From c8479ceff6aea37def538c902324c68930947f21 Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Sun, 18 Oct 2026 09:42:45 +0000
Subject: add self pipe, and non-block-input

---
 include/error.h                |  3 +++
 include/pipe.h                 |  9 ++++++++
 include/util/non_block_input.h |  8 +++++++
 src/self_pipe.cc               | 21 ++++++++++++++++++
 src/util/non_block_io.cc       | 49 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 90 insertions(+)
 create mode 100644 include/pipe.h
 create mode 100644 include/util/non_block_input.h
 create mode 100644 src/self_pipe.cc
 create mode 100644 src/util/non_block_io.cc

diff --git a/include/error.h b/include/error.h
index 50ca23e..ec0bffe 100644
--- a/include/error.h
+++ b/include/error.h
@@ -26,6 +26,9 @@ enum class error_code
     FILE_OFLAG_ERROR,
     FILE_POINTER_FAIL_TO_OPEN,
 
+    // pipe
+    FAIL_TO_OPEN_PIPE,
+
 };
 
 class T_error : public std::runtime_error {
diff --git a/include/pipe.h b/include/pipe.h
new file mode 100644
index 0000000..e7d7b67
--- /dev/null
+++ b/include/pipe.h
@@ -0,0 +1,9 @@
+#pragma once
+
+
+namespace ov4
+{
+
+inline int self_pipe_fd[2] = {-1, -1};
+
+}
\ No newline at end of file
diff --git a/include/util/non_block_input.h b/include/util/non_block_input.h
new file mode 100644
index 0000000..f5937a7
--- /dev/null
+++ b/include/util/non_block_input.h
@@ -0,0 +1,8 @@
+#pragma once
+
+namespace pv4
+{
+
+int non_block_read_char(char *c, int *src = nullptr);
+
+}
\ No newline at end of file
diff --git a/src/self_pipe.cc b/src/self_pipe.cc
new file mode 100644
index 0000000..42e61d8
--- /dev/null
+++ b/src/self_pipe.cc
@@ -0,0 +1,21 @@
+#include "pipe.h"
+
+#include <unistd.h>
+#include <cstdlib>
+#include <fcntl.h>
+
+#include "error.h"
+
+namespace ov4
+{
+
+void self_pipe_init()
+{
+    int ret = pipe2(self_pipe_fd, O_NONBLOCK);
+    if (ret != 0)
+    {
+        throw T_error(error_code::FAIL_TO_OPEN_PIPE, "Fail to open self pipe");
+    }
+}
+
+}
\ No newline at end of file
diff --git a/src/util/non_block_io.cc b/src/util/non_block_io.cc
new file mode 100644
index 0000000..31edbc9
--- /dev/null
+++ b/src/util/non_block_io.cc
@@ -0,0 +1,49 @@
+#include "util/non_block_input.h"
+
+#include <unistd.h>
+#include <sys/select.h>
+
+#include "pipe.h"
+
+using namespace std;
+
+namespace ov4
+{
+
+
+/*
+ * read from both stdin, and self pipe
+ * returns immediately as soon as stdin or pipe is "readable"
+ * returns read()'s ret value
+ * and set src to the the read source (stdin or pipe)
+ */
+int non_block_read_char(char *c, int *src)
+{
+    // get fd check range
+    int max_fd;
+    if (STDIN_FILENO > self_pipe_fd[0]) max_fd = STDIN_FILENO;
+    else max_fd = self_pipe_fd[0];
+
+    // monitor STDIN, and self pipe
+    fd_set rset;
+    FD_ZERO(&rset);
+    FD_SET(STDIN_FILENO, &rset);
+    FD_SET(self_pipe_fd[0], &rset);
+
+    select(max_fd+1, &rset, nullptr, nullptr, nullptr);
+
+    int ret = -1;
+    if (FD_ISSET(self_pipe_fd[0], &rset))
+    {
+        ret = read(self_pipe_fd[0], c, 1);
+        if (src != nullptr) *src = self_pipe_fd[0];
+    }
+    else if (FD_ISSET(STDIN_FILENO, &rset))
+    {
+        ret = read(STDIN_FILENO, c, 1);
+        if (src != nullptr) *src = self_pipe_fd[0];
+    }
+    return ret;
+} 
+
+}
\ No newline at end of file
-- 
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