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mandreyel 2018-04-15 19:01:25 +02:00
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@ -6,7 +6,9 @@ mio has been created with the goal to be easily includable (i.e. no dependencies
Please feel free to open an issue, I'll try to address any concerns as best I can.
### Why?
The primary motivation for writing this library instead of using Boost.Iostreams, was the lack of support for establishing a memory mapping with an already open file handle/descriptor. This is possible with mio.
Because memory mapping is the best thing since sliced bread!
More seriously, the primary motivation for writing this library instead of using Boost.Iostreams, was the lack of support for establishing a memory mapping with an already open file handle/descriptor. This is possible with mio.
Albeit a minor nitpick, Boost.Iostreams implements memory mapped file IO with a `std::shared_ptr` to provide shared semantics, even if not needed, and the overhead of the heap allocation may be unnecessary and/or unwanted.
In mio, there are two classes to cover the two use-cases: one that is move-only (basically a zero-cost abstraction over the system specific mmapping functions), and the other that acts just like its Boost.Iostreams counterpart, with shared semantics.
@ -48,7 +50,7 @@ int main()
// ...
}
```
However, mio does not check whether the provided file descriptor has the same access permissions as the desired mapping, so the mapping may fail.
However, mio does not check whether the provided file descriptor has the same access permissions as the desired mapping, so the mapping may fail. Such errors are reported via the `std::error_code` out parameter that is passed to the mapping function.
### Example
```c++