ikegami is right that you can use pack and unpack create / read from structs. however, using pack() to write structs does not work portably, especially when you've got a struct made up of different-sized elements - AFAIK C compilers are allowed to switch elements in struct around, and anyway insert unused bytes to align elements depending on their type. IOW:
struct {
byte a;
long b;
}
may take up 6 bytes on a system with 4-byte integers and a 2-byte alignment requirement for integers. OTOH on a system with 4-byte aligned 4-byte integers, it might take up 8 bytes.
Ofcourse, there are modules to deal with all of this, a CPAN search gave me this (probably incomplete) list:
note -
I've not tested any of these and if none of them work, I know Inline::C does, but it's probably overkill for this application. Also, if you only need it to work on a specific system, you can hardcode the pack() template anyway (you might have to experiment to get the right one).
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The C standard allows for arbitrary padding for alignment reasons but in practice how structs are padded is pretty consistent among most C compilers.
Also, most good structs are laid out such that no padding is required.
So you can use pack quite portably in most cases. But, yes, there are exceptions.
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You're right about Class::Struct. pack is the function designed to create C-style structs. If ioctl returns values using the struct, you can unpack it using unpack.
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Sometimes it is just easier to do it in C Inline C lets you get data back to perl easily. Re: MAC Address of An Interface in one of my ioctl inline C examples. There are a few others I posted here to change an interfaces IP....
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Thanks tachyon,
Maybe I should do it in c so...
For the record, I'm trying to get NIC speed and Duplex mode. Machines can be one of (Linux|SunOS|AIX|HP-UX)...
I need to go away now and beat my forehead off the keyboard for another while...
C.
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