From a01af4cb4991f6d5f0320f03d1f1d918df07caec Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@posteo.net>
Date: Sat, 11 May 2024 17:51:38 +0200
Subject: [PATCH] Wrapper targets: Add endpoints for -Wl,wrap=...

This adds aliases needed to wrap printf() and friends.
---
 printf.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

diff --git a/printf.c b/printf.c
index edf41d1..e00c3e5 100644
--- a/printf.c
+++ b/printf.c
@@ -32,6 +32,9 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
 
 #include "printf.h"
 #include "stdio_base.h"
@@ -920,3 +923,99 @@ static void _putchar(char character)
 {
   stdio_write(&character, sizeof(character));
 }
+
+
+/* provide entry points for linker to redirect stdio */
+__attribute__((alias("printf_")))
+int __wrap_printf(const char* format, ...);
+
+
+__attribute__((alias("sprintf_")))
+int __wrap_sprintf(char* buffer, const char* format, ...);
+
+
+__attribute__((alias("snprintf_")))
+int __wrap_snprintf(char* buffer, size_t count, const char* format, ...);
+
+
+__attribute__((alias("vprintf_")))
+int __wrap_vprintf(const char* format, va_list va);
+
+
+__attribute__((alias("vsnprintf_")))
+int __wrap_vsnprintf(char* buffer, size_t count, const char* format, va_list va);
+
+
+int __wrap_putchar(int c)
+{
+  _putchar((char)c);
+  return 1;
+}
+
+
+int __wrap_putc(int c, FILE *stream)
+{
+  (void)stream;
+  _putchar((char)c);
+  return 1;
+}
+
+
+__attribute__((alias("__wrap_putc")))
+int __wrap_fputc(int c, FILE *stream);
+
+
+int __wrap_puts(const char *s)
+{
+  size_t len = strlen(s);
+  stdio_write(s, len);
+  stdio_write("\n", 1);
+  return len + 1;
+}
+
+
+int __wrap_vfprintf(FILE *stream, const char *format, va_list va)
+{
+  if (stream != stdout) {
+    return 0;
+  }
+
+  return vprintf_(format, va);
+}
+
+
+int __wrap_fprintf(FILE *stream, const char *format, ...)
+{
+  va_list va;
+  va_start(va, format);
+  int result = __wrap_vfprintf(stream, format, va);
+  va_end(va);
+  return result;
+}
+
+
+int __wrap_vdprintf(int fd, const char *format, va_list va)
+{
+  if (fd != STDOUT_FILENO) {
+    return 0;
+  }
+
+  return vprintf_(format, va);
+}
+
+
+int __wrap_vsprintf(char* buffer, const char* format, va_list va)
+{
+  return __wrap_vsnprintf(buffer, (size_t)-1, format, va);
+}
+
+
+int __wrap_dprintf(int fd, const char *format, ...)
+{
+  va_list va;
+  va_start(va, format);
+  int result = __wrap_vdprintf(fd, format, va);
+  va_end(va);
+  return result;
+  
+}
-- 
2.43.0