Description:
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In socket_write(), socket_send() and socket_sendto(), it is not checked whether the length parameter is negative. If it is negative, it will be converted to a size_t for the underlying syscall, so a write of more than 2GB will be requested. In my testing, this fails with EFAULT. It is conceivable that it may instead be a buffer overflow on some embedded systems.

I suggest validating the length parameter.

Test script:
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$f = socket_create(AF_INET, SOCK_STREAM,  SOL_TCP);
socket_connect($f, '127.0.0.1',8888);
socket_write($f, "Hello\n", -1);


Actual result:
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Warning: socket_write(): unable to write to socket [14]: Bad address