Refactored memcopy range check.

bacnet-stack/include/memcopy.h

@@ -33,14 +33,16 @@
 extern "C" {
 #endif /* __cplusplus */
 
-/* copy len bytes from src to offset of dest if there is enough space. */
+    bool memcopylen(
-/* returns 0 if there is not enough space, or the number of bytes copied. */
+        size_t offset,
+        size_t max,
+        size_t len);
     size_t memcopy(
         void *dest,
         void *src,
-        size_t offset,  /* where in dest to put the data */
+        size_t offset,
-        size_t len,     /* amount of data to copy */
+        size_t len,
-        size_t max);    /* total size of destination */
+        size_t max);
 
 #ifdef __cplusplus
 }

bacnet-stack/src/memcopy.c

@@ -1,44 +1,118 @@
-/*####COPYRIGHTBEGIN####
+/**
- -------------------------------------------
+* @file
- Copyright (C) 2008 Steve Karg
+* @author Steve Karg
-
+* @date 2008
- This program is free software; you can redistribute it and/or
+* @section LICENSE
- modify it under the terms of the GNU General Public License
+*
- as published by the Free Software Foundation; either version 2
+* This program is free software; you can redistribute it and/or
- of the License, or (at your option) any later version.
+* modify it under the terms of the GNU General Public License
-
+* as published by the Free Software Foundation; either version 2
- This program is distributed in the hope that it will be useful,
+* of the License, or (at your option) any later version.
- but WITHOUT ANY WARRANTY; without even the implied warranty of
+*
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* This program is distributed in the hope that it will be useful,
- GNU General Public License for more details.
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
-
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- You should have received a copy of the GNU General Public License
+* GNU General Public License for more details.
- along with this program; if not, write to:
+*
- The Free Software Foundation, Inc.
+* You should have received a copy of the GNU General Public License
- 59 Temple Place - Suite 330
+* along with this program; if not, write to:
- Boston, MA  02111-1307, USA.
+* The Free Software Foundation, Inc.
-
+* 59 Temple Place - Suite 330
- As a special exception, if other files instantiate templates or
+* Boston, MA  02111-1307
- use macros or inline functions from this file, or you compile
+* USA.
- this file and link it with other works to produce a work based
+*
- on this file, this file does not by itself cause the resulting
+* As a special exception, if other files instantiate templates or
- work to be covered by the GNU General Public License. However
+* use macros or inline functions from this file, or you compile
- the source code for this file must still be made available in
+* this file and link it with other works to produce a work based
- accordance with section (3) of the GNU General Public License.
+* on this file, this file does not by itself cause the resulting
-
+* work to be covered by the GNU General Public License. However
- This exception does not invalidate any other reasons why a work
+* the source code for this file must still be made available in
- based on this file might be covered by the GNU General Public
+* accordance with section (3) of the GNU General Public License.
- License.
+*
- -------------------------------------------
+* This exception does not invalidate any other reasons why a work
-####COPYRIGHTEND####*/
+* based on this file might be covered by the GNU General Public
+* License.
+*
+* @section DESCRIPTION
+*
+* Memory copy functions for deeply embedded system.  The functions
+* are used with a buffer, the buffer offset, the sizeof the buffer,
+* and the number of bytes to copy to the buffer.
+*/
 #include <stddef.h>
 #include "memcopy.h"
 #include <string.h>
 
-/** @file memcopy.c  Custom memcopy function */
+/**
+* Tests to see if the number of bytes is available from an offset
+* given the maximum sizeof a buffer.
+*
+* @param offset - offset into a buffer
+* @param max - maximum sizeof a buffer
+* @param len - number of bytes to add to the buffer starting at offset.
+*
+* @return True if there is enough space to copy len bytes.
+*/
+bool memcopylen(
+    size_t offset,
+    size_t max,
+    size_t len) 
+{
+    return ((offset + len) <= max);
+}
 
-/* copy len bytes from src to offset of dest if there is enough space. */
+#if defined (MEMCOPY_SIMPLE)
-/* returns 0 if there is not enough space, or the number of bytes copied. */
+/**
+* Copy len bytes from src to offset of dest if there is enough space
+* in a buffer of max bytes.
+*
+* @param dest - pointer to the destination buffer
+* @param src - pointer to the source buffer
+* @param offset - offset into the destination buffer
+* @param max - maximum sizeof the destination buffer
+* @param len - number of bytes to add to the destination buffer
+* starting at offset.
+*
+* @return returns zero if there is not enough space, or returns
+* the number of bytes copied.
+*/
+size_t memcopy(
+    void *dest,
+    void *src,
+    size_t offset,
+    size_t len,
+    size_t max)
+{
+    size_t i;
+    size_t copy_len = 0;
+    char *s1, *s2;
+
+    s1 = dest;
+    s2 = src;
+    if (memcopylen(offset, max, len)) {
+        for (i = 0; i < len; i++) {
+            s1[offset + i] = s2[i];
+            copy_len++;
+        }
+    }
+
+    return copy_len;
+}
+#else
+/**
+* Copy len bytes from src to offset of dest if there is enough space
+* in a buffer of max bytes.
+*
+* @param dest - pointer to the destination buffer
+* @param src - pointer to the source buffer
+* @param offset - offset into the destination buffer
+* @param max - maximum sizeof the destination buffer
+* @param len - number of bytes to add to the destination buffer
+* starting at offset.
+*
+* @return returns zero if there is not enough space, or returns
+* the number of bytes copied.
+*/
 size_t memcopy(
     void *dest,
     void *src,
@@ -46,23 +120,14 @@ size_t memcopy(
     size_t len, /* amount of data to copy */
     size_t max)
 {       /* total size of destination */
-/*    size_t i; */
+    if (memcopylen(offset, max, len)) {
-/*    size_t copy_len = 0; */
-/*    char *s1, *s2; */
-
-/*    s1 = dest; */
-/*    s2 = src; */
-    if (len <= (max - offset)) {
         memcpy(&((char *) dest)[offset], src, len);
         return (len);
-/*        for (i = 0; i < len; i++) { */
-/*            s1[offset + i] = s2[i]; */
-/*            copy_len++; */
-/*        } */
     }
 
     return 0;
 }
+#endif
 
 #ifdef TEST
 #include <assert.h>