implement F_{GET,SET}FL for fcntl for sockets (#742)

This provides another way to get/set blocking-ness besides `ioctl`.

Author: dicej

libc-bottom-half/sources/wasip2_tcp.c

@@ -1237,6 +1237,25 @@ static int tcp_poll_finish(void *data, poll_state_t *state, short events) {
   return 0;
 }
 
+static int tcp_fcntl_getfl(void *data) {
+  tcp_socket_t *socket = (tcp_socket_t *)data;
+  int flags = 0;
+  if (!socket->blocking) {
+    flags |= O_NONBLOCK;
+  }
+  return flags;
+}
+
+static int tcp_fcntl_setfl(void *data, int flags) {
+  tcp_socket_t *socket = (tcp_socket_t *)data;
+  if (flags & O_NONBLOCK) {
+    socket->blocking = false;
+  } else {
+    socket->blocking = true;
+  }
+  return 0;
+}
+
 static descriptor_vtable_t tcp_vtable = {
     .free = tcp_free,
 
@@ -1259,6 +1278,9 @@ static descriptor_vtable_t tcp_vtable = {
 
     .poll_register = tcp_poll_register,
     .poll_finish = tcp_poll_finish,
+
+    .fcntl_getfl = tcp_fcntl_getfl,
+    .fcntl_setfl = tcp_fcntl_setfl,
 };
 
 #endif // __wasip2__

libc-bottom-half/sources/wasip2_udp.c

@@ -1,4 +1,5 @@
 #include <errno.h>
+#include <fcntl.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ -869,6 +870,25 @@ static int udp_poll_register(void *data, poll_state_t *state, short events) {
   return 0;
 }
 
+static int udp_fcntl_getfl(void *data) {
+  udp_socket_t *socket = (udp_socket_t *)data;
+  int flags = 0;
+  if (!socket->blocking) {
+    flags |= O_NONBLOCK;
+  }
+  return flags;
+}
+
+static int udp_fcntl_setfl(void *data, int flags) {
+  udp_socket_t *socket = (udp_socket_t *)data;
+  if (flags & O_NONBLOCK) {
+    socket->blocking = false;
+  } else {
+    socket->blocking = true;
+  }
+  return 0;
+}
+
 static descriptor_vtable_t udp_vtable = {
     .free = udp_free,
 
@@ -885,6 +905,9 @@ static descriptor_vtable_t udp_vtable = {
     .setsockopt = udp_setsockopt,
 
     .poll_register = udp_poll_register,
+
+    .fcntl_getfl = udp_fcntl_getfl,
+    .fcntl_setfl = udp_fcntl_setfl,
 };
 
 #endif // __wasip2__

test/CMakeLists.txt

@@ -317,6 +317,7 @@ if (NOT (WASI STREQUAL "p1"))
   add_wasilibc_test(sockets-nonblocking-udp.c NETWORK FAILP3)
   add_wasilibc_test(sockets-nonblocking-multiple.c NETWORK FAILP3)
   add_wasilibc_test(sockets-nonblocking-udp-multiple.c NETWORK FAILP3)
+  add_wasilibc_test(sockets-fcntl.c NETWORK FAILP3)
 
   # TODO: flaky tests
   # add_wasilibc_test(sockets-nonblocking.c NETWORK)

test/src/sockets-fcntl.c

@@ -0,0 +1,62 @@
+#include "test.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+
+#define TEST(c)                                                                \
+  do {                                                                         \
+    errno = 0;                                                                 \
+    if (!(c))                                                                  \
+      t_error("%s failed (errno = %d)\n", #c, errno);                          \
+  } while (0)
+
+#define TEST2(c)                                                               \
+  do {                                                                         \
+    if (!(c))                                                                  \
+      t_error("%s failed (errno = %d)\n", #c, errno);                          \
+  } while (0)
+
+#define ASSERT(c)                                                              \
+  do {                                                                         \
+    if (!(c))                                                                  \
+      t_error("%s failed\n", #c);                                              \
+  } while (0)
+
+int main() {
+  int types[2] = {SOCK_STREAM, SOCK_DGRAM};
+
+  for (int i = 0; i < 2; ++i) {
+    errno = 0;
+    int fd = socket(AF_INET, types[i], 0);
+    TEST2(fd != -1);
+
+    {
+      errno = 0;
+      int flags = fcntl(fd, F_GETFL, 0);
+      TEST2(flags != -1);
+      ASSERT((flags & O_NONBLOCK) == 0);
+    }
+
+    TEST(fcntl(fd, F_SETFL, O_NONBLOCK) != -1);
+
+    {
+      errno = 0;
+      int flags = fcntl(fd, F_GETFL, 0);
+      TEST2(flags != -1);
+      ASSERT((flags & O_NONBLOCK) != 0);
+    }
+
+    int zero = 0;
+    TEST(ioctl(fd, FIONBIO, &zero) != -1);
+
+    {
+      errno = 0;
+      int flags = fcntl(fd, F_GETFL, 0);
+      TEST2(flags != -1);
+      ASSERT((flags & O_NONBLOCK) == 0);
+    }
+  }
+
+  return t_status;
+}