tools/testing/selftests/net/af_unix/Makefile | 1 + .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++ 2 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/af_unix/Makefile | 1 +
.../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
2 files changed, 180 insertions(+)
create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
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..6f43435d96e2
--- /dev/null
+++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
@@ -0,0 +1,179 @@
+// 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;
+};
+
+/* Define variants: stream and datagram */
+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, 0);
+ ASSERT_LT(-1, self->client);
+
+ err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
+ ASSERT_EQ(0, err);
+
+ self->child = accept(self->server, NULL, NULL);
+ ASSERT_LT(-1, self->child);
+ } else {
+ /* Datagram: bind and connect only */
+ self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
+ 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;
+
+ /* Peer closes normally */
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET)
+ close(self->child);
+ else
+ close(self->server);
+
+ n = recv(self->client, buf, sizeof(buf), 0);
+ TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
+ 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)
+{
+ char buf[16] = {};
+ ssize_t n;
+
+ /* Send data that will remain unread by client */
+ send(self->client, "hello", 5, 0);
+ close(self->child);
+
+ n = recv(self->client, buf, sizeof(buf), 0);
+ TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) {
+ ASSERT_EQ(-1, n);
+ ASSERT_EQ(ECONNRESET, errno);
+ } else {
+ ASSERT_EQ(-1, n);
+ ASSERT_EQ(EAGAIN, errno);
+ }
+}
+
+/* Test 3: SOCK_DGRAM peer close */
+TEST_F(unix_sock, dgram_reset)
+{
+ char buf[16] = {};
+ ssize_t n;
+
+ send(self->client, "hello", 5, 0);
+ close(self->server);
+
+ n = recv(self->client, buf, sizeof(buf), 0);
+ TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
+ if (variant->socket_type == SOCK_STREAM ||
+ variant->socket_type == SOCK_SEQPACKET) {
+ ASSERT_EQ(-1, n);
+ ASSERT_EQ(ECONNRESET, errno);
+ } else {
+ ASSERT_EQ(-1, n);
+ ASSERT_EQ(EAGAIN, errno);
+ }
+}
+
+TEST_HARNESS_MAIN
+
--
2.43.0
On Sat, Nov 1, 2025 at 10:23 AM 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/af_unix/Makefile | 1 +
> .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
> 2 files changed, 180 insertions(+)
> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>
> 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 \
patchwork caught this test is not added to .gitignore.
https://patchwork.kernel.org/project/netdevbpf/patch/20251101172230.10179-1-adelodunolaoluwa@yahoo.com/
Could you add it to this file ?
tools/testing/selftests/net/.gitignore
> # 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..6f43435d96e2
> --- /dev/null
> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
> @@ -0,0 +1,179 @@
> +// 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;
> +};
> +
> +/* Define variants: stream and datagram */
nit: outdated, maybe simply remove ?
> +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) {
patchwork caught mis-alignment here and other places.
I'm using this for emacs, and other editors will have a similar config.
(setq-default c-default-style "linux")
You can check if lines are aligned properly by
$ git show --format=email | ./scripts/checkpatch.pl
> + err = listen(self->server, 1);
> + ASSERT_EQ(0, err);
> +
> + self->client = socket(AF_UNIX, variant->socket_type, 0);
Could you add SOCK_NONBLOCK here too ?
> + ASSERT_LT(-1, self->client);
> +
> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
> + ASSERT_EQ(0, err);
> +
> + self->child = accept(self->server, NULL, NULL);
> + ASSERT_LT(-1, self->child);
> + } else {
> + /* Datagram: bind and connect only */
> + self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
> + 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;
> +
> + /* Peer closes normally */
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET)
> + close(self->child);
> + else
> + close(self->server);
> +
> + n = recv(self->client, buf, sizeof(buf), 0);
> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
errno is undefined if not set, and same for strerror(errno).
Also, if ASSERT_XXX() below fails, the same information
(test case, errno) is logged. So, TH_LOG() seems unnecessary.
Maybe try modifying the condition below and see how the
assertion is logged.
> + 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)
> +{
> + char buf[16] = {};
> + ssize_t n;
> +
> + /* Send data that will remain unread by client */
> + send(self->client, "hello", 5, 0);
> + close(self->child);
> +
> + n = recv(self->client, buf, sizeof(buf), 0);
> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) {
> + ASSERT_EQ(-1, n);
> + ASSERT_EQ(ECONNRESET, errno);
> + } else {
> + ASSERT_EQ(-1, n);
> + ASSERT_EQ(EAGAIN, errno);
> + }
> +}
> +
> +/* Test 3: SOCK_DGRAM peer close */
Now Test 2 and Test 3 look identical ;)
Thanks!
> +TEST_F(unix_sock, dgram_reset)
> +{
> + char buf[16] = {};
> + ssize_t n;
> +
> + send(self->client, "hello", 5, 0);
> + close(self->server);
> +
> + n = recv(self->client, buf, sizeof(buf), 0);
> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> + if (variant->socket_type == SOCK_STREAM ||
> + variant->socket_type == SOCK_SEQPACKET) {
> + ASSERT_EQ(-1, n);
> + ASSERT_EQ(ECONNRESET, errno);
> + } else {
> + ASSERT_EQ(-1, n);
> + ASSERT_EQ(EAGAIN, errno);
> + }
> +}
> +
> +TEST_HARNESS_MAIN
> +
> --
> 2.43.0
>
On 11/2/25 08:32, Kuniyuki Iwashima wrote:
> On Sat, Nov 1, 2025 at 10:23 AM 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/af_unix/Makefile | 1 +
>> .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
>> 2 files changed, 180 insertions(+)
>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>>
>> 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 \
> patchwork caught this test is not added to .gitignore.
> https://patchwork.kernel.org/project/netdevbpf/patch/20251101172230.10179-1-adelodunolaoluwa@yahoo.com/
>
> Could you add it to this file ?
>
> tools/testing/selftests/net/.gitignore
Oh, thank you for this. will add it
>
>
>> # 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..6f43435d96e2
>> --- /dev/null
>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
>> @@ -0,0 +1,179 @@
>> +// 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;
>> +};
>> +
>> +/* Define variants: stream and datagram */
> nit: outdated, maybe simply remove ?
oh..skipped me.
will do so.
>
>> +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) {
> patchwork caught mis-alignment here and other places.
>
> I'm using this for emacs, and other editors will have a similar config.
>
> (setq-default c-default-style "linux")
>
> You can check if lines are aligned properly by
>
> $ git show --format=email | ./scripts/checkpatch.pl
>
>
>> + err = listen(self->server, 1);
>> + ASSERT_EQ(0, err);
>> +
>> + self->client = socket(AF_UNIX, variant->socket_type, 0);
> Could you add SOCK_NONBLOCK here too ?
This is noted
>
>> + ASSERT_LT(-1, self->client);
>> +
>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
>> + ASSERT_EQ(0, err);
>> +
>> + self->child = accept(self->server, NULL, NULL);
>> + ASSERT_LT(-1, self->child);
>> + } else {
>> + /* Datagram: bind and connect only */
>> + self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
>> + 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;
>> +
>> + /* Peer closes normally */
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET)
>> + close(self->child);
>> + else
>> + close(self->server);
>> +
>> + n = recv(self->client, buf, sizeof(buf), 0);
>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> errno is undefined if not set, and same for strerror(errno).
>
> Also, if ASSERT_XXX() below fails, the same information
> (test case, errno) is logged. So, TH_LOG() seems unnecessary.
>
> Maybe try modifying the condition below and see how the
> assertion is logged.
Oh..thank you. Didn't it through that way.
I understand.
I will remove the TH_LOG()'s
>
>> + 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)
>> +{
>> + char buf[16] = {};
>> + ssize_t n;
>> +
>> + /* Send data that will remain unread by client */
>> + send(self->client, "hello", 5, 0);
>> + close(self->child);
>> +
>> + n = recv(self->client, buf, sizeof(buf), 0);
>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) {
>> + ASSERT_EQ(-1, n);
>> + ASSERT_EQ(ECONNRESET, errno);
>> + } else {
>> + ASSERT_EQ(-1, n);
>> + ASSERT_EQ(EAGAIN, errno);
>> + }
>> +}
>> +
>> +/* Test 3: SOCK_DGRAM peer close */
>> Now Test 2 and Test 3 look identical ;)
seems so, but the only difference is:
close(self->child); is used in Test 2, while
close(self->server); is used in Test 3.
Maybe I should find a way to collapse Tests 2 and 3 (if statement might
work)
I am just afraid the tests to run will reduce to 6 from 9 and we will have 6
cases passed as against 7 as before.
What do you think?
>> Thanks!
>>
>> +TEST_F(unix_sock, dgram_reset)
>> +{
>> + char buf[16] = {};
>> + ssize_t n;
>> +
>> + send(self->client, "hello", 5, 0);
>> + close(self->server);
>> +
>> + n = recv(self->client, buf, sizeof(buf), 0);
>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
>> + if (variant->socket_type == SOCK_STREAM ||
>> + variant->socket_type == SOCK_SEQPACKET) {
>> + ASSERT_EQ(-1, n);
>> + ASSERT_EQ(ECONNRESET, errno);
>> + } else {
>> + ASSERT_EQ(-1, n);
>> + ASSERT_EQ(EAGAIN, errno);
>> + }
>> +}
>> +
>> +TEST_HARNESS_MAIN
>> +
>> --
>> 2.43.0
>>
On Mon, Nov 3, 2025 at 4:08 PM Sunday Adelodun
<adelodunolaoluwa@yahoo.com> wrote:
>
> On 11/2/25 08:32, Kuniyuki Iwashima wrote:
> > On Sat, Nov 1, 2025 at 10:23 AM 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/af_unix/Makefile | 1 +
> >> .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
> >> 2 files changed, 180 insertions(+)
> >> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
> >>
> >> 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 \
> > patchwork caught this test is not added to .gitignore.
> > https://patchwork.kernel.org/project/netdevbpf/patch/20251101172230.10179-1-adelodunolaoluwa@yahoo.com/
> >
> > Could you add it to this file ?
> >
> > tools/testing/selftests/net/.gitignore
> Oh, thank you for this. will add it
> >
> >
> >> # 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..6f43435d96e2
> >> --- /dev/null
> >> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
> >> @@ -0,0 +1,179 @@
> >> +// 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;
> >> +};
> >> +
> >> +/* Define variants: stream and datagram */
> > nit: outdated, maybe simply remove ?
> oh..skipped me.
> will do so.
> >
> >> +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) {
> > patchwork caught mis-alignment here and other places.
> >
> > I'm using this for emacs, and other editors will have a similar config.
> >
> > (setq-default c-default-style "linux")
> >
> > You can check if lines are aligned properly by
> >
> > $ git show --format=email | ./scripts/checkpatch.pl
> >
> >
> >> + err = listen(self->server, 1);
> >> + ASSERT_EQ(0, err);
> >> +
> >> + self->client = socket(AF_UNIX, variant->socket_type, 0);
> > Could you add SOCK_NONBLOCK here too ?
> This is noted
> >
> >> + ASSERT_LT(-1, self->client);
> >> +
> >> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
> >> + ASSERT_EQ(0, err);
> >> +
> >> + self->child = accept(self->server, NULL, NULL);
> >> + ASSERT_LT(-1, self->child);
> >> + } else {
> >> + /* Datagram: bind and connect only */
> >> + self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
> >> + 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;
> >> +
> >> + /* Peer closes normally */
> >> + if (variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET)
> >> + close(self->child);
> >> + else
> >> + close(self->server);
> >> +
> >> + n = recv(self->client, buf, sizeof(buf), 0);
> >> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> > errno is undefined if not set, and same for strerror(errno).
> >
> > Also, if ASSERT_XXX() below fails, the same information
> > (test case, errno) is logged. So, TH_LOG() seems unnecessary.
> >
> > Maybe try modifying the condition below and see how the
> > assertion is logged.
> Oh..thank you. Didn't it through that way.
> I understand.
> I will remove the TH_LOG()'s
> >
> >> + 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)
> >> +{
> >> + char buf[16] = {};
> >> + ssize_t n;
> >> +
> >> + /* Send data that will remain unread by client */
> >> + send(self->client, "hello", 5, 0);
> >> + close(self->child);
> >> +
> >> + n = recv(self->client, buf, sizeof(buf), 0);
> >> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> >> + if (variant->socket_type == SOCK_STREAM ||
> >> + variant->socket_type == SOCK_SEQPACKET) {
> >> + ASSERT_EQ(-1, n);
> >> + ASSERT_EQ(ECONNRESET, errno);
> >> + } else {
> >> + ASSERT_EQ(-1, n);
> >> + ASSERT_EQ(EAGAIN, errno);
> >> + }
> >> +}
> >> +
> >> +/* Test 3: SOCK_DGRAM peer close */
> >> Now Test 2 and Test 3 look identical ;)
>
> seems so, but the only difference is:
>
> close(self->child); is used in Test 2, while
> close(self->server); is used in Test 3.
> Maybe I should find a way to collapse Tests 2 and 3 (if statement might
> work)
>
> I am just afraid the tests to run will reduce to 6 from 9 and we will have 6
> cases passed as against 7 as before.
>
> What do you think?
The name of Test 2 is a bit confusing, which is not true
for SOCK_DGRAM. So, I'd use "if" to change which fd
to close() depending on the socket type.
Also, close(self->server) does nothing for SOCK_STREAM
and SOCK_SEQPACKET after accept(). Rather, that close()
should have the same effect if self->child is not accept()ed.
(In this case, Skip() for SOCK_DGRAM makes sense)
I think covering that scenario would be nicer.
If interested, you can check the test coverage with this patch.
https://lore.kernel.org/linux-kselftest/20251028024339.2028774-1-kuniyu@google.com/
Thanks!
On 11/4/25 01:30, Kuniyuki Iwashima wrote:
> On Mon, Nov 3, 2025 at 4:08 PM Sunday Adelodun
> <adelodunolaoluwa@yahoo.com> wrote:
>> On 11/2/25 08:32, Kuniyuki Iwashima wrote:
>>> On Sat, Nov 1, 2025 at 10:23 AM 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/af_unix/Makefile | 1 +
>>>> .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
>>>> 2 files changed, 180 insertions(+)
>>>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>
>>>> 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 \
>>> patchwork caught this test is not added to .gitignore.
>>> https://patchwork.kernel.org/project/netdevbpf/patch/20251101172230.10179-1-adelodunolaoluwa@yahoo.com/
>>>
>>> Could you add it to this file ?
>>>
>>> tools/testing/selftests/net/.gitignore
>> Oh, thank you for this. will add it
>>>
>>>> # 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..6f43435d96e2
>>>> --- /dev/null
>>>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
>>>> @@ -0,0 +1,179 @@
>>>> +// 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;
>>>> +};
>>>> +
>>>> +/* Define variants: stream and datagram */
>>> nit: outdated, maybe simply remove ?
>> oh..skipped me.
>> will do so.
>>>> +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) {
>>> patchwork caught mis-alignment here and other places.
>>>
>>> I'm using this for emacs, and other editors will have a similar config.
>>>
>>> (setq-default c-default-style "linux")
>>>
>>> You can check if lines are aligned properly by
>>>
>>> $ git show --format=email | ./scripts/checkpatch.pl
>>>
>>>
>>>> + err = listen(self->server, 1);
>>>> + ASSERT_EQ(0, err);
>>>> +
>>>> + self->client = socket(AF_UNIX, variant->socket_type, 0);
>>> Could you add SOCK_NONBLOCK here too ?
>> This is noted
>>>> + ASSERT_LT(-1, self->client);
>>>> +
>>>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
>>>> + ASSERT_EQ(0, err);
>>>> +
>>>> + self->child = accept(self->server, NULL, NULL);
>>>> + ASSERT_LT(-1, self->child);
>>>> + } else {
>>>> + /* Datagram: bind and connect only */
>>>> + self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
>>>> + 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;
>>>> +
>>>> + /* Peer closes normally */
>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET)
>>>> + close(self->child);
>>>> + else
>>>> + close(self->server);
>>>> +
>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
>>> errno is undefined if not set, and same for strerror(errno).
>>>
>>> Also, if ASSERT_XXX() below fails, the same information
>>> (test case, errno) is logged. So, TH_LOG() seems unnecessary.
>>>
>>> Maybe try modifying the condition below and see how the
>>> assertion is logged.
>> Oh..thank you. Didn't it through that way.
>> I understand.
>> I will remove the TH_LOG()'s
>>>> + 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)
>>>> +{
>>>> + char buf[16] = {};
>>>> + ssize_t n;
>>>> +
>>>> + /* Send data that will remain unread by client */
>>>> + send(self->client, "hello", 5, 0);
>>>> + close(self->child);
>>>> +
>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>> + ASSERT_EQ(-1, n);
>>>> + ASSERT_EQ(ECONNRESET, errno);
>>>> + } else {
>>>> + ASSERT_EQ(-1, n);
>>>> + ASSERT_EQ(EAGAIN, errno);
>>>> + }
>>>> +}
>>>> +
>>>> +/* Test 3: SOCK_DGRAM peer close */
>>>> Now Test 2 and Test 3 look identical ;)
>> seems so, but the only difference is:
>>
>> close(self->child); is used in Test 2, while
>> close(self->server); is used in Test 3.
>> Maybe I should find a way to collapse Tests 2 and 3 (if statement might
>> work)
>>
>> I am just afraid the tests to run will reduce to 6 from 9 and we will have 6
>> cases passed as against 7 as before.
>>
>> What do you think?
> The name of Test 2 is a bit confusing, which is not true
> for SOCK_DGRAM. So, I'd use "if" to change which fd
> to close() depending on the socket type.
>
> Also, close(self->server) does nothing for SOCK_STREAM
> and SOCK_SEQPACKET after accept(). Rather, that close()
> should have the same effect if self->child is not accept()ed.
> (In this case, Skip() for SOCK_DGRAM makes sense)
>
> I think covering that scenario would be nicer.
>
> If interested, you can check the test coverage with this patch.
> https://lore.kernel.org/linux-kselftest/20251028024339.2028774-1-kuniyu@google.com/
>
> Thanks!
Thank you!
kindly check these if any conforms to what it should be:
TEST_F(unix_sock, reset_unread_behavior)
{
char buf[16] = {};
ssize_t n;
/* Send data that will remain unread by client */
send(self->client, "hello", 5, 0);
if (variant->socket_type == SOCK_DGRAM) {
close(self->server);
}
else {
if (!self->child)
SKIP(return);
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)
do { ASSERT_EQ(ECONNRESET, errno); } while (0);
else
ASSERT_EQ(EAGAIN, errno);
}
OR
TEST_F(unix_sock, reset_unread_behavior)
{
char buf[16] = {};
ssize_t n;
/* Send data that will remain unread by client */
send(self->client, "hello", 5, 0);
if (variant->socket_type == SOCK_DGRAM) {
close(self->server);
}
else {
if (self->child)
close(self->child);
else
close(self->server);
}
n = recv(self->client, buf, sizeof(buf), 0);
ASSERT_EQ(-1, n);
if (variant->socket_type == SOCK_STREAM ||
variant->socket_type == SOCK_SEQPACKET)
do { ASSERT_EQ(ECONNRESET, errno); } while (0);
else
ASSERT_EQ(EAGAIN, errno);
}
OR
is there a better way to handle this?
I ran the KCOV_OUTPUT command using the first *TEST_F above* as the Test
2 and got the output below:
*$ KCOV_OUTPUT=kcov KCOV_SLOTS=8192
./tools/testing/selftests/net/af_unix/unix_connreset*
TAP version 13
1..6
# Starting 6 tests from 3 test cases.
# RUN unix_sock.stream.eof ...
# OK unix_sock.stream.eof
ok 1 unix_sock.stream.eof
# RUN unix_sock.stream.reset_unread_behavior ...
# OK unix_sock.stream.reset_unread_behavior
ok 2 unix_sock.stream.reset_unread_behavior
# RUN unix_sock.dgram.eof ...
# OK unix_sock.dgram.eof
ok 3 unix_sock.dgram.eof
# RUN unix_sock.dgram.reset_unread_behavior ...
# OK unix_sock.dgram.reset_unread_behavior
ok 4 unix_sock.dgram.reset_unread_behavior
# RUN unix_sock.seqpacket.eof ...
# OK unix_sock.seqpacket.eof
ok 5 unix_sock.seqpacket.eof
# RUN unix_sock.seqpacket.reset_unread_behavior ...
# OK unix_sock.seqpacket.reset_unread_behavior
ok 6 unix_sock.seqpacket.reset_unread_behavior
# PASSED: 6 / 6 tests passed.
# Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0
Thank you once again for your continuous guidance and patience.
It's a worthy and rewarding learning period for me.
From: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
Date: Tue, 4 Nov 2025 11:42:47 +0100
> On 11/4/25 01:30, Kuniyuki Iwashima wrote:
> > On Mon, Nov 3, 2025 at 4:08 PM Sunday Adelodun
> > <adelodunolaoluwa@yahoo.com> wrote:
> >> On 11/2/25 08:32, Kuniyuki Iwashima wrote:
> >>> On Sat, Nov 1, 2025 at 10:23 AM 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/af_unix/Makefile | 1 +
> >>>> .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
> >>>> 2 files changed, 180 insertions(+)
> >>>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
> >>>>
> >>>> 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 \
> >>> patchwork caught this test is not added to .gitignore.
> >>> https://patchwork.kernel.org/project/netdevbpf/patch/20251101172230.10179-1-adelodunolaoluwa@yahoo.com/
> >>>
> >>> Could you add it to this file ?
> >>>
> >>> tools/testing/selftests/net/.gitignore
> >> Oh, thank you for this. will add it
> >>>
> >>>> # 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..6f43435d96e2
> >>>> --- /dev/null
> >>>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
> >>>> @@ -0,0 +1,179 @@
> >>>> +// 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;
> >>>> +};
> >>>> +
> >>>> +/* Define variants: stream and datagram */
> >>> nit: outdated, maybe simply remove ?
> >> oh..skipped me.
> >> will do so.
> >>>> +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) {
> >>> patchwork caught mis-alignment here and other places.
> >>>
> >>> I'm using this for emacs, and other editors will have a similar config.
> >>>
> >>> (setq-default c-default-style "linux")
> >>>
> >>> You can check if lines are aligned properly by
> >>>
> >>> $ git show --format=email | ./scripts/checkpatch.pl
> >>>
> >>>
> >>>> + err = listen(self->server, 1);
> >>>> + ASSERT_EQ(0, err);
> >>>> +
> >>>> + self->client = socket(AF_UNIX, variant->socket_type, 0);
> >>> Could you add SOCK_NONBLOCK here too ?
> >> This is noted
> >>>> + ASSERT_LT(-1, self->client);
> >>>> +
> >>>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
> >>>> + ASSERT_EQ(0, err);
> >>>> +
> >>>> + self->child = accept(self->server, NULL, NULL);
> >>>> + ASSERT_LT(-1, self->child);
> >>>> + } else {
> >>>> + /* Datagram: bind and connect only */
> >>>> + self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
> >>>> + 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;
> >>>> +
> >>>> + /* Peer closes normally */
> >>>> + if (variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET)
> >>>> + close(self->child);
> >>>> + else
> >>>> + close(self->server);
> >>>> +
> >>>> + n = recv(self->client, buf, sizeof(buf), 0);
> >>>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> >>> errno is undefined if not set, and same for strerror(errno).
> >>>
> >>> Also, if ASSERT_XXX() below fails, the same information
> >>> (test case, errno) is logged. So, TH_LOG() seems unnecessary.
> >>>
> >>> Maybe try modifying the condition below and see how the
> >>> assertion is logged.
> >> Oh..thank you. Didn't it through that way.
> >> I understand.
> >> I will remove the TH_LOG()'s
> >>>> + 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)
> >>>> +{
> >>>> + char buf[16] = {};
> >>>> + ssize_t n;
> >>>> +
> >>>> + /* Send data that will remain unread by client */
> >>>> + send(self->client, "hello", 5, 0);
> >>>> + close(self->child);
> >>>> +
> >>>> + n = recv(self->client, buf, sizeof(buf), 0);
> >>>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
> >>>> + if (variant->socket_type == SOCK_STREAM ||
> >>>> + variant->socket_type == SOCK_SEQPACKET) {
> >>>> + ASSERT_EQ(-1, n);
> >>>> + ASSERT_EQ(ECONNRESET, errno);
> >>>> + } else {
> >>>> + ASSERT_EQ(-1, n);
> >>>> + ASSERT_EQ(EAGAIN, errno);
> >>>> + }
> >>>> +}
> >>>> +
> >>>> +/* Test 3: SOCK_DGRAM peer close */
> >>>> Now Test 2 and Test 3 look identical ;)
> >> seems so, but the only difference is:
> >>
> >> close(self->child); is used in Test 2, while
> >> close(self->server); is used in Test 3.
> >> Maybe I should find a way to collapse Tests 2 and 3 (if statement might
> >> work)
> >>
> >> I am just afraid the tests to run will reduce to 6 from 9 and we will have 6
> >> cases passed as against 7 as before.
> >>
> >> What do you think?
> > The name of Test 2 is a bit confusing, which is not true
> > for SOCK_DGRAM. So, I'd use "if" to change which fd
> > to close() depending on the socket type.
> >
> > Also, close(self->server) does nothing for SOCK_STREAM
> > and SOCK_SEQPACKET after accept(). Rather, that close()
> > should have the same effect if self->child is not accept()ed.
> > (In this case, Skip() for SOCK_DGRAM makes sense)
> >
> > I think covering that scenario would be nicer.
> >
> > If interested, you can check the test coverage with this patch.
> > https://lore.kernel.org/linux-kselftest/20251028024339.2028774-1-kuniyu@google.com/
> >
> > Thanks!
> Thank you!
>
> kindly check these if any conforms to what it should be:
>
> TEST_F(unix_sock, reset_unread_behavior)
> {
> char buf[16] = {};
> ssize_t n;
>
> /* Send data that will remain unread by client */
> send(self->client, "hello", 5, 0);
>
> if (variant->socket_type == SOCK_DGRAM) {
> close(self->server);
> }
> else {
> if (!self->child)
> SKIP(return);
>
> 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)
> do { ASSERT_EQ(ECONNRESET, errno); } while (0);
> else
> ASSERT_EQ(EAGAIN, errno);
> }
>
> OR
>
> TEST_F(unix_sock, reset_unread_behavior)
> {
> char buf[16] = {};
> ssize_t n;
>
> /* Send data that will remain unread by client */
> send(self->client, "hello", 5, 0);
>
> if (variant->socket_type == SOCK_DGRAM) {
> close(self->server);
> }
> else {
> if (self->child)
> close(self->child);
> else
> close(self->server);
> }
>
> n = recv(self->client, buf, sizeof(buf), 0);
>
> ASSERT_EQ(-1, n);
>
> if (variant->socket_type == SOCK_STREAM ||
> variant->socket_type == SOCK_SEQPACKET)
> do { ASSERT_EQ(ECONNRESET, errno); } while (0);
> else
> ASSERT_EQ(EAGAIN, errno);
> }
>
> OR
>
> is there a better way to handle this?
Sorry for late!
What I had in mind is to move accept() in FIXTURE_SETUP() to
Test 1 & 2 (then, only listen() is conditional in FIXTURE_SETUP())
and rewrite Test 3 to cover the last ECONNRESET case caused by
close()ing un-accept()ed sockets:
TEST_F(unix_sock, reset_closed_embryo)
{
if (variant->socket_type == SOCK_DGRAM)
SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
close(self->server);
n = recv(self->client, ...);
ASSERT_EQ(-1, n);
ASSERT_EQ(ECONNRESET, errno);
}
>
> I ran the KCOV_OUTPUT command using the first *TEST_F above* as the Test
> 2 and got the output below:
> *$ KCOV_OUTPUT=kcov KCOV_SLOTS=8192
> ./tools/testing/selftests/net/af_unix/unix_connreset*
You should be able to see line-by-line coverage by decoding
files under kcov with addr2line or vock/report.py.
Thanks!
On 11/7/25 08:05, Kuniyuki Iwashima wrote:
> From: Sunday Adelodun <adelodunolaoluwa@yahoo.com>
> Date: Tue, 4 Nov 2025 11:42:47 +0100
>> On 11/4/25 01:30, Kuniyuki Iwashima wrote:
>>> On Mon, Nov 3, 2025 at 4:08 PM Sunday Adelodun
>>> <adelodunolaoluwa@yahoo.com> wrote:
>>>> On 11/2/25 08:32, Kuniyuki Iwashima wrote:
>>>>> On Sat, Nov 1, 2025 at 10:23 AM 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/af_unix/Makefile | 1 +
>>>>>> .../selftests/net/af_unix/unix_connreset.c | 179 ++++++++++++++++++
>>>>>> 2 files changed, 180 insertions(+)
>>>>>> create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>>>
>>>>>> 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 \
>>>>> patchwork caught this test is not added to .gitignore.
>>>>> https://patchwork.kernel.org/project/netdevbpf/patch/20251101172230.10179-1-adelodunolaoluwa@yahoo.com/
>>>>>
>>>>> Could you add it to this file ?
>>>>>
>>>>> tools/testing/selftests/net/.gitignore
>>>> Oh, thank you for this. will add it
>>>>>> # 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..6f43435d96e2
>>>>>> --- /dev/null
>>>>>> +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c
>>>>>> @@ -0,0 +1,179 @@
>>>>>> +// 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;
>>>>>> +};
>>>>>> +
>>>>>> +/* Define variants: stream and datagram */
>>>>> nit: outdated, maybe simply remove ?
>>>> oh..skipped me.
>>>> will do so.
>>>>>> +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) {
>>>>> patchwork caught mis-alignment here and other places.
>>>>>
>>>>> I'm using this for emacs, and other editors will have a similar config.
>>>>>
>>>>> (setq-default c-default-style "linux")
>>>>>
>>>>> You can check if lines are aligned properly by
>>>>>
>>>>> $ git show --format=email | ./scripts/checkpatch.pl
>>>>>
>>>>>
>>>>>> + err = listen(self->server, 1);
>>>>>> + ASSERT_EQ(0, err);
>>>>>> +
>>>>>> + self->client = socket(AF_UNIX, variant->socket_type, 0);
>>>>> Could you add SOCK_NONBLOCK here too ?
>>>> This is noted
>>>>>> + ASSERT_LT(-1, self->client);
>>>>>> +
>>>>>> + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr));
>>>>>> + ASSERT_EQ(0, err);
>>>>>> +
>>>>>> + self->child = accept(self->server, NULL, NULL);
>>>>>> + ASSERT_LT(-1, self->child);
>>>>>> + } else {
>>>>>> + /* Datagram: bind and connect only */
>>>>>> + self->client = socket(AF_UNIX, SOCK_DGRAM | 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)
>>>>>> + 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;
>>>>>> +
>>>>>> + /* Peer closes normally */
>>>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET)
>>>>>> + close(self->child);
>>>>>> + else
>>>>>> + close(self->server);
>>>>>> +
>>>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>>>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
>>>>> errno is undefined if not set, and same for strerror(errno).
>>>>>
>>>>> Also, if ASSERT_XXX() below fails, the same information
>>>>> (test case, errno) is logged. So, TH_LOG() seems unnecessary.
>>>>>
>>>>> Maybe try modifying the condition below and see how the
>>>>> assertion is logged.
>>>> Oh..thank you. Didn't it through that way.
>>>> I understand.
>>>> I will remove the TH_LOG()'s
>>>>>> + 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)
>>>>>> +{
>>>>>> + char buf[16] = {};
>>>>>> + ssize_t n;
>>>>>> +
>>>>>> + /* Send data that will remain unread by client */
>>>>>> + send(self->client, "hello", 5, 0);
>>>>>> + close(self->child);
>>>>>> +
>>>>>> + n = recv(self->client, buf, sizeof(buf), 0);
>>>>>> + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno));
>>>>>> + if (variant->socket_type == SOCK_STREAM ||
>>>>>> + variant->socket_type == SOCK_SEQPACKET) {
>>>>>> + ASSERT_EQ(-1, n);
>>>>>> + ASSERT_EQ(ECONNRESET, errno);
>>>>>> + } else {
>>>>>> + ASSERT_EQ(-1, n);
>>>>>> + ASSERT_EQ(EAGAIN, errno);
>>>>>> + }
>>>>>> +}
>>>>>> +
>>>>>> +/* Test 3: SOCK_DGRAM peer close */
>>>>>> Now Test 2 and Test 3 look identical ;)
>>>> seems so, but the only difference is:
>>>>
>>>> close(self->child); is used in Test 2, while
>>>> close(self->server); is used in Test 3.
>>>> Maybe I should find a way to collapse Tests 2 and 3 (if statement might
>>>> work)
>>>>
>>>> I am just afraid the tests to run will reduce to 6 from 9 and we will have 6
>>>> cases passed as against 7 as before.
>>>>
>>>> What do you think?
>>> The name of Test 2 is a bit confusing, which is not true
>>> for SOCK_DGRAM. So, I'd use "if" to change which fd
>>> to close() depending on the socket type.
>>>
>>> Also, close(self->server) does nothing for SOCK_STREAM
>>> and SOCK_SEQPACKET after accept(). Rather, that close()
>>> should have the same effect if self->child is not accept()ed.
>>> (In this case, Skip() for SOCK_DGRAM makes sense)
>>>
>>> I think covering that scenario would be nicer.
>>>
>>> If interested, you can check the test coverage with this patch.
>>> https://lore.kernel.org/linux-kselftest/20251028024339.2028774-1-kuniyu@google.com/
>>>
>>> Thanks!
>> Thank you!
>>
>> kindly check these if any conforms to what it should be:
>>
>> TEST_F(unix_sock, reset_unread_behavior)
>> {
>> char buf[16] = {};
>> ssize_t n;
>>
>> /* Send data that will remain unread by client */
>> send(self->client, "hello", 5, 0);
>>
>> if (variant->socket_type == SOCK_DGRAM) {
>> close(self->server);
>> }
>> else {
>> if (!self->child)
>> SKIP(return);
>>
>> 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)
>> do { ASSERT_EQ(ECONNRESET, errno); } while (0);
>> else
>> ASSERT_EQ(EAGAIN, errno);
>> }
>>
>> OR
>>
>> TEST_F(unix_sock, reset_unread_behavior)
>> {
>> char buf[16] = {};
>> ssize_t n;
>>
>> /* Send data that will remain unread by client */
>> send(self->client, "hello", 5, 0);
>>
>> if (variant->socket_type == SOCK_DGRAM) {
>> close(self->server);
>> }
>> else {
>> if (self->child)
>> close(self->child);
>> else
>> close(self->server);
>> }
>>
>> n = recv(self->client, buf, sizeof(buf), 0);
>>
>> ASSERT_EQ(-1, n);
>>
>> if (variant->socket_type == SOCK_STREAM ||
>> variant->socket_type == SOCK_SEQPACKET)
>> do { ASSERT_EQ(ECONNRESET, errno); } while (0);
>> else
>> ASSERT_EQ(EAGAIN, errno);
>> }
>>
>> OR
>>
>> is there a better way to handle this?
> Sorry for late!
>
> What I had in mind is to move accept() in FIXTURE_SETUP() to
> Test 1 & 2 (then, only listen() is conditional in FIXTURE_SETUP())
> and rewrite Test 3 to cover the last ECONNRESET case caused by
> close()ing un-accept()ed sockets:
>
> TEST_F(unix_sock, reset_closed_embryo)
> {
> if (variant->socket_type == SOCK_DGRAM)
> SKIP(return, "This test only applies to SOCK_STREAM and SOCK_SEQPACKET");
>
> close(self->server);
>
> n = recv(self->client, ...);
> ASSERT_EQ(-1, n);
> ASSERT_EQ(ECONNRESET, errno);
> }
>
>
>> I ran the KCOV_OUTPUT command using the first *TEST_F above* as the Test
>> 2 and got the output below:
>> *$ KCOV_OUTPUT=kcov KCOV_SLOTS=8192
>> ./tools/testing/selftests/net/af_unix/unix_connreset*
> You should be able to see line-by-line coverage by decoding
> files under kcov with addr2line or vock/report.py.
>
> Thanks!
>
So sorry for the late reply.
I have noted all and I will send v4 shortly
Thanks once again
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