   94G   0% /dev/shm
tmpfs          tmpfs      94G   18M   94G   1% /run
tmpfs          tmpfs      94G     0   94G   0% /sys/fs/cgroup
/dev/sda3      ext4      7.6G  2.6G  4.6G  36% /
/dev/sda2      ext4      2.0G  389M  1.5G  22% /boot
/dev/sda4      ext4      1.7T   60K  1.6T   1% /home/search
tmpfs          tmpfs      19G     0   19G   0% /run/user/0
tmpfs          tmpfs      19G     0   19G   0% /run/user/1006
​
[SME@search-10 ~]$ sudo fdisk -l
Disk /dev/sda: 2.6 TiB, 2876997894144 bytes, 5619136512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes
Disklabel type: gpt
Disk identifier: 40992439-8FB1-4EF3-AF5D-0B180C07EA05
​
Device          Start        End    Sectors  Size Type
/dev/sda1        2048       4095       2048    1M BIOS boot
/dev/sda2        4096    4198399    4194304    2G Linux filesystem
/dev/sda3     4198400 2101350399 2097152000 1000G Linux filesystem
/dev/sda4  2101350400 5619003391 3517652992  1.7T Microsoft basic data
/dev/sda5  5619003392 5619136478     133087   65M Linux filesystem

由于是根分区，无法重新格式化，且重新通过分配之后，重启也无法获得扩展，如下所示：

[SME@search-10 ~]$ sudo fdisk /dev/sda
​
Welcome to fdisk (util-linux 2.32.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
​
​
Command (m for help): p
Disk /dev/sda: 2.6 TiB, 2876997894144 bytes, 5619136512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes
Disklabel type: gpt
Disk identifier: 40992439-8FB1-4EF3-AF5D-0B180C07EA05
​
Device          Start        End    Sectors  Size Type
/dev/sda1        2048       4095       2048    1M BIOS boot
/dev/sda2        4096    4198399    4194304    2G Linux filesystem
/dev/sda3     4198400 2101350399 2097152000 1000G Linux filesystem
/dev/sda4  2101350400 5619003391 3517652992  1.7T Microsoft basic data
/dev/sda5  5619003392 5619136478     133087   65M Linux filesystem
​
Command (m for help): d
Partition number (1-5, default 5): 3
​
Partition 3 has been deleted.
​
Command (m for help): p
Disk /dev/sda: 2.6 TiB, 2876997894144 bytes, 5619136512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes
Disklabel type: gpt
Disk identifier: 40992439-8FB1-4EF3-AF5D-0B180C07EA05
​
Device          Start        End    Sectors  Size Type
/dev/sda1        2048       4095       2048    1M BIOS boot
/dev/sda2        4096    4198399    4194304    2G Linux filesystem
/dev/sda4  2101350400 5619003391 3517652992  1.7T Microsoft basic data
/dev/sda5  5619003392 5619136478     133087   65M Linux filesystem
​
Command (m for help): n
Partition number (3,6-128, default 3):
First sector (4198400-2101350399, default 4198400):
Last sector, +sectors or +size{K,M,G,T,P} (4198400-2101350399, default 2101350399):
​
Created a new partition 3 of type 'Linux filesystem' and of size 1000 GiB.
Partition #3 contains a ext4 signature.
​
Do you want to remove the signature? [Y]es/[N]o: Y
​
The signature will be removed by a write command.
​
Command (m for help): p
Disk /dev/sda: 2.6 TiB, 2876997894144 bytes, 5619136512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 262144 bytes / 786432 bytes
Disklabel type: gpt
Disk identifier: 40992439-8FB1-4EF3-AF5D-0B180C07EA05
​
Device          Start        End    Sectors  Size Type
/dev/sda1        2048       4095       2048    1M BIOS boot
/dev/sda2        4096    4198399    4194304    2G Linux filesystem
/dev/sda3     4198400 2101350399 2097152000 1000G Linux filesystem
/dev/sda4  2101350400 5619003391 3517652992  1.7T Microsoft basic data
/dev/sda5  5619003392 5619136478     133087   65M Linux filesystem
​
Filesystem/RAID signature on partition 3 will be wiped.
​
Command (m for help): w
The partition table has been altered.
Syncing disks.
​
[SME@search-10 ~]$ sudo partprobe /dev/sda
Warning: The disk CHS geometry (11017914,255,2) reported by the operating system does not match the geometry stored on the disk label (22095,255,63).
Error: Can't have overlapping partitions.

于是，尝试使用resize2fs，如下所示：

[SME@search-10 ~]$ sudo resize2fs /dev/sda3
resize2fs 1.45.6 (20-Mar-2020)
Filesystem at /dev/sda3 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 125
The filesystem on /dev/sda3 is now 262144000 (4k) blocks long.
​
[SME@search-10 ~]$ df -Th
Filesystem     Type      Size  Used Avail Use% Mounted on
devtmpfs       devtmpfs   94G     0   94G   0% /dev
tmpfs          tmpfs      94G     0   94G   0% /dev/shm
tmpfs          tmpfs      94G   18M   94G   1% /run
tmpfs          tmpfs      94G     0   94G   0% /sys/fs/cgroup
/dev/sda3      ext4      985G  2.6G  942G   1% /
/dev/sda2      ext4      2.0G  389M  1.5G  22% /boot
/dev/sda4      ext4      1.7T   60K  1.6T   1% /home/search
tmpfs          tmpfs      19G     0   19G   0% /run/user/0

结果成功扩展了分区。