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Ayke van Laethem
d94f42f6e2
This package provides access to an operating system resource
(cryptographic numbers) and so needs to be replaced with a TinyGo
version that does this in a different way.
I've made the following choices while adding this feature:
- I'm using the getentropy call whenever possible (most POSIX like
systems), because it is easier to use and more reliable. Linux is
the exception: it only added getentropy relatively recently.
- I've left bare-metal implementations to a future patch. This because
it's hard to reliably get cryptographically secure random numbers on
embedded devices: most devices do not have a hardware PRNG for this
purpose.
39 lines
761 B
Go
39 lines
761 B
Go
// +build darwin freebsd wasi
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// This implementation of crypto/rand uses the getentropy system call (available
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// on both MacOS and WASI) to generate random numbers.
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package rand
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import (
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"errors"
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"unsafe"
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)
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var errReadFailed = errors.New("rand: could not read random bytes")
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func init() {
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Reader = &reader{}
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}
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type reader struct {
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}
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func (r *reader) Read(b []byte) (n int, err error) {
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if len(b) != 0 {
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if len(b) > 256 {
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b = b[:256]
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}
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result := libc_getentropy(unsafe.Pointer(&b[0]), len(b))
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if result < 0 {
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// Maybe we should return a syscall.Errno here?
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return 0, errReadFailed
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}
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}
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return len(b), nil
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}
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// int getentropy(void *buf, size_t buflen);
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//export getentropy
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func libc_getentropy(buf unsafe.Pointer, buflen int) int
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