fix: accept_loop race condition, auto-detect valgrind, cppcheck suppressions

src/server/server.c

@@ -153,6 +153,7 @@ static volatile sig_atomic_t g_server_cleanup_requested = 0;
 
 static void cleanup(int sig) {
   (void)sig;
+  server_request_shutdown();
   g_server_cleanup_requested = 1;
 }
 

src/shared/transport_tcp.c

@@ -2,6 +2,7 @@
 #include "log.h"
 #include "protocol.h"
 #include <arpa/inet.h>
+#include <errno.h>
 #include <netdb.h>
 #include <openssl/ssl.h>
 #include <signal.h>
@@ -142,6 +143,15 @@ void server_delete(Server** server) {
   *server = NULL;
 }
 
+/* Flag set by server_request_shutdown() to request graceful shutdown
+   of the accept loop. Accessed only from transport_tcp.c so it won't
+   cause linker errors when this file is compiled into client/test targets. */
+static volatile sig_atomic_t g_tcp_cleanup_requested = 0;
+
+void server_request_shutdown(void) {
+  g_tcp_cleanup_requested = 1;
+}
+
 static void accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt) {
   if (listen(server->file_descriptor, SOMAXCONN) < 0) {
@@ -149,11 +159,13 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
     return;
   }
   signal(SIGCHLD, SIG_IGN);
-  while (1) {
+  while (!g_tcp_cleanup_requested) {
     struct sockaddr_storage client_addr;
     socklen_t client_len = sizeof(client_addr);
     int fd = accept(server->file_descriptor, (struct sockaddr*)&client_addr, &client_len);
     if (fd < 0) {
+      if (errno == EINTR)
+        break;
       perror("Could not accept the connection");
       continue;
     }

src/shared/transport_tcp.h

@@ -28,6 +28,7 @@ bool server_listen(Server* server, void (*handler)(int file_descriptor));
 void server_accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt);
 void server_delete(Server** server);
+void server_request_shutdown(void);
 Client* client_create();
 bool client_connect(Client* client, char* host, int port);
 void client_disconnect(Client* client);

tests/test_file.c

@@ -275,7 +275,7 @@ void test_file() {
   test_to_disk_basic();
   test_to_disk_creates_dirs();
   test_file_content_to_buffer();
-  if (!getenv("FASTSYNC_UNDER_VALGRIND")) {
+  if (!is_running_under_valgrind()) {
     // Fork tests are skipped under valgrind because the parent process runs
     // orders of magnitude slower than the child (parent is instrumented, child
     // is not), which causes pipe-based protocol handshake timeouts. The parent

tests/test_file_sendfile.c

@@ -258,9 +258,16 @@ static void test_sendfile_no_path() {
 }
 
 void test_file_sendfile() {
-  test_sendfile_basic();
-  test_sendfile_empty_file();
-  test_sendfile_missing_file();
-  test_sendfile_compression_fallback();
-  test_sendfile_no_path();
+  if (!is_running_under_valgrind()) {
+    // Fork tests are skipped under valgrind because the parent process runs
+    // orders of magnitude slower than the child (parent is instrumented, child
+    // is not), which causes pipe-based protocol handshake timeouts. The parent
+    // process itself has zero valgrind errors -- the failures are all in the
+    // forked children where inherited allocations are reported as leaks.
+    test_sendfile_basic();
+    test_sendfile_empty_file();
+    test_sendfile_compression_fallback();
+    test_sendfile_no_path();
+  }
+  test_sendfile_missing_file(); // no fork, safe under valgrind
 }

tests/test_protocol.c

@@ -179,6 +179,7 @@ static void test_receive_str_oversized() {
   size_t huge = MAX_STRING_SIZE + 1;
   EXPECT_TRUE(send_n_data(0, &huge, sizeof(size_t)));
 
+  /* cppcheck-suppress constVariablePointer */
   char* received = receive_str(0);
   EXPECT_NULL(received);
 

tests/test_transport_ssh.c

@@ -8,12 +8,14 @@
 /* Test client_connect_ssh with invalid destination (missing colon) */
 static void test_ssh_connect_invalid_dest() {
   /* Missing colon — parse_remote_dest should fail and return NULL */
+  /* cppcheck-suppress constVariablePointer */
   Client* client = client_connect_ssh("invalid-destination-no-colon", 22);
   EXPECT_NULL(client);
 }
 
 /* Test client_connect_ssh with empty destination */
 static void test_ssh_connect_empty_dest() {
+  /* cppcheck-suppress constVariablePointer */
   Client* client = client_connect_ssh("", 22);
   EXPECT_NULL(client);
 }

tests/test_utils.h

@@ -2,9 +2,24 @@
 #define TEST_UTILS_H
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
 
+// Detect if running under valgrind by checking /proc/self/maps for vgpreload.
+// This is used to skip fork-based tests that are incompatible with valgrind
+// (the instrumented parent runs too slowly, causing pipe timeouts).
+static inline bool is_running_under_valgrind(void) {
+  FILE* f = fopen("/proc/self/maps", "r");
+  if (!f)
+    return false;
+  char buf[4096];
+  size_t n = fread(buf, 1, sizeof(buf) - 1, f);
+  fclose(f);
+  buf[n] = '\0';
+  return strstr(buf, "vgpreload") != NULL;
+}
+
 // Global test suite status
 extern int tests_run;
 extern int tests_failed;