stdlib: Add strlcat

Adds strlcat which can be used to safely concatenate strings

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>

Author: JPEWdev

Makefile.in

@@ -104,7 +104,7 @@ PROGOBJ = $(NASM) $(NDISASM)
 PROGS   = nasm$(X) ndisasm$(X)
 
 LIBOBJ_NW = stdlib/snprintf.$(O) stdlib/vsnprintf.$(O) stdlib/strlcpy.$(O) \
-	stdlib/strnlen.$(O) stdlib/strrchrnul.$(O) \
+	stdlib/strnlen.$(O) stdlib/strrchrnul.$(O) stdlib/strlcat.$(O) \
 	\
 	nasmlib/ver.$(O) \
 	nasmlib/alloc.$(O) nasmlib/asprintf.$(O) nasmlib/errfile.$(O) \

configure.ac

@@ -234,6 +234,7 @@ PA_FUNC_SNPRINTF
 PA_FUNC_VSNPRINTF
 AC_CHECK_FUNCS([strlcpy])
 AC_CHECK_FUNCS([strrchrnul])
+AC_CHECK_FUNCS([strlcat])
 
 dnl These types are POSIX-specific, and Windows does it differently...
 AC_CHECK_TYPES([struct _stati64])
@@ -253,6 +254,7 @@ AC_CHECK_DECLS(strsep)
 AC_CHECK_DECLS(strlcpy)
 AC_CHECK_DECLS(strnlen)
 AC_CHECK_DECLS(strrchrnul)
+AC_CHECK_DECLS(strlcat)
 
 dnl Check for missing types
 AC_TYPE_UINTPTR_T

include/compiler.h

@@ -169,6 +169,10 @@ size_t strlcpy(char *, const char *, size_t);
 char *strrchrnul(const char *, int);
 #endif
 
+#if !defined(HAVE_STRLCAT) || !HAVE_DECL_STRLCAT
+size_t strlcat(char *, const char *, size_t);
+#endif
+
 #ifndef __cplusplus		/* C++ has false, true, bool as keywords */
 # ifdef HAVE_STDBOOL_H
 #  include <stdbool.h>

stdlib/strlcat.c

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2019 Garmin Ltd. or its subsidiaries
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "compiler.h"
+
+/*
+ * Concatenate src string to dest of size size. The destination buffer will
+ * have no more than size-1 character when the operation finishes. Always NUL
+ * terminates, unless size == 0 or dest has no NUL terminator. Returns
+ * strlen(initial dest) + strlen(src); if retval >= size, truncation occurred.
+ */
+#ifndef HAVE_STRLCAT
+
+size_t strlcat(char *dest, const char *src, size_t size)
+{
+    size_t n;
+
+    /* find the NULL terminator in dest */
+    for (n = 0; i < size && dest[n] != '\0'; n++)
+        ;
+
+    /* destination was not NULL terminated. Return the initial size */
+    if (n == size)
+        return size;
+
+    return strlcpy(&dest[n], src, size - n) + n;
+}
+
+#endif
+