如何在 64 位 Perl 中解压(64 位)unsigned long? [英] How to unpack (64-bit) unsigned long in 64-bit Perl?

问题描述

我正在尝试解压缩从 C 程序通过 SysV::IPC 传递到 Perl 脚本的无符号长值.

I'm trying to unpack an unsigned long value that is passed from a C program to a Perl script via SysV::IPC.

已知该值是正确的(我做了一个测试，将相同的值发送到两个队列中，一个由 Perl 读取，第二个由 C 应用程序读取)，并且所有前面的值都被正确读取(使用 q 而不是 i! 来处理 64 位整数).

It is known that the value is correct (I made a test which sends the same value into two queues, one read by Perl and the second by the C application), and all predecessing values are read correctly (used q instead of i! to work with 64-bit integers).

众所周知，PHP 有类似的东西(搜索对于64 位机器上的 unsigned long")(似乎类似:在 64 位架构上打包/解包 64 位 int在 PHP 中)

It is also known that PHP had something similar in bugs (search for "unsigned long on 64 bit machines") (seems to be similar: Pack / unpack a 64-bit int on 64-bit architecture in PHP)

到目前为止测试的参数:

Arguments tested so far:

• ...Q(=某个值大于预期)
• ..L ( = 0)
• ..L！( = 大值)
• ..l (=0)
• ..l！( = 大值)
• ..ln！( = 0)
• ..N，..N！( = 0)

使用 bigint；使用 bignum; -- 没有效果.

详情:

• sizeof(unsigned long) = 8;
• Data::Dumper->new([$thatstring])->Useqq(1)->Dump(); 一些有意义的空字节..莉>
• byteorder='12345678';

• sizeof(unsigned long) = 8;
• Data::Dumper->new([$thatstring])->Useqq(1)->Dump(); a lot of null bytes along some meaningful..
• byteorder='12345678';

解决办法:- x4Q 填充四个字节.

Solution: - x4Q with padding four bytes.

推荐答案

解决方案很简单:添加 x4Q 以跳过实际值前的四个字节；需要更直观地考虑填充/对齐..

The solution was simple: added x4Q to skip four bytes before actual value; need to more visually think of padding/alignment..

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