From 6c701b6e9f99c53630a511f4a0a0cd13db8dea80 Mon Sep 17 00:00:00 2001
From: Konstantin <konstantin8105@gmail.com>
Date: Tue, 2 Jan 2018 01:22:17 +0300
Subject: [PATCH] Add implementation for strcat(). Fixes #514 (#516)

---
 darwin/string.go               |  6 ++++++
 noarch/string.go               | 12 +++++++++++-
 program/function_definition.go |  6 ++++++
 tests/string.c                 | 11 ++++++++++-
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/darwin/string.go b/darwin/string.go
index 3f5b980ee..b5eada3fa 100644
--- a/darwin/string.go
+++ b/darwin/string.go
@@ -19,3 +19,9 @@ func BuiltinObjectSize(ptr []byte, theType int) int {
 func BuiltinStrncpy(dest, src []byte, len, size int) []byte {
 	return noarch.Strncpy(dest, src, len)
 }
+
+// BuiltinStrcat is for __builtin___strcat_chk
+// https://opensource.apple.com/source/Libc/Libc-763.12/include/secure/_string.h.auto.html
+func BuiltinStrcat(dest, src []byte, _ int) []byte {
+	return noarch.Strcat(dest, src)
+}
diff --git a/noarch/string.go b/noarch/string.go
index 967841a12..89c73fcc7 100644
--- a/noarch/string.go
+++ b/noarch/string.go
@@ -26,7 +26,7 @@ func Strcpy(dest, src []byte) []byte {
 
 		// We only need to copy until the first NULL byte. Make sure we also
 		// include that NULL byte on the end.
-		if c == 0 {
+		if c == '\x00' {
 			break
 		}
 	}
@@ -59,3 +59,13 @@ func Strncpy(dest, src []byte, len int) []byte {
 
 	return dest
 }
+
+// Strcat - concatenate strings
+// Appends a copy of the source string to the destination string.
+// The terminating null character in destination is overwritten by the first
+// character of source, and a null-character is included at the end
+// of the new string formed by the concatenation of both in destination.
+func Strcat(dest, src []byte) []byte {
+	Strcpy(dest[Strlen(dest):], src)
+	return dest
+}
diff --git a/program/function_definition.go b/program/function_definition.go
index 2e330a149..368fffa7e 100644
--- a/program/function_definition.go
+++ b/program/function_definition.go
@@ -168,6 +168,8 @@ var builtInFunctionDefinitions = []string{
 	"int fsetpos(FILE*, int*) -> noarch.Fsetpos",
 
 	// string.h
+	"char* strcat(char *, const char *) -> noarch.Strcat",
+
 	"char* strcpy(const char*, char*) -> noarch.Strcpy",
 	// should be: "char* strncpy(const char*, char*, size_t) -> noarch.Strncpy",
 	"char* strncpy(const char*, char*, int) -> noarch.Strncpy",
@@ -185,6 +187,10 @@ var builtInFunctionDefinitions = []string{
 	// should be: size_t __builtin_object_size(const void*, int)
 	"int __builtin_object_size(const char*, int) -> darwin.BuiltinObjectSize",
 
+	// see https://opensource.apple.com/source/Libc/Libc-763.12/include/secure/_string.h.auto.html
+	"char* __builtin___strcat_chk(char *, const char *, int) -> darwin.BuiltinStrcat",
+	"char* __inline_strcat_chk(char *, const char *) -> noarch.Strcat",
+
 	// stdlib.h
 	"int abs(int) -> noarch.Abs",
 	"double atof(const char *) -> noarch.Atof",
diff --git a/tests/string.c b/tests/string.c
index c65dfd095..6b0df3241 100644
--- a/tests/string.c
+++ b/tests/string.c
@@ -3,7 +3,7 @@
 
 int main()
 {
-    plan(24);
+    plan(25);
 
     diag("TODO: __builtin_object_size")
     // https://github.com/elliotchance/c2go/issues/359
@@ -81,6 +81,15 @@ int main()
         // is_eq(strlen(NULL), 0);
         is_eq(strlen("fo\0o"), 2);
     }
+	{
+		diag("strcat")
+		char str[80];
+		strcpy (str,"these ");
+		strcat (str,"strings ");
+		strcat (str,"are ");
+		strcat (str,"concatenated.");
+		is_streq(str,"these strings are concatenated.");
+	}
 
     done_testing();
 }