mirror of
https://github.com/tinygo-org/tinygo.git
synced 2026-08-09 05:23:40 +00:00
Ayke van Laethem
41 lines
1.1 KiB
Go
41 lines
1.1 KiB
Go
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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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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var errRandom = errors.New("failed to obtain random data from rand_s")
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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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return
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}
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// Use the old RtlGenRandom, introduced in Windows XP.
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// Even though the documentation says it is deprecated, it is widely used
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// and probably won't go away anytime soon.
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// See for example: https://github.com/golang/go/issues/33542
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// For Windows 7 and newer, we might switch to ProcessPrng in the future
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// (which is a documented function and might be a tiny bit faster).
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ok := libc_RtlGenRandom(unsafe.Pointer(unsafe.SliceData(b)), len(b))
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if !ok {
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return 0, errRandom
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}
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return len(b), nil
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}
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// This function is part of advapi32.dll, and is called SystemFunction036 for
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// some reason. It's available on Windows XP and newer.
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// See: https://learn.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom
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//
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//export SystemFunction036
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func libc_RtlGenRandom(buf unsafe.Pointer, len int) bool
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