OffsetToPtr documentation and test

inc/qcbor/UsefulBuf.h

@@ -1,6 +1,6 @@
 /* =========================================================================
  * Copyright (c) 2016-2018, The Linux Foundation.
- * Copyright (c) 2018-2022, Laurence Lundblade.
+ * Copyright (c) 2018-2024, Laurence Lundblade.
  * Copyright (c) 2021, Arm Limited. All rights reserved.
  * All rights reserved.
  *
@@ -43,6 +43,7 @@
 
  when         who             what, where, why
  --------     ----            --------------------------------------------------
+ 10/05/2024   llundblade      Add Xxx_OffsetToPointer.
  19/12/2022   llundblade      Document that adding empty data is allowed.
  4/11/2022    llundblade      Add GetOutPlace and Advance to UsefulOutBuf.
  9/21/2021    llundbla        Clarify UsefulOutBuf size calculation mode
@@ -647,16 +648,27 @@ size_t UsefulBuf_FindBytes(UsefulBufC BytesToSearch, UsefulBufC BytesToFind);
 
 
 /**
- @brief Convert a pointer to an offset with bounds checking.
-
- @param[in] UB  Pointer to the UsefulInputBuf.
- @param[in] p   Pointer to convert to offset.
-
- @return SIZE_MAX if @c p is out of range, the byte offset if not.
+ * @brief Convert a pointer to an offset with bounds checking.
+ *
+ * @param[in] UB  A UsefulBuf.
+ * @param[in] p   Pointer to convert to offset.
+ *
+ * @return SIZE_MAX if @c p is out of range, the byte offset if not.
 */
 static inline size_t UsefulBuf_PointerToOffset(UsefulBufC UB, const void *p);
 
 
+/**
+ * @brief Convert an offset to a pointer with bounds checking.
+ *
+ * @param[in] UB       A UsefulBuf.
+ * @param[in] uOffset  Offset in @c pUInBuf.
+ *
+ * @return @c NULL if @c uOffset is out of range, a pointer into the buffer if not.
+ */
+static inline const void *UsefulBuf_OffsetToPointer(UsefulBufC UB, size_t uOffset);
+
+
 #ifndef USEFULBUF_DISABLE_DEPRECATED
 /** Deprecated macro; use @ref UsefulBuf_FROM_SZ_LITERAL instead */
 #define SZLiteralToUsefulBufC(szString)  UsefulBuf_FROM_SZ_LITERAL(szString)
@@ -1494,6 +1506,14 @@ static int UsefulInputBuf_BytesAvailable(UsefulInputBuf *pUInBuf, size_t uLen);
 static size_t UsefulInputBuf_PointerToOffset(UsefulInputBuf *pUInBuf, const void *p);
 
 
+/**
+ * @brief Convert an offset to a pointer with bounds checking.
+ *
+ * @param[in] pUInBuf  Pointer to the @ref UsefulInputBuf.
+ * @param[in] uOffset  Offset in @c pUInBuf.
+ *
+ * @return @c NULL if @c uOffset is out of range, a pointer into the buffer if not.
+ */
 static const void *UsefulInputBuf_OffsetToPointer(UsefulInputBuf *pUInBuf, size_t uOffset);
 
 
@@ -1860,6 +1880,18 @@ static inline size_t UsefulBuf_PointerToOffset(UsefulBufC UB, const void *p)
 }
 
 
+static inline const void *UsefulBuf_OffsetToPointer(UsefulBufC UB, size_t uOffset)
+{
+   if(UsefulBuf_IsNULLC(UB) || uOffset >= UB.len) {
+      return NULL;
+   }
+
+   return (const uint8_t *)UB.ptr + uOffset;
+}
+
+
+
+
 #ifndef USEFULBUF_DISABLE_ALL_FLOAT
 static inline uint32_t UsefulBufUtil_CopyFloatToUint32(float f)
 {
@@ -2266,22 +2298,10 @@ static inline size_t UsefulInputBuf_PointerToOffset(UsefulInputBuf *pUInBuf, con
 }
 
 
-// TODO: move and test this
-static inline const void *UsefulBuf_OffsetToPointer(UsefulBufC UB, size_t uOffset)
-{
-   if(uOffset > UB.len) {
-      return NULL;
-   }
-
-   return (const uint8_t *)UB.ptr + uOffset;
-}
-
-
 static inline const void *UsefulInputBuf_OffsetToPointer(UsefulInputBuf *pUInBuf, size_t uOffset)
-{
-   return UsefulBuf_OffsetToPointer(pUInBuf->UB, uOffset);
-}
-
+ {
+    return UsefulBuf_OffsetToPointer(pUInBuf->UB, uOffset);
+ }
 
 
 static inline UsefulBufC UsefulInputBuf_GetUsefulBuf(UsefulInputBuf *pMe, size_t uNum)

test/UsefulBuf_Tests.c

@@ -673,6 +673,22 @@ const char *UBUtilTests(void)
       return "Incorrect pointer offset for start";
    }
 
+   if(UsefulBuf_OffsetToPointer(Boo, 0) != &pB[0]) {
+      return "Wrong OffsetToPointer";
+   }
+
+   if(UsefulBuf_OffsetToPointer(Boo, 3) != NULL) {
+      return "Didn't validate offset correctly";
+   }
+
+   if(UsefulBuf_OffsetToPointer(Boo, 2) != &pB[2]) {
+      return "Wrong OffsetToPointer 2";
+   }
+
+   if(UsefulBuf_OffsetToPointer(NULLUsefulBufC, 2) != NULL) {
+      return "Failed OffsetToPtr on NULLUsefulBufC";
+   }
+
    return NULL;
 }
 
@@ -800,6 +816,20 @@ const char *  UIBTest_IntegerFormat(void)
       return "PointerToOffset not working";
    }
 
+
+   const uint8_t pB[] = {0x01, 0x02, 0x03};
+   UsefulBufC Boo = UsefulBuf_FROM_BYTE_ARRAY_LITERAL(pB);
+
+   UsefulInputBuf_Init(&UIB, Boo);
+
+   if(UsefulInputBuf_OffsetToPointer(&UIB, 0) != &pB[0]) {
+      return "OffsetToPointer fail";
+   }
+
+   if(UsefulInputBuf_OffsetToPointer(&UIB, SIZE_MAX) != NULL) {
+      return "OffsetToPointer SIZE_MAX fail";
+   }
+
    return NULL;
 }