Convert select example to use pipes

tests/select.c

@@ -6,19 +6,37 @@
 #include "test_helpers.h"
 
 int main(void) {
-    int fd = open("select.c", 0, 0);
+    int pipefd[2];
+    if (pipe2(pipefd, O_NONBLOCK) < 0) {
+        perror("pipe");
+        return 1;
+    }
+
+    char c = 'c';
+    if (write(pipefd[1], &c, sizeof(c)) < 0) {
+        perror("write");
+        return 1;
+    }
 
     fd_set read;
     FD_ZERO(&read);
-    FD_SET(fd, &read);
+    FD_SET(pipefd[0], &read);
 
-    printf("Is set before? %d\n", FD_ISSET(fd, &read));
+    printf("Is set before? %d\n", FD_ISSET(pipefd[0], &read));
 
     // This should actually test TCP streams and stuff, but for now I'm simply
     // testing whether it ever returns or not.
-    printf("Amount of things ready: %d\n", select(fd + 1, &read, NULL, NULL, NULL));
+    int nfds = select(pipefd[0] + 1, &read, NULL, NULL, NULL);
+    if (nfds < 0) {
+        perror("select");
+        return 1;
+    }
+    printf("Amount of things ready: %d\n", nfds);
+
+    printf("Is set after? %d\n", FD_ISSET(pipefd[0], &read));
 
-    printf("Is set after? %d\n", FD_ISSET(fd, &read));
+    close(pipefd[0]);
+    close(pipefd[1]);
 
-    close(fd);
+    return 0;
 }