From 5a6b17235a10aea87b3b74122df861536a6efdd2 Mon Sep 17 00:00:00 2001
From: _ov4 <ov4@ov4.org>
Date: Thu, 3 Sep 2026 12:40:05 +0000
Subject: add safe_output: async-signal-safe output

---
 include/util/io.h | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/util/io.h b/include/util/io.h
index aaeac02..4f55fec 100644
--- a/include/util/io.h
+++ b/include/util/io.h
@@ -12,6 +12,7 @@
 #include <iostream>
 #include <vector>
 #include <string>
+#include <type_traits>
 
 #include "global.h"
 
@@ -23,16 +24,80 @@ namespace ov4
 struct LogVoidify { void operator&(std::ostream&) const {} };
 
 inline constexpr int DECIMAL = 10;
-inline constexpr int LENGTH = 32;
+inline constexpr int NUMBER_LENGTH = 70; // even enough for binary
 
+// async-signal-safe
 void safe_print(const char *s, bool ignore_wrap = false);
+
+// async-signal-safe
 void safe_print(int x);
+
+// async-signal-safe
 void safe_debug(const char *s, bool ignore_wrap = false);
+
+// async-signal-safe
 void safe_debug(int x);
+
+// async-signal-safe
 bool isnum(const char *s);
+
+// async-signal-safe
 void reverse(char *str, int length);
+
+// async-signal-safe
 char *itoa(int num, char* str, int base);
 
+// async-signal-safe
+// remove '\n' from the string
+// when replacemen = '\0', '\n' is deleted (instead of really replacing by '\0' )
+void wrap_eliminator(char *s, char replacement = '\0');
+
+// async-signal-safe
+void _write_helper(const char *s);
+
+template <typename T>
+void _safe_output_handler(T x)
+{
+    int errno_old = errno;
+
+    if constexpr (std::is_same_v<T, int>) // int
+    {
+        char buffer[MAXLINE];
+        itoa(x, buffer, DECIMAL);
+        _write_helper(buffer);
+    } 
+    else if constexpr (std::is_same_v<T, char*> || std::is_same_v<T, const char*>) // C-style string
+    {
+        _write_helper(x);
+    }
+    else // ???
+    {
+        static_assert(false, "_safe_output_handler: unsopported type");
+    }
+
+    errno = errno_old;
+}
+
+inline void safe_output()
+{
+    ; // empty
+}
+
+
+// async-signal-safe output function
+// example:
+// safe_output("string", 123, variable);
+template <typename T, typename ...T_arg>
+void safe_output(T x, T_arg ...arg)
+{
+    int errno_old = errno;
+
+    _safe_output_handler(x);
+    safe_output(arg...);
+
+    errno = errno_old;
+}
+
 void usage(void);
 void unix_error(const char *msg);
 void app_error(const char *msg);
-- 
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