Revert "net: move context cancellation logic of blocking calls to a common function."
This reverts CL 463231.
Reason for revert: introduced a data race on darwin.
Fixes #58169.
Change-Id: I35f02273db38c257369c166547bb4945f92fdc3a
Reviewed-on: https://go-review.googlesource.com/c/go/+/464375
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
diff --git a/src/net/cgo_unix.go b/src/net/cgo_unix.go
index d76652f..8e43bad 100644
--- a/src/net/cgo_unix.go
+++ b/src/net/cgo_unix.go
@@ -29,33 +29,20 @@
func (eai addrinfoErrno) Temporary() bool { return eai == _C_EAI_AGAIN }
func (eai addrinfoErrno) Timeout() bool { return false }
-// doBlockingWithCtx executes a blocking function in a separate goroutine when the provided
-// context is cancellable. It is intended for use with calls that don't support context
-// cancellation (cgo, syscalls). blocking func may still be running after this function finishes.
-func doBlockingWithCtx[T any](ctx context.Context, blocking func() (T, error)) (T, error) {
- if ctx.Done() == nil {
- return blocking()
- }
+type portLookupResult struct {
+ port int
+ err error
+}
- type result struct {
- res T
- err error
- }
+type ipLookupResult struct {
+ addrs []IPAddr
+ cname string
+ err error
+}
- res := make(chan result, 1)
- go func() {
- var r result
- r.res, r.err = blocking()
- res <- r
- }()
-
- select {
- case r := <-res:
- return r.res, r.err
- case <-ctx.Done():
- var zero T
- return zero, mapErr(ctx.Err())
- }
+type reverseLookupResult struct {
+ names []string
+ err error
}
func cgoLookupHost(ctx context.Context, name string) (hosts []string, err error, completed bool) {
@@ -85,11 +72,20 @@
case '6':
*_C_ai_family(&hints) = _C_AF_INET6
}
-
- port, err = doBlockingWithCtx(ctx, func() (int, error) {
- return cgoLookupServicePort(&hints, network, service)
- })
- return port, err, true
+ if ctx.Done() == nil {
+ port, err := cgoLookupServicePort(&hints, network, service)
+ return port, err, true
+ }
+ result := make(chan portLookupResult, 1)
+ go cgoPortLookup(result, &hints, network, service)
+ select {
+ case r := <-result:
+ return r.port, r.err, true
+ case <-ctx.Done():
+ // Since there isn't a portable way to cancel the lookup,
+ // we just let it finish and write to the buffered channel.
+ return 0, mapErr(ctx.Err()), false
+ }
}
func cgoLookupServicePort(hints *_C_struct_addrinfo, network, service string) (port int, err error) {
@@ -131,6 +127,11 @@
return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}
}
+func cgoPortLookup(result chan<- portLookupResult, hints *_C_struct_addrinfo, network, service string) {
+ port, err := cgoLookupServicePort(hints, network, service)
+ result <- portLookupResult{port, err}
+}
+
func cgoLookupIPCNAME(network, name string) (addrs []IPAddr, cname string, err error) {
acquireThread()
defer releaseThread()
@@ -205,12 +206,24 @@
return addrs, cname, nil
}
+func cgoIPLookup(result chan<- ipLookupResult, network, name string) {
+ addrs, cname, err := cgoLookupIPCNAME(network, name)
+ result <- ipLookupResult{addrs, cname, err}
+}
+
func cgoLookupIP(ctx context.Context, network, name string) (addrs []IPAddr, err error, completed bool) {
- addrs, err = doBlockingWithCtx(ctx, func() ([]IPAddr, error) {
+ if ctx.Done() == nil {
addrs, _, err = cgoLookupIPCNAME(network, name)
- return addrs, err
- })
- return addrs, err, true
+ return addrs, err, true
+ }
+ result := make(chan ipLookupResult, 1)
+ go cgoIPLookup(result, network, name)
+ select {
+ case r := <-result:
+ return r.addrs, r.err, true
+ case <-ctx.Done():
+ return nil, mapErr(ctx.Err()), true
+ }
}
// These are roughly enough for the following:
@@ -239,11 +252,18 @@
if sa == nil {
return nil, &DNSError{Err: "invalid address " + ip.String(), Name: addr}, true
}
-
- names, err = doBlockingWithCtx(ctx, func() ([]string, error) {
- return cgoLookupAddrPTR(addr, sa, salen)
- })
- return names, err, true
+ if ctx.Done() == nil {
+ names, err := cgoLookupAddrPTR(addr, sa, salen)
+ return names, err, true
+ }
+ result := make(chan reverseLookupResult, 1)
+ go cgoReverseLookup(result, addr, sa, salen)
+ select {
+ case r := <-result:
+ return r.names, r.err, true
+ case <-ctx.Done():
+ return nil, mapErr(ctx.Err()), true
+ }
}
func cgoLookupAddrPTR(addr string, sa *_C_struct_sockaddr, salen _C_socklen_t) (names []string, err error) {
@@ -285,6 +305,11 @@
return []string{absDomainName(string(b))}, nil
}
+func cgoReverseLookup(result chan<- reverseLookupResult, addr string, sa *_C_struct_sockaddr, salen _C_socklen_t) {
+ names, err := cgoLookupAddrPTR(addr, sa, salen)
+ result <- reverseLookupResult{names, err}
+}
+
func cgoSockaddr(ip IP, zone string) (*_C_struct_sockaddr, _C_socklen_t) {
if ip4 := ip.To4(); ip4 != nil {
return cgoSockaddrInet4(ip4), _C_socklen_t(syscall.SizeofSockaddrInet4)
@@ -310,9 +335,30 @@
// resSearch will make a call to the 'res_nsearch' routine in the C library
// and parse the output as a slice of DNS resources.
func resSearch(ctx context.Context, hostname string, rtype, class int) ([]dnsmessage.Resource, error) {
- return doBlockingWithCtx(ctx, func() ([]dnsmessage.Resource, error) {
+ if ctx.Done() == nil {
return cgoResSearch(hostname, rtype, class)
- })
+ }
+
+ type result struct {
+ res []dnsmessage.Resource
+ err error
+ }
+
+ res := make(chan result, 1)
+ go func() {
+ r, err := cgoResSearch(hostname, rtype, class)
+ res <- result{
+ res: r,
+ err: err,
+ }
+ }()
+
+ select {
+ case res := <-res:
+ return res.res, res.err
+ case <-ctx.Done():
+ return nil, mapErr(ctx.Err())
+ }
}
func cgoResSearch(hostname string, rtype, class int) ([]dnsmessage.Resource, error) {
