apps/examples/pipe: check POSIX-compliant behavior of NuttX's FIFOs

Adjust the test considering the POSIX-compliant behavior of the
NuttX's FIFO (mkfifo), which should block `open` for read-only
and write-only. This test's result is expected to be the same with
any other POSIX-compliant system.

This commit also:

 * Fix redirect test;
 * Use pthread instead `task_create` to be able to run this test
on POSIX-compliant systems;
 * General fixes regarding formatting and error messages;

examples/pipe/pipe_main.c

@@ -33,6 +33,31 @@
 
 #include "pipe.h"
 
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: open_write_only
+ ****************************************************************************/
+
+static void *open_write_only(pthread_addr_t pvarg)
+{
+  void *fd_addr = (void *)pvarg;
+
+  printf("open_write_only: Opening FIFO for write access\n");
+  ((int *)fd_addr)[1] = open(FIFO_PATH1, O_WRONLY);
+  if (((int *)fd_addr)[1] < 0)
+    {
+      fprintf(stderr, \
+              "open_write_only: Failed to open FIFO %s for writing,"
+              "errno=%d\n", FIFO_PATH1, errno);
+      return (void *)(uintptr_t)1;
+    }
+
+  return NULL;
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -53,6 +78,15 @@ int main(int argc, FAR char *argv[])
 
   printf("\npipe_main: Performing FIFO test\n");
 
+  pthread_t writeonly;
+  void *status;
+
+  /* Open one end of the FIFO for reading and the other end for writing.
+   * NOTE: This test's result is expected to be the same on any other
+   * POSIX-compliant system. NuttX FIFOs block for write-only and
+   * read-only (see interlock_test()).
+   */
+
   ret = mkfifo(FIFO_PATH1, 0666);
   if (ret < 0)
     {
@@ -60,18 +94,12 @@ int main(int argc, FAR char *argv[])
       return 1;
     }
 
-  /* Open one end of the FIFO for reading and the other end for writing.
-   * NOTE: The following might not work on most FIFO implementations because
-   * the attempt to open just one end of the FIFO for writing might block.
-   * The NuttX FIFOs block only on open for read-only (see interlock_test()).
-   */
+  ret = pthread_create(&writeonly, NULL, open_write_only, &fd);
 
-  fd[1] = open(FIFO_PATH1, O_WRONLY);
-  if (fd[1] < 0)
+  if (ret < 0)
     {
-      fprintf(stderr,
-              "pipe_main: Failed to open FIFO %s for writing, errno=%d\n",
-              FIFO_PATH1, errno);
+      fprintf(stderr, "redirection_test: "
+              "Failed to create open_write_only task: %d\n", ret);
       return 2;
     }
 
@@ -89,9 +117,28 @@ int main(int argc, FAR char *argv[])
       return 3;
     }
 
+  /* Wait for open_write_only thread to complete */
+
+  fprintf(stderr, "open_write_only: Waiting for open_write_only thread\n");
+  ret = pthread_join(writeonly, &status);
+  if (ret != 0)
+    {
+      fprintf(stderr, "pipe_main: pthread_join failed, error=%d\n", ret);
+      return 4;
+    }
+  else
+    {
+      fprintf(stderr, "pipe_main: open_write_only returned %p\n", status);
+      if (status != NULL)
+        {
+          return 5;
+        }
+    }
+
   /* Then perform the test using those file descriptors */
 
   ret = transfer_test(fd[0], fd[1]);
+
   if (close(fd[0]) != 0)
     {
       fprintf(stderr, "pipe_main: close failed: %d\n", errno);
@@ -107,9 +154,21 @@ int main(int argc, FAR char *argv[])
   if (ret != 0)
     {
       fprintf(stderr, "pipe_main: FIFO test FAILED (%d)\n", ret);
-      return 4;
+      return 6;
     }
 
+  /* Perform the FIFO interlock test */
+
+  printf("\npipe_main: Performing pipe interlock test\n");
+  ret = interlock_test();
+  if (ret != 0)
+    {
+      fprintf(stderr, "pipe_main: FIFO interlock test FAILED (%d)\n", ret);
+      return 7;
+    }
+
+  printf("pipe_main: FIFO interlock test PASSED\n");
+
   printf("pipe_main: FIFO test PASSED\n");
 
 #else
@@ -126,16 +185,18 @@ int main(int argc, FAR char *argv[])
   if (ret < 0)
     {
       fprintf(stderr, "pipe_main: pipe failed with errno=%d\n", errno);
-      return 5;
+      return 8;
     }
 
   /* Then perform the test using those file descriptors */
 
   ret = transfer_test(fd[0], fd[1]);
+
   if (close(fd[0]) != 0)
     {
       fprintf(stderr, "pipe_main: close failed: %d\n", errno);
     }
+
   if (close(fd[1]) != 0)
     {
       fprintf(stderr, "pipe_main: close failed: %d\n", errno);
@@ -144,35 +205,23 @@ int main(int argc, FAR char *argv[])
   if (ret != 0)
     {
       fprintf(stderr, "pipe_main: PIPE test FAILED (%d)\n", ret);
-      return 6;
+      return 9;
     }
 
-  printf("pipe_main: PIPE test PASSED\n");
-
-  /* Perform the FIFO interlock test */
-
-  printf("\npipe_main: Performing pipe interlock test\n");
-  ret = interlock_test();
-  if (ret != 0)
-    {
-      fprintf(stderr, "pipe_main: FIFO interlock test FAILED (%d)\n", ret);
-      return 7;
-    }
-
-  printf("pipe_main: PIPE interlock test PASSED\n");
-
   /* Perform the pipe redirection test */
 
   printf("\npipe_main: Performing redirection test\n");
   ret = redirection_test();
   if (ret != 0)
     {
-      fprintf(stderr, "pipe_main: FIFO redirection test FAILED (%d)\n", ret);
-      return 7;
+      fprintf(stderr, "pipe_main: PIPE redirection test FAILED (%d)\n", ret);
+      return 10;
     }
 
   printf("pipe_main: PIPE redirection test PASSED\n");
 
+  printf("pipe_main: PIPE test PASSED\n");
+
 #else
   printf("\npipe_main: Skipping pipe test\n");