tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/af_unix/Makefile | 1 + .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++ 3 files changed, 180 insertions(+) create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
Add selftests to verify and document Linux’s intended behaviour for
UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
The tests verify that:
1. SOCK_STREAM returns EOF when the peer closes normally.
2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
3. SOCK_SEQPACKET returns EOF when the peer closes normally.
4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
This follows up on review feedback suggesting a selftest to clarify
Linux’s semantics.
Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
---
tools/testing/selftests/net/.gitignore | 1 +
tools/testing/selftests/net/af_unix/Makefile | 1 +
.../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
3 files changed, 180 insertions(+)
create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
index 439101b518ee..e89a60581a13 100644
--- a/tools/testing/selftests/net/.gitignore
+++ b/tools/testing/selftests/net/.gitignore
@@ -65,3 +65,4 @@ udpgso
udpgso_bench_rx
udpgso_bench_tx
unix_connect
+unix_connreset
diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
index de805cbbdf69..5826a8372451 100644
--- a/tools/testing/selftests/net/af_unix/Makefile
+++ b/tools/testing/selftests/net/af_unix/Makefile
@@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
scm_pidfd \
scm_rights \
unix_connect \
+ unix_connreset \
# end of TEST_GEN_PROGS
include ../../lib.mk
diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
new file mode 100644
index 000000000000..9413f8a0814f
--- /dev/null
+++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
+ *
+ * This test verifies:
+ * 1. SOCK_STREAM returns EOF when the peer closes normally.
+ * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
+ * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
+ * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
+ * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
+ *
+ * These tests document the intended Linux behaviour.
+ *
+ */
+
+#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/af_unix_connreset.sock"
+
+static void remove_socket_file(void)
+{
+ unlink(SOCK_PATH);
+}
+
+FIXTURE(unix_sock)
+{
+ int server;
+ int client;
+ int child;
+};
+
+FIXTURE_VARIANT(unix_sock)
+{
+ int socket_type;
+ const char *name;
+};
+
+FIXTURE_VARIANT_ADD(unix_sock, stream) {
+ .socket_type = SOCK_STREAM,
+ .name = "SOCK_STREAM",
+};
+
+FIXTURE_VARIANT_ADD(unix_sock, dgram) {
+ .socket_type = SOCK_DGRAM,
+ .name = "SOCK_DGRAM",
+};
+
+FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
+ .socket_type = SOCK_SEQPACKET,
+ .name = "SOCK_SEQPACKET",
+};
+
+FIXTURE_SETUP(unix_sock)
+{
+ struct sockaddr_un addr = {};
+ int err;
+
+ addr.sun_family = AF_UNIX;
+ strcpy(addr.sun_path, SOCK_PATH);
+ remove_socket_file();
+
+ self->server = socket(AF_UNIX, variant->socket_type, 0);
+ ASSERT_LT(-1, self->server);
+
+ err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
+ ASSERT_EQ(0, err);
+
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) {
+ err = listen(self->server, 1);
+ ASSERT_EQ(0, err);
+ }
+
+ self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
+ ASSERT_LT(-1, self->client);
+
+ err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
+ ASSERT_EQ(0, err);
+}
+
+FIXTURE_TEARDOWN(unix_sock)
+{
+ if ((variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
+ close(self->child);
+
+ close(self->client);
+ close(self->server);
+ remove_socket_file();
+}
+
+/* Test 1: peer closes normally */
+TEST_F(unix_sock, eof)
+{
+ char buf[16] = {};
+ ssize_t n;
+
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) {
+ self->child = accept(self->server, NULL, NULL);
+ ASSERT_LT(-1, self->child);
+
+ close(self->child);
+ } else {
+ close(self->server);
+ }
+
+ n = recv(self->client, buf, sizeof(buf), 0);
+
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) {
+ ASSERT_EQ(0, n);
+ } else {
+ ASSERT_EQ(-1, n);
+ ASSERT_EQ(EAGAIN, errno);
+ }
+}
+
+/* Test 2: peer closes with unread data */
+TEST_F(unix_sock, reset_unread_behavior)
+{
+ char buf[16] = {};
+ ssize_t n;
+
+ if (variant->socket_type == SOCK_DGRAM) {
+ /* No real connection, just close the server */
+ close(self->server);
+ } else {
+ /* Establish full connection first */
+ self->child = accept(self->server, NULL, NULL);
+ ASSERT_LT(-1, self->child);
+
+ /* Send data that will remain unread */
+ send(self->client, "hello", 5, 0);
+
+ /* Peer closes before client reads */
+ close(self->child);
+ }
+
+ n = recv(self->client, buf, sizeof(buf), 0);
+ ASSERT_EQ(-1, n);
+
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) {
+ ASSERT_EQ(ECONNRESET, errno);
+ } else {
+ ASSERT_EQ(EAGAIN, errno);
+ }
+}
+
+/* Test 3: closing unaccepted (embryo) server socket should reset client. */
+TEST_F(unix_sock, reset_closed_embryo)
+{
+ char buf[16] = {};
+ ssize_t n;
+
+ if (variant->socket_type == SOCK_DGRAM)
+ SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
+
+ /* Close server without accept()ing */
+ close(self->server);
+
+ n = recv(self->client, buf, sizeof(buf), 0);
+
+ ASSERT_EQ(-1, n);
+ ASSERT_EQ(ECONNRESET, errno);
+}
+
+TEST_HARNESS_MAIN
+
--
2.43.0
On Wed, Nov 12, 2025 at 1:20 PM Sunday Adelodun
<adelodunolaoluwa@yahoo.com> wrote:
>
> Add selftests to verify and document Linux’s intended behaviour for
> UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
> The tests verify that:
>
> 1. SOCK_STREAM returns EOF when the peer closes normally.
> 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
> 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
> 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
> 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>
> This follows up on review feedback suggesting a selftest to clarify
> Linux’s semantics.
>
> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
> Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
> ---
> tools/testing/selftests/net/.gitignore | 1 +
> tools/testing/selftests/net/af_unix/Makefile | 1 +
> .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
> 3 files changed, 180 insertions(+)
> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>
> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
> index 439101b518ee..e89a60581a13 100644
> --- a/tools/testing/selftests/net/.gitignore
> +++ b/tools/testing/selftests/net/.gitignore
> @@ -65,3 +65,4 @@ udpgso
> udpgso_bench_rx
> udpgso_bench_tx
> unix_connect
> +unix_connreset
> diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
> index de805cbbdf69..5826a8372451 100644
> --- a/tools/testing/selftests/net/af_unix/Makefile
> +++ b/tools/testing/selftests/net/af_unix/Makefile
> @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
> scm_pidfd \
> scm_rights \
> unix_connect \
> + unix_connreset \
> # end of TEST_GEN_PROGS
>
> include ../../lib.mk
> diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
> new file mode 100644
> index 000000000000..9413f8a0814f
> --- /dev/null
> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
> @@ -0,0 +1,178 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
> + *
> + * This test verifies:
> + * 1. SOCK_STREAM returns EOF when the peer closes normally.
> + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
> + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
> + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
> + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
> + *
> + * These tests document the intended Linux behaviour.
> + *
> + */
> +
> +#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/af_unix_connreset.sock"
> +
> +static void remove_socket_file(void)
> +{
> + unlink(SOCK_PATH);
> +}
> +
> +FIXTURE(unix_sock)
> +{
> + int server;
> + int client;
> + int child;
> +};
> +
> +FIXTURE_VARIANT(unix_sock)
> +{
> + int socket_type;
> + const char *name;
> +};
> +
> +FIXTURE_VARIANT_ADD(unix_sock, stream) {
> + .socket_type = SOCK_STREAM,
> + .name = "SOCK_STREAM",
> +};
> +
> +FIXTURE_VARIANT_ADD(unix_sock, dgram) {
> + .socket_type = SOCK_DGRAM,
> + .name = "SOCK_DGRAM",
> +};
> +
> +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
> + .socket_type = SOCK_SEQPACKET,
> + .name = "SOCK_SEQPACKET",
> +};
> +
> +FIXTURE_SETUP(unix_sock)
> +{
> + struct sockaddr_un addr = {};
> + int err;
> +
> + addr.sun_family = AF_UNIX;
> + strcpy(addr.sun_path, SOCK_PATH);
> + remove_socket_file();
> +
> + self->server = socket(AF_UNIX, variant->socket_type, 0);
> + ASSERT_LT(-1, self->server);
> +
> + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
> + ASSERT_EQ(0, err);
> +
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) {
> + err = listen(self->server, 1);
> + ASSERT_EQ(0, err);
> + }
> +
> + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
> + ASSERT_LT(-1, self->client);
> +
> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
> + ASSERT_EQ(0, err);
> +}
> +
> +FIXTURE_TEARDOWN(unix_sock)
> +{
> + if ((variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
> + close(self->child);
> +
> + close(self->client);
> + close(self->server);
> + remove_socket_file();
> +}
> +
> +/* Test 1: peer closes normally */
> +TEST_F(unix_sock, eof)
> +{
> + char buf[16] = {};
> + ssize_t n;
> +
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) {
> + self->child = accept(self->server, NULL, NULL);
> + ASSERT_LT(-1, self->child);
> +
> + close(self->child);
> + } else {
> + close(self->server);
> + }
> +
> + n = recv(self->client, buf, sizeof(buf), 0);
> +
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) {
> + ASSERT_EQ(0, n);
> + } else {
> + ASSERT_EQ(-1, n);
> + ASSERT_EQ(EAGAIN, errno);
> + }
> +}
> +
> +/* Test 2: peer closes with unread data */
> +TEST_F(unix_sock, reset_unread_behavior)
> +{
> + char buf[16] = {};
> + ssize_t n;
> +
> + if (variant->socket_type == SOCK_DGRAM) {
> + /* No real connection, just close the server */
> + close(self->server);
> + } else {
> + /* Establish full connection first */
> + self->child = accept(self->server, NULL, NULL);
> + ASSERT_LT(-1, self->child);
> +
> + /* Send data that will remain unread */
> + send(self->client, "hello", 5, 0);
Could you move this send() before "if (...)" because we want
to test unread_data behaviour for SOCK_DGRAM too ?
Otherwise looks good, so with that fixed:
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Thanks!
> +
> + /* Peer closes before client reads */
> + close(self->child);
> + }
> +
> + n = recv(self->client, buf, sizeof(buf), 0);
> + ASSERT_EQ(-1, n);
> +
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) {
> + ASSERT_EQ(ECONNRESET, errno);
> + } else {
> + ASSERT_EQ(EAGAIN, errno);
> + }
> +}
> +
> +/* Test 3: closing unaccepted (embryo) server socket should reset client. */
> +TEST_F(unix_sock, reset_closed_embryo)
> +{
> + char buf[16] = {};
> + ssize_t n;
> +
> + if (variant->socket_type == SOCK_DGRAM)
> + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
> +
> + /* Close server without accept()ing */
> + close(self->server);
> +
> + n = recv(self->client, buf, sizeof(buf), 0);
> +
> + ASSERT_EQ(-1, n);
> + ASSERT_EQ(ECONNRESET, errno);
> +}
> +
> +TEST_HARNESS_MAIN
> +
> --
> 2.43.0
>
On 11/12/25 23:04, Kuniyuki Iwashima wrote:
> On Wed, Nov 12, 2025 at 1:20 PM Sunday Adelodun
> <adelodunolaoluwa@yahoo.com> wrote:
>> Add selftests to verify and document Linux’s intended behaviour for
>> UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
>> The tests verify that:
>>
>> 1. SOCK_STREAM returns EOF when the peer closes normally.
>> 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
>> 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
>> 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
>> 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>>
>> This follows up on review feedback suggesting a selftest to clarify
>> Linux’s semantics.
>>
>> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
>> Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
>> ---
>> tools/testing/selftests/net/.gitignore | 1 +
>> tools/testing/selftests/net/af_unix/Makefile | 1 +
>> .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
>> 3 files changed, 180 insertions(+)
>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>>
>> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
>> index 439101b518ee..e89a60581a13 100644
>> --- a/tools/testing/selftests/net/.gitignore
>> +++ b/tools/testing/selftests/net/.gitignore
>> @@ -65,3 +65,4 @@ udpgso
>> udpgso_bench_rx
>> udpgso_bench_tx
>> unix_connect
>> +unix_connreset
>> diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
>> index de805cbbdf69..5826a8372451 100644
>> --- a/tools/testing/selftests/net/af_unix/Makefile
>> +++ b/tools/testing/selftests/net/af_unix/Makefile
>> @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
>> scm_pidfd \
>> scm_rights \
>> unix_connect \
>> + unix_connreset \
>> # end of TEST_GEN_PROGS
>>
>> include ../../lib.mk
>> diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
>> new file mode 100644
>> index 000000000000..9413f8a0814f
>> --- /dev/null
>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
>> @@ -0,0 +1,178 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
>> + *
>> + * This test verifies:
>> + * 1. SOCK_STREAM returns EOF when the peer closes normally.
>> + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
>> + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
>> + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
>> + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>> + *
>> + * These tests document the intended Linux behaviour.
>> + *
>> + */
>> +
>> +#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/af_unix_connreset.sock"
>> +
>> +static void remove_socket_file(void)
>> +{
>> + unlink(SOCK_PATH);
>> +}
>> +
>> +FIXTURE(unix_sock)
>> +{
>> + int server;
>> + int client;
>> + int child;
>> +};
>> +
>> +FIXTURE_VARIANT(unix_sock)
>> +{
>> + int socket_type;
>> + const char *name;
>> +};
>> +
>> +FIXTURE_VARIANT_ADD(unix_sock, stream) {
>> + .socket_type = SOCK_STREAM,
>> + .name = "SOCK_STREAM",
>> +};
>> +
>> +FIXTURE_VARIANT_ADD(unix_sock, dgram) {
>> + .socket_type = SOCK_DGRAM,
>> + .name = "SOCK_DGRAM",
>> +};
>> +
>> +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
>> + .socket_type = SOCK_SEQPACKET,
>> + .name = "SOCK_SEQPACKET",
>> +};
>> +
>> +FIXTURE_SETUP(unix_sock)
>> +{
>> + struct sockaddr_un addr = {};
>> + int err;
>> +
>> + addr.sun_family = AF_UNIX;
>> + strcpy(addr.sun_path, SOCK_PATH);
>> + remove_socket_file();
>> +
>> + self->server = socket(AF_UNIX, variant->socket_type, 0);
>> + ASSERT_LT(-1, self->server);
>> +
>> + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
>> + ASSERT_EQ(0, err);
>> +
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) {
>> + err = listen(self->server, 1);
>> + ASSERT_EQ(0, err);
>> + }
>> +
>> + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
>> + ASSERT_LT(-1, self->client);
>> +
>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
>> + ASSERT_EQ(0, err);
>> +}
>> +
>> +FIXTURE_TEARDOWN(unix_sock)
>> +{
>> + if ((variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
>> + close(self->child);
>> +
>> + close(self->client);
>> + close(self->server);
>> + remove_socket_file();
>> +}
>> +
>> +/* Test 1: peer closes normally */
>> +TEST_F(unix_sock, eof)
>> +{
>> + char buf[16] = {};
>> + ssize_t n;
>> +
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) {
>> + self->child = accept(self->server, NULL, NULL);
>> + ASSERT_LT(-1, self->child);
>> +
>> + close(self->child);
>> + } else {
>> + close(self->server);
>> + }
>> +
>> + n = recv(self->client, buf, sizeof(buf), 0);
>> +
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) {
>> + ASSERT_EQ(0, n);
>> + } else {
>> + ASSERT_EQ(-1, n);
>> + ASSERT_EQ(EAGAIN, errno);
>> + }
>> +}
>> +
>> +/* Test 2: peer closes with unread data */
>> +TEST_F(unix_sock, reset_unread_behavior)
>> +{
>> + char buf[16] = {};
>> + ssize_t n;
>> +
>> + if (variant->socket_type == SOCK_DGRAM) {
>> + /* No real connection, just close the server */
>> + close(self->server);
>> + } else {
>> + /* Establish full connection first */
>> + self->child = accept(self->server, NULL, NULL);
>> + ASSERT_LT(-1, self->child);
>> +
>> + /* Send data that will remain unread */
>> + send(self->client, "hello", 5, 0);
> Could you move this send() before "if (...)" because we want
> to test unread_data behaviour for SOCK_DGRAM too ?
>
> Otherwise looks good, so with that fixed:
>
> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
>
> Thanks!
Thank you for the prompt response.
I thought of putting the send before the if the statement , but I was afraid
STREAM and SEQPACKET connections won't be accepted before data sending.
I will start working on v5.
That part will look like this now:
/* Test 2: peer closes with unread data */
TEST_F(unix_sock, reset_unread_behavior)
{
char buf[16] = {};
ssize_t n;
*/* Send data that will remain unread */
send(self->client, "hello", 5, 0);*
*if (variant->socket_type == SOCK_DGRAM) {
/* No real connection, just close the server */
close(self->server);
} else {
/* Establish full connection first */
self->child = accept(self->server, NULL, NULL);
ASSERT_LT(-1, self->child);
/* Peer closes before client reads */
close(self->child);
}*
n = recv(self->client, buf, sizeof(buf), 0);
ASSERT_EQ(-1, n);
if (variant->socket_type == SOCK_STREAM ||
variant->socket_type == SOCK_SEQPACKET) {
ASSERT_EQ(ECONNRESET, errno);
} else {
ASSERT_EQ(EAGAIN, errno);
}
}
Thank you once again.
>
>
>> +
>> + /* Peer closes before client reads */
>> + close(self->child);
>> + }
>> +
>> + n = recv(self->client, buf, sizeof(buf), 0);
>> + ASSERT_EQ(-1, n);
>> +
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) {
>> + ASSERT_EQ(ECONNRESET, errno);
>> + } else {
>> + ASSERT_EQ(EAGAIN, errno);
>> + }
>> +}
>> +
>> +/* Test 3: closing unaccepted (embryo) server socket should reset client. */
>> +TEST_F(unix_sock, reset_closed_embryo)
>> +{
>> + char buf[16] = {};
>> + ssize_t n;
>> +
>> + if (variant->socket_type == SOCK_DGRAM)
>> + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
>> +
>> + /* Close server without accept()ing */
>> + close(self->server);
>> +
>> + n = recv(self->client, buf, sizeof(buf), 0);
>> +
>> + ASSERT_EQ(-1, n);
>> + ASSERT_EQ(ECONNRESET, errno);
>> +}
>> +
>> +TEST_HARNESS_MAIN
>> +
>> --
>> 2.43.0
>>
On Wed, Nov 12, 2025 at 9:25 PM Sunday Adelodun
<adelodunolaoluwa@yahoo.com> wrote:
>
> On 11/12/25 23:04, Kuniyuki Iwashima wrote:
> > On Wed, Nov 12, 2025 at 1:20 PM Sunday Adelodun
> > <adelodunolaoluwa@yahoo.com> wrote:
> >> Add selftests to verify and document Linux’s intended behaviour for
> >> UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
> >> The tests verify that:
> >>
> >> 1. SOCK_STREAM returns EOF when the peer closes normally.
> >> 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
> >> 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
> >> 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
> >> 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
> >>
> >> This follows up on review feedback suggesting a selftest to clarify
> >> Linux’s semantics.
> >>
> >> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
> >> Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
> >> ---
> >> tools/testing/selftests/net/.gitignore | 1 +
> >> tools/testing/selftests/net/af_unix/Makefile | 1 +
> >> .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
> >> 3 files changed, 180 insertions(+)
> >> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
> >>
> >> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
> >> index 439101b518ee..e89a60581a13 100644
> >> --- a/tools/testing/selftests/net/.gitignore
> >> +++ b/tools/testing/selftests/net/.gitignore
> >> @@ -65,3 +65,4 @@ udpgso
> >> udpgso_bench_rx
> >> udpgso_bench_tx
> >> unix_connect
> >> +unix_connreset
> >> diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
> >> index de805cbbdf69..5826a8372451 100644
> >> --- a/tools/testing/selftests/net/af_unix/Makefile
> >> +++ b/tools/testing/selftests/net/af_unix/Makefile
> >> @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
> >> scm_pidfd \
> >> scm_rights \
> >> unix_connect \
> >> + unix_connreset \
> >> # end of TEST_GEN_PROGS
> >>
> >> include ../../lib.mk
> >> diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
> >> new file mode 100644
> >> index 000000000000..9413f8a0814f
> >> --- /dev/null
> >> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
> >> @@ -0,0 +1,178 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
> >> + *
> >> + * This test verifies:
> >> + * 1. SOCK_STREAM returns EOF when the peer closes normally.
> >> + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
> >> + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
> >> + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
> >> + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
> >> + *
> >> + * These tests document the intended Linux behaviour.
> >> + *
> >> + */
> >> +
> >> +#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/af_unix_connreset.sock"
> >> +
> >> +static void remove_socket_file(void)
> >> +{
> >> + unlink(SOCK_PATH);
> >> +}
> >> +
> >> +FIXTURE(unix_sock)
> >> +{
> >> + int server;
> >> + int client;
> >> + int child;
> >> +};
> >> +
> >> +FIXTURE_VARIANT(unix_sock)
> >> +{
> >> + int socket_type;
> >> + const char *name;
> >> +};
> >> +
> >> +FIXTURE_VARIANT_ADD(unix_sock, stream) {
> >> + .socket_type = SOCK_STREAM,
> >> + .name = "SOCK_STREAM",
> >> +};
> >> +
> >> +FIXTURE_VARIANT_ADD(unix_sock, dgram) {
> >> + .socket_type = SOCK_DGRAM,
> >> + .name = "SOCK_DGRAM",
> >> +};
> >> +
> >> +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
> >> + .socket_type = SOCK_SEQPACKET,
> >> + .name = "SOCK_SEQPACKET",
> >> +};
> >> +
> >> +FIXTURE_SETUP(unix_sock)
> >> +{
> >> + struct sockaddr_un addr = {};
> >> + int err;
> >> +
> >> + addr.sun_family = AF_UNIX;
> >> + strcpy(addr.sun_path, SOCK_PATH);
> >> + remove_socket_file();
> >> +
> >> + self->server = socket(AF_UNIX, variant->socket_type, 0);
> >> + ASSERT_LT(-1, self->server);
> >> +
> >> + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
> >> + ASSERT_EQ(0, err);
> >> +
> >> + if (variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET) {
> >> + err = listen(self->server, 1);
> >> + ASSERT_EQ(0, err);
> >> + }
> >> +
> >> + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
> >> + ASSERT_LT(-1, self->client);
> >> +
> >> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
> >> + ASSERT_EQ(0, err);
> >> +}
> >> +
> >> +FIXTURE_TEARDOWN(unix_sock)
> >> +{
> >> + if ((variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
> >> + close(self->child);
> >> +
> >> + close(self->client);
> >> + close(self->server);
> >> + remove_socket_file();
> >> +}
> >> +
> >> +/* Test 1: peer closes normally */
> >> +TEST_F(unix_sock, eof)
> >> +{
> >> + char buf[16] = {};
> >> + ssize_t n;
> >> +
> >> + if (variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET) {
> >> + self->child = accept(self->server, NULL, NULL);
> >> + ASSERT_LT(-1, self->child);
> >> +
> >> + close(self->child);
> >> + } else {
> >> + close(self->server);
> >> + }
> >> +
> >> + n = recv(self->client, buf, sizeof(buf), 0);
> >> +
> >> + if (variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET) {
> >> + ASSERT_EQ(0, n);
> >> + } else {
> >> + ASSERT_EQ(-1, n);
> >> + ASSERT_EQ(EAGAIN, errno);
> >> + }
> >> +}
> >> +
> >> +/* Test 2: peer closes with unread data */
> >> +TEST_F(unix_sock, reset_unread_behavior)
> >> +{
> >> + char buf[16] = {};
> >> + ssize_t n;
> >> +
> >> + if (variant->socket_type == SOCK_DGRAM) {
> >> + /* No real connection, just close the server */
> >> + close(self->server);
> >> + } else {
> >> + /* Establish full connection first */
> >> + self->child = accept(self->server, NULL, NULL);
> >> + ASSERT_LT(-1, self->child);
> >> +
> >> + /* Send data that will remain unread */
> >> + send(self->client, "hello", 5, 0);
> > Could you move this send() before "if (...)" because we want
> > to test unread_data behaviour for SOCK_DGRAM too ?
> >
> > Otherwise looks good, so with that fixed:
> >
> > Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
> >
> > Thanks!
> Thank you for the prompt response.
> I thought of putting the send before the if the statement , but I was afraid
> STREAM and SEQPACKET connections won't be accepted before data sending.
connect() create the paired child socket and accept()
allocates a file descriptor to expose the socket to user
space.
In that sense, the comment above accept() sounds a
bit weird ;)
>
> I will start working on v5.
>
> That part will look like this now:
> /* Test 2: peer closes with unread data */
> TEST_F(unix_sock, reset_unread_behavior)
> {
> char buf[16] = {};
> ssize_t n;
>
> */* Send data that will remain unread */
> send(self->client, "hello", 5, 0);*
>
> *if (variant->socket_type == SOCK_DGRAM) {
> /* No real connection, just close the server */
> close(self->server);
> } else {
> /* Establish full connection first */
> self->child = accept(self->server, NULL, NULL);
> ASSERT_LT(-1, self->child);
>
> /* Peer closes before client reads */
> close(self->child);
> }*
>
> n = recv(self->client, buf, sizeof(buf), 0);
> ASSERT_EQ(-1, n);
>
> if (variant->socket_type == SOCK_STREAM ||
> variant->socket_type == SOCK_SEQPACKET) {
> ASSERT_EQ(ECONNRESET, errno);
> } else {
> ASSERT_EQ(EAGAIN, errno);
> }
> }
>
> Thank you once again.
> >
> >
> >> +
> >> + /* Peer closes before client reads */
> >> + close(self->child);
> >> + }
> >> +
> >> + n = recv(self->client, buf, sizeof(buf), 0);
> >> + ASSERT_EQ(-1, n);
> >> +
> >> + if (variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET) {
> >> + ASSERT_EQ(ECONNRESET, errno);
> >> + } else {
> >> + ASSERT_EQ(EAGAIN, errno);
> >> + }
> >> +}
> >> +
> >> +/* Test 3: closing unaccepted (embryo) server socket should reset client. */
> >> +TEST_F(unix_sock, reset_closed_embryo)
> >> +{
> >> + char buf[16] = {};
> >> + ssize_t n;
> >> +
> >> + if (variant->socket_type == SOCK_DGRAM)
> >> + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
> >> +
> >> + /* Close server without accept()ing */
> >> + close(self->server);
> >> +
> >> + n = recv(self->client, buf, sizeof(buf), 0);
> >> +
> >> + ASSERT_EQ(-1, n);
> >> + ASSERT_EQ(ECONNRESET, errno);
> >> +}
> >> +
> >> +TEST_HARNESS_MAIN
> >> +
> >> --
> >> 2.43.0
> >>
>
On 11/13/25 07:10, Kuniyuki Iwashima wrote:
> On Wed, Nov 12, 2025 at 9:25 PM Sunday Adelodun
> <adelodunolaoluwa@yahoo.com> wrote:
>> On 11/12/25 23:04, Kuniyuki Iwashima wrote:
>>> On Wed, Nov 12, 2025 at 1:20 PM Sunday Adelodun
>>> <adelodunolaoluwa@yahoo.com> wrote:
>>>> Add selftests to verify and document Linux’s intended behaviour for
>>>> UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
>>>> The tests verify that:
>>>>
>>>> 1. SOCK_STREAM returns EOF when the peer closes normally.
>>>> 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
>>>> 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
>>>> 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
>>>> 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>>>>
>>>> This follows up on review feedback suggesting a selftest to clarify
>>>> Linux’s semantics.
>>>>
>>>> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
>>>> Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
>>>> ---
>>>> tools/testing/selftests/net/.gitignore | 1 +
>>>> tools/testing/selftests/net/af_unix/Makefile | 1 +
>>>> .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
>>>> 3 files changed, 180 insertions(+)
>>>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>
>>>> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
>>>> index 439101b518ee..e89a60581a13 100644
>>>> --- a/tools/testing/selftests/net/.gitignore
>>>> +++ b/tools/testing/selftests/net/.gitignore
>>>> @@ -65,3 +65,4 @@ udpgso
>>>> udpgso_bench_rx
>>>> udpgso_bench_tx
>>>> unix_connect
>>>> +unix_connreset
>>>> diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
>>>> index de805cbbdf69..5826a8372451 100644
>>>> --- a/tools/testing/selftests/net/af_unix/Makefile
>>>> +++ b/tools/testing/selftests/net/af_unix/Makefile
>>>> @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
>>>> scm_pidfd \
>>>> scm_rights \
>>>> unix_connect \
>>>> + unix_connreset \
>>>> # end of TEST_GEN_PROGS
>>>>
>>>> include ../../lib.mk
>>>> diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
>>>> new file mode 100644
>>>> index 000000000000..9413f8a0814f
>>>> --- /dev/null
>>>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
>>>> @@ -0,0 +1,178 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
>>>> + *
>>>> + * This test verifies:
>>>> + * 1. SOCK_STREAM returns EOF when the peer closes normally.
>>>> + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
>>>> + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
>>>> + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
>>>> + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>>>> + *
>>>> + * These tests document the intended Linux behaviour.
>>>> + *
>>>> + */
>>>> +
>>>> +#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/af_unix_connreset.sock"
>>>> +
>>>> +static void remove_socket_file(void)
>>>> +{
>>>> + unlink(SOCK_PATH);
>>>> +}
>>>> +
>>>> +FIXTURE(unix_sock)
>>>> +{
>>>> + int server;
>>>> + int client;
>>>> + int child;
>>>> +};
>>>> +
>>>> +FIXTURE_VARIANT(unix_sock)
>>>> +{
>>>> + int socket_type;
>>>> + const char *name;
>>>> +};
>>>> +
>>>> +FIXTURE_VARIANT_ADD(unix_sock, stream) {
>>>> + .socket_type = SOCK_STREAM,
>>>> + .name = "SOCK_STREAM",
>>>> +};
>>>> +
>>>> +FIXTURE_VARIANT_ADD(unix_sock, dgram) {
>>>> + .socket_type = SOCK_DGRAM,
>>>> + .name = "SOCK_DGRAM",
>>>> +};
>>>> +
>>>> +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
>>>> + .socket_type = SOCK_SEQPACKET,
>>>> + .name = "SOCK_SEQPACKET",
>>>> +};
>>>> +
>>>> +FIXTURE_SETUP(unix_sock)
>>>> +{
>>>> + struct sockaddr_un addr = {};
>>>> + int err;
>>>> +
>>>> + addr.sun_family = AF_UNIX;
>>>> + strcpy(addr.sun_path, SOCK_PATH);
>>>> + remove_socket_file();
>>>> +
>>>> + self->server = socket(AF_UNIX, variant->socket_type, 0);
>>>> + ASSERT_LT(-1, self->server);
>>>> +
>>>> + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
>>>> + ASSERT_EQ(0, err);
>>>> +
>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>> + err = listen(self->server, 1);
>>>> + ASSERT_EQ(0, err);
>>>> + }
>>>> +
>>>> + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
>>>> + ASSERT_LT(-1, self->client);
>>>> +
>>>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
>>>> + ASSERT_EQ(0, err);
>>>> +}
>>>> +
>>>> +FIXTURE_TEARDOWN(unix_sock)
>>>> +{
>>>> + if ((variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
>>>> + close(self->child);
>>>> +
>>>> + close(self->client);
>>>> + close(self->server);
>>>> + remove_socket_file();
>>>> +}
>>>> +
>>>> +/* Test 1: peer closes normally */
>>>> +TEST_F(unix_sock, eof)
>>>> +{
>>>> + char buf[16] = {};
>>>> + ssize_t n;
>>>> +
>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>> + self->child = accept(self->server, NULL, NULL);
>>>> + ASSERT_LT(-1, self->child);
>>>> +
>>>> + close(self->child);
>>>> + } else {
>>>> + close(self->server);
>>>> + }
>>>> +
>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>> +
>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>> + ASSERT_EQ(0, n);
>>>> + } else {
>>>> + ASSERT_EQ(-1, n);
>>>> + ASSERT_EQ(EAGAIN, errno);
>>>> + }
>>>> +}
>>>> +
>>>> +/* Test 2: peer closes with unread data */
>>>> +TEST_F(unix_sock, reset_unread_behavior)
>>>> +{
>>>> + char buf[16] = {};
>>>> + ssize_t n;
>>>> +
>>>> + if (variant->socket_type == SOCK_DGRAM) {
>>>> + /* No real connection, just close the server */
>>>> + close(self->server);
>>>> + } else {
>>>> + /* Establish full connection first */
>>>> + self->child = accept(self->server, NULL, NULL);
>>>> + ASSERT_LT(-1, self->child);
>>>> +
>>>> + /* Send data that will remain unread */
>>>> + send(self->client, "hello", 5, 0);
>>> Could you move this send() before "if (...)" because we want
>>> to test unread_data behaviour for SOCK_DGRAM too ?
>>>
>>> Otherwise looks good, so with that fixed:
>>>
>>> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
>>>
>>> Thanks!
>> Thank you for the prompt response.
>> I thought of putting the send before the if the statement , but I was afraid
>> STREAM and SEQPACKET connections won't be accepted before data sending.
> connect() create the paired child socket and accept()
> allocates a file descriptor to expose the socket to user
> space.
Thank you for this explanation.
>
> In that sense, the comment above accept() sounds a
> bit weird ;)
I understand.
I am changing it to
/* Accept client connection */
If this is accepted, I will send v5 immediately
Thank you for your guidance.
>
>
>> I will start working on v5.
>>
>> That part will look like this now:
>> /* Test 2: peer closes with unread data */
>> TEST_F(unix_sock, reset_unread_behavior)
>> {
>> char buf[16] = {};
>> ssize_t n;
>>
>> */* Send data that will remain unread */
>> send(self->client, "hello", 5, 0);*
>>
>> *if (variant->socket_type == SOCK_DGRAM) {
>> /* No real connection, just close the server */
>> close(self->server);
>> } else {
>> /* Establish full connection first */
>> self->child = accept(self->server, NULL, NULL);
>> ASSERT_LT(-1, self->child);
>>
>> /* Peer closes before client reads */
>> close(self->child);
>> }*
>>
>> n = recv(self->client, buf, sizeof(buf), 0);
>> ASSERT_EQ(-1, n);
>>
>> if (variant->socket_type == SOCK_STREAM ||
>> variant->socket_type == SOCK_SEQPACKET) {
>> ASSERT_EQ(ECONNRESET, errno);
>> } else {
>> ASSERT_EQ(EAGAIN, errno);
>> }
>> }
>>
>> Thank you once again.
>>>
>>>> +
>>>> + /* Peer closes before client reads */
>>>> + close(self->child);
>>>> + }
>>>> +
>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>> + ASSERT_EQ(-1, n);
>>>> +
>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>> + ASSERT_EQ(ECONNRESET, errno);
>>>> + } else {
>>>> + ASSERT_EQ(EAGAIN, errno);
>>>> + }
>>>> +}
>>>> +
>>>> +/* Test 3: closing unaccepted (embryo) server socket should reset client. */
>>>> +TEST_F(unix_sock, reset_closed_embryo)
>>>> +{
>>>> + char buf[16] = {};
>>>> + ssize_t n;
>>>> +
>>>> + if (variant->socket_type == SOCK_DGRAM)
>>>> + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
>>>> +
>>>> + /* Close server without accept()ing */
>>>> + close(self->server);
>>>> +
>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>> +
>>>> + ASSERT_EQ(-1, n);
>>>> + ASSERT_EQ(ECONNRESET, errno);
>>>> +}
>>>> +
>>>> +TEST_HARNESS_MAIN
>>>> +
>>>> --
>>>> 2.43.0
>>>>
On Wed, Nov 12, 2025 at 10:41 PM Sunday Adelodun
<adelodunolaoluwa@yahoo.com> wrote:
>
> On 11/13/25 07:10, Kuniyuki Iwashima wrote:
> > On Wed, Nov 12, 2025 at 9:25 PM Sunday Adelodun
> > <adelodunolaoluwa@yahoo.com> wrote:
> >> On 11/12/25 23:04, Kuniyuki Iwashima wrote:
> >>> On Wed, Nov 12, 2025 at 1:20 PM Sunday Adelodun
> >>> <adelodunolaoluwa@yahoo.com> wrote:
> >>>> Add selftests to verify and document Linux’s intended behaviour for
> >>>> UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
> >>>> The tests verify that:
> >>>>
> >>>> 1. SOCK_STREAM returns EOF when the peer closes normally.
> >>>> 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
> >>>> 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
> >>>> 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
> >>>> 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
> >>>>
> >>>> This follows up on review feedback suggesting a selftest to clarify
> >>>> Linux’s semantics.
> >>>>
> >>>> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
> >>>> Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
> >>>> ---
> >>>> tools/testing/selftests/net/.gitignore | 1 +
> >>>> tools/testing/selftests/net/af_unix/Makefile | 1 +
> >>>> .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
> >>>> 3 files changed, 180 insertions(+)
> >>>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
> >>>>
> >>>> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
> >>>> index 439101b518ee..e89a60581a13 100644
> >>>> --- a/tools/testing/selftests/net/.gitignore
> >>>> +++ b/tools/testing/selftests/net/.gitignore
> >>>> @@ -65,3 +65,4 @@ udpgso
> >>>> udpgso_bench_rx
> >>>> udpgso_bench_tx
> >>>> unix_connect
> >>>> +unix_connreset
> >>>> diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
> >>>> index de805cbbdf69..5826a8372451 100644
> >>>> --- a/tools/testing/selftests/net/af_unix/Makefile
> >>>> +++ b/tools/testing/selftests/net/af_unix/Makefile
> >>>> @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
> >>>> scm_pidfd \
> >>>> scm_rights \
> >>>> unix_connect \
> >>>> + unix_connreset \
> >>>> # end of TEST_GEN_PROGS
> >>>>
> >>>> include ../../lib.mk
> >>>> diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
> >>>> new file mode 100644
> >>>> index 000000000000..9413f8a0814f
> >>>> --- /dev/null
> >>>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
> >>>> @@ -0,0 +1,178 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0
> >>>> +/*
> >>>> + * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
> >>>> + *
> >>>> + * This test verifies:
> >>>> + * 1. SOCK_STREAM returns EOF when the peer closes normally.
> >>>> + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
> >>>> + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
> >>>> + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
> >>>> + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
> >>>> + *
> >>>> + * These tests document the intended Linux behaviour.
> >>>> + *
> >>>> + */
> >>>> +
> >>>> +#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/af_unix_connreset.sock"
> >>>> +
> >>>> +static void remove_socket_file(void)
> >>>> +{
> >>>> + unlink(SOCK_PATH);
> >>>> +}
> >>>> +
> >>>> +FIXTURE(unix_sock)
> >>>> +{
> >>>> + int server;
> >>>> + int client;
> >>>> + int child;
> >>>> +};
> >>>> +
> >>>> +FIXTURE_VARIANT(unix_sock)
> >>>> +{
> >>>> + int socket_type;
> >>>> + const char *name;
> >>>> +};
> >>>> +
> >>>> +FIXTURE_VARIANT_ADD(unix_sock, stream) {
> >>>> + .socket_type = SOCK_STREAM,
> >>>> + .name = "SOCK_STREAM",
> >>>> +};
> >>>> +
> >>>> +FIXTURE_VARIANT_ADD(unix_sock, dgram) {
> >>>> + .socket_type = SOCK_DGRAM,
> >>>> + .name = "SOCK_DGRAM",
> >>>> +};
> >>>> +
> >>>> +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
> >>>> + .socket_type = SOCK_SEQPACKET,
> >>>> + .name = "SOCK_SEQPACKET",
> >>>> +};
> >>>> +
> >>>> +FIXTURE_SETUP(unix_sock)
> >>>> +{
> >>>> + struct sockaddr_un addr = {};
> >>>> + int err;
> >>>> +
> >>>> + addr.sun_family = AF_UNIX;
> >>>> + strcpy(addr.sun_path, SOCK_PATH);
> >>>> + remove_socket_file();
> >>>> +
> >>>> + self->server = socket(AF_UNIX, variant->socket_type, 0);
> >>>> + ASSERT_LT(-1, self->server);
> >>>> +
> >>>> + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
> >>>> + ASSERT_EQ(0, err);
> >>>> +
> >>>> + if (variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET) {
> >>>> + err = listen(self->server, 1);
> >>>> + ASSERT_EQ(0, err);
> >>>> + }
> >>>> +
> >>>> + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
> >>>> + ASSERT_LT(-1, self->client);
> >>>> +
> >>>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
> >>>> + ASSERT_EQ(0, err);
> >>>> +}
> >>>> +
> >>>> +FIXTURE_TEARDOWN(unix_sock)
> >>>> +{
> >>>> + if ((variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
> >>>> + close(self->child);
> >>>> +
> >>>> + close(self->client);
> >>>> + close(self->server);
> >>>> + remove_socket_file();
> >>>> +}
> >>>> +
> >>>> +/* Test 1: peer closes normally */
> >>>> +TEST_F(unix_sock, eof)
> >>>> +{
> >>>> + char buf[16] = {};
> >>>> + ssize_t n;
> >>>> +
> >>>> + if (variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET) {
> >>>> + self->child = accept(self->server, NULL, NULL);
> >>>> + ASSERT_LT(-1, self->child);
> >>>> +
> >>>> + close(self->child);
> >>>> + } else {
> >>>> + close(self->server);
> >>>> + }
> >>>> +
> >>>> + n = recv(self->client, buf, sizeof(buf), 0);
> >>>> +
> >>>> + if (variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET) {
> >>>> + ASSERT_EQ(0, n);
> >>>> + } else {
> >>>> + ASSERT_EQ(-1, n);
> >>>> + ASSERT_EQ(EAGAIN, errno);
> >>>> + }
> >>>> +}
> >>>> +
> >>>> +/* Test 2: peer closes with unread data */
> >>>> +TEST_F(unix_sock, reset_unread_behavior)
> >>>> +{
> >>>> + char buf[16] = {};
> >>>> + ssize_t n;
> >>>> +
> >>>> + if (variant->socket_type == SOCK_DGRAM) {
> >>>> + /* No real connection, just close the server */
> >>>> + close(self->server);
> >>>> + } else {
> >>>> + /* Establish full connection first */
> >>>> + self->child = accept(self->server, NULL, NULL);
> >>>> + ASSERT_LT(-1, self->child);
> >>>> +
> >>>> + /* Send data that will remain unread */
> >>>> + send(self->client, "hello", 5, 0);
> >>> Could you move this send() before "if (...)" because we want
> >>> to test unread_data behaviour for SOCK_DGRAM too ?
> >>>
> >>> Otherwise looks good, so with that fixed:
> >>>
> >>> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
> >>>
> >>> Thanks!
> >> Thank you for the prompt response.
> >> I thought of putting the send before the if the statement , but I was afraid
> >> STREAM and SEQPACKET connections won't be accepted before data sending.
> > connect() create the paired child socket and accept()
> > allocates a file descriptor to expose the socket to user
> > space.
> Thank you for this explanation.
> >
> > In that sense, the comment above accept() sounds a
> > bit weird ;)
> I understand.
> I am changing it to
> /* Accept client connection */
I'd remove it since it just repeats the code, but up to you.
Thanks!
>
> If this is accepted, I will send v5 immediately
>
> Thank you for your guidance.
> >
> >
> >> I will start working on v5.
> >>
> >> That part will look like this now:
> >> /* Test 2: peer closes with unread data */
> >> TEST_F(unix_sock, reset_unread_behavior)
> >> {
> >> char buf[16] = {};
> >> ssize_t n;
> >>
> >> */* Send data that will remain unread */
> >> send(self->client, "hello", 5, 0);*
> >>
> >> *if (variant->socket_type == SOCK_DGRAM) {
> >> /* No real connection, just close the server */
> >> close(self->server);
> >> } else {
> >> /* Establish full connection first */
> >> self->child = accept(self->server, NULL, NULL);
> >> ASSERT_LT(-1, self->child);
> >>
> >> /* Peer closes before client reads */
> >> close(self->child);
> >> }*
> >>
> >> n = recv(self->client, buf, sizeof(buf), 0);
> >> ASSERT_EQ(-1, n);
> >>
> >> if (variant->socket_type == SOCK_STREAM ||
> >> variant->socket_type == SOCK_SEQPACKET) {
> >> ASSERT_EQ(ECONNRESET, errno);
> >> } else {
> >> ASSERT_EQ(EAGAIN, errno);
> >> }
> >> }
> >>
> >> Thank you once again.
> >>>
> >>>> +
> >>>> + /* Peer closes before client reads */
> >>>> + close(self->child);
> >>>> + }
> >>>> +
> >>>> + n = recv(self->client, buf, sizeof(buf), 0);
> >>>> + ASSERT_EQ(-1, n);
> >>>> +
> >>>> + if (variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET) {
> >>>> + ASSERT_EQ(ECONNRESET, errno);
> >>>> + } else {
> >>>> + ASSERT_EQ(EAGAIN, errno);
> >>>> + }
> >>>> +}
> >>>> +
> >>>> +/* Test 3: closing unaccepted (embryo) server socket should reset client. */
> >>>> +TEST_F(unix_sock, reset_closed_embryo)
> >>>> +{
> >>>> + char buf[16] = {};
> >>>> + ssize_t n;
> >>>> +
> >>>> + if (variant->socket_type == SOCK_DGRAM)
> >>>> + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
> >>>> +
> >>>> + /* Close server without accept()ing */
> >>>> + close(self->server);
> >>>> +
> >>>> + n = recv(self->client, buf, sizeof(buf), 0);
> >>>> +
> >>>> + ASSERT_EQ(-1, n);
> >>>> + ASSERT_EQ(ECONNRESET, errno);
> >>>> +}
> >>>> +
> >>>> +TEST_HARNESS_MAIN
> >>>> +
> >>>> --
> >>>> 2.43.0
> >>>>
>
On 11/13/25 07:52, Kuniyuki Iwashima wrote:
> On Wed, Nov 12, 2025 at 10:41 PM Sunday Adelodun
> <adelodunolaoluwa@yahoo.com> wrote:
>> On 11/13/25 07:10, Kuniyuki Iwashima wrote:
>>> On Wed, Nov 12, 2025 at 9:25 PM Sunday Adelodun
>>> <adelodunolaoluwa@yahoo.com> wrote:
>>>> On 11/12/25 23:04, Kuniyuki Iwashima wrote:
>>>>> On Wed, Nov 12, 2025 at 1:20 PM Sunday Adelodun
>>>>> <adelodunolaoluwa@yahoo.com> wrote:
>>>>>> Add selftests to verify and document Linux’s intended behaviour for
>>>>>> UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes.
>>>>>> The tests verify that:
>>>>>>
>>>>>> 1. SOCK_STREAM returns EOF when the peer closes normally.
>>>>>> 2. SOCK_STREAM returns ECONNRESET if the peer closes with unread data.
>>>>>> 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
>>>>>> 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
>>>>>> 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>>>>>>
>>>>>> This follows up on review feedback suggesting a selftest to clarify
>>>>>> Linux’s semantics.
>>>>>>
>>>>>> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
>>>>>> Signed-off-by: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
>>>>>> ---
>>>>>> tools/testing/selftests/net/.gitignore | 1 +
>>>>>> tools/testing/selftests/net/af_unix/Makefile | 1 +
>>>>>> .../selftests/net/af_unix/unix_connreset.c | 178 ++++++++++++++++++
>>>>>> 3 files changed, 180 insertions(+)
>>>>>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>>>
>>>>>> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
>>>>>> index 439101b518ee..e89a60581a13 100644
>>>>>> --- a/tools/testing/selftests/net/.gitignore
>>>>>> +++ b/tools/testing/selftests/net/.gitignore
>>>>>> @@ -65,3 +65,4 @@ udpgso
>>>>>> udpgso_bench_rx
>>>>>> udpgso_bench_tx
>>>>>> unix_connect
>>>>>> +unix_connreset
>>>>>> diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
>>>>>> index de805cbbdf69..5826a8372451 100644
>>>>>> --- a/tools/testing/selftests/net/af_unix/Makefile
>>>>>> +++ b/tools/testing/selftests/net/af_unix/Makefile
>>>>>> @@ -7,6 +7,7 @@ TEST_GEN_PROGS := \
>>>>>> scm_pidfd \
>>>>>> scm_rights \
>>>>>> unix_connect \
>>>>>> + unix_connreset \
>>>>>> # end of TEST_GEN_PROGS
>>>>>>
>>>>>> include ../../lib.mk
>>>>>> diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>>> new file mode 100644
>>>>>> index 000000000000..9413f8a0814f
>>>>>> --- /dev/null
>>>>>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>>> @@ -0,0 +1,178 @@
>>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>>> +/*
>>>>>> + * Selftest for AF_UNIX socket close and ECONNRESET behaviour.
>>>>>> + *
>>>>>> + * This test verifies:
>>>>>> + * 1. SOCK_STREAM returns EOF when the peer closes normally.
>>>>>> + * 2. SOCK_STREAM returns ECONNRESET if peer closes with unread data.
>>>>>> + * 3. SOCK_SEQPACKET returns EOF when the peer closes normally.
>>>>>> + * 4. SOCK_SEQPACKET returns ECONNRESET if the peer closes with unread data.
>>>>>> + * 5. SOCK_DGRAM does not return ECONNRESET when the peer closes.
>>>>>> + *
>>>>>> + * These tests document the intended Linux behaviour.
>>>>>> + *
>>>>>> + */
>>>>>> +
>>>>>> +#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/af_unix_connreset.sock"
>>>>>> +
>>>>>> +static void remove_socket_file(void)
>>>>>> +{
>>>>>> + unlink(SOCK_PATH);
>>>>>> +}
>>>>>> +
>>>>>> +FIXTURE(unix_sock)
>>>>>> +{
>>>>>> + int server;
>>>>>> + int client;
>>>>>> + int child;
>>>>>> +};
>>>>>> +
>>>>>> +FIXTURE_VARIANT(unix_sock)
>>>>>> +{
>>>>>> + int socket_type;
>>>>>> + const char *name;
>>>>>> +};
>>>>>> +
>>>>>> +FIXTURE_VARIANT_ADD(unix_sock, stream) {
>>>>>> + .socket_type = SOCK_STREAM,
>>>>>> + .name = "SOCK_STREAM",
>>>>>> +};
>>>>>> +
>>>>>> +FIXTURE_VARIANT_ADD(unix_sock, dgram) {
>>>>>> + .socket_type = SOCK_DGRAM,
>>>>>> + .name = "SOCK_DGRAM",
>>>>>> +};
>>>>>> +
>>>>>> +FIXTURE_VARIANT_ADD(unix_sock, seqpacket) {
>>>>>> + .socket_type = SOCK_SEQPACKET,
>>>>>> + .name = "SOCK_SEQPACKET",
>>>>>> +};
>>>>>> +
>>>>>> +FIXTURE_SETUP(unix_sock)
>>>>>> +{
>>>>>> + struct sockaddr_un addr = {};
>>>>>> + int err;
>>>>>> +
>>>>>> + addr.sun_family = AF_UNIX;
>>>>>> + strcpy(addr.sun_path, SOCK_PATH);
>>>>>> + remove_socket_file();
>>>>>> +
>>>>>> + self->server = socket(AF_UNIX, variant->socket_type, 0);
>>>>>> + ASSERT_LT(-1, self->server);
>>>>>> +
>>>>>> + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr));
>>>>>> + ASSERT_EQ(0, err);
>>>>>> +
>>>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>>>> + err = listen(self->server, 1);
>>>>>> + ASSERT_EQ(0, err);
>>>>>> + }
>>>>>> +
>>>>>> + self->client = socket(AF_UNIX, variant->socket_type | SOCK_NONBLOCK, 0);
>>>>>> + ASSERT_LT(-1, self->client);
>>>>>> +
>>>>>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
>>>>>> + ASSERT_EQ(0, err);
>>>>>> +}
>>>>>> +
>>>>>> +FIXTURE_TEARDOWN(unix_sock)
>>>>>> +{
>>>>>> + if ((variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET) & self->child > 0)
>>>>>> + close(self->child);
>>>>>> +
>>>>>> + close(self->client);
>>>>>> + close(self->server);
>>>>>> + remove_socket_file();
>>>>>> +}
>>>>>> +
>>>>>> +/* Test 1: peer closes normally */
>>>>>> +TEST_F(unix_sock, eof)
>>>>>> +{
>>>>>> + char buf[16] = {};
>>>>>> + ssize_t n;
>>>>>> +
>>>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>>>> + self->child = accept(self->server, NULL, NULL);
>>>>>> + ASSERT_LT(-1, self->child);
>>>>>> +
>>>>>> + close(self->child);
>>>>>> + } else {
>>>>>> + close(self->server);
>>>>>> + }
>>>>>> +
>>>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>>>> +
>>>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>>>> + ASSERT_EQ(0, n);
>>>>>> + } else {
>>>>>> + ASSERT_EQ(-1, n);
>>>>>> + ASSERT_EQ(EAGAIN, errno);
>>>>>> + }
>>>>>> +}
>>>>>> +
>>>>>> +/* Test 2: peer closes with unread data */
>>>>>> +TEST_F(unix_sock, reset_unread_behavior)
>>>>>> +{
>>>>>> + char buf[16] = {};
>>>>>> + ssize_t n;
>>>>>> +
>>>>>> + if (variant->socket_type == SOCK_DGRAM) {
>>>>>> + /* No real connection, just close the server */
>>>>>> + close(self->server);
>>>>>> + } else {
>>>>>> + /* Establish full connection first */
>>>>>> + self->child = accept(self->server, NULL, NULL);
>>>>>> + ASSERT_LT(-1, self->child);
>>>>>> +
>>>>>> + /* Send data that will remain unread */
>>>>>> + send(self->client, "hello", 5, 0);
>>>>> Could you move this send() before "if (...)" because we want
>>>>> to test unread_data behaviour for SOCK_DGRAM too ?
>>>>>
>>>>> Otherwise looks good, so with that fixed:
>>>>>
>>>>> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
>>>>>
>>>>> Thanks!
>>>> Thank you for the prompt response.
>>>> I thought of putting the send before the if the statement , but I was afraid
>>>> STREAM and SEQPACKET connections won't be accepted before data sending.
>>> connect() create the paired child socket and accept()
>>> allocates a file descriptor to expose the socket to user
>>> space.
>> Thank you for this explanation.
>>> In that sense, the comment above accept() sounds a
>>> bit weird ;)
>> I understand.
>> I am changing it to
>> /* Accept client connection */
> I'd remove it since it just repeats the code, but up to you.
>
> Thanks!
Sent.
I removed the comment, but unfortunately I didn't know it didn't save.
so, the comment was sent along with patch.
Thank you for the guidance and patience.
I am open to any feedback if any.
>
>> If this is accepted, I will send v5 immediately
>>
>> Thank you for your guidance.
>>>
>>>> I will start working on v5.
>>>>
>>>> That part will look like this now:
>>>> /* Test 2: peer closes with unread data */
>>>> TEST_F(unix_sock, reset_unread_behavior)
>>>> {
>>>> char buf[16] = {};
>>>> ssize_t n;
>>>>
>>>> */* Send data that will remain unread */
>>>> send(self->client, "hello", 5, 0);*
>>>>
>>>> *if (variant->socket_type == SOCK_DGRAM) {
>>>> /* No real connection, just close the server */
>>>> close(self->server);
>>>> } else {
>>>> /* Establish full connection first */
>>>> self->child = accept(self->server, NULL, NULL);
>>>> ASSERT_LT(-1, self->child);
>>>>
>>>> /* Peer closes before client reads */
>>>> close(self->child);
>>>> }*
>>>>
>>>> n = recv(self->client, buf, sizeof(buf), 0);
>>>> ASSERT_EQ(-1, n);
>>>>
>>>> if (variant->socket_type == SOCK_STREAM ||
>>>> variant->socket_type == SOCK_SEQPACKET) {
>>>> ASSERT_EQ(ECONNRESET, errno);
>>>> } else {
>>>> ASSERT_EQ(EAGAIN, errno);
>>>> }
>>>> }
>>>>
>>>> Thank you once again.
>>>>>> +
>>>>>> + /* Peer closes before client reads */
>>>>>> + close(self->child);
>>>>>> + }
>>>>>> +
>>>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>>>> + ASSERT_EQ(-1, n);
>>>>>> +
>>>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>>>> + ASSERT_EQ(ECONNRESET, errno);
>>>>>> + } else {
>>>>>> + ASSERT_EQ(EAGAIN, errno);
>>>>>> + }
>>>>>> +}
>>>>>> +
>>>>>> +/* Test 3: closing unaccepted (embryo) server socket should reset client. */
>>>>>> +TEST_F(unix_sock, reset_closed_embryo)
>>>>>> +{
>>>>>> + char buf[16] = {};
>>>>>> + ssize_t n;
>>>>>> +
>>>>>> + if (variant->socket_type == SOCK_DGRAM)
>>>>>> + SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
>>>>>> +
>>>>>> + /* Close server without accept()ing */
>>>>>> + close(self->server);
>>>>>> +
>>>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>>>> +
>>>>>> + ASSERT_EQ(-1, n);
>>>>>> + ASSERT_EQ(ECONNRESET, errno);
>>>>>> +}
>>>>>> +
>>>>>> +TEST_HARNESS_MAIN
>>>>>> +
>>>>>> --
>>>>>> 2.43.0
>>>>>>
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