From b131ce006a3af81a1fc0510b9a36cfe3adebc5a8 Mon Sep 17 00:00:00 2001
From: Kevin Day <thekevinday@gmail.com>
Date: Wed, 11 Sep 2019 22:38:30 -0500
Subject: [PATCH] Update: documentation for f_pipe and add additional pipe
 functions

Provide f_pipe_warning_exists(), f_pipe_error_exists(), and f_pipe_debug_exists().
In theory, the program should be able to grab data piped from any of these sources, if both the source exists and a way to pipe the source exists.
---
 level_0/f_pipe/c/pipe.c | 49 +++++++++++++++++++++++++++++++++++-
 level_0/f_pipe/c/pipe.h | 67 ++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 111 insertions(+), 5 deletions(-)

diff --git a/level_0/f_pipe/c/pipe.c b/level_0/f_pipe/c/pipe.c
index 24dc45f..3e0e3b0 100644
--- a/level_0/f_pipe/c/pipe.c
+++ b/level_0/f_pipe/c/pipe.c
@@ -5,7 +5,6 @@ extern "C" {
 #endif
 
 #ifndef _di_f_pipe_exists_
-  // returns f_true if the standard input contains piped data.
   f_return_status f_pipe_exists() {
     struct stat st_info;
 
@@ -21,6 +20,54 @@ extern "C" {
   }
 #endif // _di_f_pipe_exists_
 
+#ifndef _di_f_pipe_warning_exists_
+  f_return_status f_pipe_warning_exists() {
+    struct stat st_info;
+
+    if (fstat(fileno(f_pipe_warning), &st_info) != 0) {
+      return f_status_set_error(f_file_stat_error);
+    }
+
+    if (S_ISFIFO(st_info.st_mode)) {
+      return f_true;
+    }
+
+    return f_false;
+  }
+#endif // _di_f_pipe_warning_exists_
+
+#ifndef _di_f_pipe_error_exists_
+  f_return_status f_pipe_error_exists() {
+    struct stat st_info;
+
+    if (fstat(fileno(f_pipe_error), &st_info) != 0) {
+      return f_status_set_error(f_file_stat_error);
+    }
+
+    if (S_ISFIFO(st_info.st_mode)) {
+      return f_true;
+    }
+
+    return f_false;
+  }
+#endif // _di_f_pipe_error_exists_
+
+#ifndef _di_f_pipe_debug_exists_
+  f_return_status f_pipe_debug_exists() {
+    struct stat st_info;
+
+    if (fstat(fileno(f_pipe_debug), &st_info) != 0) {
+      return f_status_set_error(f_file_stat_error);
+    }
+
+    if (S_ISFIFO(st_info.st_mode)) {
+      return f_true;
+    }
+
+    return f_false;
+  }
+#endif // _di_f_pipe_debug_exists_
+
 #ifdef __cplusplus
 } // extern "C"
 #endif
diff --git a/level_0/f_pipe/c/pipe.h b/level_0/f_pipe/c/pipe.h
index 2fb27dd..fcaefc5 100644
--- a/level_0/f_pipe/c/pipe.h
+++ b/level_0/f_pipe/c/pipe.h
@@ -22,17 +22,76 @@
 extern "C" {
 #endif
 
+/**
+ * Default pipe sources.
+ */
 #ifndef _di_f_pipe_
-  #define f_pipe f_standard_input
+  #define f_pipe         f_standard_input
+  #define f_pipe_warning f_standard_warning
+  #define f_pipe_error   f_standard_error
+  #define f_pipe_debug   f_standard_debug
 #endif // _di_f_pipe_
 
+/**
+ * Identify whether or not the default f_pipe source (generally standard input) contains piped data.
+ *
+ * @return
+ *   f_true if there is piped data.
+ *   f_false if there is no piped data.
+ *   f_file_stat_error (with error bit) on stat() error.
+ *
+ * @see stat()
+ */
 #ifndef _di_f_pipe_exists_
-  /**
-   * returns f_true if the standard input contains piped data.
-   */
   extern f_return_status f_pipe_exists();
 #endif // _di_f_pipe_exists_
 
+/**
+ * Identify whether or not the default f_pipe_warning source (generally standard warning) contains piped data.
+ *
+ * For most systems, standard warning does not exist and instead maps to standard output.
+ *
+ * @return
+ *   f_true if there is piped data.
+ *   f_false if there is no piped data.
+ *   f_file_stat_error (with error bit) on stat() error.
+ *
+ * @see stat()
+ */
+#ifndef _di_f_pipe_warning_exists_
+  extern f_return_status f_pipe_warning_exists();
+#endif // _di_f_pipe_warning_exists_
+
+/**
+ * Identify whether or not the default f_pipe_error source (generally standard error) contains piped data.
+ *
+ * @return
+ *   f_true if there is piped data.
+ *   f_false if there is no piped data.
+ *   f_file_stat_error (with error bit) on stat() error.
+ *
+ * @see stat()
+ */
+#ifndef _di_f_pipe_error_exists_
+  extern f_return_status f_pipe_error_exists();
+#endif // _di_f_pipe_error_exists_
+
+/**
+ * Identify whether or not the default f_pipe_debug source (generally standard warning) contains piped data.
+ *
+ * For most systems, standard debug does not exist and instead maps to standard output.
+ *
+ * @return
+ *   f_true if there is piped data.
+ *   f_false if there is no piped data.
+ *   f_file_stat_error (with error bit) on stat() error.
+ *
+ * @see stat()
+ */
+#ifndef _di_f_pipe_debug_exists_
+  extern f_return_status f_pipe_debug_exists();
+#endif // _di_f_pipe_debug_exists_
+
 #ifdef __cplusplus
 } // extern "C"
 #endif
-- 
1.8.3.1