x/sys/unix: use uintptr for tracee addresses on FreeBSD

Change PtraceLwpInfoStruct, PtraceIoDesc and PtraceIO to not use *byte
to represent addresses that belong to the traced process.

Fixes golang/go#54113

Change-Id: I6efad26046b784d79b83fed4498cac93957274ca
Reviewed-on: https://go-review.googlesource.com/c/sys/+/419915
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>

unix/mkpost.go

@@ -70,6 +70,32 @@ func main() {
 		b = convertEprocRegex.ReplaceAll(b, []byte("$1$2[$3]byte"))
 	}
 
+	if goos == "freebsd" {
+		// Inside PtraceLwpInfoStruct replace __Siginfo with __PtraceSiginfo,
+		// Create __PtraceSiginfo as a copy of __Siginfo where every *byte instance is replaced by uintptr
+		ptraceLwpInfoStruct := regexp.MustCompile(`(?s:type PtraceLwpInfoStruct struct \{.*?\})`)
+		b = ptraceLwpInfoStruct.ReplaceAllFunc(b, func(in []byte) []byte {
+			return bytes.ReplaceAll(in, []byte("__Siginfo"), []byte("__PtraceSiginfo"))
+		})
+
+		siginfoStruct := regexp.MustCompile(`(?s:type __Siginfo struct \{.*?\})`)
+		b = siginfoStruct.ReplaceAllFunc(b, func(in []byte) []byte {
+			out := append([]byte{}, in...)
+			out = append(out, '\n', '\n')
+			out = append(out,
+				bytes.ReplaceAll(
+					bytes.ReplaceAll(in, []byte("__Siginfo"), []byte("__PtraceSiginfo")),
+					[]byte("*byte"), []byte("uintptr"))...)
+			return out
+		})
+
+		// Inside PtraceIoDesc replace all *byte with uintptr
+		ptraceIoDescStruct := regexp.MustCompile(`(?s:type PtraceIoDesc struct \{.*?\})`)
+		b = ptraceIoDescStruct.ReplaceAllFunc(b, func(in []byte) []byte {
+			return bytes.ReplaceAll(in, []byte("*byte"), []byte("uintptr"))
+		})
+	}
+
 	// Intentionally export __val fields in Fsid and Sigset_t
 	valRegex := regexp.MustCompile(`type (Fsid|Sigset_t) struct {(\s+)X__(bits|val)(\s+\S+\s+)}`)
 	b = valRegex.ReplaceAll(b, []byte("type $1 struct {${2}Val$4}"))