Add tests for select, recv and send over socket pairs

tests/wasix/socket_pair/main.c

@@ -1,65 +1,141 @@
+// Note: we need this test because we're hacking around
+// socket pairs and using a duplex pipe underneath, which
+// creates huge potential for edge cases and errors.
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <unistd.h>
+#include <errno.h>
+
+int test_communication(int from, int to)
+{
+    int result;
+    char buf[32];
+    ssize_t numRead;
+    fd_set fdset;
+    struct timeval timeout = {
+        .tv_sec = 0,
+        .tv_usec = 0,
+    };
+
+    // Test 1: do it through select, with read and write
+    FD_ZERO(&fdset);
+    FD_SET(to, &fdset);
+    result = select(to + 1, NULL, &fdset, NULL, &timeout);
+    if (result < 0)
+    {
+        perror("select");
+        return -1;
+    }
+    else if (result == 0)
+    {
+        printf("Timeout: nothing can be written.\n");
+        return -1;
+    }
+    else
+    {
+        if (FD_ISSET(to, &fdset))
+        {
+            int bytes_written = write(to, "foo", 3);
+            if (bytes_written < 0)
+            {
+                perror("write");
+                return -1;
+            }
+        }
+        else
+        {
+            printf("Expected send socket to be ready to write to\n");
+            return -1;
+        }
+    }
+
+    FD_ZERO(&fdset);
+    FD_SET(from, &fdset);
+    result = select(from + 1, &fdset, NULL, NULL, &timeout);
+    if (result < 0)
+    {
+        perror("select");
+        return -1;
+    }
+    else if (result == 0)
+    {
+        printf("Timeout: No data available to read.\n");
+        return -1;
+    }
+    else
+    {
+        if (FD_ISSET(from, &fdset))
+        {
+            int bytes_read = read(from, buf, sizeof(buf));
+            if (bytes_read < 0)
+            {
+                perror("read");
+                return -1;
+            }
+            buf[bytes_read] = 0;
+            if (strncmp(buf, "foo", 3) != 0)
+            {
+                printf("expected 'foo', received: %s\n", buf);
+                return -1;
+            }
+        }
+        else
+        {
+            printf("Expected recv socket to be ready to read from\n");
+            return -1;
+        }
+    }
+
+    // test 2: do it through send and recv
+
+    int bytes_sent = send(to, "bar", 3, 0);
+    if (bytes_sent < 0)
+    {
+        perror("send");
+        return -1;
+    }
+
+    int bytes_received = recv(from, buf, sizeof(buf), 0);
+    if (bytes_received < 0)
+    {
+        perror("recv");
+        return -1;
+    }
+    buf[bytes_received] = 0;
+
+    if (strncmp(buf, "bar", 3) != 0)
+    {
+        printf("expected 'bar', received: %s\n", buf);
+        return -1;
+    }
+
+    return 0;
+}
 
 int main()
 {
-    int status = EXIT_FAILURE;
-
     int socks[2];
-    char buf[1024];
-    ssize_t numRead;
 
     if (socketpair(AF_UNIX, SOCK_STREAM, 0, socks) == -1)
     {
         perror("socketpair");
-        goto end;
+        return -1;
     }
 
-    if (write(socks[0], "foo", 3) == -1)
+    if (test_communication(socks[0], socks[1]) == -1)
     {
-        perror("write");
-        goto end;
+        return -1;
     }
 
-    memset(buf, 0, sizeof(buf));
-    numRead = read(socks[1], buf, sizeof(buf));
-    if (numRead == -1)
+    // try it in reverse as well, since the connection should be duplex
+    if (test_communication(socks[1], socks[0]) == -1)
     {
-        perror("read");
-        goto end;
-    }
-    if (strncmp(buf, "foo", 3) != 0)
-    {
-        printf("buf: %s\n", buf);
-        goto end;
+        return -1;
     }
 
-    if (write(socks[1], "bar", 3) == -1)
-    {
-        perror("write 2");
-        goto end;
-    }
-
-    memset(buf, 0, sizeof(buf));
-    numRead = read(socks[0], buf, sizeof(buf));
-    if (numRead == -1)
-    {
-        perror("read 2");
-        goto end;
-    }
-    if (strncmp(buf, "bar", 3) != 0)
-    {
-        printf("buf 2: %s\n", buf);
-        goto end;
-    }
-
-    status = EXIT_SUCCESS;
-
-end:
-    printf("%d", status);
-    return status;
-}
+    return 0;
+}

tests/wasix/socket_pair/run.sh

@@ -1,3 +1 @@
-$WASMER -q run main.wasm > output
-
-printf "0" | diff -u output - 1>/dev/null
+$WASMER -q run main.wasm