remote: add keep-alive and references to the repository

Especially in 1.8, the garbage collector can decide to finalize an object even
as we are in one of its methods. This means it can free a remote while we're in
one of its calls, as we're referencing the pointer inside the object, rather
than the `Remote` itself.

remote.go

@@ -144,6 +144,7 @@ type ProxyOptions struct {
 type Remote struct {
 	ptr       *C.git_remote
 	callbacks RemoteCallbacks
+	repo      *Repository
 }
 
 type CertificateKind uint
@@ -370,6 +371,7 @@ func RemoteIsValidName(name string) bool {
 func (r *Remote) Free() {
 	runtime.SetFinalizer(r, nil)
 	C.git_remote_free(r.ptr)
+	r.ptr = nil
 }
 
 type RemoteCollection struct {
@@ -383,6 +385,7 @@ func (c *RemoteCollection) List() ([]string, error) {
 	defer runtime.UnlockOSThread()
 
 	ecode := C.git_remote_list(&r, c.repo.ptr)
+	runtime.KeepAlive(c.repo)
 	if ecode < 0 {
 		return nil, MakeGitError(ecode)
 	}
@@ -393,7 +396,7 @@ func (c *RemoteCollection) List() ([]string, error) {
 }
 
 func (c *RemoteCollection) Create(name string, url string) (*Remote, error) {
-	remote := &Remote{}
+	remote := &Remote{repo: c.repo}
 
 	cname := C.CString(name)
 	defer C.free(unsafe.Pointer(cname))
@@ -419,6 +422,7 @@ func (c *RemoteCollection) Delete(name string) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_delete(c.repo.ptr, cname)
+	runtime.KeepAlive(c.repo)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -426,7 +430,7 @@ func (c *RemoteCollection) Delete(name string) error {
 }
 
 func (c *RemoteCollection) CreateWithFetchspec(name string, url string, fetch string) (*Remote, error) {
-	remote := &Remote{}
+	remote := &Remote{repo: c.repo}
 
 	cname := C.CString(name)
 	defer C.free(unsafe.Pointer(cname))
@@ -447,7 +451,7 @@ func (c *RemoteCollection) CreateWithFetchspec(name string, url string, fetch st
 }
 
 func (c *RemoteCollection) CreateAnonymous(url string) (*Remote, error) {
-	remote := &Remote{}
+	remote := &Remote{repo: c.repo}
 
 	curl := C.CString(url)
 	defer C.free(unsafe.Pointer(curl))
@@ -464,7 +468,7 @@ func (c *RemoteCollection) CreateAnonymous(url string) (*Remote, error) {
 }
 
 func (c *RemoteCollection) Lookup(name string) (*Remote, error) {
-	remote := &Remote{}
+	remote := &Remote{repo: c.repo}
 
 	cname := C.CString(name)
 	defer C.free(unsafe.Pointer(cname))
@@ -481,15 +485,21 @@ func (c *RemoteCollection) Lookup(name string) (*Remote, error) {
 }
 
 func (o *Remote) Name() string {
-	return C.GoString(C.git_remote_name(o.ptr))
+	s := C.git_remote_name(o.ptr)
+	runtime.KeepAlive(o)
+	return C.GoString(s)
 }
 
 func (o *Remote) Url() string {
-	return C.GoString(C.git_remote_url(o.ptr))
+	s := C.git_remote_url(o.ptr)
+	runtime.KeepAlive(o)
+	return C.GoString(s)
 }
 
 func (o *Remote) PushUrl() string {
-	return C.GoString(C.git_remote_pushurl(o.ptr))
+	s := C.git_remote_pushurl(o.ptr)
+	runtime.KeepAlive(o)
+	return C.GoString(s)
 }
 
 func (c *RemoteCollection) Rename(remote, newname string) ([]string, error) {
@@ -504,6 +514,7 @@ func (c *RemoteCollection) Rename(remote, newname string) ([]string, error) {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_rename(&cproblems, c.repo.ptr, cremote, cnewname)
+	runtime.KeepAlive(c.repo)
 	if ret < 0 {
 		return []string{}, MakeGitError(ret)
 	}
@@ -522,6 +533,7 @@ func (c *RemoteCollection) SetUrl(remote, url string) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_set_url(c.repo.ptr, cremote, curl)
+	runtime.KeepAlive(c.repo)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -538,6 +550,7 @@ func (c *RemoteCollection) SetPushUrl(remote, url string) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_set_pushurl(c.repo.ptr, cremote, curl)
+	runtime.KeepAlive(c.repo)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -554,6 +567,7 @@ func (c *RemoteCollection) AddFetch(remote, refspec string) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_add_fetch(c.repo.ptr, cremote, crefspec)
+	runtime.KeepAlive(c.repo)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -605,6 +619,7 @@ func (o *Remote) FetchRefspecs() ([]string, error) {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_get_fetch_refspecs(&crefspecs, o.ptr)
+	runtime.KeepAlive(o)
 	if ret < 0 {
 		return nil, MakeGitError(ret)
 	}
@@ -624,6 +639,7 @@ func (c *RemoteCollection) AddPush(remote, refspec string) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_add_push(c.repo.ptr, cremote, crefspec)
+	runtime.KeepAlive(c.repo)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -641,12 +657,16 @@ func (o *Remote) PushRefspecs() ([]string, error) {
 		return nil, MakeGitError(ret)
 	}
 	defer C.git_strarray_free(&crefspecs)
+	runtime.KeepAlive(o)
+
 	refspecs := makeStringsFromCStrings(crefspecs.strings, int(crefspecs.count))
 	return refspecs, nil
 }
 
 func (o *Remote) RefspecCount() uint {
-	return uint(C.git_remote_refspec_count(o.ptr))
+	count := C.git_remote_refspec_count(o.ptr)
+	runtime.KeepAlive(o)
+	return uint(count)
 }
 
 func populateFetchOptions(options *C.git_fetch_options, opts *FetchOptions) {
@@ -706,6 +726,7 @@ func (o *Remote) Fetch(refspecs []string, opts *FetchOptions, msg string) error
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_fetch(o.ptr, &crefspecs, coptions, cmsg)
+	runtime.KeepAlive(o)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -734,17 +755,18 @@ func (o *Remote) Connect(direction ConnectDirection, callbacks *RemoteCallbacks,
 	var cproxy C.git_proxy_options
 	populateProxyOptions(&cproxy, proxyOpts)
 	defer freeProxyOptions(&cproxy)
-	
+
 	cheaders := C.git_strarray{}
 	cheaders.count = C.size_t(len(headers))
 	cheaders.strings = makeCStringsFromStrings(headers)
 	defer freeStrarray(&cheaders)
 
-
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
-	if ret := C.git_remote_connect(o.ptr, C.git_direction(direction), &ccallbacks, &cproxy, &cheaders); ret != 0 {
+	ret := C.git_remote_connect(o.ptr, C.git_direction(direction), &ccallbacks, &cproxy, &cheaders)
+	runtime.KeepAlive(o)
+	if ret != 0 {
 		return MakeGitError(ret)
 	}
 	return nil
@@ -755,6 +777,7 @@ func (o *Remote) Disconnect() {
 	defer runtime.UnlockOSThread()
 
 	C.git_remote_disconnect(o.ptr)
+	runtime.KeepAlive(o)
 }
 
 func (o *Remote) Ls(filterRefs ...string) ([]RemoteHead, error) {
@@ -765,7 +788,9 @@ func (o *Remote) Ls(filterRefs ...string) ([]RemoteHead, error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
-	if ret := C.git_remote_ls(&refs, &length, o.ptr); ret != 0 {
+	ret := C.git_remote_ls(&refs, &length, o.ptr)
+	runtime.KeepAlive(o)
+	if ret != 0 {
 		return nil, MakeGitError(ret)
 	}
 
@@ -820,6 +845,7 @@ func (o *Remote) Push(refspecs []string, opts *PushOptions) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_push(o.ptr, &crefspecs, coptions)
+	runtime.KeepAlive(o)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}
@@ -838,6 +864,7 @@ func (o *Remote) Prune(callbacks *RemoteCallbacks) error {
 	defer runtime.UnlockOSThread()
 
 	ret := C.git_remote_prune(o.ptr, &ccallbacks)
+	runtime.KeepAlive(o)
 	if ret < 0 {
 		return MakeGitError(ret)
 	}