libc: sync socket control files to check for write errors

Ref #2335

repos/libports/src/lib/libc/socket_fs_plugin.cc

@@ -82,6 +82,8 @@ namespace Socket_fs {
 	struct Local_functor;
 
 	Plugin & plugin();
+
+	enum { MAX_CONTROL_PATH_LEN = 16 };
 }
 
 
@@ -447,7 +449,7 @@ extern "C" int socket_fs_accept(int libc_fd, sockaddr *addr, socklen_t *addrlen)
 	/* TODO EOPNOTSUPP - no SOCK_STREAM */
 	/* TODO ECONNABORTED */
 
-	char accept_socket[10];
+	char accept_socket[MAX_CONTROL_PATH_LEN];
 	{
 		int n = 0;
 		/* XXX currently reading accept may return without new connection */
@@ -503,8 +505,9 @@ extern "C" int socket_fs_bind(int libc_fd, sockaddr const *addr, socklen_t addrl
 		int const len = strlen(addr_string.base());
 		int const n   = write(context->bind_fd(), addr_string.base(), len);
 		if (n != len) return Errno(EACCES);
-		fsync(context->bind_fd());
-		return 0;
+
+		/* sync to block for write completion */
+		return fsync(context->bind_fd());
 	} catch (Socket_fs::Context::Inaccessible) {
 		return Errno(EINVAL);
 	}
@@ -537,7 +540,8 @@ extern "C" int socket_fs_connect(int libc_fd, sockaddr const *addr, socklen_t ad
 	int const n   = write(context->connect_fd(), addr_string.base(), len);
 	if (n != len) return Errno(ECONNREFUSED);
 
-	return 0;
+	/* sync to block for write completion */
+	return fsync(context->connect_fd());
 }
 
 
@@ -549,7 +553,7 @@ extern "C" int socket_fs_listen(int libc_fd, int backlog)
 	Socket_fs::Context *context = dynamic_cast<Socket_fs::Context *>(fd->context);
 	if (!context) return Errno(ENOTSOCK);
 
-	char buf[10];
+	char buf[MAX_CONTROL_PATH_LEN];
 	int const len = snprintf(buf, sizeof(buf), "%d", backlog);
 	int const n   = write(context->listen_fd(), buf, len);
 	if (n != len) return Errno(EOPNOTSUPP);
@@ -742,23 +746,23 @@ extern "C" int socket_fs_shutdown(int libc_fd, int how)
 }
 
 
-static Genode::String<16> new_socket(Absolute_path const &path)
+static Genode::String<MAX_CONTROL_PATH_LEN> new_socket(Absolute_path const &path)
 {
 	Absolute_path new_socket("new_socket", path.base());
 
 	int const fd = open(new_socket.base(), O_RDONLY);
 	if (fd == -1) {
-		Genode::error(__func__, ": new_socket file not accessible - socket fs not mounted?");
+		Genode::error(__func__, ": ", new_socket, " file not accessible - socket fs not mounted?");
 		throw New_socket_failed();
 	}
-	char buf[10];
+	char buf[MAX_CONTROL_PATH_LEN];
 	int const n = read(fd, buf, sizeof(buf));
 	close(fd);
 	if (n == -1 || !n || n >= (int)sizeof(buf) - 1)
 		throw New_socket_failed();
 	buf[n] = 0;
 
-	return Genode::String<16>(buf);
+	return Genode::String<MAX_CONTROL_PATH_LEN>(buf);
 }
 
 
@@ -789,7 +793,7 @@ extern "C" int socket_fs_socket(int domain, int type, int protocol)
 		case Proto::UDP: proto_path.append("/udp"); break;
 		}
 
-		Genode::String<16> socket_path = new_socket(proto_path);
+		auto socket_path = new_socket(proto_path);
 		path.append("/");
 		path.append(socket_path.string());
 	} catch (New_socket_failed) { return Errno(EACCES); }

repos/libports/src/lib/libc/vfs_plugin.cc

@@ -884,8 +884,7 @@ int Libc::Vfs_plugin::fcntl(Libc::File_descriptor *fd, int cmd, long arg)
 int Libc::Vfs_plugin::fsync(Libc::File_descriptor *fd)
 {
 	Vfs::Vfs_handle *handle = vfs_handle(fd);
-	_vfs_sync(handle);
-	return 0;
+	return _vfs_sync(handle);
 }
 
 

repos/libports/src/lib/libc/vfs_plugin.h

@@ -18,7 +18,6 @@
 
 /* Genode includes */
 #include <libc/component.h>
-#include "task.h"
 
 /* libc includes */
 #include <fcntl.h>
@@ -28,6 +27,11 @@
 #include <libc-plugin/plugin.h>
 #include <libc-plugin/fd_alloc.h>
 
+/* local includes */
+#include "task.h"
+#include "libc_errno.h"
+
+
 namespace Libc { class Vfs_plugin; }
 
 
@@ -76,8 +80,14 @@ class Libc::Vfs_plugin : public Libc::Plugin
 			}
 		}
 
-		void _vfs_sync(Vfs::Vfs_handle *vfs_handle)
+		/**
+		 * Sync a handle and propagate errors
+		 */
+		int _vfs_sync(Vfs::Vfs_handle *vfs_handle)
 		{
+			typedef Vfs::File_io_service::Sync_result Result;
+			Result result = Result::SYNC_QUEUED;
+
 			{
 				struct Check : Libc::Suspend_functor
 				{
@@ -112,29 +122,32 @@ class Libc::Vfs_plugin : public Libc::Plugin
 					bool retry { false };
 
 					Vfs::Vfs_handle *vfs_handle;
+					Result          &result;
 
-					Check(Vfs::Vfs_handle *vfs_handle)
-					: vfs_handle(vfs_handle) { }
+					Check(Vfs::Vfs_handle *vfs_handle, Result &result)
+					: vfs_handle(vfs_handle), result(result) { }
 
 					bool suspend() override
 					{
-						retry = (vfs_handle->fs().complete_sync(vfs_handle) ==
-						         Vfs::File_io_service::SYNC_QUEUED);
+						result = vfs_handle->fs().complete_sync(vfs_handle);
+						retry = result == Vfs::File_io_service::SYNC_QUEUED;
 						return retry;
 					}
-				} check(vfs_handle);
+				} check(vfs_handle, result);
 
 				/*
 				 * Cannot call Libc::suspend() immediately, because the Libc kernel
 				 * might not be running yet.
 				 */
-				if (vfs_handle->fs().complete_sync(vfs_handle) ==
-				    Vfs::File_io_service::SYNC_QUEUED) {
+				result = vfs_handle->fs().complete_sync(vfs_handle);
+				if (result == Result::SYNC_QUEUED) {
 					do {
 						Libc::suspend(check);
 					} while (check.retry);
 				}
 			}
+
+			return result == Result::SYNC_OK ? 0 : Libc::Errno(EIO);
 		}
 
 	public: