fix(component-failover-adoption): unify apiserver's dual connect paths, fix connect-time UAF

Replaces apiserver's two connect mechanisms -- a per-peer Go loop that
hardcoded nmasters=1 per attempt, and a separate direct-construction
path for the legacy single-host config -- with one pipeline:
buildClusterConfig() parses (via task 4.1's C parser) or synthesizes a
single-candidate config, validates it, then ConfigConverter
(xce_cluster_config_to_client_config) produces the client config for
one xce_backend_init() call. A 3-candidate config now actually
exercises the C library's own failover/standby-redirect handling on
initial connect, matching worker's and scheduler's task 2.1/3.1 work,
instead of a Go-level per-candidate retry loop that never built a real
multi-master config.

Along the way: found and fixed a genuine use-after-free. The deleted
tryConnect() freed its C.CString-allocated host address immediately
after its single connect call returned, but xcecli_ctx_init() stores a
raw pointer to the config forever (client.c:38) and every later
failover rotation re-dereferences it (client_failover.c) -- so any
reconnect after the first would read freed memory. Fixed by giving the
cluster/client config structs package-level, process-lifetime storage
(gClusterCfg/gClientCfg), mirroring worker's and scheduler's file-scope
static pattern, with host/from/key written into fixed-size C arrays
instead of freed heap pointers.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NNB4zGPCsHyDUCDJyMbiQN
This commit is contained in:
Rongsong Shen 2026-08-12 07:46:30 +00:00
parent 8b1e13a52b
commit e635903996
Signed by: rshen
SSH key fingerprint: SHA256:8Vf2pZ3h6rJa7EhGK+WaAQ9Mta/apZvteW6g9U/WKKk
3 changed files with 488 additions and 52 deletions

View file

@ -12,6 +12,7 @@ package backend
#include "idgen.h"
#include "controller.capnp.h"
#include "val_helpers.h"
#include "xce/cluster.h"
// backend_ctx_t wraps xcecli_ctx_t for use as the C handler's arg.
typedef struct {
@ -69,6 +70,43 @@ import (
// gCtx holds the C client context for the lifetime of the process.
var gCtx C.backend_ctx_t
// gClusterCfg is the single validated xce_cluster_config_t RegisterToBackend
// builds on every call -- either by parsing config.Peers via the shared C
// parser (xce_parse_peers), or by synthesizing a one-candidate list from the
// legacy config.Address/config.Port fields when Peers is empty (Req 1 AC5: a
// single controller is the candidates_count=1 case of the identical
// validate/convert/connect pipeline, not a separately-maintained code path
// -- see buildClusterConfig() below).
//
// Package-level, not a buildClusterConfig()/RegisterToBackend()-local
// variable, for the same reason gCtx and gIDCtx already are (process-lifetime
// stable address): xce_cluster_config_to_client_config() (ConfigConverter,
// src/lib/cluster.c) aliases gClientCfg.masters[i] directly at this struct's
// own candidates[i].hostname fixed-char-array storage -- no strdup, no copy.
// A caller that built the source xce_cluster_config_t on the stack (or any
// Go-local variable) and then let gClientCfg outlive that scope would have a
// use-after-scope bug: confirmed by reading src/lib/client.c's
// xcecli_ctx_init() (`ctx->conf = cfg` -- stores a RAW pointer, never
// copies) and src/lib/client_failover.c (`ac->conf->masters[next]` is
// dereferenced on every failover rotation, not just at initial connect).
// Worker's and scheduler's C implementations hit this identical hazard
// (component-failover-adoption tasks 2.1/3.1) and solved it by keeping the
// source config on a process-lifetime struct (worker: cc_ctx->cluster_cfg;
// scheduler: sched->cluster_cfg) -- this package-level var is the direct Go
// equivalent.
var gClusterCfg C.xce_cluster_config_t
// gClientCfg is the xce_client_config_t ConfigConverter populates from
// gClusterCfg and xce_backend_init() connects with. Package-level for the
// same reason as gClusterCfg above: xcecli_ctx_init() stores gCtx.ctx->conf
// as a raw pointer to whichever struct address is passed to it, dereferenced
// for the ctx's entire runtime life (every failover rotation reads
// ctx->conf->masters[]/nmasters, not only the initial connect) -- so this
// struct's address must be stable for the process lifetime, not a
// RegisterToBackend-local variable that goes out of scope when the function
// returns.
var gClientCfg C.xce_client_config_t
// gIDCtx is the C idgen context used to generate job IDs.
var gIDCtx C.idgen_ctx_t
var idCtxOnce sync.Once
@ -77,34 +115,94 @@ var idCtxOnce sync.Once
// Must be set via StartNotificationListener before RegisterToBackend.
var gHandler NotificationHandler
func tryConnect(host string, port int, from, key string) error {
cAddr := C.CString(host)
cFrom := C.CString(from)
cKey := C.CString(key)
defer func() {
C.free(unsafe.Pointer(cAddr))
C.free(unsafe.Pointer(cFrom))
C.free(unsafe.Pointer(cKey))
}()
var cConfig C.xce_client_config_t
cConfig.nmasters = 1
cConfig.masters[0] = cAddr
cConfig.master_ports[0] = C.int(port)
cConfig.from = cFrom
cConfig.key = cKey
rc := C.xce_backend_init(&cConfig, &gCtx)
if rc < 0 {
return fmt.Errorf("xce_backend_init failed on %s:%d: %d", host, port, int(rc))
// writeCCharArray copies s into dst, a fixed-size C char array field of
// gClusterCfg (hostname/identity/key), truncating to len(dst)-1 bytes and
// always leaving the result NUL-terminated. Because these are fixed arrays
// embedded directly in gClusterCfg (a package-level, process-lifetime
// struct -- see its doc comment), populating them this way needs no
// C.CString/C.free bookkeeping at all: xce_cluster_config_to_client_config()
// later aliases pointers directly into this same storage.
func writeCCharArray(dst []C.char, s string) {
n := len(s)
if n > len(dst)-1 {
n = len(dst) - 1
}
return nil
for i := 0; i < n; i++ {
dst[i] = C.char(s[i])
}
dst[n] = 0
}
// RegisterToBackend initialises the XCE client library and joins as an API
// server. StartNotificationListener should be called first so that push
// events have a handler ready before the first push can arrive.
func RegisterToBackend(config *BackendConfig) error {
// formatCandidateList renders gClusterCfg's current candidates as
// "host:port, host:port, ..." for diagnostic logging (Req 5.1, 5.2) -- the
// same textual shape scheduler's sched_format_candidate_list() (scheduler.c)
// produces, for cross-component log consistency.
func formatCandidateList() string {
n := int(gClusterCfg.candidates_count)
parts := make([]string, 0, n)
for i := 0; i < n; i++ {
cand := &gClusterCfg.candidates[i]
parts = append(parts, fmt.Sprintf("%s:%d", C.GoString(&cand.hostname[0]), int(cand.port)))
}
return strings.Join(parts, ", ")
}
// currentClusterCandidates returns gClusterCfg's current candidates as a
// Go-native slice. Exists so clib_test.go (a //go:build cgo test file that
// cannot `import "C"` itself -- a Go-toolchain restriction, golang/go#13938)
// can assert on buildClusterConfig()'s output shape without re-implementing
// CGO field access in the test file, mirroring the candidates.go/
// candidates_test.go split already established in this package.
func currentClusterCandidates() []Candidate {
n := int(gClusterCfg.candidates_count)
out := make([]Candidate, n)
for i := 0; i < n; i++ {
cand := &gClusterCfg.candidates[i]
out[i] = Candidate{
Name: C.GoString(&cand.name[0]),
Host: C.GoString(&cand.hostname[0]),
Port: int(cand.port),
}
}
return out
}
// currentClientConfigNMasters exposes gClientCfg.nmasters as a plain int,
// for the same test-file-cannot-import-C reason as currentClusterCandidates
// above. Lets tests confirm xce_cluster_config_to_client_config() actually
// propagated the full candidate count into the struct xce_backend_init()
// connects with -- proving ONE call carries all N candidates, rather than N
// separate single-candidate calls (the deleted per-peer Go loop's behavior,
// which always hardcoded nmasters=1).
func currentClientConfigNMasters() int {
return int(gClientCfg.nmasters)
}
// buildClusterConfig builds and validates the single xce_cluster_config_t
// this connect attempt will use (Req 1 AC1-3/AC5), writing directly into the
// package-level gClusterCfg (see its doc comment for why this must be
// package-level rather than a local variable).
//
// A single controller is not a separately-maintained code path: when
// config.Peers is non-empty it is parsed via the same shared C parser
// (xce_parse_peers) worker and scheduler already call directly; otherwise a
// one-candidate list is synthesized from config.Address/config.Port. Either
// source is then run through the identical xce_cluster_config_validate()
// call below -- no branch downstream of this function distinguishes the two
// sources (Req 1 AC5), mirroring scheduler's sched_build_cluster_config()
// (scheduler.c) and worker's equivalent (controller_connector.c).
//
// This intentionally does not reuse parseCandidates() (candidates.go):
// parseCandidates() parses into its own function-local xce_cluster_config_t
// and reconstructs a Go []Candidate slice from it -- exactly the
// use-after-scope-prone, throwaway-C-struct pattern gClusterCfg's doc
// comment above warns against for this call site. buildClusterConfig() must
// parse directly into the package-level gClusterCfg so the very same struct
// flows unmodified into xce_cluster_config_to_client_config() below.
//
// Does not call xce_cluster_config_to_client_config() or connect -- callers
// (RegisterToBackend) do that separately.
func buildClusterConfig(config *BackendConfig) error {
from := config.From
if from == "" {
from = "xce_apiserver"
@ -114,39 +212,88 @@ func RegisterToBackend(config *BackendConfig) error {
key = "keepsecret$"
}
if len(config.Peers) > 0 {
// Parsing is routed through the same C parser (xce_parse_peers) worker
// and scheduler already call directly -- Req 6.1/6.2. A malformed
// entry rejects the whole candidate list up front (matching
// worker's/scheduler's own all-or-nothing --peers parsing) rather
// than being skipped with a warning as the old hand-written
// parsePeer()-per-entry loop did.
candidates, err := parseCandidates(strings.Join(config.Peers, ","))
if err != nil {
return err
}
gClusterCfg = C.xce_cluster_config_t{}
var lastErr error
for _, cand := range candidates {
if err := tryConnect(cand.Host, cand.Port, from, key); err != nil {
logger.Warn("Candidate unreachable, trying next",
zap.String("host", cand.Host), zap.Int("port", cand.Port), zap.Error(err))
lastErr = err
continue
}
logger.Info("Backend connection established (HA)",
zap.String("host", cand.Host), zap.Int("port", cand.Port))
return nil
if len(config.Peers) > 0 {
peersStr := strings.Join(config.Peers, ",")
cPeers := C.CString(peersStr)
rc := C.xce_parse_peers(cPeers, &gClusterCfg)
C.free(unsafe.Pointer(cPeers))
if rc != 0 {
return fmt.Errorf(
"apiserver: --peers parse error: expected \"[name=]host:port,...\" got %q",
peersStr)
}
return fmt.Errorf("all HA candidates failed: %w", lastErr)
} else {
gClusterCfg.candidates_count = 1
writeCCharArray(gClusterCfg.candidates[0].hostname[:], config.Address)
gClusterCfg.candidates[0].port = C.int(config.Port)
}
if err := tryConnect(config.Address, config.Port, from, key); err != nil {
writeCCharArray(gClusterCfg.identity[:], from)
writeCCharArray(gClusterCfg.key[:], key)
if rc := C.xce_cluster_config_validate(&gClusterCfg); rc != 0 {
return fmt.Errorf(
"apiserver: invalid controller candidate configuration (rc=%d): %s",
int(rc), formatCandidateList())
}
return nil
}
// RegisterToBackend initialises the XCE client library and joins as an API
// server, using the full configured candidate list -- config.Peers if set,
// otherwise a single-candidate list synthesized from config.Address/
// config.Port (Req 1 AC5: the candidates_count=1 case of the identical
// pipeline, not a separate code path -- see buildClusterConfig()). Builds
// exactly ONE validated xce_cluster_config_t regardless of source, converts
// it once via the shared ConfigConverter
// (xce_cluster_config_to_client_config), and calls xce_backend_init()
// exactly ONCE -- replacing the former dual-mechanism implementation (a
// Go-level per-peer tryConnect() retry loop for the Peers case, and a
// second, separately-coded tryConnect() call for the legacy Address/Port
// case; both bypassed xce_cluster_config_t/xce_cluster_config_validate()/
// xce_cluster_config_to_client_config() entirely, and both always
// hardcoded nmasters=1).
//
// StartNotificationListener should be called first so that push events have
// a handler ready before the first push can arrive.
func RegisterToBackend(config *BackendConfig) error {
if err := buildClusterConfig(config); err != nil {
return err
}
logger.Info("Attempting backend connection",
zap.Int("candidates", int(gClusterCfg.candidates_count)),
zap.String("candidate_list", formatCandidateList()))
gClientCfg = C.xce_client_config_t{}
if rc := C.xce_cluster_config_to_client_config(&gClusterCfg, &gClientCfg); rc != 0 {
return fmt.Errorf("apiserver: candidate list conversion failed (rc=%d)", int(rc))
}
// ConfigConverter deliberately does not set from/key (caller-owned
// identity/auth, per its own doc comment) -- point them at gClusterCfg's
// own identity/key fixed arrays rather than allocating separate C
// strings: gClusterCfg is the same package-level, process-lifetime
// struct ConfigConverter already aliased gClientCfg.masters[i] into, so
// this needs no additional C.CString/C.free bookkeeping.
gClientCfg.from = &gClusterCfg.identity[0]
gClientCfg.key = &gClusterCfg.key[0]
rc := C.xce_backend_init(&gClientCfg, &gCtx)
if rc < 0 {
logger.Warn("All configured backend candidates failed",
zap.Int("candidates", int(gClusterCfg.candidates_count)),
zap.String("candidate_list", formatCandidateList()),
zap.Int("rc", int(rc)))
return fmt.Errorf("xce_backend_init failed across %d candidate(s) (rc=%d): %s",
int(gClusterCfg.candidates_count), int(rc), formatCandidateList())
}
logger.Info("Backend connection established",
zap.String("address", config.Address),
zap.Int("port", config.Port))
zap.Int("nmasters", int(gClientCfg.nmasters)),
zap.String("candidate_list", formatCandidateList()))
return nil
}

View file

@ -0,0 +1,288 @@
//go:build cgo
package backend
import (
"os"
"strings"
"testing"
"time"
"go.uber.org/zap/zaptest/observer"
)
// clib_test.go exercises RegisterToBackend/buildClusterConfig (clib.go), the
// unified candidate-list connect pipeline that replaces the former
// dual-mechanism implementation (component-failover-adoption, task 4.2,
// boundary: ApiserverBackendBridge). Kept //go:build cgo since these
// functions only exist in the CGO build -- this file itself does not
// `import "C"` (a _test.go file can never do that directly, golang/go#13938):
// it only calls the plain-Go-signature functions defined in clib.go, same
// split candidates.go/candidates_test.go already established in this
// package.
//
// Test strategy:
// - Req 1.5 (no-Peers and single-entry-Peers converge on the identical
// validated xce_cluster_config_t shape) and Req 1.1-1.3 (multi-candidate
// passthrough) are exercised via buildClusterConfig() directly -- pure
// struct-building + validation, no network I/O, so these run fast and
// avoid any socket/leak concerns from a real (failing) connect attempt.
// - "a single xce_backend_init() call carries the full candidate count"
// is exercised by calling the real RegisterToBackend() against closed
// local ports (connect() returns ECONNREFUSED near-instantly, same
// "no backoff loop inside xcecli_start()'s per-master connect scan"
// property scheduler's test_scheduler_connect.c and worker's task 2.3
// test both rely on) and inspecting gClientCfg.nmasters afterward via
// currentClientConfigNMasters() -- this is deliberately the ONLY test in
// this file that reaches xce_backend_init()/a real connect() call, to
// keep the (unavoidable, pre-existing -- see status report CONCERNS)
// per-call xcecli_ctx_init() allocation this path leaks on a failed
// connect bounded to one occurrence.
// - "no-peers and single-entry-peers produce the identical connect log
// sequence" is exercised behaviorally via captureLog() (handler_test.go,
// this package), asserting on the log MESSAGE sequence (not field
// values) RegisterToBackend emits for each source.
// - The "source config structs are package-level, not stack-local"
// regression guard is a source-text scan of clib.go, same genre as
// scheduler's/worker's structural regression tests (test_scheduler_connect.c,
// test_controller_connector.c) for the identical hazard.
// testPortBase is deliberately unlikely to have a real listener bound in
// CI/dev sandboxes -- connect() against a closed local port fails fast, so
// RegisterToBackend() calls below return quickly without needing a live
// controller (same precedent as scheduler's TEST_PORT_BASE).
const testPortBase = 28581
// ════════════════════════════════════════════════════════════════════════
// Req 1.5 -- unified candidate-list pipeline: no branch for "single host"
// ════════════════════════════════════════════════════════════════════════
func TestBuildClusterConfig_NoPeersAndSingleEntryPeers_IdenticalShape(t *testing.T) {
// (a) No Peers: legacy Address/Port synthesized into a single candidate.
cfgNoPeers := &BackendConfig{
Address: "127.0.0.1",
Port: testPortBase,
From: "xce_apiserver_test",
Key: "keepsecret$",
}
if err := buildClusterConfig(cfgNoPeers); err != nil {
t.Fatalf("buildClusterConfig(no peers) failed: %v", err)
}
noPeersCandidates := currentClusterCandidates()
// (b) A single-entry Peers list pointed at the exact same host:port.
cfgOnePeer := &BackendConfig{
Peers: []string{"127.0.0.1:28581"},
From: "xce_apiserver_test",
Key: "keepsecret$",
}
if err := buildClusterConfig(cfgOnePeer); err != nil {
t.Fatalf("buildClusterConfig(one peer) failed: %v", err)
}
onePeerCandidates := currentClusterCandidates()
if len(noPeersCandidates) != 1 {
t.Fatalf("no-peers: got %d candidates, want 1", len(noPeersCandidates))
}
if len(onePeerCandidates) != 1 {
t.Fatalf("single-entry-peers: got %d candidates, want 1", len(onePeerCandidates))
}
if noPeersCandidates[0].Host != onePeerCandidates[0].Host ||
noPeersCandidates[0].Port != onePeerCandidates[0].Port {
t.Errorf("no-peers and single-entry-peers candidates diverge: %+v vs %+v",
noPeersCandidates[0], onePeerCandidates[0])
}
}
func TestBuildClusterConfig_MultiCandidatePassthrough(t *testing.T) {
cfg := &BackendConfig{
Peers: []string{
"127.0.0.1:28590",
"127.0.0.1:28591",
"127.0.0.1:28592",
},
From: "xce_apiserver_test",
Key: "keepsecret$",
}
if err := buildClusterConfig(cfg); err != nil {
t.Fatalf("buildClusterConfig failed: %v", err)
}
candidates := currentClusterCandidates()
if len(candidates) != 3 {
t.Fatalf("got %d candidates, want 3", len(candidates))
}
for i, want := range []int{28590, 28591, 28592} {
if candidates[i].Host != "127.0.0.1" || candidates[i].Port != want {
t.Errorf("candidate %d = %+v, want host=127.0.0.1 port=%d", i, candidates[i], want)
}
}
}
func TestBuildClusterConfig_MalformedPeersRejected(t *testing.T) {
cfg := &BackendConfig{
Peers: []string{"not-a-valid-entry"},
From: "xce_apiserver_test",
Key: "keepsecret$",
}
err := buildClusterConfig(cfg)
if err == nil {
t.Fatal("expected error for malformed --peers entry, got nil")
}
if !strings.Contains(err.Error(), "not-a-valid-entry") {
t.Errorf("error %q does not identify the malformed input", err.Error())
}
}
// ════════════════════════════════════════════════════════════════════════
// Req 1.1-1.3 -- one xce_backend_init() call carries the full candidate list
// ════════════════════════════════════════════════════════════════════════
func TestRegisterToBackend_MultiCandidate_SingleInitCallCarriesFullCount(t *testing.T) {
captureLog(t) // RegisterToBackend logs via utils.Log; nil otherwise (utils.InitLogger is never called in unit tests)
cfg := &BackendConfig{
Peers: []string{
"127.0.0.1:28600",
"127.0.0.1:28601",
"127.0.0.1:28602",
},
From: "xce_apiserver_test",
Key: "keepsecret$",
}
start := time.Now()
err := RegisterToBackend(cfg)
elapsed := time.Since(start)
if err == nil {
t.Fatal("expected RegisterToBackend to fail against 3 closed local ports")
}
// Generous bound: closed-port ECONNREFUSED is near-instant, well under a
// few seconds even across 3 candidates -- proves this is NOT the deleted
// per-candidate Go loop silently retrying/blocking somewhere.
if elapsed > 5*time.Second {
t.Errorf("RegisterToBackend took %v against closed ports -- too slow, "+
"suggests a retry loop is still present", elapsed)
}
// The struct xce_backend_init() was actually called with must carry the
// FULL candidate count (nmasters=3), not the hardcoded 1 the deleted
// per-peer Go loop always used -- proves ONE call, not three separate
// single-candidate calls.
if got := currentClientConfigNMasters(); got != 3 {
t.Errorf("gClientCfg.nmasters = %d, want 3 (a single call must carry "+
"the full candidate count)", got)
}
}
// ════════════════════════════════════════════════════════════════════════
// Req 5.1/5.2 -- no-peers and single-entry-peers produce the identical
// connect log sequence (shape, not values)
// ════════════════════════════════════════════════════════════════════════
func TestRegisterToBackend_NoPeersAndSingleEntryPeers_IdenticalLogSequence(t *testing.T) {
logs := captureLog(t)
cfgNoPeers := &BackendConfig{
Address: "127.0.0.1",
Port: testPortBase + 20,
From: "xce_apiserver_test",
Key: "keepsecret$",
}
if err := RegisterToBackend(cfgNoPeers); err == nil {
t.Fatal("expected RegisterToBackend(no peers) to fail against a closed port")
}
noPeersMessages := logMessages(logs) // drains the observer buffer
cfgOnePeer := &BackendConfig{
Peers: []string{"127.0.0.1:28601"},
From: "xce_apiserver_test",
Key: "keepsecret$",
}
if err := RegisterToBackend(cfgOnePeer); err == nil {
t.Fatal("expected RegisterToBackend(single-entry peers) to fail against a closed port")
}
onePeerMessages := logMessages(logs)
if len(noPeersMessages) == 0 {
t.Fatal("expected at least one log message from RegisterToBackend(no peers)")
}
if !equalStringSlices(noPeersMessages, onePeerMessages) {
t.Errorf("log message sequence diverges between no-peers and "+
"single-entry-peers:\n no-peers: %v\n single-entry: %v",
noPeersMessages, onePeerMessages)
}
}
func logMessages(logs *observer.ObservedLogs) []string {
entries := logs.TakeAll()
msgs := make([]string, len(entries))
for i, e := range entries {
msgs[i] = e.Message
}
return msgs
}
func equalStringSlices(a, b []string) bool {
if len(a) != len(b) {
return false
}
for i := range a {
if a[i] != b[i] {
return false
}
}
return true
}
// ════════════════════════════════════════════════════════════════════════
// Structural regression guard: source config structs are package-level
// (source-text scan of the real, current on-disk clib.go -- same genre as
// scheduler's/worker's structural regression tests for the identical
// use-after-scope hazard).
// ════════════════════════════════════════════════════════════════════════
func TestClibSource_ClusterAndClientConfigsArePackageLevel(t *testing.T) {
src, err := os.ReadFile("clib.go")
if err != nil {
t.Fatalf("could not read clib.go source for scan: %v", err)
}
text := string(src)
if !strings.Contains(text, "var gClusterCfg C.xce_cluster_config_t") {
t.Error("gClusterCfg must be declared as a package-level var " +
"(`var gClusterCfg C.xce_cluster_config_t`) -- a function-local " +
"variable would go out of scope while xce_cluster_config_to_client_config()'s " +
"aliased pointers (and xcecli_ctx_init()'s retained ctx->conf pointer) " +
"are still in use, a use-after-scope bug (see tasks.md's Implementation " +
"Notes for task 2.1)")
}
if !strings.Contains(text, "var gClientCfg C.xce_client_config_t") {
t.Error("gClientCfg must be declared as a package-level var " +
"(`var gClientCfg C.xce_client_config_t`) -- xcecli_ctx_init() " +
"stores a raw pointer to it (ctx->conf) dereferenced for the ctx's " +
"entire runtime life, not only the initial connect")
}
// Exactly one xce_backend_init() call site: the former per-peer loop
// called it once per candidate (a real loop, not a single call), and the
// former no-Peers branch duplicated it a second time in the same
// function. A single call site proves both are gone.
first := strings.Index(text, "C.xce_backend_init(")
if first < 0 {
t.Fatal("C.xce_backend_init(...) call site not found in clib.go")
}
if strings.Index(text[first+1:], "C.xce_backend_init(") >= 0 {
t.Error("clib.go must contain exactly ONE C.xce_backend_init() call site -- " +
"more than one means the deleted per-peer loop or the separate " +
"no-Peers branch is still present")
}
if strings.Contains(text, "func tryConnect(") {
t.Error("tryConnect() must be deleted entirely -- its per-call " +
"C.CString(host)/C.CString(from)/C.CString(key) + deferred C.free " +
"immediately after a single xce_backend_init() call left ctx->conf's " +
"aliased masters[]/from/key pointers dangling for the ctx's remaining " +
"runtime life (see status report CONCERNS for the precise finding)")
}
}