Thanks for adding tests. > [PATCH] selftests/unix: Add test for ECONNRESET and EOF behaviour
nit: The common prefix is "selftest: af_unix:". On Thu, Oct 23, 2025 at 9:59 AM Sunday Adelodun <[email protected]> wrote: > > Add selftests verifying the EOF and ECONNRESET behaviour of > UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM). The tests document > Linux's semantics and clarify the long-standing differences with BSD. > > Suggested-by: Kuniyuki Iwashima <[email protected]> > Signed-off-by: Sunday Adelodun <[email protected]> > --- > tools/testing/selftests/net/unix/Makefile | 5 + > .../selftests/net/unix/test_unix_connreset.c | 147 ++++++++++++++++++ > 2 files changed, 152 insertions(+) > create mode 100644 tools/testing/selftests/net/unix/Makefile > create mode 100644 tools/testing/selftests/net/unix/test_unix_connreset.c The test for af_unix is placed under tools/testing/selftests/net/af_unix. > > diff --git a/tools/testing/selftests/net/unix/Makefile > b/tools/testing/selftests/net/unix/Makefile > new file mode 100644 > index 000000000000..a52992ba23d9 > --- /dev/null > +++ b/tools/testing/selftests/net/unix/Makefile > @@ -0,0 +1,5 @@ > +# SPDX-License-Identifier: GPL-2.0 > +TEST_GEN_PROGS := test_unix_connreset > + > +include ../../lib.mk > + > diff --git a/tools/testing/selftests/net/unix/test_unix_connreset.c > b/tools/testing/selftests/net/unix/test_unix_connreset.c > new file mode 100644 > index 000000000000..a8720c7565cb > --- /dev/null > +++ b/tools/testing/selftests/net/unix/test_unix_connreset.c > @@ -0,0 +1,147 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Selftest for UNIX socket close and ECONNRESET behaviour. nit: s/UNIX/AF_UNIX/ > + * > + * This test verifies that: > + * 1. SOCK_STREAM sockets return EOF when peer closes normally. > + * 2. SOCK_STREAM sockets return ECONNRESET if peer closes with unread data. > + * 3. SOCK_DGRAM sockets do not return ECONNRESET when peer closes, > + * unlike BSD where this error is observed. > + * > + * These tests document the intended Linux behaviour, distinguishing it from > BSD. I'd not mention BSD as it could be outdated again. > + * > + */ > + > +#define _GNU_SOURCE > +#include <stdlib.h> > +#include <string.h> > +#include <fcntl.h> > +#include <unistd.h> > +#include <errno.h> > +#include <sys/socket.h> > +#include <sys/un.h> > +#include "../../kselftest_harness.h" > + > +#define SOCK_PATH "/tmp/test_unix_connreset.sock" > + > +static void remove_socket_file(void) > +{ > + unlink(SOCK_PATH); > +} > + > +/* Test 1: peer closes normally */ > +TEST(stream_eof) I think most of the code can be shared by defining FIXTURE_VARIANT(). e.g. variant->unread_data can consolidate Test 1&2. > +{ > + int server, client, child; > + struct sockaddr_un addr = {0}; > + char buf[16] = {0}; IIRC, {0} only initialises the first entry and we had a problem in kernel code, so simply use "= {};" everywhere. > + ssize_t n; > + > + server = socket(AF_UNIX, SOCK_STREAM, 0); Try using variant->type for SOCK_STREAM, SOCK_DGRAM, and SOCK_SEQPACKET. See unix_connect.c, or you could reuse the fixtures of err == 0 there. > + ASSERT_GE(server, 0); nit: The 1st arg is "expected", and the 2nd is "seen", so ASSERT_NE(-1, server) (or ASSERT_LT(-1, server)). Same for other places. > + > + addr.sun_family = AF_UNIX; > + strcpy(addr.sun_path, SOCK_PATH); > + remove_socket_file(); > + > + ASSERT_EQ(bind(server, (struct sockaddr *)&addr, sizeof(addr)), 0); I personally feel easy to read this style: err = bind(); ASSERT_EQ(0, err); > + ASSERT_EQ(listen(server, 1), 0); > + > + client = socket(AF_UNIX, SOCK_STREAM, 0); > + ASSERT_GE(client, 0); > + ASSERT_EQ(connect(client, (struct sockaddr *)&addr, sizeof(addr)), 0); > + > + child = accept(server, NULL, NULL); > + ASSERT_GE(child, 0); > + > + /* Peer closes normally */ > + close(child); > + > + n = recv(client, buf, sizeof(buf), 0); > + EXPECT_EQ(n, 0); > + TH_LOG("recv=%zd errno=%d (%s)", n, errno, strerror(errno)); I printed errno just for visibility, and you can simply use ASSERT here too like if (n == -1) ASSERT_EQ(ECONNRESET, errno) (I'm assuming Test 1 & 2 will share most code) > + > + close(client); > + close(server); > + remove_socket_file(); This will not be executed if the program fails at ASSERT_XX(), so move it to FIXTURE_TEARDOWN(). > +} > + > +/* Test 2: peer closes with unread data */ > +TEST(stream_reset_unread) > +{ > + int server, client, child; > + struct sockaddr_un addr = {0}; > + char buf[16] = {0}; > + ssize_t n; > + > + server = socket(AF_UNIX, SOCK_STREAM, 0); > + ASSERT_GE(server, 0); > + > + addr.sun_family = AF_UNIX; > + strcpy(addr.sun_path, SOCK_PATH); > + remove_socket_file(); > + > + ASSERT_EQ(bind(server, (struct sockaddr *)&addr, sizeof(addr)), 0); > + ASSERT_EQ(listen(server, 1), 0); > + > + client = socket(AF_UNIX, SOCK_STREAM, 0); > + ASSERT_GE(client, 0); > + ASSERT_EQ(connect(client, (struct sockaddr *)&addr, sizeof(addr)), 0); > + > + child = accept(server, NULL, NULL); > + ASSERT_GE(child, 0); > + > + /* Send data that will remain unread by client */ > + send(client, "hello", 5, 0); > + close(child); > + > + n = recv(client, buf, sizeof(buf), 0); > + EXPECT_LT(n, 0); > + EXPECT_EQ(errno, ECONNRESET); > + TH_LOG("recv=%zd errno=%d (%s)", n, errno, strerror(errno)); > + > + close(client); > + close(server); > + remove_socket_file(); > +} > + > +/* Test 3: SOCK_DGRAM peer close */ > +TEST(dgram_reset) > +{ > + int server, client; > + int flags; > + struct sockaddr_un addr = {0}; > + char buf[16] = {0}; > + ssize_t n; > + > + server = socket(AF_UNIX, SOCK_DGRAM, 0); > + ASSERT_GE(server, 0); > + > + addr.sun_family = AF_UNIX; > + strcpy(addr.sun_path, SOCK_PATH); > + remove_socket_file(); > + > + ASSERT_EQ(bind(server, (struct sockaddr *)&addr, sizeof(addr)), 0); > + > + client = socket(AF_UNIX, SOCK_DGRAM, 0); > + ASSERT_GE(client, 0); > + ASSERT_EQ(connect(client, (struct sockaddr *)&addr, sizeof(addr)), 0); > + > + send(client, "hello", 5, 0); > + close(server); > + > + flags = fcntl(client, F_GETFL, 0); > + fcntl(client, F_SETFL, flags | O_NONBLOCK); You can save fcntl() with socket(..., ... | SOCK_NONBLOCK, ...). > + > + n = recv(client, buf, sizeof(buf), 0); > + TH_LOG("recv=%zd errno=%d (%s)", n, errno, strerror(errno)); > + /* Expect EAGAIN or EWOULDBLOCK because there is no datagram and peer > is closed. */ > + EXPECT_LT(n, 0); > + EXPECT_TRUE(errno == EAGAIN); > + > + close(client); > + remove_socket_file(); > +} > + > +TEST_HARNESS_MAIN > + > -- > 2.43.0 >
